WO2021085066A1 - Motor drive device and refrigerator using same - Google Patents

Motor drive device and refrigerator using same Download PDF

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Publication number
WO2021085066A1
WO2021085066A1 PCT/JP2020/038070 JP2020038070W WO2021085066A1 WO 2021085066 A1 WO2021085066 A1 WO 2021085066A1 JP 2020038070 W JP2020038070 W JP 2020038070W WO 2021085066 A1 WO2021085066 A1 WO 2021085066A1
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WO
WIPO (PCT)
Prior art keywords
dead center
compressor
bottom dead
motor
piston
Prior art date
Application number
PCT/JP2020/038070
Other languages
French (fr)
Japanese (ja)
Inventor
義典 竹岡
堀尾　好正
Original Assignee
パナソニックＩｐマネジメント株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
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Application filed by パナソニックＩｐマネジメント株式会社 filed Critical パナソニックＩｐマネジメント株式会社
Priority to JP2021554256A priority Critical patent/JPWO2021085066A1/ja
Priority to CN202080053325.XA priority patent/CN114175494A/en
Publication of WO2021085066A1 publication Critical patent/WO2021085066A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/20—Arrangements for starting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B35/00—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for
    • F04B35/04—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for the means being electric
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/02—Stopping, starting, unloading or idling control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D11/00—Self-contained movable devices, e.g. domestic refrigerators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/04—Arrangements or methods for the control of AC motors characterised by a control method other than vector control specially adapted for damping motor oscillations, e.g. for reducing hunting

Definitions

  • the present disclosure relates to a motor drive device for driving a brushless DC motor of a compressor and a refrigerator using the motor drive device.
  • Patent Document 1 discloses a motor drive device for a refrigerator that drives a brushless DC motor of a conventional compressor.
  • Refrigerators such as refrigerators equipped with a compressor driven by a motor drive device divide the refrigeration cycle into a high-pressure side and a low-pressure side in a cycle when the cooling operation is stopped to prevent the inflow of refrigerant and save energy. I'm trying.
  • the position of the piston of the compressor before starting is set to the upper dead center between the top dead center and the bottom dead center (in a predetermined position, above). Move to the position closest to the top dead center, which is not the dead center). Then, the motor drive device is started from the position next to the top dead center.
  • the piston of the compressor is greatly accelerated, energy is stored, the compression step is overcome, and the compressor is started.
  • FIG. 6 is a block diagram of the conventional motor drive device described in Patent Document 1.
  • the conventional motor drive device includes a brushless DC motor 201, a compressor 203, a control unit 204, an inverter 205, and the like.
  • the compressor 203 has a brushless DC motor 201 and a piston 202 connected to the rotor of the brushless DC motor 201.
  • the control unit 204 has an initial alignment step of moving the motor to the bottom dead center, a forced alignment step of moving the starting position next to the top dead center in the suction step, an acceleration step of accelerating the rotor of the brushless DC motor 201, and the like. Including the control operation of.
  • the inverter 205 supplies electric power to the brushless DC motor 201 based on the drive signal from the control unit 204.
  • the control unit 204 sends a signal to the inverter 205 in which the piston 202 is in phase at the bottom dead center in the initial alignment stage. Then, the inverter 205 causes a current to flow through the stator of the brushless DC motor 201 to rotate the rotor of the brushless DC motor 201. As a result, the piston 202 moves to the bottom dead center.
  • control unit 204 sends a signal to the inverter 205 that sequentially switches from the phase of the bottom dead center of the piston 202 in the reverse direction. As a result, the position of the piston 202 is moved to the position next to the top dead center on the suction step side.
  • the control unit 204 starts the brushless DC motor 201 in the acceleration stage and sends a signal for accelerating to the inverter 205.
  • the brushless DC motor 201 rotates. That is, since the piston 202 is accelerated from the vicinity of top dead center, the speed in the compression step increases. As a result, the compression step can be overcome and the motor drive device for driving the compressor can be easily started.
  • the present disclosure provides a motor drive device that is inexpensive and can be stably started while suppressing vibration even in a compressor having a large fluctuation in load torque, which has a difference between suction pressure and discharge pressure.
  • the motor drive device of the present disclosure includes a compressor and a brushless DC motor as a drive source for the compressor to perform a compression operation.
  • the motor drive device is configured to determine the starting torque and rotation start position of the brushless DC motor so that the vibration at the start of operation of the compressor and the vibration due to the decrease in load torque cancel each other out.
  • the motor drive device of the present disclosure is configured to cancel the peak of the vibration amplitude generated at the start of operation and the peak of the vibration amplitude generated by sudden acceleration due to a decrease in load torque. Therefore, the peaks of the vibration amplitudes are canceled out and become smaller than the case where the peaks of the respective vibration amplitudes are generated independently. As a result, a motor drive device capable of stably starting the compressor at low cost by suppressing vibration generated from the compressor to a small extent is provided.
  • FIG. 1 is a block diagram of a motor drive device according to an embodiment.
  • FIG. 2A is a schematic diagram showing the relationship with the rotor at the bottom dead center of the piston of the compressor as the driven body in the same embodiment.
  • FIG. 2B is a schematic diagram showing the relationship between the piston and the rotor in a state where the piston of the compressor as the driven body is rotated 90 degrees in the normal rotation direction from the bottom dead center in the same embodiment.
  • FIG. 2C is a schematic diagram showing the relationship with the rotor at the top dead center of the piston of the compressor as the driven body in the same embodiment.
  • FIG. 2A is a schematic diagram showing the relationship with the rotor at the bottom dead center of the piston of the compressor as the driven body in the same embodiment.
  • FIG. 2B is a schematic diagram showing the relationship between the piston and the rotor in a state where the piston of the compressor as the driven body is rotated 90 degrees in the normal rotation direction from the bottom dead center in the same embodiment.
  • FIG. 2C
  • FIG. 2D is a schematic diagram showing the relationship between the piston and the rotor in a state where the piston of the compressor as the driven body is rotated 90 degrees in the normal rotation direction from the top dead center in the same embodiment.
  • FIG. 3A is a waveform diagram showing the vibration of the compressor as the driven body generated at the start of operation in the same embodiment.
  • FIG. 3B is a waveform diagram showing vibration of the compressor as a driven body generated when the compression step is first overcome from the start of operation in the same embodiment.
  • FIG. 3C is a waveform diagram showing the vibration of the compressor as the driven body, which is a combination of the vibration at the start of operation and the vibration when the compression step is overcome in the same embodiment.
  • FIG. 3A is a waveform diagram showing the vibration of the compressor as the driven body generated at the start of operation in the same embodiment.
  • FIG. 3B is a waveform diagram showing vibration of the compressor as a driven body generated when the compression step is first overcome from the start of operation in the same embodiment.
  • FIG. 4A shows the vibration of the compressor as the driven body generated at the start of operation when the time to reach the top dead center in the same embodiment is out of phase by 30 degrees from the vibration cycle at the start of operation. It is a waveform diagram.
  • FIG. 4B shows a driven drive generated when the compression step is first overcome from the start of operation when the time to reach top dead center in the same embodiment is out of phase by 30 degrees from the vibration cycle at the start of operation. It is a waveform diagram which shows the vibration of a compressor as a body.
  • FIG. 4C shows compression as a driven body at the start of operation and when the compression step is overcome when the time to reach top dead center in the same embodiment is out of phase by 30 degrees from the vibration cycle at the start of operation. It is a waveform diagram which shows the synthetic vibration generated in the machine.
  • FIG. 5 is a flowchart in which the bottom dead center search unit in the same embodiment searches for the bottom dead center.
  • FIG. 6 is a block diagram of a conventional motor drive device.
  • the present disclosure provides a motor drive device that can start stably while suppressing vibration even in a compressor having a large fluctuation in load torque.
  • FIG. 1 is a block diagram of the motor drive device 30 according to the present embodiment.
  • 2A to 2D are schematic views showing the positional relationship between the piston 17b of the compressor 17, which is the driven body of the same embodiment, and the rotor 5a.
  • the motor drive device 30 of the present embodiment is connected to the AC power supply 1 and drives the brushless DC motor 5.
  • the rotor 5a of the brushless DC motor 5 constitutes a reciprocating compressor 17 with a crankshaft 17a, a piston 17b, a cylinder 17c, and the like.
  • the compressor 17 is mounted on the refrigerator 22 and constitutes a part of the refrigeration cycle.
  • the AC power supply 1 is a general commercial power supply, and in Japan, it is a 50 Hz or 60 Hz power supply with an effective value of 100 V.
  • the motor drive device 30 of the present embodiment has a rectifier circuit 2, a smoothing unit 3, an inverter 4, a position detection unit 6, a speed detection unit 7, a voltage detection unit 8, a drive unit 9, and an output determination. It is composed of a unit 10, a bottom dead center search unit 11, a torque determination unit 12, and the like.
  • the rectifier circuit 2 takes the AC power supply 1 as an input and rectifies the input AC power into DC power.
  • the rectifier circuit 2 is composed of four bridge-connected rectifier diodes 2a, 2b, 2c, and 2d.
  • the smoothing unit 3 is connected to the output side of the rectifier circuit 2 and smoothes the output of the rectifier circuit 2.
  • the smoothing portion 3 is composed of a smoothing capacitor 3e, a reactor 3f, and the like.
  • the output from the smoothing unit 3 is input to the inverter 4.
  • the reactor 3f is inserted between the AC power supply 1 and the smoothing capacitor 3e, it may be provided before or after the rectifying diodes 2a to 2d. Further, when the common mode filter constituting the high frequency removing section is provided in the circuit, it is desirable that the reactor 3f is configured in consideration of the combined component with the reactance component of the high frequency removing section.
  • the inverter 4 sequentially switches the DC power containing a large ripple component to the voltage input from the smoothing unit 3 at a cycle twice the power supply cycle of the AC power supply 1 and converts it into three-phase AC power.
  • the inverter 4 is composed of six switching elements 4a, 4b, 4c, 4d, 4e, and 4f connected by a three-phase bridge. At this time, six recirculation current diodes 4g, 4h, 4i, 4j, 4k, and 4l are connected to the respective switching elements 4a to 4f in opposite directions.
  • the brushless DC motor 5 is composed of a rotor 5a having a permanent magnet, a stator 5b having a three-phase winding, and the like. Then, the three-phase alternating current generated by the inverter 4 is supplied to the three-phase winding of the stator 5b of the brushless DC motor 5. As a result, the rotor 5a of the brushless DC motor 5 rotates.
  • the position detection unit 6 determines the magnetic pole position of the stator 5b of the brushless DC motor 5 from the induced voltage generated in the three-phase winding of the stator 5b, the current flowing in the three-phase winding of the stator 5b, the applied voltage, and the like. Is detected.
  • the position detection unit 6 acquires the terminal voltage of the brushless DC motor 5 and detects the relative position of the magnetic poles of the rotor 5a of the brushless DC motor 5. Specifically, the position detection unit 6 detects the relative rotation position of the rotor 5a based on the induced voltage generated in the three-phase winding of the stator 5b. Further, the position detection unit 6 compares the induced voltage with the reference voltage and detects the zero cross.
  • the voltage that serves as a reference for zero crossing of the induced voltage may be a voltage at the virtual midpoint created from the terminal voltages for three phases and used as the voltage. Further, the DC bus voltage may be acquired and the voltage may be used as a reference voltage for zero crossing of the induced voltage. In the present embodiment, the voltage at the virtual midpoint is used as a reference voltage for zero crossing of the induced voltage.
  • the position detection unit 6 describes a method of detecting the relative position of the magnetic poles of the stator 5b of the brushless DC motor 5 by an induced voltage as an example, but the present invention is not limited to this.
  • the relative position of the magnetic poles may be detected from the current flowing through the brushless DC motor 5.
  • the voltage generated in the shunt resistance arranged on the DC bus of the inverter 4 is detected, the current flowing through the DC bus is calculated from the resistance value of the shunt resistance, and each phase is further measured from the energized state of the motor.
  • a method of separating and detecting the current flowing through the inverter may also be used.
  • a method of individually detecting the current of each of the three phases by arranging a sensor, a shunt resistor, or the like may be used.
  • the method of detecting from the current value of the DC bus has an inexpensive configuration, but the waveform may be distorted in order to separate the currents of each phase. Therefore, when detecting the relative position of the magnetic poles of the rotor 5a, the method of detecting by the induced voltage is more preferable than the method of estimating the position from the current. This is because the method of detecting from the induced voltage requires a small amount of calculation, is simple in configuration, and can be realized at a lower cost. Further, the method of detecting the current of each of the three phases individually has many circuit parts and the cost is high, and the method of detecting the induced voltage can be configured at a lower cost.
  • the speed detection unit 7 calculates the current drive speed of the brushless DC motor 5 from the position information of the magnetic poles detected by the position detection unit 6. Specifically, in the present embodiment, the speed detection unit 7 measures the time from the detection of the zero cross of the induced voltage, and calculates the current speed from the measured time. As a result, the speed detection unit 7 calculates the drive speed of the brushless DC motor 5.
  • the voltage detection unit 8 detects the voltage between the DC bus of the inverter 4. Generally, first, the voltage between the DC buses of the inverter 4 is divided by a resistor, and the detected voltage is divided into a voltage within a range that can be handled by the microcomputer, which is about 140 V to 5 V or less. Then, from the voltage detected by the voltage division, the microcomputer back-calculates and calculates the voltage between the original DC bus. In this embodiment, for example, a value obtained by dividing the voltage by 1/100 is used.
  • the bottom dead center search unit 11 drives the brushless DC motor 5 when the target speed input from the outside changes from 0 (zero) to a value other than 0 (zero), and under the piston 17b of the compressor 17. Search for the dead center. Specifically, the bottom dead center search unit 11 outputs a drive waveform of a predetermined pattern to the brushless DC motor 5 in order to search for the bottom dead center, and moves the piston 17b to the vicinity of the bottom dead center. That is, the energization pattern corresponding to the bottom dead center is output to the brushless DC motor 5 to move the piston 17b to the bottom dead center.
  • the bottom dead center search unit 11 outputs a pattern for moving the piston 17b to the position where the start is started to the brushless DC motor 5.
  • the start-up start position is set as the bottom dead center, it is not necessary to particularly provide a step of moving the piston 17b to the start-up position after the bottom dead center is moved.
  • the bottom dead center search unit 11 stops the output to the brushless DC motor 5 until the target speed changes from 0 (zero) to a value other than 0 (zero).
  • the torque determination unit 12 When the target speed input from the outside changes from 0 (zero) to other than 0 (zero), the torque determination unit 12 first uses the bottom dead center search unit 11 to find the bottom dead center of the piston 17b of the compressor 17. Outputs the torque required when searching for. The movement in the bottom dead center direction is hardly affected by the load condition because the piston 17b does not perform the compression work. Therefore, the torque required for movement in the bottom dead center direction is smaller than the torque at the start of operation and is a constant torque. Finally, when the piston 17b is moved to the bottom dead center, the torque determination unit 12 outputs the torque to the brushless DC motor 5 so that the torque is larger than that for searching for the bottom dead center.
  • the torque determination unit 12 outputs the torque required for that period to the brushless DC motor 5 if there is time to move the piston 17b of the compressor 17 to the starting position after the bottom dead center search. That is, in the present embodiment, the motor drive device 30 controls the piston 17b to start from the bottom dead center. Therefore, the torque determination unit 12 determines the torque (corresponding to the starting torque) required for starting the operation from the bottom dead center when the output time to the bottom dead center ends. At this time, the torque determining unit 12 starts the piston 17b from the bottom dead center and outputs the torque determined so that the time until reaching the top dead center coincides with the period of vibration generated at the time of starting.
  • the torque determination unit 12 also determines the torque for performing normal operation after the time when the output from the bottom dead center search unit 11 is stopped has elapsed. At that time, the torque is determined by comparing the current speed of the brushless DC motor 5 input from the speed detection unit 7 with the target speed input from the outside. That is, if the current speed is insufficient with respect to the target speed, the output torque is increased. On the other hand, if the current speed is higher than the target speed, the output torque is reduced. As a result, the speed of the brushless DC motor 5 is brought to the target speed.
  • the output determination unit 10 determines the applied voltage from the torque determined by the torque determination unit 12 from the torque constant, the induced voltage constant, the resistance value, and the like of the brushless DC motor 5. Then, the output determination unit 10 calculates the PWM duty width for driving the inverter 4 based on the determined applied voltage and the voltage between the DC buses detected by the voltage detection unit 8.
  • phase of the three-phase brushless DC motor 5 is energized by the output determination unit 10 based on the information from the position detection unit 6 and the speed detection unit 7 or the output from the bottom dead center search unit 11.
  • the output determination unit 10 determines the phase to be energized by using the signal input from the bottom dead center search unit 11.
  • the output determination unit 10 determines the signal to be output based on the position information of the position detection unit 6 and the speed information of the speed detection unit 7.
  • the drive waveform for driving the brushless DC motor 5 includes, for example, a rectangular wave and a sine wave, but is not particularly limited.
  • a square wave since it has a simple configuration and simple calculation, it can be handled by an inexpensive microcomputer. Therefore, the output determination unit 10 can be realized at low cost.
  • the brushless DC motor 5 is driven by adopting a rectangular wave drive that can be realized at a lower cost.
  • the motor drive device 30 is driven by a rectangular wave energized at 120 degrees. Therefore, the switching elements 4a, 4c, and 4e of the upper arm of the inverter 4 are energized with a drive waveform shifted by 120 degrees, respectively. Similarly, the switching elements 4b, 4d, and 4f of the lower arm of the inverter 4 are also energized with a drive waveform shifted by 120 degrees, respectively. As a result, the switching elements 4a and 4b, 4c and 4d, and 4e and 4f each have an off period of 60 degrees between the energization periods of each other.
  • the drive unit 9 transmits a drive signal to each switching element of the inverter 4 based on the on ratio determined by the output determination unit 10, the power supply timing of the brushless DC motor 5, and the PWM cycle determined in advance. Output.
  • the drive signal turns on or off the switching elements 4a to 4f of the inverter 4.
  • the optimum AC power is applied to the stator 5b of the brushless DC motor 5.
  • the rotor 5a of the brushless DC motor 5 rotates, and the piston 17b is driven.
  • the motor drive device 30 is configured.
  • the refrigerator 22 using the motor drive device 30 of the present embodiment will be described with reference to FIGS. 1 to 2D.
  • the refrigerator 22 will be described as an example, but the same applies to the refrigerating apparatus.
  • the refrigerator 22 is equipped with a compressor 17.
  • the compressor 17 is composed of a reciprocating type. That is, the compressor 17 is composed of a compression mechanism including a brushless DC motor 5, a crankshaft 17a, a piston 17b, a cylinder 17c, and the like.
  • the rotary motion of the rotor 5a of the brushless DC motor 5 is converted into a reciprocating motion by the crankshaft 17a.
  • the piston 17b connected to the crankshaft 17a reciprocates in the cylinder 17c.
  • the refrigerant is sucked into the cylinder 17c, and the sucked refrigerant is compressed.
  • the refrigerant compressed by the compressor 17 passes through the condenser 19, the two-way valve 18, the decompressor 20, and the evaporator 21 in this order, and returns to the compressor 17 in a refrigerating cycle. At this time, heat is dissipated in the condenser 19, and heat is absorbed in the evaporator 21. As a result, the inside of the refrigerator 22 can be cooled and heated. That is, the refrigerator 22 is configured by mounting the compressor 17 that realizes the refrigeration cycle.
  • the two-way valve 18 an electromagnetic valve or the like that can be opened and closed by energization is used.
  • the two-way valve 18 is opened during the operation of the compressor 17, and the condenser 19 and the decompressor 20 are communicated with each other to allow the refrigerant to flow.
  • the two-way valve 18 is closed and the space between the condenser 19 and the decompressor 20 is closed to prevent the refrigerant from flowing.
  • the refrigerator 22 using the motor drive device 30 is configured.
  • the horizontal axis represents time
  • the vertical axis represents the vibration amplitude in the direction perpendicular to the reciprocating direction of the piston 17b and perpendicular to the rotation axis of the brushless DC motor 5.
  • the piston 17b reciprocates in the cylinder 17c in the same manner. Therefore, when the piston 17b rotates in the forward or reverse direction from the bottom dead center state, the refrigerant compression / discharge step is similarly executed. Further, when the piston 17b rotates in the forward or reverse direction from the top dead center state, the suction step of sucking the refrigerant into the piston 17b is similarly executed.
  • the motor drive device 30 of the present embodiment utilizes the above characteristics, and first, the bottom dead center search unit 11 sets a pattern of rotating 180 degrees in the normal rotation direction from the top dead center to the bottom dead center. Output to the brushless DC motor 5. After that, the bottom dead center search unit 11 outputs a pattern of rotating 180 degrees from the top dead center to the bottom dead center in the reverse direction to the brushless DC motor 5.
  • the torque determination unit 12 determines in advance the torque when the bottom dead center search unit 11 is performing the bottom dead center search. That is, the torque determination unit 12 is stopped under the pressure condition when the inside of the refrigerator 22 is sufficiently cooled, and when the refrigerator 22 is started, the rotor 5a of the piston 17b is less than 60 degrees from the bottom dead center. Only the torque that rotates in the compression direction is determined.
  • the torque determined by the torque determination unit 12 cannot rotate in the forward rotation direction because it is in the compression direction.
  • torque is almost unnecessary because it is a suction step. Therefore, even with a small torque determined by the torque determination unit 12, the piston 17b can be rotated in the bottom dead center direction and moved to the bottom dead center.
  • the piston 17b moves to the bottom dead center.
  • the piston 17b rotates to a position of 60 degrees from the bottom dead center and stops.
  • the output determination unit 10 outputs the phase corresponding to the bottom dead center.
  • the rotor 5a near the bottom dead center rotates to a position where the piston 17b moves to the bottom dead center. That is, when the output determination unit 10 outputs a phase corresponding to the bottom dead center, the piston 17b rotates in a direction close to the bottom dead center.
  • the phases for moving to the top dead center and the bottom dead center are the same.
  • the piston 17b since the piston 17b is located near the bottom dead center, it moves to the bottom dead center side.
  • the same phase as the bottom dead center is a position rotated 120 degrees from the bottom dead center in the direction of the top dead center. Therefore, since the rotor 5a rotates only to less than 60 degrees, the piston 17b moves in the bottom dead center direction.
  • the brushless DC motor 5 having an 8-pole configuration
  • the range of rotation of the rotor 5a is less than the value obtained by dividing 360 by the number of poles.
  • the piston 17b can be similarly moved in the direction of the bottom dead center.
  • the compressor 17 has vibration generated at the start of operation as a factor of vibration generation. Further, in the operation of switching from compression to discharge and switching to suction after the start of operation of the compressor 17, acceleration may occur due to a rapid decrease in torque, and vibration may occur.
  • the kinetic energy of the rotor 5a of the brushless DC motor 5 is proportional to the square of the angular velocity. Therefore, the lower the speed of the rotor 5a, the larger the decrease and increase in the speed, and the larger the vibration generated.
  • the compressor 17 is subjected to a large torque at the start when there is a pressure difference between suction and discharge. Therefore, by increasing the speed of the rotor 5a and increasing the kinetic energy, the vibration generated from the start of operation to the speed at which normal operation is performed can be suppressed to some extent. However, when the top dead center is exceeded for the first time from the start of operation of the compressor 17, the speed of the rotor 5a is the lowest, so that vibration is most likely to occur.
  • crankshaft 17a is connected to the rotor 5a. Therefore, when the piston 17b starts rotating from the bottom dead center, vibration is generated by the inertia in the direction perpendicular to the reciprocating direction of the piston 17b and the direction perpendicular to the rotation axis of the brushless DC motor 5. Further, when the piston 17b gets over the top dead center, sudden acceleration occurs. Therefore, the inertia causes vibration in the direction perpendicular to the reciprocating direction of the piston 17b and in the direction perpendicular to the rotation axis of the brushless DC motor 5.
  • the vibration generated from the bottom dead center of the piston 17b and the rotation direction of the rotor 5a from the top dead center is in the same direction.
  • the crankshaft 17a is located symmetrically with respect to the rotation axis of the rotor 5a, so that the generated vibration is in the opposite direction.
  • FIG. 3A is a diagram showing vibration generated at the start of operation from the bottom dead center of the piston 17b.
  • FIG. 3B is a diagram showing vibration generated when the top dead center of the piston 17b is exceeded. That is, as shown in FIGS. 3A and 3B, the directions of vibration generation start are opposite in the rotation from the bottom dead center of the piston 17b and the rotation from the top dead center of the piston 17b.
  • the torque determination unit 12 determines the torque so as to overcome the top dead center at the timing of the vibration cycle when the piston 17b is started from the bottom dead center. At this time, the period of vibration of the start from the bottom dead center of the piston 17b is determined by the complex natural vibration of the parts constituting the compressor 17. The natural vibration is examined in advance by, for example, a hammering test.
  • the time to reach is calculated based on the compression work of the compressor 17, the torque generated in the brushless DC motor 5, and the inertia of the rotor 5a and the parts connected to the rotor 5a. At this time, the inertia is fixed (constant), and the compression work of the compressor 17 changes.
  • the torque generated in the brushless DC motor 5 can be determined by selecting the central load condition in the normal operation range in a state where the inside of the refrigerator 22 is sufficiently cooled. Specifically, the torque applied to the brushless DC motor 5 is calculated and held in advance under the selected load condition. As a result, the load on the control system that calculates the torque in real time can be reduced. Therefore, even with a low-performance microcomputer, the time required to reach the above can be easily calculated. As a result, the cost related to the control system can be reduced.
  • the waveform of FIG. 3A which is the vibration when the piston 17b is started from the bottom dead center
  • the waveform of FIG. 3B which is the vibration when the piston 17b is overcome by the torque determined in advance by the above method
  • the start positions of the vibration cycles coincide with each other, and the phases are opposite to each other. Therefore, the vibration of FIG. 3A and the vibration of FIG. 3B cancel each other out.
  • the combined vibration of the vibration at the start of operation and the vibration when the top dead center is exceeded is about 50% as compared with the peak of the vibration at the start shown in FIG. 3A. To a degree, it is suppressed.
  • the vibration cycles do not match at a constant torque.
  • the load when the refrigerator is sufficiently cooled has a small change as compared with when the power is turned on, and the change in the vibration phase is within ⁇ 30 degrees.
  • FIG. 4A is a diagram showing the vibration amplitude when the piston 17b is started from the bottom dead center, as in FIG. 3A.
  • FIG. 4B is a diagram showing vibration when the piston 17b gets over the top dead center. Note that FIG. 4B shows a waveform when the phase is delayed by +30 degrees from the vibration cycle at the start of operation.
  • FIG. 4C is a diagram showing a combined vibration waveform of FIGS. 4A and 4B.
  • the start of vibration when the piston 17b crosses the top dead center is shifted by 30 degrees.
  • the vibration peak value is about 60% of the vibration peak in FIG. 4A. Therefore, even if the phase shift occurs, a sufficient vibration suppressing effect can be obtained.
  • FIG. 5 is a flowchart in which the bottom dead center search unit 11 searches for the bottom dead center.
  • the bottom dead center search unit 11 confirms whether or not the target speed input from the outside when entering this process last time was 0 (zero) (STEP201). At this time, if the target speed is 0 (zero) (Yes in STEP201), the process proceeds to STEP202, and if the target speed is other than 0 (zero) (No in STEP201), the process proceeds to STEP203. Here, assuming that the previous target speed is 0 (zero), the process proceeds to STEP202.
  • Step202 check whether the current target speed input from the outside is other than 0 (STEP202). At this time, if the target speed is other than 0 (Yes in STEP202), the process proceeds to STEP204, and if the target speed is 0 (No in STEP201), the process proceeds to STEP203. That is, it is determined whether or not the target speed has changed so as to start from the stopped state between the previous process and the current process. Here, assuming that the current target speed is other than 0, the process proceeds to STEP204.
  • the bottom dead center search unit 11 sets 0 (zero) to the phase change amount for recording how much the rotor 5a is rotated for bottom dead center search, and sets the current output phase to top dead center. Initialize as a point (STEP204).
  • the bottom dead center search unit 11 determines whether or not the phase change amount, which is the amount obtained by rotating the rotor 5a for bottom dead center search, is less than 180 (STEP205). At this time, if the phase change amount is less than 180 (Yes in STEP205), the process proceeds to STEP206, and if the phase change amount is 180 or more (No in STEP205), the process proceeds to STEP207.
  • the phase rotated 30 degrees in the forward rotation direction from the current output phase is output as a new output phase (STEP206). Further, 30 which is equal to the rotated angle is added to the phase change amount recorded by how much the rotor 5a is rotated by the bottom dead center search unit 11 (STEP206). Then, after waiting for 100 ms, the process proceeds to STEP205.
  • the waiting time of 100 ms is the time waiting for the rotor 5a to rotate reliably. For this waiting time, a predetermined value is used while actually checking the operation.
  • STEP205 and STEP206 are executed 6 times each. After that, when returning to STEP205, the phase change amount is 180 (No of STEP205), so the process shifts from STEP205 to STEP207.
  • the phase rotated 180 degrees from the top dead center is output.
  • the connecting portion between the crankshaft 17a and the rotor 5a is between the top dead center and the bottom dead center in the normal rotation direction
  • the normal rotation corresponds to the suction step. Therefore, it is possible to rotate the rotor 5a in the forward rotation direction even with a small torque. As a result, the piston 17b moves to the bottom dead center.
  • the connecting portion between the crankshaft 17a and the rotor 5a is between the bottom dead center and the top dead center in the normal rotation direction, it corresponds to the compression / discharge step. Therefore, except when the piston 17b is near the bottom dead center, it can hardly rotate in the forward rotation direction. As a result, the piston 17b stays between the bottom dead center and the top dead center.
  • the brushless DC motor 5 since the brushless DC motor 5 is driven by a rectangular wave of 4 poles and 120 degrees, the amount of change in the output phase is rotated by 30 degrees. This corresponds to electrically changing the phase of a 120-degree square wave by 60 degrees, and makes one rotation with six types of output patterns. Further, since the brushless DC motor 5 has a 4-pole configuration, one rotation of the rotor electrically outputs 360 degrees in two cycles equal to the logarithm of the poles. That is, the output phase change of the 120-degree rectangular wave becomes 30 degrees when converted to the rotor angle. On the other hand, in the case of the 6-pole configuration, in order for the rotor to make one rotation, 360 degrees is electrically output for 3 cycles equal to the logarithm of the poles. Therefore, the rotor rotates 20 degrees for one change of the output phase. That is, the amount of change in STEP 206 shown in FIG. 5 is the result of dividing 360 by the number of pole pairs of the motor and the number of commutation patterns 6.
  • phase change amount is set to 0 and the current output phase is top dead.
  • initialization is performed (STEP207).
  • the bottom dead center search unit 11 determines whether or not the phase change amount, which records how much the rotor 5a is rotated in reverse for the bottom dead center search, is less than 180 (STEP208). If the phase change amount is less than 180 (Yes in STEP208), the process proceeds to STEP209, and if the phase change amount is 180 or more (No in STEP208), the process proceeds to STEP210. Here, since it is immediately after the phase change amount is initialized to 0 in STEP 207, the process shifts to STEP 209.
  • the phase rotated 30 degrees in the reverse direction from the current output phase is output as a new output phase (STEP209). Further, 30 equal to the rotation angle is added to the phase change amount recorded by the bottom dead center search unit 11 how much the rotor 5a is rotated in the opposite direction (STEP 209). Then, after waiting for 100 ms, the process proceeds to STEP208.
  • STEP208 and STEP209 are executed 6 times each. After that, when returning to STEP205, the phase change amount is 180 (No of STEP208), so the process shifts from STEP208 to STEP210.
  • the current target speed is recorded as the previous target speed, and the process is completed (STEP211).
  • the refrigerator 22 stops the refrigeration cycle when the inside of the refrigerator is sufficiently cooled. Therefore, the target speed becomes 0 (zero). If the process shown in FIG. 5 is executed again in this state, the previous target speed is not 0 (zero), so STEP201, STEP203, STEP211 shown in FIG. 5 and the same process as the flow during operation are executed. To. Therefore, in STEP211, when the previous target speed is updated, the target speed is recorded as 0 (zero).
  • the piston 17b is moved to the bottom dead center in the synchronous operation in which the current flowing through the brushless DC motor 5 and the induced voltage are not detected. , Can be activated. As a result, even if there is a difference between the suction and discharge pressures of the compressor 17, the peak of the vibration generated by the compressor 17 can be suppressed and the vibration can be reduced.
  • the two-way valve 18 is opened and the decompressor 20 and the condenser 19 are communicated with each other.
  • the example in which the two-way valve 18 is opened at the same time as the compressor 17 is started has been described, but there is no problem even if the time is slightly changed.
  • the condenser 19 becomes high pressure.
  • the evaporator 21 is decompressed by the decompressor 20 to become a low pressure.
  • the discharge side connected to the condenser 19 of the compressor 17 has a high pressure
  • the suction side connected to the evaporator 21 has a low pressure.
  • the two-way valve 18 is closed while the compressor 17 is stopped, and the pressure difference is maintained and the pressure is increased. Compare with the case of starting from a balanced state. In this case, if the two-way valve 18 is closed and the compressor 17 is started while maintaining the pressure difference, the electric power for providing the pressure difference again between the condenser 19 and the evaporator 21 is smaller. Become. Therefore, energy saving of the refrigerator 22 can be realized.
  • the motor drive device 30 can be started only when the pressure difference between the suction side and the discharge side of the compressor 17 is 0.05 MPa or less. Therefore, in the above state, it is necessary to wait for the motor drive device 30 to start until 10 minutes have passed.
  • the refrigerator 22 of the present embodiment can start the motor drive device 30 even with a differential pressure larger than 0.05 MPa. Therefore, when the temperature inside the refrigerator rises, the motor drive device 30 can be started at a timing when the compressor 17 needs to be operated. As a result, the electric power for providing a pressure difference between the condenser 19 and the evaporator 21 can be reduced as compared with the case where the compressor 17 is started in a state where the pressures on the suction side and the discharge side are balanced. Therefore, it is possible to further save energy in the refrigerator 22.
  • the two-way valve 18 can simplify the system configuration such as a refrigerator as compared with the three-way valve or the four-way valve. Further, the two-way valve 18 can more reliably maintain the pressure difference between the suction side and the discharge side of the compressor 17.
  • the compressor 17 may be arranged above the refrigerator 22.
  • the refrigerator 22 is arranged at the position farthest from the compressor 17, which is the vibration source. Therefore, in the refrigerator 22, the vibration of the compressor 17 is easily transmitted by the principle of leverage with the floor as a fulcrum.
  • the refrigerator 22 of the present embodiment can effectively suppress the peak of vibration of the compressor 17. Therefore, even if the compressor 17 is arranged at the upper part, the vibration and noise generated from the refrigerator 22 can be reduced.
  • the motor drive device 30 of the present embodiment includes a compressor 17 and a brushless DC motor 5 for the compressor 17 to perform a compression operation.
  • the motor drive device is configured to determine the starting torque and the rotation start position of the brushless DC motor 5 so that the vibration at the start of operation of the compressor 17 and the vibration due to the decrease in load torque cancel each other out.
  • the motor drive device 30 is configured to cancel the peak of the vibration amplitude generated at the start of operation and the peak of the vibration amplitude generated by the sudden acceleration due to the decrease of the load torque. Therefore, the peak of the vibration amplitude becomes smaller than the case where the peak of each of the above vibration amplitudes is generated independently. As a result, the vibration generated from the compressor 17 can be suppressed to be small.
  • the motor drive device 30 of the present embodiment includes a bottom dead center search unit 11 that searches for and moves the bottom dead center of the piston 17b of the compressor 17, and the bottom dead center search unit 11 causes the piston 17b to die down.
  • the brushless DC motor 5 is configured to move to the rotation start position.
  • the motor drive device 30 can grasp the position of the piston 17b of the compressor 17 and secure an acceleration period for obtaining a sufficient speed in order to overcome the compression step. As a result, the compressor 17 can be started stably.
  • the motor drive device 30 of the present embodiment includes 12 torque determination units, and the torque determination unit 12 determines the starting torque with the rotation start position determined by the bottom dead center search unit 11 as the bottom dead center. ..
  • the direction of vibration generated at the start of operation and the direction of start of vibration due to a decrease in load torque at top dead center are opposite to each other. Therefore, the vibrations of each other cancel each other out. As a result, the vibration generated by the compressor 17 can be suppressed more effectively.
  • the motor drive device 30 does not need to move the piston 17b to the bottom dead center and then to the operation start position. As a result, the motor drive device 30 can have a simpler configuration. Therefore, it is possible to configure with an inexpensive microcomputer having low capacity, and the cost of the product can be reduced.
  • the starting position of the piston 17b of the motor driving device 30 is fixed. Therefore, the calculation for determining the starting torque becomes simple. As a result, the development period can be shortened when the starting torque is determined in advance. On the other hand, even when the starting torque is determined in real time, it can be calculated in a short time with an inexpensive microcomputer.
  • both forward rotation and reverse rotation are uncompressed steps
  • both and reversal include compression steps.
  • the bottom dead center search unit 11 is configured to have a step of rotating the brushless DC motor 5 in the forward and reverse directions.
  • the motor drive device 30 does not need to detect the position of the brushless DC motor 5 at a low speed, which is difficult to detect, from the current, the induced voltage, or the like. That is, the motor drive device 30 can move the piston 17b to the bottom dead center by rotating the brushless DC motor 5 in synchronous operation. As a result, the position of the piston 17b of the compressor 17 can be reliably grasped by an inexpensive microcomputer.
  • the refrigerator 22 of the present embodiment is configured to include the motor driving device 30.
  • the compressor 17 can be started from a state in which the load torque fluctuates greatly. Therefore, there is no need to wait until the suction pressure and the discharge pressure of the compressor 17 are balanced between the time when the refrigerator 22 is stopped and the time when the operation is restarted again. As a result, when the power supply is restored from the power failure due to a power failure or the movement of the refrigerator 22, the cooling inside the refrigerator 22 can be restarted immediately.
  • the refrigerator 22 of the present embodiment is configured by providing a compressor 17 on the upper part of the housing.
  • the vibration is transmitted to the housing by driving the motor driving device 30. Is suppressed.
  • the refrigerator 22 having high quietness can be provided.
  • the compressor is arranged in a portion of the upper part of the housing that tends to be a dead space. Therefore, the storage volume in the refrigerator that can be actually used is expanded. This makes it possible to provide an easy-to-use refrigerator having a large effective storage volume.
  • the present disclosure can be used for a motor drive device for starting a compressor in which the load torque fluctuates greatly. Therefore, it can be suitably applied to refrigerators, freezers, showcases, and other various refrigerating devices using a compressor activated by a motor drive device.

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Abstract

In the present invention, a start-up torque and a rotation start position of a brushless DC motor (5) are determined such that vibration when operation of a compressor (17) is started and vibration due to a decrease in load torque cancel each other out. As a result of this configuration, a motor drive device (30) can suppress vibrations generated by the compressor (17) because a vibration amplitude peak generated when the operation is started and a vibration amplitude peak generated by a sudden acceleration due to the decrease in load torque are lower than when either vibration amplitude peak occurs alone. The present invention thereby provides a motor drive device (30) capable of stable start-up while suppressing vibrations even in a compressor (17) having large variations in torque.

Description

モータ駆動装置およびこれを用いた冷蔵庫Motor drive device and refrigerator using it
　本開示は、圧縮機のブラシレスＤＣモータを駆動するモータ駆動装置およびこれを用いた冷蔵庫に関する。 The present disclosure relates to a motor drive device for driving a brushless DC motor of a compressor and a refrigerator using the motor drive device.
　特許文献１は、従来の圧縮機のブラシレスＤＣモータを駆動する冷蔵庫用のモータ駆動装置を開示する。モータ駆動装置で駆動する圧縮機を搭載した冷蔵庫などの冷凍装置は、冷却運転停止時、冷凍サイクルを高圧側と低圧側とにサイクル上分離して、冷媒の流れ込みを防いで、省エネルギ化を図っている。 Patent Document 1 discloses a motor drive device for a refrigerator that drives a brushless DC motor of a conventional compressor. Refrigerators such as refrigerators equipped with a compressor driven by a motor drive device divide the refrigeration cycle into a high-pressure side and a low-pressure side in a cycle when the cooling operation is stopped to prevent the inflow of refrigerant and save energy. I'm trying.
　しかしながら、上記構成の場合、圧縮機の内部で、吸入圧力と吐出圧力とに大きな差が残る。そのため、圧縮機の起動時、圧縮ステップを乗り越えるために大きなエネルギが必要となる。 However, in the case of the above configuration, a large difference remains between the suction pressure and the discharge pressure inside the compressor. Therefore, when the compressor is started, a large amount of energy is required to overcome the compression step.
　そこで、従来の圧縮機駆動用のモータ駆動装置は、起動前の圧縮機のピストンの位置を、上死点から下死点の間の、上死点隣（あらかじめ決められた位置中で、上死点ではない上死点に最も近づく位置に相当）まで移動させる。そして、上死点隣の位置から、モータ駆動装置を起動させる。これにより、圧縮機のピストンに大きな加速を与え、エネルギを蓄えて、圧縮ステップを乗り越え、圧縮機の起動を行うように構成される。 Therefore, in the conventional motor drive device for driving a compressor, the position of the piston of the compressor before starting is set to the upper dead center between the top dead center and the bottom dead center (in a predetermined position, above). Move to the position closest to the top dead center, which is not the dead center). Then, the motor drive device is started from the position next to the top dead center. As a result, the piston of the compressor is greatly accelerated, energy is stored, the compression step is overcome, and the compressor is started.
　以下、上記特許文献１に記載の従来のモータ駆動装置について、図６を用いて、説明する。 Hereinafter, the conventional motor drive device described in Patent Document 1 will be described with reference to FIG.
　図６は、上記特許文献１に記載の従来のモータ駆動装置のブロック図である。 FIG. 6 is a block diagram of the conventional motor drive device described in Patent Document 1.
　図６に示すように、従来のモータ駆動装置は、ブラシレスＤＣモータ２０１と、圧縮機２０３と、制御部２０４と、インバータ２０５などから構成される。圧縮機２０３は、ブラシレスＤＣモータ２０１、およびブラシレスＤＣモータ２０１のロータに連結されたピストン２０２を有する。制御部２０４は、モータを下死点に移動させる初期整列段階と、吸入ステップ内の上死点隣に起動位置を移動させる強制整列段階と、ブラシレスＤＣモータ２０１の回転子を加速させる加速段階などの制御動作を含む。インバータ２０５は、制御部２０４からの駆動信号に基づいて、ブラシレスＤＣモータ２０１に電力を供給する。 As shown in FIG. 6, the conventional motor drive device includes a brushless DC motor 201, a compressor 203, a control unit 204, an inverter 205, and the like. The compressor 203 has a brushless DC motor 201 and a piston 202 connected to the rotor of the brushless DC motor 201. The control unit 204 has an initial alignment step of moving the motor to the bottom dead center, a forced alignment step of moving the starting position next to the top dead center in the suction step, an acceleration step of accelerating the rotor of the brushless DC motor 201, and the like. Including the control operation of. The inverter 205 supplies electric power to the brushless DC motor 201 based on the drive signal from the control unit 204.
　上記構成のモータ駆動装置は、圧縮機２０３の停止時において、ピストン２０２が圧縮ステップ手前で停止する確率が高く、下死点付近にピストン２０２が停止しやすい。そのため、制御部２０４は、初期整列段階において、ピストン２０２が下死点の位相となる信号をインバータ２０５に送る。そして、インバータ２０５は、電流をブラシレスＤＣモータ２０１のステータに流して、ブラシレスＤＣモータ２０１のロータを回転させる。これにより、ピストン２０２が、下死点に移動する。 In the motor drive device having the above configuration, when the compressor 203 is stopped, the piston 202 has a high probability of stopping before the compression step, and the piston 202 tends to stop near the bottom dead center. Therefore, the control unit 204 sends a signal to the inverter 205 in which the piston 202 is in phase at the bottom dead center in the initial alignment stage. Then, the inverter 205 causes a current to flow through the stator of the brushless DC motor 201 to rotate the rotor of the brushless DC motor 201. As a result, the piston 202 moves to the bottom dead center.
　つぎに、制御部２０４は、強制整列段階において、ピストン２０２の下死点の位相から、逆転方向に、順次切り替わるような信号を、インバータ２０５に送る。これにより、ピストン２０２の位置を、吸入ステップ側の上死点隣まで移動させる。 Next, in the forced alignment stage, the control unit 204 sends a signal to the inverter 205 that sequentially switches from the phase of the bottom dead center of the piston 202 in the reverse direction. As a result, the position of the piston 202 is moved to the position next to the top dead center on the suction step side.
　そして、制御部２０４は、加速段階において、ブラシレスＤＣモータ２０１を起動して、加速させるための信号をインバータ２０５に送る。これにより、ブラシレスＤＣモータ２０１が回転する。つまり、ピストン２０２を上死点近傍から加速させるため、圧縮ステップでの速度が大きくなる。その結果、圧縮ステップを乗り越え、圧縮機駆動用のモータ駆動装置の容易な起動が可能となる。 Then, the control unit 204 starts the brushless DC motor 201 in the acceleration stage and sends a signal for accelerating to the inverter 205. As a result, the brushless DC motor 201 rotates. That is, since the piston 202 is accelerated from the vicinity of top dead center, the speed in the compression step increases. As a result, the compression step can be overcome and the motor drive device for driving the compressor can be easily started.
特開２００７－１０７５２３号公報JP-A-2007-107523
　本開示は、吸入圧力と吐出圧力との差がある負荷トルクの変動が大きな圧縮機でも、安価で、かつ、振動を抑制しながら安定した起動が可能なモータ駆動装置を提供する。 The present disclosure provides a motor drive device that is inexpensive and can be stably started while suppressing vibration even in a compressor having a large fluctuation in load torque, which has a difference between suction pressure and discharge pressure.
　本開示のモータ駆動装置は、圧縮機と、圧縮機が圧縮動作を行う駆動源となるブラシレスＤＣモータを備える。そして、モータ駆動装置は、圧縮機の運転開始時の振動と、負荷トルク減少による振動とが、打ち消しあうようにブラシレスＤＣモータの起動トルクと回転開始位置を決定するように構成される。 The motor drive device of the present disclosure includes a compressor and a brushless DC motor as a drive source for the compressor to perform a compression operation. The motor drive device is configured to determine the starting torque and rotation start position of the brushless DC motor so that the vibration at the start of operation of the compressor and the vibration due to the decrease in load torque cancel each other out.
　本開示のモータ駆動装置は、運転開始時に発生する振動振幅のピークと、負荷トルクの減少による急加速によって発生する振動振幅のピークと、を打ち消すように構成される。そのため、上記それぞれの振動振幅のピークが単独で発生する場合と比べて、振動振幅のピークが打ち消されて、小さくなる。これにより、圧縮機から発生する振動を小さく抑制して、安価で、安定して圧縮機を起動できるモータ駆動装置を提供する。 The motor drive device of the present disclosure is configured to cancel the peak of the vibration amplitude generated at the start of operation and the peak of the vibration amplitude generated by sudden acceleration due to a decrease in load torque. Therefore, the peaks of the vibration amplitudes are canceled out and become smaller than the case where the peaks of the respective vibration amplitudes are generated independently. As a result, a motor drive device capable of stably starting the compressor at low cost by suppressing vibration generated from the compressor to a small extent is provided.
図１は、実施の形態におけるモータ駆動装置のブロック図である。FIG. 1 is a block diagram of a motor drive device according to an embodiment. 図２Ａは、同実施の形態において、被駆動体となる圧縮機のピストンの下死点における回転子との関係を表す略式図である。FIG. 2A is a schematic diagram showing the relationship with the rotor at the bottom dead center of the piston of the compressor as the driven body in the same embodiment. 図２Ｂは、同実施の形態において、被駆動体となる圧縮機のピストンが下死点から正転方向に９０度回転した状態のピストンと回転子との関係を表す略式図である。FIG. 2B is a schematic diagram showing the relationship between the piston and the rotor in a state where the piston of the compressor as the driven body is rotated 90 degrees in the normal rotation direction from the bottom dead center in the same embodiment. 図２Ｃは、同実施の形態において、被駆動体となる圧縮機のピストンの上死点における回転子との関係を表す略式図である。FIG. 2C is a schematic diagram showing the relationship with the rotor at the top dead center of the piston of the compressor as the driven body in the same embodiment. 図２Ｄは、同実施の形態において、被駆動体となる圧縮機のピストンが上死点から正転方向に９０度回転した状態のピストンと回転子との関係を表す略式図である。FIG. 2D is a schematic diagram showing the relationship between the piston and the rotor in a state where the piston of the compressor as the driven body is rotated 90 degrees in the normal rotation direction from the top dead center in the same embodiment. 図３Ａは、同実施の形態において、運転開始時に発生する被駆動体としての圧縮機の振動を表す波形図である。FIG. 3A is a waveform diagram showing the vibration of the compressor as the driven body generated at the start of operation in the same embodiment. 図３Ｂは、同実施の形態において、運転開始から最初に圧縮ステップを乗り越えた際に発生する被駆動体としての圧縮機の振動を表す波形図である。FIG. 3B is a waveform diagram showing vibration of the compressor as a driven body generated when the compression step is first overcome from the start of operation in the same embodiment. 図３Ｃは、同実施の形態において、運転開始時の振動と圧縮ステップを乗り越えた際の振動を合成した被駆動体としての圧縮機の振動を表す波形図である。FIG. 3C is a waveform diagram showing the vibration of the compressor as the driven body, which is a combination of the vibration at the start of operation and the vibration when the compression step is overcome in the same embodiment. 図４Ａは、同実施の形態における上死点到達までの時間が運転開始時の振動の周期より３０度位相がずれた際の、運転開始時に発生する被駆動体としての圧縮機の振動を表す波形図である。FIG. 4A shows the vibration of the compressor as the driven body generated at the start of operation when the time to reach the top dead center in the same embodiment is out of phase by 30 degrees from the vibration cycle at the start of operation. It is a waveform diagram. 図４Ｂは、同実施の形態における上死点到達までの時間が運転開始時の振動の周期より３０度位相がずれた際の、運転開始時から最初に圧縮ステップを乗り越える際に発生する被駆動体としての圧縮機の振動を表す波形図である。FIG. 4B shows a driven drive generated when the compression step is first overcome from the start of operation when the time to reach top dead center in the same embodiment is out of phase by 30 degrees from the vibration cycle at the start of operation. It is a waveform diagram which shows the vibration of a compressor as a body. 図４Ｃは、同実施の形態における上死点到達までの時間が運転開始時の振動の周期より３０度位相がずれた際の、運転開始時と圧縮ステップを乗り越える際に被駆動体としての圧縮機に発生する合成の振動を表す波形図である。FIG. 4C shows compression as a driven body at the start of operation and when the compression step is overcome when the time to reach top dead center in the same embodiment is out of phase by 30 degrees from the vibration cycle at the start of operation. It is a waveform diagram which shows the synthetic vibration generated in the machine. 図５は、同実施の形態における下死点探索部が下死点を探索するフローチャートである。FIG. 5 is a flowchart in which the bottom dead center search unit in the same embodiment searches for the bottom dead center. 図６は、従来のモータ駆動装置のブロック図である。FIG. 6 is a block diagram of a conventional motor drive device.
　（本開示の基礎となった知見等）
　発明者らが本開示に想到するに至った当時、特許文献１に記載されたモータ駆動装置があった。モータ駆動装置は、圧縮機の吸入圧力と吐出圧力とに差があるため、負荷トルクの変動が大きく、振動を抑制しながら、安定して起動することが困難であった。すなわち、特許文献１の構成の場合、圧縮ステップを乗り越える速度は、十分に出るが、圧縮ステップを乗り越え、吸入ステップになった際に、急加速するため、振動が発生しやすい。また、モータ駆動装置は、圧縮機の停止時において、ピストンが下死点付近に停止することを前提に、圧縮機に電圧を印加する。これにより、ピストンが下死点へ移動される。そのため、ブラシレスＤＣモータの極数が２極以外の構成の場合、ピストンが上死点付近に停止した場合、想定したピストンの位置から円滑に起動できず、振動の発生や起動不良などが発生する、という課題があった。発明者らは、上記課題を見出し、その課題を解決するために、本開示の主題を構成するに至った。 (Knowledge, etc. that was the basis of this disclosure)
At the time when the inventors came up with the present disclosure, there was a motor drive device described in Patent Document 1. Since there is a difference between the suction pressure and the discharge pressure of the compressor, the motor drive device has a large fluctuation in the load torque, and it is difficult to start the motor drive device stably while suppressing the vibration. That is, in the case of the configuration of Patent Document 1, the speed of overcoming the compression step is sufficiently high, but when the compression step is overcome and the suction step is reached, the speed is rapidly accelerated, so that vibration is likely to occur. Further, the motor drive device applies a voltage to the compressor on the assumption that the piston stops near the bottom dead center when the compressor is stopped. This moves the piston to bottom dead center. Therefore, when the number of poles of the brushless DC motor is other than 2 poles, if the piston stops near the top dead center, it cannot be started smoothly from the assumed piston position, and vibration or start failure occurs. There was a problem. The inventors have found the above-mentioned problems and have come to construct the subject matter of the present disclosure in order to solve the problems.
　つまり、本開示は、負荷トルクの変動が大きな圧縮機でも、振動を抑制しながら、安定して起動できるモータ駆動装置を提供する。 That is, the present disclosure provides a motor drive device that can start stably while suppressing vibration even in a compressor having a large fluctuation in load torque.
　以下、図面を参照しながら、実施の形態、この場合は冷蔵庫に搭載した圧縮機のモータ駆動装置を例に説明する。但し、必要以上に詳細な説明は、省略する場合がある。例えば、既によく知られた事項の詳細説明、または、実質的に同一の構成に対する重複説明を省略する場合がある。これは、以下の説明が必要以上に冗長になるのを避け、当業者の理解を容易にするためである。 Hereinafter, the embodiment, in this case, the motor drive device of the compressor mounted on the refrigerator will be described as an example with reference to the drawings. However, an unnecessarily detailed description may be omitted. For example, detailed explanations of already well-known matters or duplicate explanations for substantially the same configuration may be omitted. This is to prevent the following explanation from becoming unnecessarily redundant and to facilitate the understanding of those skilled in the art.
　なお、添付図面および以下の説明は、当業者が本開示を十分に理解するために提供されるのであって、これらにより請求の範囲に記載の主題を限定することを意図していない。 It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.
　（実施の形態）
　以下、本実施の形態のモータ駆動装置について、項分けして、説明する。 (Embodiment)
Hereinafter, the motor drive device of the present embodiment will be described by dividing it into items.
　［１－１．構成］
　まず、本実施の形態のモータ駆動装置３０の構成について、図１から図２Ｄを参照しながら、説明する。 [1-1. Constitution]
First, the configuration of the motor drive device 30 of the present embodiment will be described with reference to FIGS. 1 to 2D.
　図１は、本実施の形態におけるモータ駆動装置３０のブロック図である。図２Ａから図２Ｄは、同実施の形態の被駆動体となる圧縮機１７のピストン１７ｂと回転子５ａとの位置関係を表す略式図である。 FIG. 1 is a block diagram of the motor drive device 30 according to the present embodiment. 2A to 2D are schematic views showing the positional relationship between the piston 17b of the compressor 17, which is the driven body of the same embodiment, and the rotor 5a.
　図１に示すように、本実施の形態のモータ駆動装置３０は、交流電源１に接続され、ブラシレスＤＣモータ５を駆動する。ブラシレスＤＣモータ５の回転子５ａは、図２Ａから図２Ｄに示すように、クランクシャフト１７ａ、ピストン１７ｂおよびシリンダ１７ｃなどと、レシプロ型の圧縮機１７を構成する。圧縮機１７は、本実施の形態では、冷蔵庫２２に搭載され、冷凍サイクルの一部を構成する。 As shown in FIG. 1, the motor drive device 30 of the present embodiment is connected to the AC power supply 1 and drives the brushless DC motor 5. As shown in FIGS. 2A to 2D, the rotor 5a of the brushless DC motor 5 constitutes a reciprocating compressor 17 with a crankshaft 17a, a piston 17b, a cylinder 17c, and the like. In the present embodiment, the compressor 17 is mounted on the refrigerator 22 and constitutes a part of the refrigeration cycle.
　交流電源１は、一般的な商用電源で、日本においては、実効値１００Ｖの５０Ｈｚまたは６０Ｈｚの電源である。 The AC power supply 1 is a general commercial power supply, and in Japan, it is a 50 Hz or 60 Hz power supply with an effective value of 100 V.
　以下、モータ駆動装置３０の構成について、具体的に、説明する。 Hereinafter, the configuration of the motor drive device 30 will be specifically described.
　図１に示すように、本実施の形態のモータ駆動装置３０は、整流回路２、平滑部３、インバータ４、位置検出部６、速度検出部７、電圧検出部８、ドライブ部９、出力決定部１０、下死点探索部１１、トルク決定部１２などから構成される。 As shown in FIG. 1, the motor drive device 30 of the present embodiment has a rectifier circuit 2, a smoothing unit 3, an inverter 4, a position detection unit 6, a speed detection unit 7, a voltage detection unit 8, a drive unit 9, and an output determination. It is composed of a unit 10, a bottom dead center search unit 11, a torque determination unit 12, and the like.
　整流回路２は、交流電源１を入力として、入力される交流電力を、直流電力に整流する。整流回路２は、ブリッジ接続された４個の整流ダイオード２ａ、２ｂ、２ｃ、２ｄで構成される。 The rectifier circuit 2 takes the AC power supply 1 as an input and rectifies the input AC power into DC power. The rectifier circuit 2 is composed of four bridge-connected rectifier diodes 2a, 2b, 2c, and 2d.
　平滑部３は、整流回路２の出力側に接続され、整流回路２の出力を平滑する。平滑部３は、平滑コンデンサ３ｅと、リアクタ３ｆなどから構成される。平滑部３からの出力は、インバータ４に入力される。 The smoothing unit 3 is connected to the output side of the rectifier circuit 2 and smoothes the output of the rectifier circuit 2. The smoothing portion 3 is composed of a smoothing capacitor 3e, a reactor 3f, and the like. The output from the smoothing unit 3 is input to the inverter 4.
　なお、リアクタ３ｆは、交流電源１と平滑コンデンサ３ｅとの間に挿入されるため、整流ダイオード２ａ～２ｄの前後のどちらに設けてもよい。また、リアクタ３ｆは、高周波除去部を構成するコモンモードフィルタが回路に設けられる場合、高周波除去部のリアクタンス成分との合成成分を考慮して構成することが望ましい。 Since the reactor 3f is inserted between the AC power supply 1 and the smoothing capacitor 3e, it may be provided before or after the rectifying diodes 2a to 2d. Further, when the common mode filter constituting the high frequency removing section is provided in the circuit, it is desirable that the reactor 3f is configured in consideration of the combined component with the reactance component of the high frequency removing section.
　インバータ４は、平滑部３からの入力される電圧に、交流電源１の電源周期の２倍周期で大きなリプル成分を含んだ直流電力を、順次切り替えて、３相の交流電力に変換する。インバータ４は、６個のスイッチング素子４ａ、４ｂ、４ｃ、４ｄ、４ｅ、４ｆを、３相のブリッジ接続により構成される。このとき、６個の還流電流用ダイオード４ｇ、４ｈ、４ｉ、４ｊ、４ｋ、４ｌが、それぞれのスイッチング素子４ａ～４ｆに、逆方向に接続される。 The inverter 4 sequentially switches the DC power containing a large ripple component to the voltage input from the smoothing unit 3 at a cycle twice the power supply cycle of the AC power supply 1 and converts it into three-phase AC power. The inverter 4 is composed of six switching elements 4a, 4b, 4c, 4d, 4e, and 4f connected by a three-phase bridge. At this time, six recirculation current diodes 4g, 4h, 4i, 4j, 4k, and 4l are connected to the respective switching elements 4a to 4f in opposite directions.
　なお、上記ブラシレスＤＣモータ５は、永久磁石を有する回転子５ａと、３相巻線を有する固定子５ｂなどから構成される。そして、インバータ４により作られた３相交流電流は、ブラシレスＤＣモータ５の固定子５ｂの３相巻線に供給される。これにより、ブラシレスＤＣモータ５の回転子５ａが回転する。 The brushless DC motor 5 is composed of a rotor 5a having a permanent magnet, a stator 5b having a three-phase winding, and the like. Then, the three-phase alternating current generated by the inverter 4 is supplied to the three-phase winding of the stator 5b of the brushless DC motor 5. As a result, the rotor 5a of the brushless DC motor 5 rotates.
　位置検出部６は、固定子５ｂの３相巻線に発生する誘起電圧、ならびに、固定子５ｂの３相巻線に流れる電流および印加電圧などから、ブラシレスＤＣモータ５の固定子５ｂの磁極位置を検出する。 The position detection unit 6 determines the magnetic pole position of the stator 5b of the brushless DC motor 5 from the induced voltage generated in the three-phase winding of the stator 5b, the current flowing in the three-phase winding of the stator 5b, the applied voltage, and the like. Is detected.
　本実施の形態では、位置検出部６は、ブラシレスＤＣモータ５の端子電圧を取得し、ブラシレスＤＣモータ５の回転子５ａの磁極の相対位置を検出する。具体的には、位置検出部６は、固定子５ｂの３相巻線に発生する誘起電圧に基づいて、回転子５ａの相対的な回転位置を検出する。さらに、位置検出部６は、誘起電圧と、基準となる電圧とを比較し、ゼロクロスを検出する。なお、誘起電圧のゼロクロスの基準となる電圧は、３相分の端子電圧から仮想中点の電圧を作り、その電圧としてもよい。また、直流母線電圧を取得し、その電圧を、誘起電圧のゼロクロスの基準となる電圧としてもよい。本実施の形態では、仮想中点の電圧を、誘起電圧のゼロクロスの基準となる電圧とする。 In the present embodiment, the position detection unit 6 acquires the terminal voltage of the brushless DC motor 5 and detects the relative position of the magnetic poles of the rotor 5a of the brushless DC motor 5. Specifically, the position detection unit 6 detects the relative rotation position of the rotor 5a based on the induced voltage generated in the three-phase winding of the stator 5b. Further, the position detection unit 6 compares the induced voltage with the reference voltage and detects the zero cross. The voltage that serves as a reference for zero crossing of the induced voltage may be a voltage at the virtual midpoint created from the terminal voltages for three phases and used as the voltage. Further, the DC bus voltage may be acquired and the voltage may be used as a reference voltage for zero crossing of the induced voltage. In the present embodiment, the voltage at the virtual midpoint is used as a reference voltage for zero crossing of the induced voltage.
　なお、本実施の形態では、位置検出部６は、ブラシレスＤＣモータ５の固定子５ｂの磁極の相対位置を、誘起電圧で検出する方式を例に説明しているが、これに限られない。例えば、ブラシレスＤＣモータ５に流れる電流から、磁極の相対的な位置を検出してもよい。この場合、電流は、インバータ４の直流母線に配されたシャント抵抗に生じる電圧を検出し、シャント抵抗の抵抗値から、直流母線に流れる電流を算出し、さらに、モータへの通電状態から各相に流れる電流を分離し、検出する方式でもよい。また、３相のそれぞれの電流をセンサーやシャント抵抗などを配して、個別に電流を検出する方式でもよい。しかしながら、上記電流を検出する方法を比較した場合、直流母線の電流値から検出する方式は、安価な構成となるが、各相の電流を分離するために、波形にひずみが生じる場合がある。そのため、回転子５ａの磁極の相対位置を検出する場合、電流から位置を推定する方法よりも、誘起電圧で検出する方法が、より好ましい。なぜなら、誘起電圧から検出する方式は、計算量が少なく、構成が簡単で、より安価に実現できるからである。また、３相それぞれの電流を個別に検出する方式は、回路部品が多くコストが高くなり、誘起電圧を検出する方式の方が安価に構成することができる。 In the present embodiment, the position detection unit 6 describes a method of detecting the relative position of the magnetic poles of the stator 5b of the brushless DC motor 5 by an induced voltage as an example, but the present invention is not limited to this. For example, the relative position of the magnetic poles may be detected from the current flowing through the brushless DC motor 5. In this case, for the current, the voltage generated in the shunt resistance arranged on the DC bus of the inverter 4 is detected, the current flowing through the DC bus is calculated from the resistance value of the shunt resistance, and each phase is further measured from the energized state of the motor. A method of separating and detecting the current flowing through the inverter may also be used. Further, a method of individually detecting the current of each of the three phases by arranging a sensor, a shunt resistor, or the like may be used. However, when the methods for detecting the above currents are compared, the method of detecting from the current value of the DC bus has an inexpensive configuration, but the waveform may be distorted in order to separate the currents of each phase. Therefore, when detecting the relative position of the magnetic poles of the rotor 5a, the method of detecting by the induced voltage is more preferable than the method of estimating the position from the current. This is because the method of detecting from the induced voltage requires a small amount of calculation, is simple in configuration, and can be realized at a lower cost. Further, the method of detecting the current of each of the three phases individually has many circuit parts and the cost is high, and the method of detecting the induced voltage can be configured at a lower cost.
　速度検出部７は、位置検出部６で検出した磁極の位置情報から、ブラシレスＤＣモータ５の、現在の駆動速度を計算する。具体的には、本実施の形態では、速度検出部７は、誘起電圧のゼロクロスの検出からの時間を測定し、測定した時間から、現在の速度の計算を行う。これにより、速度検出部７は、ブラシレスＤＣモータ５の駆動速度を計算する。 The speed detection unit 7 calculates the current drive speed of the brushless DC motor 5 from the position information of the magnetic poles detected by the position detection unit 6. Specifically, in the present embodiment, the speed detection unit 7 measures the time from the detection of the zero cross of the induced voltage, and calculates the current speed from the measured time. As a result, the speed detection unit 7 calculates the drive speed of the brushless DC motor 5.
　電圧検出部８は、インバータ４の直流母線間の電圧を検出する。一般的には、まず、インバータ４の直流母線間を抵抗で分圧し、検出する電圧を１４０Ｖ程度から５Ｖ以下の、マイコンで扱える範囲の電圧に分圧する。そして、分圧により検出した電圧から、マイコンで逆算し、元の直流母線間の電圧を算出する。なお、本実施の形態では、例えば、電圧を１００分の１に分圧した値を用いる。 The voltage detection unit 8 detects the voltage between the DC bus of the inverter 4. Generally, first, the voltage between the DC buses of the inverter 4 is divided by a resistor, and the detected voltage is divided into a voltage within a range that can be handled by the microcomputer, which is about 140 V to 5 V or less. Then, from the voltage detected by the voltage division, the microcomputer back-calculates and calculates the voltage between the original DC bus. In this embodiment, for example, a value obtained by dividing the voltage by 1/100 is used.
　下死点探索部１１では、外部から入力される目標速度が、０（ゼロ）から０（ゼロ）以外の値に変化した時に、ブラシレスＤＣモータ５を駆動し、圧縮機１７のピストン１７ｂの下死点を探索する。具体的には、下死点探索部１１は、下死点を探索させるために、予め決められたパターンの駆動波形をブラシレスＤＣモータ５に出力し、ピストン１７ｂを下死点近傍まで移動させる。つまり、下死点に相当する通電のパターンを、ブラシレスＤＣモータ５に出力し、ピストン１７ｂを下死点へと移動させる。そして、一旦、ピストン１７ｂを下死点へ移動させた後、下死点探索部１１は、起動開始の位置までピストン１７ｂを移動させるパターンを、ブラシレスＤＣモータ５に出力する。なお、本実施の形態においては、起動開始の位置を下死点とするため、下死点移動後の起動位置までピストン１７ｂを移動させるステップを、特に、設ける必要はない。そして、下死点探索部１１は、次に目標速度が０（ゼロ）から０（ゼロ）以外に変化するまで、ブラシレスＤＣモータ５への出力を停止する。 The bottom dead center search unit 11 drives the brushless DC motor 5 when the target speed input from the outside changes from 0 (zero) to a value other than 0 (zero), and under the piston 17b of the compressor 17. Search for the dead center. Specifically, the bottom dead center search unit 11 outputs a drive waveform of a predetermined pattern to the brushless DC motor 5 in order to search for the bottom dead center, and moves the piston 17b to the vicinity of the bottom dead center. That is, the energization pattern corresponding to the bottom dead center is output to the brushless DC motor 5 to move the piston 17b to the bottom dead center. Then, once the piston 17b is moved to the bottom dead center, the bottom dead center search unit 11 outputs a pattern for moving the piston 17b to the position where the start is started to the brushless DC motor 5. In the present embodiment, since the start-up start position is set as the bottom dead center, it is not necessary to particularly provide a step of moving the piston 17b to the start-up position after the bottom dead center is moved. Then, the bottom dead center search unit 11 stops the output to the brushless DC motor 5 until the target speed changes from 0 (zero) to a value other than 0 (zero).
　トルク決定部１２は、外部から入力される目標速度が、０（ゼロ）から０（ゼロ）以外に変化した際に、まず、下死点探索部１１で圧縮機１７のピストン１７ｂの下死点を探索する際に必要なトルクを出力する。なお、下死点方向への移動は、ピストン１７ｂが圧縮の仕事を行わないため、負荷条件によって、ほとんど影響されない。そのため、下死点方向への移動に必要なトルクは、運転開始のトルクに比べて、小さく、一定のトルクとなる。そして、トルク決定部１２は、最後に、ピストン１７ｂを下死点に移動させる際において、下死点を探索するよりも大きなトルクとなるように、ブラシレスＤＣモータ５へ出力する。さらに、トルク決定部１２は、下死点探索後において、圧縮機１７のピストン１７ｂを起動位置まで移動させる時間があれば、その期間に必要なトルクを、ブラシレスＤＣモータ５へ出力する。つまり、本実施の形態では、モータ駆動装置３０は、ピストン１７ｂを下死点から起動するように制御する。そのため、トルク決定部１２は、下死点への出力の時間が終了した際に、下死点からの運転開始に必要なトルク（起動トルクに相当）を決定する。このとき、トルク決定部１２は、ピストン１７ｂを下死点から起動し、上死点に到達するまでの時間が、起動時に発生する振動の周期と一致するように決定した、トルクを出力する。 When the target speed input from the outside changes from 0 (zero) to other than 0 (zero), the torque determination unit 12 first uses the bottom dead center search unit 11 to find the bottom dead center of the piston 17b of the compressor 17. Outputs the torque required when searching for. The movement in the bottom dead center direction is hardly affected by the load condition because the piston 17b does not perform the compression work. Therefore, the torque required for movement in the bottom dead center direction is smaller than the torque at the start of operation and is a constant torque. Finally, when the piston 17b is moved to the bottom dead center, the torque determination unit 12 outputs the torque to the brushless DC motor 5 so that the torque is larger than that for searching for the bottom dead center. Further, the torque determination unit 12 outputs the torque required for that period to the brushless DC motor 5 if there is time to move the piston 17b of the compressor 17 to the starting position after the bottom dead center search. That is, in the present embodiment, the motor drive device 30 controls the piston 17b to start from the bottom dead center. Therefore, the torque determination unit 12 determines the torque (corresponding to the starting torque) required for starting the operation from the bottom dead center when the output time to the bottom dead center ends. At this time, the torque determining unit 12 starts the piston 17b from the bottom dead center and outputs the torque determined so that the time until reaching the top dead center coincides with the period of vibration generated at the time of starting.
　さらに、トルク決定部１２は、下死点探索部１１からの出力が停止する時間が経過したのちに、通常の運転を行うためのトルクも決定する。その際、トルクは、速度検出部７から入力される現在のブラシレスＤＣモータ５の速度と、外部から入力される目標速度とを比較して、決定される。つまり、目標速度に対して、現在の速度が不足していれば、出力するトルクを上昇させる。一方、目標速度に対して、現在の速度が上回っていれば、出力するトルクを減少させる。これにより、ブラシレスＤＣモータ５の速度を、目標速度に到達させる。 Further, the torque determination unit 12 also determines the torque for performing normal operation after the time when the output from the bottom dead center search unit 11 is stopped has elapsed. At that time, the torque is determined by comparing the current speed of the brushless DC motor 5 input from the speed detection unit 7 with the target speed input from the outside. That is, if the current speed is insufficient with respect to the target speed, the output torque is increased. On the other hand, if the current speed is higher than the target speed, the output torque is reduced. As a result, the speed of the brushless DC motor 5 is brought to the target speed.
　出力決定部１０は、トルク決定部１２で決定されたトルクからブラシレスＤＣモータ５のトルク定数、誘起電圧定数、および抵抗値などから、印加電圧を決定する。そして、出力決定部１０は、決定した印加電圧と、電圧検出部８で検出された直流母線間の電圧に基づいて、インバータ４を駆動する、ＰＷＭデューティ幅を計算する。 The output determination unit 10 determines the applied voltage from the torque determined by the torque determination unit 12 from the torque constant, the induced voltage constant, the resistance value, and the like of the brushless DC motor 5. Then, the output determination unit 10 calculates the PWM duty width for driving the inverter 4 based on the determined applied voltage and the voltage between the DC buses detected by the voltage detection unit 8.
　また、出力決定部１０は、位置検出部６および速度検出部７からの情報、または下死点探索部１１からの出力に基づいて、３相のブラシレスＤＣモータ５の、どの相に通電するかを決定する。このとき、下死点探索部１１からの入力信号がある場合、出力決定部１０は、下死点探索部１１から入力される信号を利用して、通電する相を決定する。一方、下死点探索部１１からの入力信号がない場合、出力決定部１０は、位置検出部６の位置情報と、速度検出部７の速度情報とに基づいて、出力する信号を決定する。 Further, which phase of the three-phase brushless DC motor 5 is energized by the output determination unit 10 based on the information from the position detection unit 6 and the speed detection unit 7 or the output from the bottom dead center search unit 11. To determine. At this time, when there is an input signal from the bottom dead center search unit 11, the output determination unit 10 determines the phase to be energized by using the signal input from the bottom dead center search unit 11. On the other hand, when there is no input signal from the bottom dead center search unit 11, the output determination unit 10 determines the signal to be output based on the position information of the position detection unit 6 and the speed information of the speed detection unit 7.
　ここで、ブラシレスＤＣモータ５を駆動する駆動波形としては、例えば、矩形波および正弦波などがあるが、特に、限定されない。矩形波の場合、単純な構成、かつ計算が簡易であるため、安価なマイコンで対応できる。そのため、出力決定部１０を、低コストで実現できる。また、正弦波の場合、複雑な計算や電流検出などが必要となるが、より細かくモータの位置の検出が可能となる。そこで、本実施の形態においては、より低コストで実現可能な矩形波駆動を採用して、ブラシレスＤＣモータ５を駆動する。 Here, the drive waveform for driving the brushless DC motor 5 includes, for example, a rectangular wave and a sine wave, but is not particularly limited. In the case of a square wave, since it has a simple configuration and simple calculation, it can be handled by an inexpensive microcomputer. Therefore, the output determination unit 10 can be realized at low cost. Further, in the case of a sine wave, complicated calculation and current detection are required, but the position of the motor can be detected more finely. Therefore, in the present embodiment, the brushless DC motor 5 is driven by adopting a rectangular wave drive that can be realized at a lower cost.
　具体的には、本実施の形態では、モータ駆動装置３０は、１２０度通電の矩形波で駆動される。そのため、インバータ４の上側アームのスイッチング素子４ａ、４ｃ、４ｅに、それぞれ１２０度ずつ、ずらした駆動波形で通電している。同様に、インバータ４の下側アームのスイッチング素子４ｂ、４ｄ、４ｆにも、それぞれ１２０度ずつ、ずらした駆動波形で通電している。これにより、スイッチング素子４ａと４ｂ、４ｃと４ｄ、および、４ｅと４ｆは、それぞれ、互いの通電期間の間に、６０度ずつのオフ期間が存在することになる。 Specifically, in the present embodiment, the motor drive device 30 is driven by a rectangular wave energized at 120 degrees. Therefore, the switching elements 4a, 4c, and 4e of the upper arm of the inverter 4 are energized with a drive waveform shifted by 120 degrees, respectively. Similarly, the switching elements 4b, 4d, and 4f of the lower arm of the inverter 4 are also energized with a drive waveform shifted by 120 degrees, respectively. As a result, the switching elements 4a and 4b, 4c and 4d, and 4e and 4f each have an off period of 60 degrees between the energization periods of each other.
　ドライブ部９は、出力決定部１０で決定されるオン比率と、ブラシレスＤＣモータ５の電力供給タイミングと、予め決定されているＰＷＭ周期に基づいて、インバータ４のそれぞれのスイッチング素子に、ドライブ信号を出力する。 The drive unit 9 transmits a drive signal to each switching element of the inverter 4 based on the on ratio determined by the output determination unit 10, the power supply timing of the brushless DC motor 5, and the PWM cycle determined in advance. Output.
　ドライブ信号は、インバータ４のスイッチング素子４ａ～４ｆを、オンまたはオフする。これにより、ブラシレスＤＣモータ５の固定子５ｂに最適な交流電力が印加される。その結果、ブラシレスＤＣモータ５の回転子５ａが回転し、ピストン１７ｂが駆動される。 The drive signal turns on or off the switching elements 4a to 4f of the inverter 4. As a result, the optimum AC power is applied to the stator 5b of the brushless DC motor 5. As a result, the rotor 5a of the brushless DC motor 5 rotates, and the piston 17b is driven.
　以上のように、モータ駆動装置３０は構成される。 As described above, the motor drive device 30 is configured.
　つぎに、本実施の形態のモータ駆動装置３０を用いた冷蔵庫２２について、図１から図２Ｄを参照しながら、説明する。以下の説明では、冷蔵庫２２を例に説明するが、冷凍装置でも同じである。 Next, the refrigerator 22 using the motor drive device 30 of the present embodiment will be described with reference to FIGS. 1 to 2D. In the following description, the refrigerator 22 will be described as an example, but the same applies to the refrigerating apparatus.
　冷蔵庫２２は、圧縮機１７が搭載される。圧縮機１７は、レシプロ型で構成される。つまり、圧縮機１７は、ブラシレスＤＣモータ５、クランクシャフト１７ａ、ピストン１７ｂおよびシリンダ１７ｃなどを含む圧縮機構で構成される。ブラシレスＤＣモータ５の回転子５ａの回転運動は、クランクシャフト１７ａにより、往復運動に変換される。そして、クランクシャフト１７ａに接続されたピストン１７ｂは、シリンダ１７ｃ内を往復運動する。この往復動作により、シリンダ１７ｃ内に冷媒が吸い込まれ、吸い込んだ冷媒が圧縮される。 The refrigerator 22 is equipped with a compressor 17. The compressor 17 is composed of a reciprocating type. That is, the compressor 17 is composed of a compression mechanism including a brushless DC motor 5, a crankshaft 17a, a piston 17b, a cylinder 17c, and the like. The rotary motion of the rotor 5a of the brushless DC motor 5 is converted into a reciprocating motion by the crankshaft 17a. Then, the piston 17b connected to the crankshaft 17a reciprocates in the cylinder 17c. By this reciprocating operation, the refrigerant is sucked into the cylinder 17c, and the sucked refrigerant is compressed.
　なお、レシプロ型の圧縮機１７は、吸入ステップおよび圧縮ステップにおいて、トルクの変動が大きく、速度および電流値が大きく変動する。 In the reciprocating compressor 17, the torque fluctuates greatly in the suction step and the compression step, and the speed and the current value fluctuate greatly.
　圧縮機１７で圧縮された冷媒は、凝縮器１９、二方弁１８、減圧器２０および蒸発器２１を順に通って、再び、圧縮機１７に戻るという冷凍サイクルを流れる。このとき、凝縮器１９では放熱が行われ、蒸発器２１では吸熱が行われる。これにより、冷蔵庫２２内の冷却および加熱を行うことができる。つまり、冷蔵庫２２は、上記冷凍サイクルを実現する圧縮機１７を搭載して構成される。 The refrigerant compressed by the compressor 17 passes through the condenser 19, the two-way valve 18, the decompressor 20, and the evaporator 21 in this order, and returns to the compressor 17 in a refrigerating cycle. At this time, heat is dissipated in the condenser 19, and heat is absorbed in the evaporator 21. As a result, the inside of the refrigerator 22 can be cooled and heated. That is, the refrigerator 22 is configured by mounting the compressor 17 that realizes the refrigeration cycle.
　二方弁１８は、通電によって開閉動作が可能な電磁弁などが用いられる。二方弁１８は、圧縮機１７の運転中において、開状態とし、凝縮器１９と減圧器２０とを連通させて、冷媒を流す。一方、圧縮機１７の停止中において、二方弁１８を閉状態とし、凝縮器１９と減圧器２０の間を閉塞させて、冷媒が流れないようにする。 As the two-way valve 18, an electromagnetic valve or the like that can be opened and closed by energization is used. The two-way valve 18 is opened during the operation of the compressor 17, and the condenser 19 and the decompressor 20 are communicated with each other to allow the refrigerant to flow. On the other hand, while the compressor 17 is stopped, the two-way valve 18 is closed and the space between the condenser 19 and the decompressor 20 is closed to prevent the refrigerant from flowing.
　以上のように、モータ駆動装置３０を用いた冷蔵庫２２は構成される。 As described above, the refrigerator 22 using the motor drive device 30 is configured.
　［１－２．動作］
　以上のように構成された冷蔵庫２２に搭載されたモータ駆動装置３０の動作について、図２Ａ～図４Ｃを用いて説明する。 [1-2. motion]
The operation of the motor drive device 30 mounted on the refrigerator 22 configured as described above will be described with reference to FIGS. 2A to 4C.
　図３Ａ～図４Ｃにおいて、横軸は時間を表し、縦軸はピストン１７ｂの往復方向と垂直、かつブラシレスＤＣモータ５の回転軸と垂直の方向の振動振幅を表している。 In FIGS. 3A to 4C, the horizontal axis represents time, and the vertical axis represents the vibration amplitude in the direction perpendicular to the reciprocating direction of the piston 17b and perpendicular to the rotation axis of the brushless DC motor 5.
　図２Ａに示すピストン１７ｂが下死点からブラシレスＤＣモータ５の回転子５ａが正転（時計回り）した場合、図２Ｂに示すように、ピストン１７ｂの上昇に伴い、シリンダ１７ｃの容積が減少する。これにより、シリンダ１７ｃ内に吸い込まれた冷媒が圧縮される。そこから、回転子５ａが、さらに回転すると、シリンダ１７ｃ内の冷媒の圧力が、凝縮器側の圧力まで上昇する。そして、冷媒の圧力が凝縮器側の圧力まで上昇すると、図２Ｃに示すように、冷媒を吐き出しながら、ピストン１７ｂが上死点へと到達する。これにより、シリンダ１７ｃの圧縮された冷媒の吐出が完了する。その後、さらに回転子５ａが回転すると、図２Ｄに示すように、ピストン１７ｂが下死点方向に移動する。これにより、シリンダ１７ｃ内の容積が増加し、蒸発器２１から低圧の冷媒が吸い込まれる。そして、さらに回転子５ａが回転すると、再び、ピストン１７ｂが図２Ａに示す下死点に到達し、シリンダ１７ｃ内の冷媒の圧縮が始まる。以上により、冷媒の吐出および吸引の動作が、繰り返し実行される。 When the rotor 5a of the brushless DC motor 5 rotates forward (clockwise) from the bottom dead center of the piston 17b shown in FIG. 2A, the volume of the cylinder 17c decreases as the piston 17b rises, as shown in FIG. 2B. .. As a result, the refrigerant sucked into the cylinder 17c is compressed. When the rotor 5a further rotates from there, the pressure of the refrigerant in the cylinder 17c rises to the pressure on the condenser side. Then, when the pressure of the refrigerant rises to the pressure on the condenser side, as shown in FIG. 2C, the piston 17b reaches the top dead center while discharging the refrigerant. As a result, the discharge of the compressed refrigerant in the cylinder 17c is completed. After that, when the rotor 5a further rotates, the piston 17b moves toward the bottom dead center direction as shown in FIG. 2D. As a result, the volume inside the cylinder 17c increases, and the low-pressure refrigerant is sucked from the evaporator 21. Then, when the rotor 5a further rotates, the piston 17b reaches the bottom dead center shown in FIG. 2A again, and compression of the refrigerant in the cylinder 17c begins. As described above, the operations of discharging and sucking the refrigerant are repeatedly executed.
　一方、図２Ａに示す下死点の状態から図２Ｄで示す状態へと、逆転（反時計回り）した場合においても、上記時計回りと同様に、シリンダ１７ｃの容積は減少して、冷媒が圧縮される。そして、図２Ｃで示す上死点へとピストン１７ｂが到達するまでに、冷媒の圧縮が行われる。さらに、図２Ｃの状態からピストン１７ｂが逆転すると、図２Ｂに示す状態となる。これにより、図２Ｃに示す冷媒の吐出が完了した状態から、シリンダ１７ｃ内へ冷媒が吸い込まれる。その後、さらにピストン１７ｂの逆転が継続されると、図２Ａに示す下死点まで、シリンダ１７ｃ内への冷媒の吸入が継続される。そして、下死点から上死点に向かってピストン１７ｂが移動する際に、冷媒が圧縮されることとなる。 On the other hand, even when the state of the bottom dead center shown in FIG. 2A is reversed (counterclockwise) to the state shown in FIG. 2D, the volume of the cylinder 17c is reduced and the refrigerant is compressed as in the clockwise direction. Will be done. Then, the refrigerant is compressed by the time the piston 17b reaches the top dead center shown in FIG. 2C. Further, when the piston 17b is reversed from the state shown in FIG. 2C, the state shown in FIG. 2B is obtained. As a result, the refrigerant is sucked into the cylinder 17c from the state in which the discharge of the refrigerant shown in FIG. 2C is completed. After that, when the reversal of the piston 17b is continued, the suction of the refrigerant into the cylinder 17c is continued until the bottom dead center shown in FIG. 2A. Then, when the piston 17b moves from the bottom dead center to the top dead center, the refrigerant is compressed.
　つまり、レシプロ型である圧縮機１７は、回転子５ａが正転、あるいは逆転でも、ピストン１７ｂは、同様に、シリンダ１７ｃ内を往復運動する。そのため、ピストン１７ｂが下死点の状態から正転、あるいは逆転方向に回転した場合、同様に、冷媒の圧縮・吐出ステップが実行される。また、ピストン１７ｂが上死点の状態から正転、あるいは逆転方向に回転した場合、同様に、ピストン１７ｂ内に冷媒を吸い込む吸入ステップが実行される。 That is, in the reciprocating compressor 17, even if the rotor 5a rotates in the forward direction or in the reverse direction, the piston 17b reciprocates in the cylinder 17c in the same manner. Therefore, when the piston 17b rotates in the forward or reverse direction from the bottom dead center state, the refrigerant compression / discharge step is similarly executed. Further, when the piston 17b rotates in the forward or reverse direction from the top dead center state, the suction step of sucking the refrigerant into the piston 17b is similarly executed.
　つまり、蒸発器２１と凝縮器１９との間に圧力差がある状態においては、ピストン１７ｂを上死点方向に動かすには、大きなトルクが必要となる。一方、下死点方向にピストン１７ｂを動かす場合、わずかなトルクでの動作が可能となる。 That is, when there is a pressure difference between the evaporator 21 and the condenser 19, a large torque is required to move the piston 17b toward the top dead center. On the other hand, when the piston 17b is moved in the direction of bottom dead center, it can be operated with a small amount of torque.
　そこで、本実施の形態のモータ駆動装置３０は、上記特性を利用して、まず、下死点探索部１１は、上死点から下死点へと正転方向に１８０度回転させるパターンを、ブラシレスＤＣモータ５に出力する。その後、下死点探索部１１は、逆転方向に、同様に、上死点から下死点へと１８０度回転させるパターンを、ブラシレスＤＣモータ５に出力する。一方、トルク決定部１２は、下死点探索部１１で下死点探索を行っている際のトルクを予め決定している。つまり、トルク決定部１２は、冷蔵庫２２の庫内が十分に冷却された状態で停止した際の圧力条件で停止し、起動した際に、ピストン１７ｂの回転子５ａが下死点から６０度未満しか圧縮方向に回転しないトルクに決定している。 Therefore, the motor drive device 30 of the present embodiment utilizes the above characteristics, and first, the bottom dead center search unit 11 sets a pattern of rotating 180 degrees in the normal rotation direction from the top dead center to the bottom dead center. Output to the brushless DC motor 5. After that, the bottom dead center search unit 11 outputs a pattern of rotating 180 degrees from the top dead center to the bottom dead center in the reverse direction to the brushless DC motor 5. On the other hand, the torque determination unit 12 determines in advance the torque when the bottom dead center search unit 11 is performing the bottom dead center search. That is, the torque determination unit 12 is stopped under the pressure condition when the inside of the refrigerator 22 is sufficiently cooled, and when the refrigerator 22 is started, the rotor 5a of the piston 17b is less than 60 degrees from the bottom dead center. Only the torque that rotates in the compression direction is determined.
　例えば、ピストン１７ｂの停止位置が上死点の手前であれば、トルク決定部１２で決定したトルクは、圧縮方向であるため、正転方向へ回転できない。しかし、次の逆転方向に１８０度回転させる場合は、吸入ステップであるため、トルクがほぼ必要ない。そのため、トルク決定部１２で決定した小さなトルクでも、ピストン１７ｂを下死点方向へ回転させ、下死点へと移動させることができる。 For example, if the stop position of the piston 17b is before the top dead center, the torque determined by the torque determination unit 12 cannot rotate in the forward rotation direction because it is in the compression direction. However, when rotating 180 degrees in the next reverse direction, torque is almost unnecessary because it is a suction step. Therefore, even with a small torque determined by the torque determination unit 12, the piston 17b can be rotated in the bottom dead center direction and moved to the bottom dead center.
　一方、ピストン１７ｂが上死点を乗り越えたところで停止していた場合、ピストン１７ｂを正転方向に上死点から１８０度回転させる場合、吸入ステップで、回転が可能である。そのため、ピストン１７ｂは、下死点まで移動する。しかし、逆転方向では、下死点から６０度の位置まで回転して、ピストン１７ｂが停止する。そして、最後に、出力決定部１０で、下死点に相当する位相を出力する。これにより、下死点付近にある回転子５ａは、ピストン１７ｂが下死点に移動する位置まで回転する。つまり、出力決定部１０が下死点に相当する位相を出力した場合、ピストン１７ｂは、下死点に近い方向に回転する。例えば、本実施の形態のように４極構成のブラシレスＤＣモータ５の場合、上死点と下死点に移動するための位相が、同じ位相となる。しかし、ピストン１７ｂは、下死点の方に近い位置にあるため、下死点側に移動することとなる。また、６極構成のブラシレスＤＣモータ５の場合、下死点と同じ位相は、下死点から１２０度、上死点方向に回転した位置となる。そのため、回転子５ａは、６０度未満までしか回転していないので、ピストン１７ｂは、下死点方向に移動する。さらに、８極構成のブラシレスＤＣモータ５の場合、下死点からの回転可能な範囲を４５度未満とするトルクを印加することにより、上記下死点方向への移動が可能となる。さらに大きな極数に関しては、回転子５ａの回転の範囲、３６０を極数で割った値、未満とする。これにより、同様に、上記下死点方向への、ピストン１７ｂの移動が可能となる。 On the other hand, when the piston 17b is stopped when it has passed the top dead center, and when the piston 17b is rotated 180 degrees from the top dead center in the forward rotation direction, the rotation is possible in the suction step. Therefore, the piston 17b moves to the bottom dead center. However, in the reverse direction, the piston 17b rotates to a position of 60 degrees from the bottom dead center and stops. Finally, the output determination unit 10 outputs the phase corresponding to the bottom dead center. As a result, the rotor 5a near the bottom dead center rotates to a position where the piston 17b moves to the bottom dead center. That is, when the output determination unit 10 outputs a phase corresponding to the bottom dead center, the piston 17b rotates in a direction close to the bottom dead center. For example, in the case of the brushless DC motor 5 having a 4-pole configuration as in the present embodiment, the phases for moving to the top dead center and the bottom dead center are the same. However, since the piston 17b is located near the bottom dead center, it moves to the bottom dead center side. Further, in the case of the brushless DC motor 5 having a 6-pole configuration, the same phase as the bottom dead center is a position rotated 120 degrees from the bottom dead center in the direction of the top dead center. Therefore, since the rotor 5a rotates only to less than 60 degrees, the piston 17b moves in the bottom dead center direction. Further, in the case of the brushless DC motor 5 having an 8-pole configuration, it is possible to move in the direction of the bottom dead center by applying a torque that makes the rotatable range from the bottom dead center less than 45 degrees. For a larger number of poles, the range of rotation of the rotor 5a is less than the value obtained by dividing 360 by the number of poles. As a result, the piston 17b can be similarly moved in the direction of the bottom dead center.
　ここで、圧縮機１７は、振動の発生の要因として、運転開始の際に生じる振動がある。また、圧縮機１７は、運転開始後、圧縮から吐出が完了し、吸入へと切り替わる動作において、トルクが急激に減少するために加速が発生し、振動が発生する場合がある。ブラシレスＤＣモータ５の回転子５ａの運動エネルギは、角速度の２乗に比例する。そのため、回転子５ａの速度が低いほど、速度の低下と上昇が大きくなるので、発生する振動が大きくなる。 Here, the compressor 17 has vibration generated at the start of operation as a factor of vibration generation. Further, in the operation of switching from compression to discharge and switching to suction after the start of operation of the compressor 17, acceleration may occur due to a rapid decrease in torque, and vibration may occur. The kinetic energy of the rotor 5a of the brushless DC motor 5 is proportional to the square of the angular velocity. Therefore, the lower the speed of the rotor 5a, the larger the decrease and increase in the speed, and the larger the vibration generated.
　一方、圧縮機１７は、吸入と吐出の圧力差がある起動において、大きなトルクがかかっている。そのため、回転子５ａの速度を上げて、運動エネルギを大きくすることにより、運転開始から通常運転を行う速度までに発生する振動は、ある程度抑制できる。しかし、圧縮機１７の運転の開始から上死点を、初めて乗り越えた際には、回転子５ａの速度が最も低くなるため、最も振動が発生しやすい。 On the other hand, the compressor 17 is subjected to a large torque at the start when there is a pressure difference between suction and discharge. Therefore, by increasing the speed of the rotor 5a and increasing the kinetic energy, the vibration generated from the start of operation to the speed at which normal operation is performed can be suppressed to some extent. However, when the top dead center is exceeded for the first time from the start of operation of the compressor 17, the speed of the rotor 5a is the lowest, so that vibration is most likely to occur.
　さらに、回転子５ａは、クランクシャフト１７ａが連結されている。そのため、ピストン１７ｂが下死点から回転を開始した際、イナーシャにより、ピストン１７ｂの往復方向と垂直、かつブラシレスＤＣモータ５の回転軸と垂直の方向に、振動が発生する。また、ピストン１７ｂが上死点を乗り越えた際、急激な加速が発生する。そのため、イナーシャにより、ピストン１７ｂの往復方向と垂直、かつブラシレスＤＣモータ５の回転軸と垂直の方向に、振動が発生する。この場合、下死点から起動と同様に、加速により発生する振動のため、ピストン１７ｂの下死点および上死点から回転子５ａの回転方向に対して発生する振動は、同じ方向である。しかし、圧縮機１７から見た場合、クランクシャフト１７ａは、回転子５ａの回転軸を中心に対称の位置となるため、発生する振動は、逆方向となる。 Further, the crankshaft 17a is connected to the rotor 5a. Therefore, when the piston 17b starts rotating from the bottom dead center, vibration is generated by the inertia in the direction perpendicular to the reciprocating direction of the piston 17b and the direction perpendicular to the rotation axis of the brushless DC motor 5. Further, when the piston 17b gets over the top dead center, sudden acceleration occurs. Therefore, the inertia causes vibration in the direction perpendicular to the reciprocating direction of the piston 17b and in the direction perpendicular to the rotation axis of the brushless DC motor 5. In this case, since the vibration is generated by acceleration as in the case of starting from the bottom dead center, the vibration generated from the bottom dead center of the piston 17b and the rotation direction of the rotor 5a from the top dead center is in the same direction. However, when viewed from the compressor 17, the crankshaft 17a is located symmetrically with respect to the rotation axis of the rotor 5a, so that the generated vibration is in the opposite direction.
　以下、上記振動の発生について、図３Ａおよび図３Ｂを用いて、説明する。 Hereinafter, the generation of the above vibration will be described with reference to FIGS. 3A and 3B.
　図３Ａは、ピストン１７ｂの下死点からの運転開始時に発生する振動を表す図である。図３Ｂは、ピストン１７ｂの上死点を乗り越えた際に発生する振動を表す図である。つまり、図３Ａおよび図３Ｂに示すように、ピストン１７ｂの下死点からの回転と、ピストン１７ｂの上死点からの回転において、振動発生開始の方向は、逆の位相となる。 FIG. 3A is a diagram showing vibration generated at the start of operation from the bottom dead center of the piston 17b. FIG. 3B is a diagram showing vibration generated when the top dead center of the piston 17b is exceeded. That is, as shown in FIGS. 3A and 3B, the directions of vibration generation start are opposite in the rotation from the bottom dead center of the piston 17b and the rotation from the top dead center of the piston 17b.
　そこで、トルク決定部１２では、ピストン１７ｂの下死点からの起動した際の振動の周期のタイミングで、上死点を乗り越えるようにトルクを決定する。このとき、ピストン１７ｂの下死点からの起動の振動の周期は、圧縮機１７を構成する部品の複合的な固有振動によって決定される。なお、固有振動は、予め、例えばハンマリング試験などで調べておく。 Therefore, the torque determination unit 12 determines the torque so as to overcome the top dead center at the timing of the vibration cycle when the piston 17b is started from the bottom dead center. At this time, the period of vibration of the start from the bottom dead center of the piston 17b is determined by the complex natural vibration of the parts constituting the compressor 17. The natural vibration is examined in advance by, for example, a hammering test.
　また、到達までの時間は、圧縮機１７の圧縮仕事と、ブラシレスＤＣモータ５に発生するトルクと、回転子５ａおよび回転子５ａに連結された部品のイナーシャに基づいて、計算する。このとき、イナーシャは固定（一定）で、圧縮機１７の圧縮仕事は変化する。一方、ブラシレスＤＣモータ５に発生するトルクは、冷蔵庫２２の庫内が十分に冷却された状態の通常運転範囲において、中央となる負荷条件の選択により決定できる。具体的には、選択した負荷条件で、予め、ブラシレスＤＣモータ５にかかるトルクを計算し、保持する。これにより、トルクをリアルタイムで計算する制御系の負荷を、軽減できる。そのため、性能の低いマイコンでも、上記到達までの時間を容易に計算できる。その結果、制御系に関するコストを、低減できる。 The time to reach is calculated based on the compression work of the compressor 17, the torque generated in the brushless DC motor 5, and the inertia of the rotor 5a and the parts connected to the rotor 5a. At this time, the inertia is fixed (constant), and the compression work of the compressor 17 changes. On the other hand, the torque generated in the brushless DC motor 5 can be determined by selecting the central load condition in the normal operation range in a state where the inside of the refrigerator 22 is sufficiently cooled. Specifically, the torque applied to the brushless DC motor 5 is calculated and held in advance under the selected load condition. As a result, the load on the control system that calculates the torque in real time can be reduced. Therefore, even with a low-performance microcomputer, the time required to reach the above can be easily calculated. As a result, the cost related to the control system can be reduced.
　そして、上記の方法で予め決定したトルクにより、ピストン１７ｂを下死点から起動した際の振動である図３Ａの波形と、上死点を乗り越えた際の振動である図３Ｂの波形は、タイミング（イ）に示すように、振動周期の開始位置が一致し、逆位相となる。そのため、図３Ａの振動と図３Ｂの振動が、互いに打ち消し合う。これにより、図３Ｃに示すように、運転開始時の振動と、上死点を乗り越えた時の振動の合成の振動が、図３Ａに示す起動時の振動のピークと比較して、約５０％程度まで、抑制される。 Then, the waveform of FIG. 3A, which is the vibration when the piston 17b is started from the bottom dead center, and the waveform of FIG. 3B, which is the vibration when the piston 17b is overcome by the torque determined in advance by the above method, are the timings. As shown in (a), the start positions of the vibration cycles coincide with each other, and the phases are opposite to each other. Therefore, the vibration of FIG. 3A and the vibration of FIG. 3B cancel each other out. As a result, as shown in FIG. 3C, the combined vibration of the vibration at the start of operation and the vibration when the top dead center is exceeded is about 50% as compared with the peak of the vibration at the start shown in FIG. 3A. To a degree, it is suppressed.
　なお、冷蔵庫２２の状態が変化した場合、一定のトルクでは、振動の周期が一致しない。しかし、冷蔵庫が十分冷却された状態での負荷は、電源投入時と比較して変化が小さく、振動位相の変化は、±３０度以内に収まる。 When the state of the refrigerator 22 changes, the vibration cycles do not match at a constant torque. However, the load when the refrigerator is sufficiently cooled has a small change as compared with when the power is turned on, and the change in the vibration phase is within ± 30 degrees.
　上記状態について、図４Ａから図４Ｃを用いて、説明する。 The above state will be described with reference to FIGS. 4A to 4C.
　図４Ａは、図３Ａと同様に、ピストン１７ｂを下死点から起動した際の振動振幅を表す図である。図４Ｂは、ピストン１７ｂが上死点を乗り越えた際の振動を表す図である。なお、図４Ｂは、運転開始の振動の周期から位相が、＋３０度遅れた際の波形を表している。図４Ｃは、図４Ａと図４Ｂの合成の振動波形を表す図である。 FIG. 4A is a diagram showing the vibration amplitude when the piston 17b is started from the bottom dead center, as in FIG. 3A. FIG. 4B is a diagram showing vibration when the piston 17b gets over the top dead center. Note that FIG. 4B shows a waveform when the phase is delayed by +30 degrees from the vibration cycle at the start of operation. FIG. 4C is a diagram showing a combined vibration waveform of FIGS. 4A and 4B.
　つまり、冷蔵庫２２が温まり、負荷状態が重くなると、図４Ｂに示すように、ピストン１７ｂの上死点までの到達の時間が遅れ、位相がずれる。一方、冷蔵庫２２が冷却され、負荷状態が軽くなると、ピストン１７ｂの上死点までの到達の時間が早くなる。そのため、上記位相が、マイナス側にずれることとなる。 That is, when the refrigerator 22 becomes warm and the load state becomes heavy, as shown in FIG. 4B, the time to reach the top dead center of the piston 17b is delayed and the phase shifts. On the other hand, when the refrigerator 22 is cooled and the load state is lightened, the time to reach the top dead center of the piston 17b becomes faster. Therefore, the above phase shifts to the minus side.
　例えば、図４Ａのタイミング（ロ）が示すように、ピストン１７ｂが上死点を乗り越えた際の振動の開始が、３０度ずれている。しかしながら、位相のずれが３０度でも、図４Ｃに示すように、図４Ａの振動のピークの６割程度の振動ピーク値となる。そのため、位相のずれが発生しても、十分な振動の抑制効果が得ることができる。 For example, as shown by the timing (b) in FIG. 4A, the start of vibration when the piston 17b crosses the top dead center is shifted by 30 degrees. However, even if the phase shift is 30 degrees, as shown in FIG. 4C, the vibration peak value is about 60% of the vibration peak in FIG. 4A. Therefore, even if the phase shift occurs, a sufficient vibration suppressing effect can be obtained.
　以下、モータ駆動装置３０の下死点探索部１１が、下死点を探す制御の詳細に関して、図５を用いて、説明する。 Hereinafter, the details of the control in which the bottom dead center search unit 11 of the motor drive device 30 searches for the bottom dead center will be described with reference to FIG.
　図５は、下死点探索部１１が下死点を探すフローチャートである。 FIG. 5 is a flowchart in which the bottom dead center search unit 11 searches for the bottom dead center.
　図５に示すように、まず、下死点探索部１１は、前回この処理に入ってきたときの外部から入力される目標速度が０（ゼロ）であったか否かを確認する（ＳＴＥＰ２０１）。このとき、目標速度が０（ゼロ）ならば（ＳＴＥＰ２０１のＹｅｓ）、ＳＴＥＰ２０２へ、目標速度が０（ゼロ）以外ならば（ＳＴＥＰ２０１のＮｏ）、ＳＴＥＰ２０３へ移行する。ここでは、前回の目標速度が０（ゼロ）であるとして、ＳＴＥＰ２０２へ移行する。 As shown in FIG. 5, first, the bottom dead center search unit 11 confirms whether or not the target speed input from the outside when entering this process last time was 0 (zero) (STEP201). At this time, if the target speed is 0 (zero) (Yes in STEP201), the process proceeds to STEP202, and if the target speed is other than 0 (zero) (No in STEP201), the process proceeds to STEP203. Here, assuming that the previous target speed is 0 (zero), the process proceeds to STEP202.
　つぎに、現在の外部から入力される目標速度が、０以外か否かを確認する（ＳＴＥＰ２０２）。このとき、目標速度が０以外であれば（ＳＴＥＰ２０２のＹｅｓ）、ＳＴＥＰ２０４へ、目標速度が０であれば（ＳＴＥＰ２０１のＮｏ）、ＳＴＥＰ２０３へ移行する。つまり、前回の処理から今回の処理の間に、停止状態から起動するように目標速度が変化したか否かを、判定している。ここでは、現在の目標速度が０以外であるとして、ＳＴＥＰ２０４へ移行する。 Next, check whether the current target speed input from the outside is other than 0 (STEP202). At this time, if the target speed is other than 0 (Yes in STEP202), the process proceeds to STEP204, and if the target speed is 0 (No in STEP201), the process proceeds to STEP203. That is, it is determined whether or not the target speed has changed so as to start from the stopped state between the previous process and the current process. Here, assuming that the current target speed is other than 0, the process proceeds to STEP204.
　つぎに、下死点探索部１１は、下死点探索のために回転子５ａを、どれだけ回転させたかを記録する位相変更量に０（ゼロ）をセットし、現在の出力位相を上死点であるとして初期化する（ＳＴＥＰ２０４）。 Next, the bottom dead center search unit 11 sets 0 (zero) to the phase change amount for recording how much the rotor 5a is rotated for bottom dead center search, and sets the current output phase to top dead center. Initialize as a point (STEP204).
　つぎに、下死点探索部１１は、下死点探索のために回転子５ａを回転させた量である位相変更量が１８０未満か否を判定する（ＳＴＥＰ２０５）。このとき、位相変更量が１８０未満であれば（ＳＴＥＰ２０５のＹｅｓ）、ＳＴＥＰ２０６へ、位相変更量が１８０以上ならば（ＳＴＥＰ２０５のＮｏ）、ＳＴＥＰ２０７へ移行する。 Next, the bottom dead center search unit 11 determines whether or not the phase change amount, which is the amount obtained by rotating the rotor 5a for bottom dead center search, is less than 180 (STEP205). At this time, if the phase change amount is less than 180 (Yes in STEP205), the process proceeds to STEP206, and if the phase change amount is 180 or more (No in STEP205), the process proceeds to STEP207.
　つぎに、現在の出力位相から３０度正転方向に回転した位相を新たな出力位相として出力する（ＳＴＥＰ２０６）。さらに、下死点探索部１１で回転子５ａをどれだけ回転させたかを記録した位相変更量に回転させた角度と等しい３０を加算する（ＳＴＥＰ２０６）。そして、１００ｍｓ待機した後、ＳＴＥＰ２０５へ移行する。なお、１００ｍｓの待機は、回転子５ａが確実に回転する時間を待っている時間である。なお、この待機時間には、実際に動作を確認しながら、予め決定した値を利用する。 Next, the phase rotated 30 degrees in the forward rotation direction from the current output phase is output as a new output phase (STEP206). Further, 30 which is equal to the rotated angle is added to the phase change amount recorded by how much the rotor 5a is rotated by the bottom dead center search unit 11 (STEP206). Then, after waiting for 100 ms, the process proceeds to STEP205. The waiting time of 100 ms is the time waiting for the rotor 5a to rotate reliably. For this waiting time, a predetermined value is used while actually checking the operation.
　そして、ＳＴＥＰ２０５とＳＴＥＰ２０６を、それぞれ、６回実行する。その後、ＳＴＥＰ２０５へ戻ってきた際には、位相変更量は１８０となっているため（ＳＴＥＰ２０５のＮｏ）、ＳＴＥＰ２０５からＳＴＥＰ２０７へ移行する。 Then, STEP205 and STEP206 are executed 6 times each. After that, when returning to STEP205, the phase change amount is 180 (No of STEP205), so the process shifts from STEP205 to STEP207.
　また、ＳＴＥＰ２０４からＳＴＥＰ２０６を実行し、ＳＴＥＰ２０７へ移行するまでに、上死点から１８０度回転する位相が出力される。このとき、クランクシャフト１７ａと回転子５ａの連結部が、上死点から正転時方向の下死点の間にある場合、正転は、吸入ステップに対応する。そのため、微小なトルクでも、正転方向に回転子５ａを回転させることが可能となる。これにより、下死点までピストン１７ｂが移動する。一方、クランクシャフト１７ａと回転子５ａの連結部が、下死点から正転方向の上死点の間にある場合、圧縮・吐出ステップに対応する。そのため、ピストン１７ｂが下死点付近にある場合を除き、ほとんど正転方向に回転することができない。これにより、ピストン１７ｂは、下死点から上死点の間にとどまることとなる。 Also, by executing STEP204 to STEP206 and shifting to STEP207, the phase rotated 180 degrees from the top dead center is output. At this time, when the connecting portion between the crankshaft 17a and the rotor 5a is between the top dead center and the bottom dead center in the normal rotation direction, the normal rotation corresponds to the suction step. Therefore, it is possible to rotate the rotor 5a in the forward rotation direction even with a small torque. As a result, the piston 17b moves to the bottom dead center. On the other hand, when the connecting portion between the crankshaft 17a and the rotor 5a is between the bottom dead center and the top dead center in the normal rotation direction, it corresponds to the compression / discharge step. Therefore, except when the piston 17b is near the bottom dead center, it can hardly rotate in the forward rotation direction. As a result, the piston 17b stays between the bottom dead center and the top dead center.
　なお、本実施の形態では、ブラシレスＤＣモータ５を、４極、かつ１２０度の矩形波で駆動する構成としたので、出力位相の変更量を３０度回転するとしている。これは、１２０度の矩形波は、電気的には、６０度ずつ位相を変更することに相当し、６種類の出力パターンで１回転となる。また、ブラシレスＤＣモータ５は、４極構成であるため、回転子の１回転で、電気的に３６０度を極対数と等しい２周期を出力することとなる。つまり、１２０度の矩形波の出力位相変更は、回転子の角度に直すと、３０度となるためである。一方、６極構成であれば、回転子が１回転するためには、電気的に３６０度を極対数と等しい３周期出力することとなる。そのため、出力位相の１回の変更に対して、回転子は、２０度回転することとなる。つまり、図５に示すＳＴＥＰ２０６の変更量は、３６０を、モータの極対数と転流パターンの数６で除算した結果となる。 In the present embodiment, since the brushless DC motor 5 is driven by a rectangular wave of 4 poles and 120 degrees, the amount of change in the output phase is rotated by 30 degrees. This corresponds to electrically changing the phase of a 120-degree square wave by 60 degrees, and makes one rotation with six types of output patterns. Further, since the brushless DC motor 5 has a 4-pole configuration, one rotation of the rotor electrically outputs 360 degrees in two cycles equal to the logarithm of the poles. That is, the output phase change of the 120-degree rectangular wave becomes 30 degrees when converted to the rotor angle. On the other hand, in the case of the 6-pole configuration, in order for the rotor to make one rotation, 360 degrees is electrically output for 3 cycles equal to the logarithm of the poles. Therefore, the rotor rotates 20 degrees for one change of the output phase. That is, the amount of change in STEP 206 shown in FIG. 5 is the result of dividing 360 by the number of pole pairs of the motor and the number of commutation patterns 6.
　つぎに、下死点探索部１１が下死点探索のために回転子５ａを逆転でどれだけ回転したかを記録するために、位相変更量を０にセットし、現在の出力位相を上死点であるとして、初期化をする（ＳＴＥＰ２０７）。 Next, in order to record how much the rotor 5a is rotated in reverse for the bottom dead center search unit 11, the phase change amount is set to 0 and the current output phase is top dead. As a point, initialization is performed (STEP207).
　つぎに、下死点探索部１１が下死点探索のために回転子５ａを逆転でどれだけ回転したかを記録した位相変更量が１８０未満か否かを判定する（ＳＴＥＰ２０８）。位相変更量が１８０未満であれば（ＳＴＥＰ２０８のＹｅｓ）、ＳＴＥＰ２０９へ、位相変更量が１８０以上であれば（ＳＴＥＰ２０８のＮｏ）、ＳＴＥＰ２１０へ移行する。ここでは、ＳＴＥＰ２０７で位相変更量を０に初期化した直後なので、ＳＴＥＰ２０９へ移行する。 Next, the bottom dead center search unit 11 determines whether or not the phase change amount, which records how much the rotor 5a is rotated in reverse for the bottom dead center search, is less than 180 (STEP208). If the phase change amount is less than 180 (Yes in STEP208), the process proceeds to STEP209, and if the phase change amount is 180 or more (No in STEP208), the process proceeds to STEP210. Here, since it is immediately after the phase change amount is initialized to 0 in STEP 207, the process shifts to STEP 209.
　つぎに、現在の出力位相から３０度逆転方向に回転した位相を新たな出力位相として出力する（ＳＴＥＰ２０９）。さらに、下死点探索部１１で回転子５ａをどれだけ逆方向に回転させたかを記録した位相変更量に回転させた角度と等しい３０を加算する（ＳＴＥＰ２０９）。そして、１００ｍｓ待機した後、ＳＴＥＰ２０８へ移行する。 Next, the phase rotated 30 degrees in the reverse direction from the current output phase is output as a new output phase (STEP209). Further, 30 equal to the rotation angle is added to the phase change amount recorded by the bottom dead center search unit 11 how much the rotor 5a is rotated in the opposite direction (STEP 209). Then, after waiting for 100 ms, the process proceeds to STEP208.
　そして、ＳＴＥＰ２０８とＳＴＥＰ２０９を、それぞれ、６回実行する。その後、ＳＴＥＰ２０５へ戻ってきた際には、位相変更量は１８０となっているため（ＳＴＥＰ２０８のＮｏ）、ＳＴＥＰ２０８からＳＴＥＰ２１０へ移行する。 Then, STEP208 and STEP209 are executed 6 times each. After that, when returning to STEP205, the phase change amount is 180 (No of STEP208), so the process shifts from STEP208 to STEP210.
　また、ＳＴＥＰ２０７からＳＴＥＰ２０９を実行し、ＳＴＥＰ２１０へ移行するまでに、上死点から逆転方向に１８０度回転する位相が出力される。このとき、クランクシャフト１７ａと回転子５ａの連結部が、上死点から逆転時方向の下死点の間にある場合、逆転では吸入ステップに対応する。つまり、正転方向の圧縮・吐出ステップで、ＳＴＥＰ２０４～ＳＴＥＰ２０６において、ピストンが下死点に移動していない場合、逆転では吸入ステップに対応する。そのため、微小なトルクでも、正転方向に回転子５ａを回転させることが可能となる。これにより、下死点までピストン１７ｂが移動する。一方、クランクシャフト１７ａと回転子５ａの連結部が、すでに下死点に移動している場合、圧縮・吐出ステップに対応する。そのため、ピストン１７ｂは、ほとんど逆方向に回転することができない。これにより、ピストン１７ｂは、下死点付近にとどまることとなる。 Also, by executing STEP 207 to STEP 209 and shifting to STEP 210, a phase that rotates 180 degrees in the reverse direction from the top dead center is output. At this time, if the connecting portion between the crankshaft 17a and the rotor 5a is between the top dead center and the bottom dead center in the reverse rotation direction, the reverse rotation corresponds to the suction step. That is, in the compression / discharge step in the forward rotation direction, when the piston does not move to the bottom dead center in STEP204 to STEP206, the reverse rotation corresponds to the suction step. Therefore, it is possible to rotate the rotor 5a in the forward rotation direction even with a small torque. As a result, the piston 17b moves to the bottom dead center. On the other hand, when the connecting portion between the crankshaft 17a and the rotor 5a has already moved to the bottom dead center, it corresponds to the compression / discharge step. Therefore, the piston 17b can hardly rotate in the opposite direction. As a result, the piston 17b stays near the bottom dead center.
　つぎに、下死点付近にあるピストン１７ｂに、下死点に相当する位相を出力する（ＳＴＥＰ２１０）。これにより、ピストン１７ｂが、確実に下死点へと移動する。 Next, the phase corresponding to the bottom dead center is output to the piston 17b near the bottom dead center (STEP210). As a result, the piston 17b surely moves to the bottom dead center.
　つぎに、今回の目標速度を前回の目標速度として記録し、処理を終了する（ＳＴＥＰ２１１）。 Next, the current target speed is recorded as the previous target speed, and the process is completed (STEP211).
　なお、上記フローが終了後、再び、図５のフローの処理が開始された場合、まず、ＳＴＥＰ２０１における前回の目標速度が０（ゼロ）ではないため（ＳＴＥＰ２０１のＮｏ）、ＳＴＥＰ２０３へと移行する。 When the processing of the flow of FIG. 5 is started again after the above flow is completed, first, since the previous target speed in STEP201 is not 0 (zero) (No in STEP201), the process proceeds to STEP203.
　そして、ＳＴＥＰ２０３では、何も出力せず、ＳＴＥＰ２１１へ移行し、ＳＴＥＰ２１１において、目標速度を更新した後、処理を終了する。 Then, in STEP203, nothing is output, the process proceeds to STEP211 and the target speed is updated in STEP211, and then the process ends.
　また、冷蔵庫２２は、庫内が十分に冷却されると、冷凍サイクルを止める。そのため、目標速度が０（ゼロ）となる。この状態で、図５に示す処理を、再び実行すると、前回の目標速度が０（ゼロ）ではないため、図５に示す、ＳＴＥＰ２０１、ＳＴＥＰ２０３、ＳＴＥＰ２１１と、運転中のフローと同じ処理が実行される。そのため、ＳＴＥＰ２１１において、前回の目標速度を更新する際に、目標速度を０（ゼロ）として記録する。 Further, the refrigerator 22 stops the refrigeration cycle when the inside of the refrigerator is sufficiently cooled. Therefore, the target speed becomes 0 (zero). If the process shown in FIG. 5 is executed again in this state, the previous target speed is not 0 (zero), so STEP201, STEP203, STEP211 shown in FIG. 5 and the same process as the flow during operation are executed. To. Therefore, in STEP211, when the previous target speed is updated, the target speed is recorded as 0 (zero).
　そして、再度、図５に示すフローの処理が実行されると、ＳＴＥＰ２０１において、前回の目標速度が０（ゼロ）と記録されているため、ＳＴＥＰ２０２へと移行する。 Then, when the flow processing shown in FIG. 5 is executed again, the previous target speed is recorded as 0 (zero) in STEP201, so the process shifts to STEP202.
　さらに、ＳＴＥＰ２０２においては、今回の目標速度が０（ゼロ）であるため（ＳＴＥＰ２０２のＮｏ）、ＳＴＥＰ２０３を処理後、ＳＴＥＰ２１１へと移行する。つまり、ＳＴＥＰ２０３では、何も出力せず、ＳＴＥＰ２１１において、前回の目標速度が、再度、０（ゼロ）に更新される。 Furthermore, in STEP202, since the target speed this time is 0 (zero) (No in STEP202), after processing STEP203, the process shifts to STEP211. That is, in STEP 203, nothing is output, and in STEP 211, the previous target speed is updated to 0 (zero) again.
　以上のように、図５に示すフロー処理を定期的に呼び出して処理することにより、ブラシレスＤＣモータ５に流れる電流や誘起電圧を検出しない同期運転において、ピストン１７ｂを下死点へと移動させて、起動させることができる。これにより、圧縮機１７の吸入と吐出の圧力に差があっても、圧縮機１７で発生する振動のピークを抑制して、振動の低減が可能となる。 As described above, by periodically calling and processing the flow process shown in FIG. 5, the piston 17b is moved to the bottom dead center in the synchronous operation in which the current flowing through the brushless DC motor 5 and the induced voltage are not detected. , Can be activated. As a result, even if there is a difference between the suction and discharge pressures of the compressor 17, the peak of the vibration generated by the compressor 17 can be suppressed and the vibration can be reduced.
　つぎに、本実施の形態のモータ駆動装置３０を圧縮機１７に用いて、冷蔵庫２２に搭載した場合について、図１を参照しながら、説明する。 Next, a case where the motor drive device 30 of the present embodiment is used in the compressor 17 and mounted on the refrigerator 22 will be described with reference to FIG.
　まず、圧縮機１７の起動と同時に、二方弁１８を開状態とし、減圧器２０と凝縮器１９とを連通させる。なお、上記では、圧縮機１７の起動と同時に、二方弁１８を開状態にする例で説明としたが、時間的に多少前後しても問題とはならない。 First, at the same time as the compressor 17 is started, the two-way valve 18 is opened and the decompressor 20 and the condenser 19 are communicated with each other. In the above description, the example in which the two-way valve 18 is opened at the same time as the compressor 17 is started has been described, but there is no problem even if the time is slightly changed.
　つぎに、圧縮機１７の駆動が継続されると、凝縮器１９は高圧となる。一方、蒸発器２１は、減圧器２０で減圧されて、低圧となる。このとき、圧縮機１７の凝縮器１９につながる吐出側が高圧に、蒸発器２１につながる吸入側が低圧となる。 Next, when the compressor 17 continues to be driven, the condenser 19 becomes high pressure. On the other hand, the evaporator 21 is decompressed by the decompressor 20 to become a low pressure. At this time, the discharge side connected to the condenser 19 of the compressor 17 has a high pressure, and the suction side connected to the evaporator 21 has a low pressure.
　ここで、冷蔵庫２２の庫内温度が低下し、圧縮機１７を停止させた状況を想定する。この場合、二方弁１８を開状態で維持すると、徐々に、凝縮器１９と蒸発器２１との圧力が、バランスしていく。このとき、圧縮機１７の吸入側と吐出側との間の圧力差が０．０５ＭＰａ以下、すなわちバランスしたといえる状態になるまで、冷蔵庫２２のシステム構成にもよるが、１０分程度かかる。 Here, it is assumed that the temperature inside the refrigerator 22 drops and the compressor 17 is stopped. In this case, when the two-way valve 18 is maintained in the open state, the pressures of the condenser 19 and the evaporator 21 are gradually balanced. At this time, it takes about 10 minutes until the pressure difference between the suction side and the discharge side of the compressor 17 becomes 0.05 MPa or less, that is, a state in which it can be said that the compressor 17 is balanced, depending on the system configuration of the refrigerator 22.
　一方、圧縮機１７の停止と同時に、二方弁１８を開状態から閉状態に移行させると、凝縮器１９と蒸発器２１との圧力差が、ほぼ維持される、これにより、圧縮機１７の吸入側と吐出側に圧力差が残る。 On the other hand, when the two-way valve 18 is shifted from the open state to the closed state at the same time as the compressor 17 is stopped, the pressure difference between the condenser 19 and the evaporator 21 is almost maintained, whereby the compressor 17 A pressure difference remains between the suction side and the discharge side.
　ここで、冷蔵庫２２の庫内温度が上昇し、再び、圧縮機１７を起動させる際に、圧縮機１７の停止中に二方弁１８を閉めて、圧力差が保持された状態と、圧力がバランスした状態から起動させる場合とを比較する。この場合、二方弁１８を閉めて、圧力差を保持した状態で圧縮機１７を起動させる方が、凝縮器１９と蒸発器２１との間に、再び、圧力差を設けるための電力が小さくなる。そのため、冷蔵庫２２の省エネルギ化を実現できる。 Here, when the temperature inside the refrigerator 22 rises and the compressor 17 is started again, the two-way valve 18 is closed while the compressor 17 is stopped, and the pressure difference is maintained and the pressure is increased. Compare with the case of starting from a balanced state. In this case, if the two-way valve 18 is closed and the compressor 17 is started while maintaining the pressure difference, the electric power for providing the pressure difference again between the condenser 19 and the evaporator 21 is smaller. Become. Therefore, energy saving of the refrigerator 22 can be realized.
　また、圧縮機１７の停止中も二方弁１８を開状態のままにする場合、および、二方弁１８が設けない冷蔵庫の動作について、考察する。 Further, consider the case where the two-way valve 18 is left in the open state even when the compressor 17 is stopped, and the operation of the refrigerator in which the two-way valve 18 is not provided.
　具体的には、圧縮機１７の停止から圧力がバランスするまでの１０分程度が経過する前に、庫内温度が上昇した場合を考察する。この場合、従来の構成であれば、圧縮機１７の吸入側と吐出側との圧力差が０．０５ＭＰａ以下でしか、モータ駆動装置３０を起動させることができない。そのため、上記状態においては、１０分が経過するまで、モータ駆動装置３０の起動を待つ必要がある。 Specifically, consider the case where the temperature inside the refrigerator rises before about 10 minutes have elapsed from the stop of the compressor 17 to the balance of pressure. In this case, in the conventional configuration, the motor drive device 30 can be started only when the pressure difference between the suction side and the discharge side of the compressor 17 is 0.05 MPa or less. Therefore, in the above state, it is necessary to wait for the motor drive device 30 to start until 10 minutes have passed.
　しかしながら、本実施の形態の冷蔵庫２２は、０．０５ＭＰａより大きな差圧でもモータ駆動装置３０を起動させることが可能となる。そのため、庫内温度が上昇した場合、圧縮機１７の運転が必要なタイミングで、モータ駆動装置３０を起動させることができる。これにより、圧縮機１７の吸入側と吐出側との圧力がバランスした状態で起動させる場合に比べて、凝縮器１９と蒸発器２１との間に圧力差を設けるための電力を低減できる。そのため、さらに、冷蔵庫２２の省エネルギ化が可能となる。 However, the refrigerator 22 of the present embodiment can start the motor drive device 30 even with a differential pressure larger than 0.05 MPa. Therefore, when the temperature inside the refrigerator rises, the motor drive device 30 can be started at a timing when the compressor 17 needs to be operated. As a result, the electric power for providing a pressure difference between the condenser 19 and the evaporator 21 can be reduced as compared with the case where the compressor 17 is started in a state where the pressures on the suction side and the discharge side are balanced. Therefore, it is possible to further save energy in the refrigerator 22.
　また、二方弁１８は、三方弁または四方弁に比べ、冷蔵庫などのシステム構成を簡略にできる。さらに、二方弁１８は、圧縮機１７の吸入側と吐出側との圧力差を、より確実に維持できる。 Further, the two-way valve 18 can simplify the system configuration such as a refrigerator as compared with the three-way valve or the four-way valve. Further, the two-way valve 18 can more reliably maintain the pressure difference between the suction side and the discharge side of the compressor 17.
　また、本実施の形態の冷蔵庫２２は、圧縮機１７を冷蔵庫２２の上部に配置してもよい。この場合、手が届きにくい、上部のデッドスペースが小さくなるため、使いやすくなるとともに、庫内体積を拡大できる。一方、圧縮機１７の上部への配置により、冷蔵庫２２は、加振源である圧縮機１７が最も遠い位置に配置される。そのため、冷蔵庫２２は、床を支点として、てこの原理で圧縮機１７の振動が伝わりやすくなる。しかし、本実施の形態の冷蔵庫２２は、圧縮機１７の振動のピークを、効果的に抑制できる。そのため、圧縮機１７を上部へ配置しても、冷蔵庫２２から発生する振動や騒音を小さくできる。 Further, in the refrigerator 22 of the present embodiment, the compressor 17 may be arranged above the refrigerator 22. In this case, since the dead space at the upper part, which is difficult to reach, becomes smaller, it becomes easier to use and the volume inside the refrigerator can be expanded. On the other hand, due to the arrangement of the compressor 17 on the upper part, the refrigerator 22 is arranged at the position farthest from the compressor 17, which is the vibration source. Therefore, in the refrigerator 22, the vibration of the compressor 17 is easily transmitted by the principle of leverage with the floor as a fulcrum. However, the refrigerator 22 of the present embodiment can effectively suppress the peak of vibration of the compressor 17. Therefore, even if the compressor 17 is arranged at the upper part, the vibration and noise generated from the refrigerator 22 can be reduced.
　［１－３．効果等］
　以上で述べたように、本実施の形態のモータ駆動装置３０は、圧縮機１７と、圧縮機１７が圧縮動作を行うためのブラシレスＤＣモータ５を備える。モータ駆動装置は、圧縮機１７の運転開始時の振動と、負荷トルク減少による振動とが、打ち消しあうようにブラシレスＤＣモータ５の起動トルクと回転開始位置を決定するように構成される。この構成により、モータ駆動装置３０は、運転開始時に発生する振動振幅のピークと負荷トルクの減少による急加速によって発生する振動振幅のピークと、を打ち消すように構成される。そのため、上記それぞれの振動振幅のピークが単独で発生する場合と比べて、振動振幅のピークが小さくなる。これにより、圧縮機１７から発生する振動を小さく抑制できる。 [1-3. Effect, etc.]
As described above, the motor drive device 30 of the present embodiment includes a compressor 17 and a brushless DC motor 5 for the compressor 17 to perform a compression operation. The motor drive device is configured to determine the starting torque and the rotation start position of the brushless DC motor 5 so that the vibration at the start of operation of the compressor 17 and the vibration due to the decrease in load torque cancel each other out. With this configuration, the motor drive device 30 is configured to cancel the peak of the vibration amplitude generated at the start of operation and the peak of the vibration amplitude generated by the sudden acceleration due to the decrease of the load torque. Therefore, the peak of the vibration amplitude becomes smaller than the case where the peak of each of the above vibration amplitudes is generated independently. As a result, the vibration generated from the compressor 17 can be suppressed to be small.
　また、本実施の形態のモータ駆動装置３０は、圧縮機１７のピストン１７ｂの下死点を探索し移動させる下死点探索部１１を備え、下死点探索部１１により、ピストン１７ｂを下死点に移動させたのち、ブラシレスＤＣモータ５を回転開始位置に移動させるように構成される。この構成により、モータ駆動装置３０は、圧縮機１７のピストン１７ｂの位置を把握して、圧縮ステップを乗り越えるために、十分な速度を得る加速期間を確保できる。これにより、圧縮機１７の安定した起動が可能となる。 Further, the motor drive device 30 of the present embodiment includes a bottom dead center search unit 11 that searches for and moves the bottom dead center of the piston 17b of the compressor 17, and the bottom dead center search unit 11 causes the piston 17b to die down. After moving to the point, the brushless DC motor 5 is configured to move to the rotation start position. With this configuration, the motor drive device 30 can grasp the position of the piston 17b of the compressor 17 and secure an acceleration period for obtaining a sufficient speed in order to overcome the compression step. As a result, the compressor 17 can be started stably.
　また、本実施の形態のモータ駆動装置３０は、トルク決定部を１２備え、トルク決定部１２は、下死点探索部１１で決定される回転開始位置を下死点とし、起動トルクを決定する。この構成により、モータ駆動装置３０は、運転開始時に発生する振動の方向と、上死点で負荷トルクの減少による振動の発生開始の方向とが逆方向となる。そのため、互いの振動が相殺される。これにより、圧縮機１７で発生する振動を、より効果的に抑制できる。 Further, the motor drive device 30 of the present embodiment includes 12 torque determination units, and the torque determination unit 12 determines the starting torque with the rotation start position determined by the bottom dead center search unit 11 as the bottom dead center. .. With this configuration, in the motor drive device 30, the direction of vibration generated at the start of operation and the direction of start of vibration due to a decrease in load torque at top dead center are opposite to each other. Therefore, the vibrations of each other cancel each other out. As a result, the vibration generated by the compressor 17 can be suppressed more effectively.
　また、上記構成により、モータ駆動装置３０は、ピストン１７ｂを下死点へ移動したのち、運転開始位置へ、さらに移動させる必要がない。これにより、モータ駆動装置３０を、より単純な構成にできる。そのため、能力の低い安価なマイコンでの構成が可能となるため、製品のコストの低減できる。 Further, according to the above configuration, the motor drive device 30 does not need to move the piston 17b to the bottom dead center and then to the operation start position. As a result, the motor drive device 30 can have a simpler configuration. Therefore, it is possible to configure with an inexpensive microcomputer having low capacity, and the cost of the product can be reduced.
　さらに、上記構成により、モータ駆動装置３０は、ピストン１７ｂの起動開始位置が固定となる。そのため、起動トルクの決定のための計算が単純となる。これにより、事前に起動トルクを決定する場合、開発期間を短縮できる。一方、起動トルクをリアルタイムに決定する場合でも、安価なマイコンで、短時間で計算できる。 Further, according to the above configuration, the starting position of the piston 17b of the motor driving device 30 is fixed. Therefore, the calculation for determining the starting torque becomes simple. As a result, the development period can be shortened when the starting torque is determined in advance. On the other hand, even when the starting torque is determined in real time, it can be calculated in a short time with an inexpensive microcomputer.
　また、本実施の形態のモータ駆動装置３０は、圧縮機１７を、上死点を基準としてみた場合、正転と逆転ともに、非圧縮ステップであり、下死点を基準としてみた場合、正転と逆転ともに、圧縮ステップを含む。下死点探索部１１は、ブラシレスＤＣモータ５を正転と逆転をさせるステップを有するように構成される。この構成により、モータ駆動装置３０は、検出することが難しい低速でのブラシレスＤＣモータ５の位置を、電流や誘起電圧などから検出する必要がない。つまり、モータ駆動装置３０は、ブラシレスＤＣモータ５を同期運転で回転させることにより、ピストン１７ｂを下死点へ移動させることができる。これにより、安価なマイコンで、確実に圧縮機１７のピストン１７ｂの位置を把握できる。 Further, in the motor drive device 30 of the present embodiment, when the compressor 17 is viewed with reference to the top dead center, both forward rotation and reverse rotation are uncompressed steps, and when the compressor 17 is viewed with reference to the bottom dead center, normal rotation Both and reversal include compression steps. The bottom dead center search unit 11 is configured to have a step of rotating the brushless DC motor 5 in the forward and reverse directions. With this configuration, the motor drive device 30 does not need to detect the position of the brushless DC motor 5 at a low speed, which is difficult to detect, from the current, the induced voltage, or the like. That is, the motor drive device 30 can move the piston 17b to the bottom dead center by rotating the brushless DC motor 5 in synchronous operation. As a result, the position of the piston 17b of the compressor 17 can be reliably grasped by an inexpensive microcomputer.
　また、本実施の形態の冷蔵庫２２は、上記モータ駆動装置３０を備えて構成される。この構成により、負荷トルクが大きく変動する状態から、圧縮機１７を起動できる。そのため、冷蔵庫２２が停止と、再度、運転を再開するまで間に、圧縮機１７の吸入圧力と吐出圧力がバランスするまでの待ち時間が不要となる。これにより、停電や冷蔵庫２２の移動などにおける電力の供給停止から復帰した際において、即座に、冷蔵庫２２の庫内の冷却の再開が可能となる。 Further, the refrigerator 22 of the present embodiment is configured to include the motor driving device 30. With this configuration, the compressor 17 can be started from a state in which the load torque fluctuates greatly. Therefore, there is no need to wait until the suction pressure and the discharge pressure of the compressor 17 are balanced between the time when the refrigerator 22 is stopped and the time when the operation is restarted again. As a result, when the power supply is restored from the power failure due to a power failure or the movement of the refrigerator 22, the cooling inside the refrigerator 22 can be restarted immediately.
　また、本実施の形態の冷蔵庫２２は、圧縮機１７を、筐体上部に備えて構成される。この構成により、冷蔵庫２２は、筐体上部に設置される圧縮機の運転開始時に発生する振動が、てこの原理により大きくなっても、モータ駆動装置３０の駆動により、筐体への振動の伝達が抑制される。これにより、静粛性の高い冷蔵庫２２を提供できる。また、筐体上部のデッドスペースとなりやすい部分に、圧縮機が配置される。そのため、実際に使用できる庫内の収容容積が広がる。これにより、有効収容容積の広い、使いやすい冷蔵庫を提供できる。 Further, the refrigerator 22 of the present embodiment is configured by providing a compressor 17 on the upper part of the housing. With this configuration, in the refrigerator 22, even if the vibration generated at the start of operation of the compressor installed in the upper part of the housing becomes large due to the principle of leverage, the vibration is transmitted to the housing by driving the motor driving device 30. Is suppressed. Thereby, the refrigerator 22 having high quietness can be provided. In addition, the compressor is arranged in a portion of the upper part of the housing that tends to be a dead space. Therefore, the storage volume in the refrigerator that can be actually used is expanded. This makes it possible to provide an easy-to-use refrigerator having a large effective storage volume.
　以上、本開示の技術を、上記実施の形態を用いて説明したが、上述の実施の形態は、本開示における技術を例示するためのものであるから、請求の範囲、またはその均等の範囲において、種々の変更、置き換え、付加、省略などを行うことができる。 The technique of the present disclosure has been described above using the above-described embodiment, but since the above-described embodiment is for exemplifying the technique of the present disclosure, it is within the scope of claims or an equivalent range thereof. , Various changes, replacements, additions, omissions, etc. can be made.
　本開示は、負荷トルクの変動が大きな圧縮機を起動するためのモータ駆動装置に使用できる。そのため、モータ駆動装置で起動される圧縮機を用いた冷蔵庫、冷凍庫、ショーケース、その他の各種冷凍装置に好適に適用できる。 The present disclosure can be used for a motor drive device for starting a compressor in which the load torque fluctuates greatly. Therefore, it can be suitably applied to refrigerators, freezers, showcases, and other various refrigerating devices using a compressor activated by a motor drive device.
　１　　交流電源（電源）
　２　　整流回路
　２ａ，２ｂ，２ｃ，２ｄ　　整流ダイオード
　３　　平滑部
　３ｅ　　平滑コンデンサ
　３ｆ　　リアクタ
　４，２０５　　インバータ
　４ａ，４ｂ，４ｃ，４ｄ，４ｅ，４ｆ　　スイッチング素子
　４ｇ，４ｈ，４ｉ，４ｊ，４ｋ，４ｌ　　還流電流用ダイオード
　５，２０１　　ブラシレスＤＣモータ
　５ａ　　回転子
　５ｂ　　固定子
　６　　位置検出部
　７　　速度検出部
　８　　電圧検出部
　９　　ドライブ部
　１０　　出力決定部
　１１　　下死点探索部
　１２　　トルク決定部
　１７，２０３　　圧縮機
　１７ａ　　クランクシャフト
　１７ｂ，２０２　　ピストン
　１７ｃ　　シリンダ
　１８　　二方弁
　１９　　凝縮器
　２０　　減圧器
　２１　　蒸発器
　２２　　冷蔵庫
　３０　　モータ駆動装置
　２０４　　制御部 1 AC power supply (power supply)
2 Rectifier circuit 2a, 2b, 2c, 2d Rectifier diode 3 Smoothing part 3e Smoothing capacitor 3f Reactor 4,205 Inverter 4a, 4b, 4c, 4d, 4e, 4f Switching element 4g, 4h, 4i, 4j, 4k, 4l Reflux current Diode 5,201 Brushless DC motor 5a Rotor 5b Fixture 6 Position detection unit 7 Speed detection unit 8 Voltage detection unit 9 Drive unit 10 Output determination unit 11 Bottom dead point search unit 12 Torque determination unit 17,203 Compressor 17a Crank Shaft 17b, 202 Piston 17c Cylinder 18 Two-way valve 19 Condenser 20 Decompressor 21 Evaporator 22 Refrigerator 30 Motor drive device 204 Control unit

Claims (6)

  1. 圧縮機と、
    前記圧縮機が圧縮動作を行う駆動源となるブラシレスＤＣモータと、を備え、
    前記圧縮機の運転開始時の振動と、負荷トルクの減少による振動とが、打ち消しあうように、前記ブラシレスＤＣモータの起動トルクと回転開始位置を決定する、
    モータ駆動装置。     With a compressor,
    The compressor is provided with a brushless DC motor as a drive source for performing a compression operation.
    The starting torque and the rotation start position of the brushless DC motor are determined so that the vibration at the start of operation of the compressor and the vibration due to the decrease in the load torque cancel each other out.
    Motor drive.
  2. 前記圧縮機のピストンの下死点を探索し移動させる下死点探索部を備え、
    前記下死点探索部により前記ピストンを下死点に移動させたのち、前記ブラシレスＤＣモータを回転開始位置に移動させる、
    請求項１に記載のモータ駆動装置。     A bottom dead center search unit for searching for and moving the bottom dead center of the piston of the compressor is provided.
    After the piston is moved to the bottom dead center by the bottom dead center search unit, the brushless DC motor is moved to the rotation start position.
    The motor drive device according to claim 1.
  3. トルク決定部を備え、
    前記トルク決定部は、前記下死点探索部で決定される回転開始位置を下死点とし、起動トルクを決定する、
    請求項１または請求項２のいずれか１項に記載のモータ駆動装置。     Equipped with a torque determination unit
    The torque determination unit determines the starting torque with the rotation start position determined by the bottom dead center search unit as the bottom dead center.
    The motor drive device according to any one of claims 1 and 2.
  4. 前記圧縮機は、上死点を基準としてみた場合、正転と逆転ともに、非圧縮ステップであり、下死点を基準としてみた場合、正転と逆転ともに、圧縮ステップを含み、
    前記下死点探索部は、前記ブラシレスＤＣモータを正転と逆転をさせるステップを有する、
    請求項１から請求項３のいずれか１項に記載のモータ駆動装置。     The compressor includes a compression step for both forward rotation and reverse rotation when viewed from top dead center, and includes a compression step for both forward rotation and reverse rotation when viewed from bottom dead center.
    The bottom dead center search unit has a step of rotating the brushless DC motor in the forward and reverse directions.
    The motor drive device according to any one of claims 1 to 3.
  5. 請求項１から請求項４のいずれか１項に記載のモータ駆動装置を備える、
    冷蔵庫。     The motor driving device according to any one of claims 1 to 4.
    refrigerator.
  6. 前記圧縮機を、筐体上部に備える、
    請求項５に記載の冷蔵庫。     The compressor is provided in the upper part of the housing.
    The refrigerator according to claim 5.
PCT/JP2020/038070 2019-10-29 2020-10-08 Motor drive device and refrigerator using same WO2021085066A1 (en)

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CN114719476B (en) * 2022-03-03 2023-12-15 上海海立（集团）股份有限公司 Compressor, operation control method and system thereof, and storage medium

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JPH01249967A (en) * 1988-03-30 1989-10-05 Fuji Electric Co Ltd Running controller for quantitative pump
JP2005106454A (en) * 2003-09-09 2005-04-21 Matsushita Electric Ind Co Ltd Refrigerator
JP2005214486A (en) * 2004-01-29 2005-08-11 Toshiba Corp Refrigerator

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JP4259173B2 (en) * 2003-04-28 2009-04-30 パナソニック株式会社 Electric compressor drive device

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JPH01249967A (en) * 1988-03-30 1989-10-05 Fuji Electric Co Ltd Running controller for quantitative pump
JP2005106454A (en) * 2003-09-09 2005-04-21 Matsushita Electric Ind Co Ltd Refrigerator
JP2005214486A (en) * 2004-01-29 2005-08-11 Toshiba Corp Refrigerator

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