WO2021100844A1 - Electric tool, control method, and program - Google Patents

Electric tool, control method, and program Download PDF

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Publication number
WO2021100844A1
WO2021100844A1 PCT/JP2020/043352 JP2020043352W WO2021100844A1 WO 2021100844 A1 WO2021100844 A1 WO 2021100844A1 JP 2020043352 W JP2020043352 W JP 2020043352W WO 2021100844 A1 WO2021100844 A1 WO 2021100844A1
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WIPO (PCT)
Prior art keywords
control unit
magnetic flux
motor
current
control
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PCT/JP2020/043352
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French (fr)
Japanese (ja)
Inventor
中原　雅之
隆司 草川
尊大 植田
Original Assignee
パナソニックＩｐマネジメント株式会社
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Publication of WO2021100844A1 publication Critical patent/WO2021100844A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • 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
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/22—Current control, e.g. using a current control loop

Definitions

  • This disclosure generally relates to power tools, control methods, and programs. More specifically, the present disclosure relates to a power tool including a power tool, a control method for the power tool, and a program.
  • Patent Document 1 describes an electric tool capable of controlling the rotation speed of an electric motor.
  • This electric tool includes a brushless DC motor (motor), a battery voltage detection unit, a rotation position detection unit, and a control unit.
  • the battery voltage detection unit detects the voltage of the battery used to drive the brushless DC motor.
  • the rotation position detection unit detects the rotation position of the brushless DC motor.
  • the control unit controls the drive output to the brushless DC motor by the signal from the rotation position detection unit.
  • the control unit sends the brushless DC motor to the brushless DC motor so that the rotation speed or energizing current of the brushless DC motor becomes the target value corresponding to the battery voltage detected by the battery voltage detection unit. Control the energization angle or advance angle.
  • the rotation speed of the electric motor may decrease due to the increase in load, and the target rotation speed of the electric motor may not be obtained. Therefore, it is desired to suppress the reduction in efficiency of the motor.
  • the present disclosure has been made in view of the above reasons, and an object of the present disclosure is to provide an electric tool, a control method, and a program capable of suppressing the reduction in efficiency of the electric motor.
  • the electric tool of one aspect of the present disclosure includes an electric motor, a driving force transmission mechanism, and a control unit.
  • the motor has a permanent magnet and a coil.
  • the driving force transmission mechanism is driven by the electric motor.
  • the control unit performs vector control for controlling the exciting current and the torque current supplied to the motor.
  • the control unit controls to increase the exciting current at least in response to an increase in a load received from the outside by the output shaft of the motor.
  • the control method of the present disclosure is a control method of an electric tool including an electric motor having a permanent magnet and a coil.
  • the control method includes a main step of performing vector control for controlling an exciting current and a torque current supplied to the electric motor that drives the driving force transmission mechanism.
  • the main step includes at least a sub-step for controlling the exciting current to increase in response to an increase in a load received from the outside by the output shaft of the motor.
  • the program of one aspect of the present disclosure is a program for causing one or more processors to execute the above control method.
  • FIG. 1 is a block configuration diagram of a power tool according to an embodiment.
  • FIG. 2 is a schematic view of the same power tool.
  • FIG. 3 is a diagram for explaining the characteristics of the same power tool.
  • FIG. 4 is a diagram for explaining the characteristics of the same power tool.
  • FIG. 5 is a flowchart for explaining the operation of the power tool of the same.
  • the power tool 1 (see FIGS. 1 and 2) according to the present embodiment is, for example, a tool used in a factory, a construction site, or the like.
  • the power tool 1 will be described on the assumption that it is an impact driver used for tightening a work object (fastening member such as a bolt or a screw).
  • the type of the power tool 1 is not particularly limited, and a drill driver, an impact wrench, or the like may be used.
  • the electric tool 1 includes an electric motor 15 (for example, an AC electric motor), a driving force transmission mechanism 18, and a control unit 4.
  • the electric motor 15 has a permanent magnet 131 and a coil 141.
  • the electric motor 15 is, for example, a brushless motor.
  • the electric motor 15 of the present embodiment is a synchronous electric motor, and more specifically, a permanent magnet synchronous electric motor (PMSM (Permanent Magnet Synchronous Motor)).
  • PMSM Permanent Magnet Synchronous Motor
  • the driving force transmission mechanism 18 is driven by the electric motor 15.
  • the control unit 4 performs vector control for controlling the exciting current (d-axis current) and the torque current (q-axis current) supplied to the motor 15.
  • the control unit 4 executes weakening magnetic flux control by vector control.
  • the control unit 4 uses a weakened magnetic flux current (d-axis current) for generating a second magnetic flux (weakened magnetic flux) that weakens the magnetic flux (first magnetic flux) of the permanent magnet 131 in the coil 141 as an exciting current. Let it flow to 141.
  • the weakening magnetic flux current is a negative exciting current. Due to the weak magnetic flux control, the rotation speed of the electric motor 15, that is, the rotation speed of the output shaft 16 (rotation shaft) is increased.
  • control unit 4 of the present embodiment controls so as to increase the exciting current at least in response to an increase in the load received from the outside by the output shaft 16 of the electric motor 15.
  • Increasing the exciting current as used in the present disclosure means increasing the magnitude (absolute value) of the exciting current.
  • the control unit 4 increases the exciting current at least in response to an increase in the load. Therefore, for example, it is possible to reduce the possibility that the rotation speed of the motor 15 decreases due to an increase in the load and the target rotation speed of the motor cannot be obtained. As a result, it is possible to suppress the reduction in efficiency of the electric motor 15.
  • the electric tool 1 includes an electric motor 15, a power supply unit 32, a driving force transmission mechanism 18, an impact mechanism 17, a chuck 23, a trigger switch 29, a control unit 4, and a bit rotation measurement.
  • a unit 25, a torque measuring unit 26, and a motor rotation measuring unit 27 are provided.
  • the power tool 1 further includes a tip tool (bit).
  • the control unit 4 will be described in detail in the next column.
  • the impact mechanism 17 has an output shaft 21.
  • the output shaft 21 is a portion that rotates by a driving force transmitted from the electric motor 15.
  • the chuck 23 is fixed to the output shaft 21 and is a portion to which the tip tool can be detachably attached.
  • the electric tool 1 is a tool that drives the tip tool with the driving force of the electric motor 15.
  • the tip tool is, for example, a screwdriver or a drill.
  • the tip tool according to the application is selectively attached to the chuck 23 and used.
  • the tip tool may be mounted directly on the output shaft 21.
  • the motor 15 (AC motor) is a drive source for driving the tip tool.
  • the electric motor 15 includes a rotor 13 having a permanent magnet 131 and a stator 14 having a coil 141.
  • the rotor 13 includes an output shaft 16 (see FIG. 2) that outputs rotational power.
  • the rotor 13 rotates with respect to the stator 14 due to the electromagnetic interaction between the coil 141 and the permanent magnet 131.
  • the power supply unit 32 is a so-called battery pack including one or a plurality of batteries 320 (for example, a secondary battery) that supply electric power to the electric motor 15.
  • the power supply unit 32 is detachably attached to the lower end of the grip portion in the body of the power tool 1, for example.
  • the driving force transmission mechanism 18 is driven by the electric motor 15.
  • the driving force transmission mechanism 18 adjusts the rotational power of the electric motor 15 to output a desired torque.
  • the driving force transmission mechanism 18 has a driving shaft 22 (see FIG. 2) which is an output unit.
  • the drive shaft 22 of the drive force transmission mechanism 18 is connected to the impact mechanism 17.
  • the impact mechanism 17 converts the rotational power of the electric motor 15 received via the driving force transmission mechanism 18 into pulsed torque to generate an impact force.
  • the impact mechanism 17 includes a hammer 19, an anvil 20, an output shaft 21, and a spring 24.
  • the hammer 19 is attached to the drive shaft 22 of the drive force transmission mechanism 18 via a cam mechanism.
  • the anvil 20 is coupled to the hammer 19 and rotates integrally with the hammer 19.
  • the spring 24 pushes the hammer 19 toward the anvil 20.
  • the anvil 20 is integrally formed with the output shaft 21.
  • the anvil 20 may be formed separately from the output shaft 21 and fixed to the output shaft 21.
  • the trigger switch 29 is an operation unit that accepts an operation for controlling the rotation of the electric motor 15. By pulling the trigger switch 29, the motor 15 can be switched on and off. Further, the rotation speed (rotation speed) of the output shaft 21, that is, the rotation speed (rotation speed) of the motor 15 can be adjusted by the pull-in amount of the operation of pulling the trigger switch 29. The larger the pull-in amount, the faster the rotation speed of the electric motor 15.
  • the control unit 4 rotates or stops the electric motor 15 according to the pull-in amount of the operation of pulling the trigger switch 29, and also controls the rotation speed of the electric motor 15. In the power tool 1, the tip tool is attached to the chuck 23. Then, the rotation speed of the tip tool is controlled by controlling the rotation speed of the electric motor 15 by operating the trigger switch 29.
  • the tip tool can be replaced according to the application, but it is not essential that the tip tool can be replaced.
  • the power tool 1 may be a power tool that can be used only with a specific tip tool.
  • the torque measuring unit 26 measures the operating torque of the motor 15.
  • the torque measuring unit 26 is, for example, a magnetostrictive strain sensor capable of detecting torsional strain.
  • the magnetostrictive strain sensor detects a change in the magnetostriction according to the strain generated by applying torque to the output shaft 16 of the motor 15 with a coil installed in the non-rotating portion of the motor 15, and a voltage signal proportional to the strain. Is output.
  • the bit rotation measuring unit 25 measures the rotation angle of the output shaft 21.
  • the rotation angle of the output shaft 21 is equal to the rotation angle of the tip tool (bit).
  • bit rotation measuring unit 25 for example, a photoelectric encoder or a magnetic encoder can be adopted.
  • the motor rotation measuring unit 27 measures the rotation angle of the electric motor 15.
  • a photoelectric encoder or a magnetic encoder can be adopted.
  • Control unit 4 includes a computer system having one or more processors and memories.
  • the processor of the computer system executes the program recorded in the memory of the computer system, at least a part of the functions of the control unit 4 are realized.
  • the program may be recorded in a memory, provided through a telecommunication line such as the Internet, or may be recorded and provided on a non-temporary recording medium such as a memory card.
  • the control unit 4 is configured to control the drive of the motor 15.
  • the control unit 4 controls (for example, independently) the exciting current and the torque current supplied to the motor 15 (vector control).
  • the drive control of the control unit 4 includes a weakening magnetic flux control and a normal control.
  • the control unit 4 has a first mode as a mode of weakening magnetic flux control and a second mode as a mode of normal control as operation modes.
  • the control unit 4 causes a weakened magnetic flux current to flow from the inverter circuit unit 51 (see FIG. 1), which will be described later, to the coil 141 of the motor 15. That is, the control unit 4 causes the coil 141 to flow a weakening magnetic flux current for generating a second magnetic flux that weakens the magnetic flux (first magnetic flux) of the permanent magnet 131 in the coil 141 by the weakening magnetic flux control.
  • control unit 4 weakens the coil 141 from the inverter circuit unit 51 so that the magnetic flux current does not flow. That is, in normal control, the current flowing through the coil 141 is only the torque current (q-axis current).
  • the normal control is performed so that the command value (target value) of the weakening magnetic flux (current) (target value) cid1 (see FIG. 1) is set to zero (0) and the weakening magnetic flux (current) converges to this command value cid1.
  • the weakening magnetic flux control can be said to be a control performed so that the command value cid1 of the weakening magnetic flux (current) is made larger than zero (0) and the weakening magnetic flux (current) converges to this command value cid1.
  • the weakening magnetic flux current minus exciting current
  • the control unit 4 includes a command value generation unit 41, a speed control unit 42, a current control unit 43, a first coordinate converter 44, a second coordinate converter 45, and a magnetic flux. It has a control unit 46, an estimation unit 47, and a step-out detection unit 48. Further, the power tool 1 further includes an inverter circuit unit 51 and a plurality of (two in FIG. 1) current sensors 61 and 62. The control unit 4 is used together with the inverter circuit unit 51, and controls the operation of the electric motor 15 by feedback control.
  • Each of the plurality of current sensors 61 and 62 includes, for example, a Hall element current sensor or a shunt resistance element.
  • the plurality of current sensors 61 and 62 measure the current supplied from the battery 320 to the motor 15 via the inverter circuit unit 51.
  • a three-phase current (U-phase current, V-phase current, and W-phase current) is supplied to the motor 15, and the plurality of current sensors 61 and 62 measure at least two-phase currents.
  • the current sensor 61 measures the U-phase current and outputs the measured current value i u 1
  • the current sensor 62 measures the V-phase current and outputs the measured current value i v 1.
  • the estimation unit 47 calculates the angular velocity ⁇ 1 (angular velocity of the output shaft 16) of the motor 15 by time-differentiating the rotation angle ⁇ 1 of the motor 15 measured by the motor rotation measurement unit 27.
  • the second coordinate converter 45 uses the current measured values i u 1 and i v 1 measured by the plurality of current sensors 61 and 62 based on the rotation angle ⁇ 1 of the motor 15 measured by the motor rotation measuring unit 27. The coordinates are converted and the current measurement values id1 and iq1 are calculated. That is, the second coordinate converter 45, a current measurement value i u 1, i v 1 corresponding to the two-phase currents of the three phases, the current measurement value id1 corresponding to the magnetic field component (d-axis current), It is converted to the current measured value iq1 corresponding to the torque component (q-axis current).
  • the command value generation unit 41 generates the command value c ⁇ 1 of the angular velocity of the motor 15.
  • the command value generation unit 41 generates, for example, the command value c ⁇ 1 according to the pull-in amount of the operation of pulling the trigger switch 29 (see FIG. 2).
  • the command value generation unit 41 increases the command value c ⁇ 1 of the angular velocity as the pull-in amount increases.
  • the speed control unit 42 generates the command value ciq1 based on the difference between the command value c ⁇ 1 generated by the command value generation unit 41 and the angular velocity ⁇ 1 calculated by the estimation unit 47.
  • the command value ciq1 is a command value that specifies the magnitude of the torque current (q-axis current) of the motor 15.
  • the speed control unit 42 determines the command value ciq1 so as to reduce the difference between the command value c ⁇ 1 and the angular velocity ⁇ 1. That is, the control unit 4 controls so that the rotation speed of the electric motor 15 matches the target value corresponding to the operation of the trigger switch 29.
  • the magnetic flux control unit 46 includes an angular velocity ⁇ 1 calculated by the estimation unit 47, a command value cvq1 (described later) generated by the current control unit 43, and a current measurement value.
  • the command value cid1 is determined based on iq1 (q-axis current).
  • the command value cid1 is a command value that specifies the magnitude of the weakening magnetic flux (magnetic flux in the d-axis direction) of the motor 15.
  • the command value cid1 generated by the magnetic flux control unit 46 is a command value for setting the weakening magnetic flux to zero (0).
  • the current control unit 43 generates the command value cvd1 based on the difference between the command value cyd1 generated by the magnetic flux control unit 46 and the current measurement value id1 calculated by the second coordinate converter 45.
  • the command value cvd1 is a command value that specifies the magnitude of the d-axis voltage of the motor 15.
  • the current control unit 43 determines the command value cvd1 so as to reduce the difference between the command value cid1 and the current measurement value id1.
  • the current control unit 43 generates the command value cvq1 based on the difference between the command value iq1 generated by the speed control unit 42 and the current measurement value iq1 calculated by the second coordinate converter 45.
  • the command value cvq1 is a command value that specifies the magnitude of the q-axis voltage of the motor 15.
  • the current control unit 43 generates the command value cvq1 so as to reduce the difference between the command value xiq1 and the current measurement value iq1.
  • the first coordinate converter 44 converts the command values cvd1 and cvq1 into coordinates based on the rotation angle ⁇ 1 of the electric motor 15 measured by the motor rotation measuring unit 27, and converts the command values cv u 1, cv v 1, and cv w. 1 is calculated. That is, the first coordinate converter 44 sets the command value cvd1 corresponding to the magnetic field component (d-axis voltage) and the command value cvq1 corresponding to the torque component (q-axis voltage) to the command value corresponding to the three-phase voltage. Convert to cv u 1, cv v 1, cv w 1.
  • the command value cv u 1 corresponds to the U-phase voltage
  • the command value cv v 1 corresponds to the V-phase voltage
  • the command value cv w 1 corresponds to the W-phase voltage.
  • the inverter circuit unit 51 supplies the three-phase voltage according to the command values cv u 1, cv v 1, and cv w 1 to the motor 15.
  • the control unit 4 controls the electric power supplied to the electric motor 15 by PWM-controlling the inverter circuit unit 51.
  • the motor 15 is driven by the electric power (three-phase voltage) supplied from the inverter circuit section 51 to generate rotational power.
  • control unit 4 controls the weakening magnetic flux current so that the weakening magnetic flux current flowing through the coil 141 of the electric motor 15 has a magnitude corresponding to the command value cid1 generated by the magnetic flux control unit 46. Further, the control unit 4 controls the angular velocity of the motor 15 so that the angular velocity of the motor 15 corresponds to the command value c ⁇ 1 generated by the command value generation unit 41.
  • the step-out detection unit 48 detects the step-out of the motor 15 based on the current measurement values id1 and iq1 acquired from the second coordinate converter 45 and the command values cvd1 and cvq1 acquired from the current control unit 43. To do. When step-out is detected, the step-out detection unit 48 transmits a stop signal cs1 to the inverter circuit unit 51 to stop the power supply from the inverter circuit unit 51 to the motor 15.
  • the control unit 4 operates in the first mode in which a weakening magnetic flux current is passed through the coil 141 of the motor 15 when the switching condition is satisfied. That is, when the switching condition is satisfied, the control of the control unit 4 becomes the weak magnetic flux control.
  • the switching condition includes, for example, a high-speed range condition that the motor 15 is operating in the high-speed range.
  • the fact that the electric motor 15 operates in the high speed range generally means that the rotational speed of the electric motor 15 is relatively high.
  • the definition that "the motor 15 is operating in the high speed range" is defined as the duty of PWM (Pulse Width Modulation) control of the control unit 4 with respect to the inverter circuit unit 51 when the rotation speed of the motor 15 is equal to or higher than a predetermined rotation speed.
  • the degree of modulation is equal to or higher than the specified value.
  • the duty of the PWM control is a value obtained by dividing the ON period in one cycle of the PWM signal by the length of one cycle.
  • the rotation speed of the electric motor 15 is substantially proportional to the duty.
  • the above-mentioned specified value is, for example, about 0.9 or 0.95.
  • the switching condition includes, for example, a torque current condition that the torque current value (q-axis current value) flowing through the coil 141 of the motor 15 is equal to or less than a predetermined current value.
  • the control unit 4 uses the current measurement value iq1 as the torque current value in order to determine whether or not the switching condition is satisfied. However, the control unit 4 may use the command value iq1 of the torque current value as the torque current value.
  • the switching condition includes both the high-speed range condition and the torque current condition, but only one of them may be included.
  • the switching condition may include only the torque current condition, for example.
  • the control unit 4 satisfies the switching condition in a low load region where the load (torque) received from the outside by the output shaft 16 of the motor 15 via the output shaft 21 and the drive shaft 22 is relatively low (including no load). , Weak magnetic flux control is performed. Thereby, the maximum rotation speed (maximum rotation speed) of the electric motor 15 can be increased. That is, the control unit 4 performs the weakening magnetic flux control when the load received from the outside by the output shaft 16 of the electric motor 15 is smaller than a predetermined magnitude.
  • the control unit 4 operates in the second mode in which the weakening magnetic flux current is not passed when the switching condition is not satisfied. That is, when the switching condition is not satisfied, the control of the control unit 4 becomes normal control.
  • the control unit 4 can obtain a relatively large torque by performing normal control in a high load region where the electric motor 15 requires a relatively large torque current.
  • the weakening magnetic flux control and the normal control may be manually switched by operating an operation unit different from the trigger switch 29.
  • the weakening magnetic flux control and the normal control may be switched by a tap operation or the like on the display unit A3 (see FIG. 1) described later.
  • FIG. 3 is a graph for explaining the operating characteristics of the power tool of the comparative example.
  • the characteristic C1 in FIG. 3 shows the TN curve (relationship between load and rotation speed (rpm)) with respect to the motor 15. As the load (torque) increases, the maximum rotation speed of the motor decreases. For example, assuming that the pull-in amount of the trigger switch 29 by the user is maintained constant, if the load is a predetermined value L1 or less, the motor 15 becomes the rotation speed N1 of the target value corresponding to the current pull-in amount. (See characteristic B1 in FIG. 3).
  • the control unit 4 of the power tool 1 of the present embodiment controls so as to increase the exciting current according to the increase in the load.
  • the control unit 4 performs weakening magnetic flux control in which a weakening magnetic flux current flows through the coil 141 as an exciting current when the rotation speed of the motor 15 decreases due to an increase in load. That is, as an example, the control unit 4 determines that the rotation speed of the electric motor 15 has decreased, and thus considers that the load has increased.
  • the magnetic flux control unit 46 of the control unit 4 monitors the rotation speed (here, the angular velocity) of the motor 15.
  • the magnetic flux control unit 46 determines whether or not the angular velocity ⁇ 1 of the motor 15 acquired from the estimation unit 47 is lower than the current command value c ⁇ 1 (target angular velocity) according to the pull-in amount of the trigger switch 29 (that is, lower than the rotation speed). Whether or not) is determined.
  • the control unit 4 satisfies the "trigger condition" that the pull-in amount is, for example, constant (however, larger than zero (0)) at a predetermined interval, and the angular velocity ⁇ 1 of the motor 15 decreases due to an increase in the load. , Performs weakening magnetic flux control.
  • the magnetic flux control unit 46 acquires the command value c ⁇ 1 from the command value generation unit 41 at a predetermined sampling cycle, and the predetermined interval is assumed to be, for example, an integral multiple of 1 or more of the sampling cycle of the command value c ⁇ 1. , Not particularly limited.
  • the magnetic flux control unit 46 operates in the first mode (weak magnetic flux control) if both the trigger condition and the "angular velocity condition" that the angular velocity ⁇ 1 acquired from the estimation unit 47 is lower than the target angular velocity are satisfied.
  • the magnetic flux control unit 46 switches from the second mode to the first mode when both the trigger condition and the angular velocity condition are satisfied during operation in the second mode (normal control).
  • the weakening magnetic flux control of the present embodiment satisfies both the first weakening magnetic flux control executed when the above-mentioned "switching condition is satisfied in the low load region" and the "trigger condition and angular velocity condition". Includes a second weakening flux control that is performed in the case.
  • the "low load region” in which the first weakening magnetic flux control is executed is assumed to be at least a region lower than the predetermined value L1. Then, the maximum rotation speed of the motor 15 in the low load region of the TN curve can be increased by the first weakening magnetic flux control.
  • the control unit 4 determines the magnitude of the exciting current so that the amount of change in the rotation speed of the motor 15 due to the change in the load is reduced.
  • the magnetic flux control unit 46 makes the command value cid1 larger than zero (0) so that the amount of change is reduced, and causes a weakening magnetic flux current (minus exciting current) to flow.
  • the command value cid1 is determined so that the angular velocity ⁇ 1 that has decreased with the increase in load returns to the current target angular velocity.
  • the command value cid1 is adjusted so that the larger the amount of change (here, the amount of decrease) of the angular velocity ⁇ 1 with respect to the target angular velocity, the larger the amount.
  • the control unit 4 stores in its own memory corresponding data in which a plurality of command values cid1 and a plurality of reduction amounts of the angular velocity ⁇ 1 (which may be the number of rotations) are associated with each other.
  • the magnetic flux control unit 46 calculates the amount of decrease in the angular velocity ⁇ 1 with respect to the current target angular velocity, and selects the command value cid1 corresponding to the calculated amount of decrease from the corresponding data.
  • the command value cid1 may be constant (fixed value) regardless of the amount of decrease in the angular velocity ⁇ 1 as long as it is larger than zero (0) in the second weakening magnetic flux control. In the second weakening magnetic flux control, even when the command value id1 is a fixed value, the amount of change in the rotation speed of the motor 15 due to the change in load can be reduced.
  • the control unit 4 of the present embodiment maintains the rotation speed of the motor 15 at the target value (corresponding to the target angular velocity here) corresponding to the operation input to the trigger switch 29 (operation unit) even if the load changes.
  • the magnitude of the exciting current is determined so as to be.
  • the magnetic flux control unit 46 increases the command value cid1 so that the rotation speed of the motor 15 is maintained substantially flat even when the load exceeds the predetermined value L1, and the magnetic flux current (minus exciting current) is weakened.
  • the magnetic flux control unit 46 increases the command value cid1 so that the rotation speed of the motor 15 is maintained at the rotation speed N1 and is in line with the characteristic D1 which is an extension of the characteristic B1.
  • FIG. 4 is a graph for explaining the operating characteristics of the power tool 1 of the present embodiment.
  • the characteristic C1 and the characteristic B1 in FIG. 4 are common to the characteristic C1 and the characteristic B1 in FIG.
  • control unit 4 continuously changes the magnitude of the exciting current. That is, the control unit 4 continuously increases the magnitude of the exciting current as the load increases.
  • the "continuous change" of the exciting current makes it easier for the rotation speed of the motor 15 to be kept substantially flat (see curve E1 in FIG. 4).
  • the control unit 4 may change (increase) the magnitude of the exciting current discontinuously (that is, stepwise) with respect to the increase in the load.
  • the control unit 4 of the present embodiment determines the increase in the load by the decrease in the rotation speed (angular velocity) of the electric motor 15, the rotation speed of the electric motor 15 is actually on the side from the characteristic D1 to the characteristic C1. It can be controlled to follow a curve E1 (see FIG. 4) that is slightly offset to. Since the consumption of the battery 320 of the power supply unit 32 may increase due to the increase in the exciting current, when the load increases to the extent that the load exceeds a certain threshold value (a value sufficiently higher than the predetermined value L1), the load becomes large. It is preferable to stop following the increase. The curve E1 can eventually reach the characteristic C1.
  • a certain threshold value a value sufficiently higher than the predetermined value L1
  • the magnetic flux control unit 46 increases the command value cid1 to increase the weakening magnetic flux current so that the rotation speed (angular velocity ⁇ 1) of the electric motor 15 does not exceed the target value (target angular velocity). However, if, for example, the load is reduced and the angular velocity ⁇ 1 becomes larger than the angular velocity during the second weakening magnetic flux control, the magnetic flux control unit 46 conversely causes the command value side1 to reduce the weakening magnetic flux current. To reduce.
  • the control unit 4 of the present embodiment further includes a notification unit A1 and a setting unit A2.
  • the control unit 4 further has a function as a notification unit A1 and a function as a setting unit A2.
  • the notification unit A1 is configured to notify the user, for example, that the magnetic flux control unit 46 is operating in the second weakening magnetic flux control. Specifically, the notification unit A1 displays a character message indicating that the power tool 1 is operating with the second weakening magnetic flux control on the touch panel type liquid crystal display (display unit A3: see FIG. 1). And notify the user.
  • the notification unit A1 may output a voice message from a speaker provided in the power tool 1 instead of (or in addition to) the character message to notify the power tool 1. Further, the notification unit A1 may notify by changing the lighting state of the indicator lamp provided in the power tool 1. The change in the lighting state may include a change from turning off to lighting, a change from lighting to blinking, and the like.
  • the notification unit A1 may also notify the user that it is operating under normal control or first weakening magnetic flux control.
  • the setting unit A2 is configured to set valid or invalid for control to increase the exciting current. Specifically, the setting unit A2 sets "valid" or “invalid” of the second weakening magnetic flux control according to the operation input received from the user through a tap operation or the like to the display unit A3.
  • the setting unit A2 stores the setting information regarding the validity or invalidity of the second weakening magnetic flux control in the memory of the control unit 4. If the setting information specifies "invalid" for the second weakening magnetic flux control, the magnetic flux control unit 46 maintains the second mode (normal control) even if both the trigger condition and the angular velocity condition are satisfied. ..
  • the operation input may be received through a push button switch, a DIP switch, or the like provided in the power tool 1 in addition to the display unit A3.
  • control unit 4 Since the control unit 4 has the notification unit A1 and the setting unit A2 in this way, the convenience is improved.
  • the control unit 4 is operating in the second mode (normal control) (step S1).
  • the control unit 4 determines whether or not the trigger condition is satisfied, that is, whether or not the pull-in amount of the trigger switch 29 is constant at a predetermined interval (step S2).
  • step S2 determines that the pull-in amount is constant
  • step S3 determines whether or not the angular velocity condition is satisfied, that is, the angular velocity ⁇ 1 of the motor 15 is lower than the target angular velocity corresponding to the current command value c ⁇ 1. Whether or not it is determined (step S3).
  • the control unit 4 determines that the pull-in amount is not constant (step S2: No)
  • the control unit 4 continues the second mode (normal control).
  • step S3: Yes When the control unit 4 determines that the angular velocity ⁇ 1 of the motor 15 is lower than the target angular velocity (step S3: Yes), the control unit 4 switches the operation mode from the second mode to the first mode (second weakening magnetic flux control) (step S4). When the control unit 4 determines that the angular velocity ⁇ 1 of the motor 15 substantially matches the target angular velocity (step S3: No), the control unit 4 continues the second mode (normal control).
  • the control unit 4 calculates the amount of decrease in the angular velocity ⁇ 1 with respect to the target angular velocity, and determines the command value cid1 corresponding to the calculated amount of decrease. After that, as long as the trigger condition is satisfied (step S5: Yes), the control unit 4 increases the command value cid1 so that the rotation speed of the motor 15 is kept substantially flat following the increase in the load. To weaken and increase the magnetic flux current. If the trigger condition is not satisfied during that time (step S5: No), the control unit 4 releases the first mode (second weakening magnetic flux control) (step S6).
  • the condition for releasing the second weakening magnetic flux control is not limited to the trigger condition.
  • the second weakening magnetic flux control may be canceled when the pull-in amount becomes zero (0).
  • control unit 4 of the present embodiment controls so that the exciting current is increased according to the increase in the load received from the outside by the output shaft 16 of the electric motor 15. Therefore, unlike the characteristic B2 of FIG. 3, for example, it is possible to reduce the possibility that the rotation speed of the motor 15 decreases due to the increase in the load and the target rotation speed of the motor cannot be obtained (see curve E1 of FIG. 4). ). Therefore, it is possible to suppress the reduction in efficiency of the motor 15. Therefore, the work efficiency of the user is less likely to decrease.
  • the weakening magnetic flux control is performed by triggering the decrease in the rotation speed of the motor 15 (here, the angular velocity ⁇ 1), the efficiency reduction of the motor 15 can be further suppressed.
  • control unit 4 determines the magnitude of the exciting current so that the amount of change in the rotation speed of the motor 15 due to the change in the load is reduced, the control unit 4 uses a sense of incongruity that the rotation slows down as the load increases. It can be difficult to give to a person.
  • the above embodiment is only one of various embodiments of the present disclosure.
  • the above-described embodiment can be changed in various ways depending on the design and the like as long as the object of the present disclosure can be achieved.
  • the same function as the control unit 4 of the power tool 1 according to the above embodiment may be realized by this control method, a computer program, a non-temporary recording medium on which the computer program is recorded, or the like.
  • the control method of the electric tool 1 includes a main step of performing vector control for controlling the exciting current and the torque current supplied to the electric motor 15 that drives the driving force transmission mechanism 18.
  • the main step includes at least a sub-step of controlling the output shaft 16 of the motor 15 to increase the exciting current in response to an increase in the load received from the outside.
  • the control unit 4 of the power tool 1 in the present disclosure includes a computer system.
  • the main configuration of a computer system is a processor and memory as hardware.
  • the processor executes the program recorded in the memory of the computer system, the function as the control unit 4 in the present disclosure is realized.
  • the program may be pre-recorded in the memory of the computer system, may be provided through a telecommunications line, and may be recorded on a non-temporary recording medium such as a memory card, optical disk, hard disk drive, etc. that can be read by the computer system. May be provided.
  • a processor in a computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large scale integrated circuit (LSI).
  • IC semiconductor integrated circuit
  • LSI large scale integrated circuit
  • the integrated circuit such as IC or LSI referred to here has a different name depending on the degree of integration, and includes an integrated circuit called a system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration).
  • an FPGA Field-Programmable Gate Array
  • a plurality of electronic circuits may be integrated on one chip, or may be distributed on a plurality of chips.
  • the plurality of chips may be integrated in one device, or may be distributed in a plurality of devices.
  • the computer system referred to here includes a microprocessor having one or more processors and one or more memories. Therefore, the microprocessor is also composed of one or a plurality of electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.
  • control unit 4 it is not an essential configuration that a plurality of functions in the control unit 4 are integrated in one housing.
  • the components of the control unit 4 may be dispersedly provided in a plurality of housings.
  • a plurality of functions in the control unit 4 may be integrated in one housing as in the basic example.
  • at least a part of the functions of the control unit 4, for example, a part of the functions of the control unit 4 may be realized by a cloud (cloud computing) or the like.
  • the control unit 4 executes the second weakening magnetic flux control so as to increase the weakening magnetic flux current when the load increases.
  • the control unit 4 may further have a mode (strong magnetic flux control) for controlling so as to increase the strong magnetic flux current.
  • the stronger magnetic flux current is a positive exciting current. Due to the strong magnetic flux control, the rotation speed of the electric motor 15, that is, the rotation speed of the output shaft 16 (rotation shaft) is reduced.
  • the magnetic flux control unit 46 causes a strong magnetic flux current to flow so that the rotation speed sharply decreases toward the characteristic C1. May be good.
  • the weakening magnetic flux control includes the first weakening magnetic flux control and the second weakening magnetic flux control.
  • the first weakening magnetic flux control is not an essential control and may be omitted.
  • the control unit 4 determines whether or not the angular velocity condition is satisfied, that is, the angular velocity ⁇ 1 of the motor 15 corresponds to the command value c ⁇ 1 (after the increase) even when the pull-in amount increases at a predetermined interval. It may be determined whether or not it is lower than.
  • the control unit 4 determines an increase in the load through a decrease in the rotation speed (angular velocity) of the electric motor 15.
  • the power tool 1 may further include a detection unit that detects the load.
  • the control unit 4 may perform weakening magnetic flux control (second weakening magnetic flux control) when the detected load increases.
  • the detection unit corresponds to the current sensors 61 and 62 in the basic example.
  • the control unit 4 has a torque current (current measurement value corresponding to the torque component) corresponding to the detection result (for example, current measurement value i u 1 and current measurement value i v 1) detected by the detection unit (current sensors 61, 62). Based on iq1), it is determined whether or not the load has increased.
  • the weakening magnetic flux control is performed by triggering the increase in the load, it is possible to further suppress the reduction in efficiency of the motor 15. Moreover, the load can be easily detected.
  • the above-mentioned detection unit may be provided separately from the current sensors 61 and 62 of the basic example.
  • the electric tool (1) includes an electric motor (15), a driving force transmission mechanism (18), and a control unit (4).
  • the motor (15) has a permanent magnet (131) and a coil (141).
  • the driving force transmission mechanism (18) is driven by the electric motor (15).
  • the control unit (4) performs vector control for controlling the exciting current and the torque current supplied to the electric motor (15).
  • the control unit (4) controls to increase the exciting current at least in response to an increase in the load received from the outside by the output shaft (16) of the electric motor (15). According to the first aspect, it is possible to suppress the reduction in efficiency of the motor (15).
  • the control unit (4) is a permanent magnet (131) when the rotation speed of the electric motor (15) decreases due to an increase in load. 1 Weak magnetic flux control is performed in which a weakening magnetic flux current for generating a second magnetic flux that weakens the magnetic flux in the coil (141) is passed through the coil (141) as an exciting current. According to the second aspect, since the weakening magnetic flux control is performed by triggering the decrease in the rotation speed, it is possible to further suppress the reduction in efficiency of the motor (15).
  • the control unit (4) reduces the amount of change in the rotation speed of the electric motor (15) due to the change in load.
  • the magnitude of the exciting current is determined. According to the third aspect, it is possible to further suppress the reduction in efficiency of the electric motor (15) and to make it difficult for the user of the electric tool (1) to feel uncomfortable that the rotation speed has changed due to a change in load. it can.
  • the power tool (1) is an operation unit (trigger switch 29) that receives an operation for controlling the rotation of the electric motor (15) in any one of the first to third aspects. Further prepare.
  • the control unit (4) adjusts the magnitude of the exciting current so that the rotation speed of the motor (15) is maintained at the target value corresponding to the operation of the operation unit (trigger switch 29) even if the load changes. decide.
  • it is possible to further suppress the reduction in efficiency of the electric motor (15) and make it difficult for the user of the electric tool (1) to feel uncomfortable that the rotation speed has changed due to a change in load. it can.
  • the control unit (4) continuously changes the magnitude of the exciting current. According to the fifth aspect, it is possible to further suppress the reduction in efficiency of the electric motor (15) as compared with the case where the magnitude of the exciting current is changed discontinuously (that is, stepwise).
  • the power tool (1) according to the sixth aspect further includes detection units (current sensors 61, 62) for detecting a load in any one of the first to fifth aspects.
  • the control unit (4) uses the weakening magnetic flux current for generating the second magnetic flux that weakens the first magnetic flux of the permanent magnet (131) in the coil (141) as the exciting current when the detected load increases.
  • the weakening magnetic flux is controlled to flow in 141). According to the sixth aspect, since the weakening magnetic flux control is performed by triggering the increase in the load, it is possible to further suppress the reduction in efficiency of the motor (15).
  • the control unit (4) is based on the torque current corresponding to the detection result detected by the detection units (current sensors 61 and 62). Determine if the load has increased. According to the seventh aspect, the load can be easily detected.
  • control unit (4) is set to set valid or invalid for the control for increasing the exciting current. It further has a part (A2). According to the eighth aspect, it is possible to further suppress the reduction in efficiency of the electric motor (15) while improving the convenience.
  • the control method according to the ninth aspect is a control method of an electric tool (1) including an electric motor (15) having a permanent magnet (131) and a coil (141).
  • the control method includes a main step of performing vector control for controlling the exciting current and the torque current supplied to the electric motor (15) that drives the driving force transmission mechanism (18).
  • the main step includes at least a sub-step of controlling the output shaft (16) of the motor (15) to increase the exciting current in response to an increase in the load received from the outside. According to the ninth aspect, it is possible to provide a control method capable of suppressing the reduction in efficiency of the motor (15).
  • the program according to the tenth aspect is a program for causing one or more processors to execute the control method in the ninth aspect. According to the tenth aspect, it is possible to provide a function capable of suppressing the reduction in efficiency of the electric motor (15).
  • the configurations according to the second to eighth aspects are not essential configurations for the power tool (1) and can be omitted as appropriate.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Control Of Ac Motors In General (AREA)

Abstract

The purpose of the present disclosure is to prevent a reduction in the efficiency of an electric motor. An electric tool (1) is provided with an electric motor (15), a drive power transmission mechanism (18), and a control unit (4). The electric motor (15) has a permanent magnet (131) and a coil (141). The drive power transmission mechanism (18) is driven by the electric motor (15). The control unit (4) performs vector control to control an excitation current and a torque current that are supplied to the electric motor (15). The control unit (4) performs control so as to increase the excitation current in accordance with at least an increase in external load to which an output shaft (16) of the electric motor (15) is subjected.

Description

電動工具、制御方法、及びプログラムPower tools, control methods, and programs
　本開示は、一般に、電動工具、制御方法、及びプログラムに関する。より詳細には、本開示は、電動機を備える電動工具、当該電動工具の制御方法、及びプログラムに関する。 This disclosure generally relates to power tools, control methods, and programs. More specifically, the present disclosure relates to a power tool including a power tool, a control method for the power tool, and a program.
　特許文献１には、電動機の回転数を制御可能な電動工具が記載されている。この電動工具は、ブラシレスＤＣモータ（電動機）と、バッテリ電圧検出部と、回転位置検出部と、制御部と、を備える。バッテリ電圧検出部は、ブラシレスＤＣモータの駆動に用いるバッテリの電圧を検出する。回転位置検出部は、ブラシレスＤＣモータの回転位置を検出する。制御部は、回転位置検出部からの信号により、ブラシレスＤＣモータへの駆動出力を制御する。制御部は、ブラシレスＤＣモータへの駆動出力制御時に、ブラシレスＤＣモータの回転数若しくは通電電流が、バッテリ電圧検出部にて検出されたバッテリ電圧に対応した目標値になるよう、ブラシレスＤＣモータへの通電角若しくは進角を制御する。 Patent Document 1 describes an electric tool capable of controlling the rotation speed of an electric motor. This electric tool includes a brushless DC motor (motor), a battery voltage detection unit, a rotation position detection unit, and a control unit. The battery voltage detection unit detects the voltage of the battery used to drive the brushless DC motor. The rotation position detection unit detects the rotation position of the brushless DC motor. The control unit controls the drive output to the brushless DC motor by the signal from the rotation position detection unit. When controlling the drive output to the brushless DC motor, the control unit sends the brushless DC motor to the brushless DC motor so that the rotation speed or energizing current of the brushless DC motor becomes the target value corresponding to the battery voltage detected by the battery voltage detection unit. Control the energization angle or advance angle.
特開２０１４－１４４４９６号公報JP-A-2014-144496
　ところで、電動工具においては、負荷が増加することで電動機の回転数が低下してしまい、電動機の目標回転数が得られない可能性がある。そのため、電動機の低効率化を抑制することが望まれる。 By the way, in the case of electric tools, the rotation speed of the electric motor may decrease due to the increase in load, and the target rotation speed of the electric motor may not be obtained. Therefore, it is desired to suppress the reduction in efficiency of the motor.
　本開示は上記事由に鑑みてなされ、電動機の低効率化の抑制を図ることができる、電動工具、制御方法、及びプログラムを提供することを目的とする。 The present disclosure has been made in view of the above reasons, and an object of the present disclosure is to provide an electric tool, a control method, and a program capable of suppressing the reduction in efficiency of the electric motor.
　本開示の一態様の電動工具は、電動機と、駆動力伝達機構と、制御部と、を備える。前記電動機は、永久磁石及びコイルを有する。前記駆動力伝達機構は、前記電動機によって駆動される。前記制御部は、前記電動機に供給される励磁電流とトルク電流とを制御するベクトル制御を行う。前記制御部は、少なくとも前記電動機の出力軸が外部から受ける負荷の増加に応じて、前記励磁電流を増加させるように制御する。 The electric tool of one aspect of the present disclosure includes an electric motor, a driving force transmission mechanism, and a control unit. The motor has a permanent magnet and a coil. The driving force transmission mechanism is driven by the electric motor. The control unit performs vector control for controlling the exciting current and the torque current supplied to the motor. The control unit controls to increase the exciting current at least in response to an increase in a load received from the outside by the output shaft of the motor.
　本開示の一態様の制御方法は、永久磁石及びコイルを有した電動機を備える電動工具の制御方法である。前記制御方法は、駆動力伝達機構を駆動する前記電動機に供給される励磁電流とトルク電流とを制御するベクトル制御を行う主ステップを含む。前記主ステップは、少なくとも前記電動機の出力軸が外部から受ける負荷の増加に応じて、前記励磁電流を増加させるように制御する副ステップを含む。 One aspect of the control method of the present disclosure is a control method of an electric tool including an electric motor having a permanent magnet and a coil. The control method includes a main step of performing vector control for controlling an exciting current and a torque current supplied to the electric motor that drives the driving force transmission mechanism. The main step includes at least a sub-step for controlling the exciting current to increase in response to an increase in a load received from the outside by the output shaft of the motor.
　本開示の一態様のプログラムは、１以上のプロセッサに上記制御方法を実行させるためのプログラムである。 The program of one aspect of the present disclosure is a program for causing one or more processors to execute the above control method.
図１は、一実施形態に係る電動工具のブロック構成図である。FIG. 1 is a block configuration diagram of a power tool according to an embodiment. 図２は、同上の電動工具の概略図である。FIG. 2 is a schematic view of the same power tool. 図３は、同上の電動工具に関する特性を説明するための図である。FIG. 3 is a diagram for explaining the characteristics of the same power tool. 図４は、同上の電動工具に関する特性を説明するための図である。FIG. 4 is a diagram for explaining the characteristics of the same power tool. 図５は、同上の電動工具の動作を説明するためのフローチャート図である。FIG. 5 is a flowchart for explaining the operation of the power tool of the same.
　（１）概要
　以下の実施形態において説明する各図は、模式的な図であり、各図中の各構成要素の大きさ及び厚さそれぞれの比が、必ずしも実際の寸法比を反映しているとは限らない。 (1) Outline Each figure described in the following embodiments is a schematic view, and the ratio of the size and the thickness of each component in each figure does not necessarily reflect the actual dimensional ratio. Not necessarily.
　本実施形態に係る電動工具１（図１及び図２参照）は、例えば、工場又は建築現場等で使用される工具である。ここでは一例として、電動工具１は、作業対象（ボルト又はねじ等の締結部材）を締め付けるために使用されるインパクトドライバであることを想定して説明する。ただし、電動工具１の種類は、特に限定されず、ドリルドライバ又はインパクトレンチ等でもよい。 The power tool 1 (see FIGS. 1 and 2) according to the present embodiment is, for example, a tool used in a factory, a construction site, or the like. Here, as an example, the power tool 1 will be described on the assumption that it is an impact driver used for tightening a work object (fastening member such as a bolt or a screw). However, the type of the power tool 1 is not particularly limited, and a drill driver, an impact wrench, or the like may be used.
　電動工具１は、電動機１５（例えば交流電動機）と、駆動力伝達機構１８と、制御部４と、を備えている。電動機１５は、永久磁石１３１及びコイル１４１を有している。電動機１５は、例えばブラシレスモータである。本実施形態の電動機１５は、同期電動機であり、より詳細には、永久磁石同期電動機（ＰＭＳＭ（Permanent Magnet Synchronous Motor））である。 The electric tool 1 includes an electric motor 15 (for example, an AC electric motor), a driving force transmission mechanism 18, and a control unit 4. The electric motor 15 has a permanent magnet 131 and a coil 141. The electric motor 15 is, for example, a brushless motor. The electric motor 15 of the present embodiment is a synchronous electric motor, and more specifically, a permanent magnet synchronous electric motor (PMSM (Permanent Magnet Synchronous Motor)).
　駆動力伝達機構１８は、電動機１５によって駆動される。制御部４は、電動機１５に供給される励磁電流（ｄ軸電流）とトルク電流（ｑ軸電流）とを制御するベクトル制御を行う。なお、制御部４は、ベクトル制御による弱め磁束制御を実行する。弱め磁束制御では、制御部４は、永久磁石１３１の磁束（第１磁束）を弱める第２磁束（弱め磁束）をコイル１４１に発生させるための弱め磁束電流（ｄ軸電流）を励磁電流としてコイル１４１に流させる。弱め磁束電流は、マイナスの励磁電流である。弱め磁束制御により、電動機１５の回転数、すなわち出力軸１６（回転軸）の回転数は増加する。 The driving force transmission mechanism 18 is driven by the electric motor 15. The control unit 4 performs vector control for controlling the exciting current (d-axis current) and the torque current (q-axis current) supplied to the motor 15. The control unit 4 executes weakening magnetic flux control by vector control. In the weakened magnetic flux control, the control unit 4 uses a weakened magnetic flux current (d-axis current) for generating a second magnetic flux (weakened magnetic flux) that weakens the magnetic flux (first magnetic flux) of the permanent magnet 131 in the coil 141 as an exciting current. Let it flow to 141. The weakening magnetic flux current is a negative exciting current. Due to the weak magnetic flux control, the rotation speed of the electric motor 15, that is, the rotation speed of the output shaft 16 (rotation shaft) is increased.
　ここで本実施形態の制御部４は、少なくとも電動機１５の出力軸１６が外部から受ける負荷の増加に応じて、励磁電流を増加させるように制御する。本開示でいう「励磁電流を増加させる」とは、励磁電流の大きさ（絶対値）を増加させることとする。 Here, the control unit 4 of the present embodiment controls so as to increase the exciting current at least in response to an increase in the load received from the outside by the output shaft 16 of the electric motor 15. "Increasing the exciting current" as used in the present disclosure means increasing the magnitude (absolute value) of the exciting current.
　この構成によれば、制御部４は、少なくとも負荷の増加に応じて、励磁電流を増加させる。そのため、例えば負荷が増加することで電動機１５の回転数が低下して、電動機の目標回転数が得られなくなる可能性を低減できる。その結果、電動機１５の低効率化の抑制を図ることができる。 According to this configuration, the control unit 4 increases the exciting current at least in response to an increase in the load. Therefore, for example, it is possible to reduce the possibility that the rotation speed of the motor 15 decreases due to an increase in the load and the target rotation speed of the motor cannot be obtained. As a result, it is possible to suppress the reduction in efficiency of the electric motor 15.
　（２）詳細
　（２．１）全体構成
　以下、本実施形態に係る電動工具１の全体構成について、図１～図５を参照しながら詳しく説明する。なお、以下では、電動工具１を利用して作業対象を締め付ける作業を行う者を単に「使用者」と呼ぶことがある。 (2) Details (2.1) Overall configuration Hereinafter, the overall configuration of the power tool 1 according to the present embodiment will be described in detail with reference to FIGS. 1 to 5. In the following, a person who performs the work of tightening the work target by using the power tool 1 may be simply referred to as a “user”.
　電動工具１は、図２に示すように、電動機１５と、電源部３２と、駆動力伝達機構１８と、インパクト機構１７と、チャック２３と、トリガスイッチ２９と、制御部４と、ビット回転測定部２５と、トルク測定部２６と、モータ回転測定部２７と、を備えている。また電動工具１は、先端工具（ビット）を更に備えている。なお、制御部４については、次の欄で詳しく説明する。 As shown in FIG. 2, the electric tool 1 includes an electric motor 15, a power supply unit 32, a driving force transmission mechanism 18, an impact mechanism 17, a chuck 23, a trigger switch 29, a control unit 4, and a bit rotation measurement. A unit 25, a torque measuring unit 26, and a motor rotation measuring unit 27 are provided. Further, the power tool 1 further includes a tip tool (bit). The control unit 4 will be described in detail in the next column.
　インパクト機構１７は、出力軸２１を有している。出力軸２１は、電動機１５から伝達された駆動力により回転する部分である。チャック２３は、出力軸２１に固定されており、先端工具が着脱自在に取り付けられる部分である。電動工具１は、先端工具を電動機１５の駆動力で駆動する工具である。先端工具は、例えば、ドライバ又はドリル等である。複数種類の先端工具のうち用途に応じた先端工具が、選択的にチャック２３に取り付けられて用いられる。先端工具は、出力軸２１に直接に装着されてもよい。 The impact mechanism 17 has an output shaft 21. The output shaft 21 is a portion that rotates by a driving force transmitted from the electric motor 15. The chuck 23 is fixed to the output shaft 21 and is a portion to which the tip tool can be detachably attached. The electric tool 1 is a tool that drives the tip tool with the driving force of the electric motor 15. The tip tool is, for example, a screwdriver or a drill. Of the plurality of types of tip tools, the tip tool according to the application is selectively attached to the chuck 23 and used. The tip tool may be mounted directly on the output shaft 21.
　電動機１５（交流電動機）は、先端工具を駆動する駆動源である。電動機１５は、図１に示すように、永久磁石１３１を有する回転子１３と、コイル１４１を有する固定子１４と、を含んでいる。回転子１３は、回転動力を出力する出力軸１６（図２参照）を含む。コイル１４１と永久磁石１３１との電磁的相互作用により、回転子１３は、固定子１４に対して回転する。 The motor 15 (AC motor) is a drive source for driving the tip tool. As shown in FIG. 1, the electric motor 15 includes a rotor 13 having a permanent magnet 131 and a stator 14 having a coil 141. The rotor 13 includes an output shaft 16 (see FIG. 2) that outputs rotational power. The rotor 13 rotates with respect to the stator 14 due to the electromagnetic interaction between the coil 141 and the permanent magnet 131.
　電源部３２は、電動機１５へ電力供給する１又は複数の電池３２０（例えば２次電池）を含んだ、いわゆる電池パックである。電源部３２は、例えば、電動工具１の器体における把持部の下端に取外し可能に装着される。駆動力伝達機構１８は、電動機１５によって駆動される。駆動力伝達機構１８は、電動機１５の回転動力を調整して所望のトルクを出力する。駆動力伝達機構１８は、出力部である駆動軸２２（図２参照）を有している。 The power supply unit 32 is a so-called battery pack including one or a plurality of batteries 320 (for example, a secondary battery) that supply electric power to the electric motor 15. The power supply unit 32 is detachably attached to the lower end of the grip portion in the body of the power tool 1, for example. The driving force transmission mechanism 18 is driven by the electric motor 15. The driving force transmission mechanism 18 adjusts the rotational power of the electric motor 15 to output a desired torque. The driving force transmission mechanism 18 has a driving shaft 22 (see FIG. 2) which is an output unit.
　駆動力伝達機構１８の駆動軸２２は、インパクト機構１７に接続されている。インパクト機構１７は、駆動力伝達機構１８を介して受け取った電動機１５の回転動力をパルス状のトルクに変換してインパクト力を発生する。インパクト機構１７は、ハンマ１９と、アンビル２０と、出力軸２１と、ばね２４と、を備えている。ハンマ１９は、駆動力伝達機構１８の駆動軸２２にカム機構を介して取り付けられている。アンビル２０はハンマ１９に結合されており、ハンマ１９と一体に回転する。ばね２４は、ハンマ１９をアンビル２０側に押している。アンビル２０は、出力軸２１と一体に形成されている。なお、アンビル２０は、出力軸２１とは別体に形成されて出力軸２１に固定されていてもよい。 The drive shaft 22 of the drive force transmission mechanism 18 is connected to the impact mechanism 17. The impact mechanism 17 converts the rotational power of the electric motor 15 received via the driving force transmission mechanism 18 into pulsed torque to generate an impact force. The impact mechanism 17 includes a hammer 19, an anvil 20, an output shaft 21, and a spring 24. The hammer 19 is attached to the drive shaft 22 of the drive force transmission mechanism 18 via a cam mechanism. The anvil 20 is coupled to the hammer 19 and rotates integrally with the hammer 19. The spring 24 pushes the hammer 19 toward the anvil 20. The anvil 20 is integrally formed with the output shaft 21. The anvil 20 may be formed separately from the output shaft 21 and fixed to the output shaft 21.
　出力軸２１に規定の大きさ以上の負荷（トルク）がかかっていないときには、カム機構により連結された駆動軸２２とハンマ１９とが一体に回転し、さらにハンマ１９とアンビル２０とが一体に回転するので、アンビル２０と一体に形成された出力軸２１が回転する。一方で、出力軸２１に規定の大きさ以上の負荷がかかった時には、ハンマ１９がカム機構による規制を受けながらばね２４に抗して後退する（つまり、アンビル２０から離れる）。そして、ハンマ１９とアンビル２０との結合が外れた時点で、ハンマ１９は回転しながら前進してアンビル２０に回転方向の打撃衝撃を与え、出力軸２１を回転させる。 When a load (torque) larger than the specified size is not applied to the output shaft 21, the drive shaft 22 and the hammer 19 connected by the cam mechanism rotate integrally, and the hammer 19 and the anvil 20 rotate integrally. Therefore, the output shaft 21 integrally formed with the anvil 20 rotates. On the other hand, when a load of a predetermined size or more is applied to the output shaft 21, the hammer 19 retracts against the spring 24 (that is, separates from the anvil 20) while being regulated by the cam mechanism. Then, when the connection between the hammer 19 and the anvil 20 is disengaged, the hammer 19 advances while rotating and gives a striking impact in the rotational direction to the anvil 20 to rotate the output shaft 21.
　トリガスイッチ２９は、電動機１５の回転を制御するための操作を受け付ける操作部である。トリガスイッチ２９を引く操作により、電動機１５のオン及びオフを切替可能である。また、トリガスイッチ２９を引く操作の引込み量で、出力軸２１の回転数（回転速度）、つまり電動機１５の回転数（回転速度）を調整可能である。上記引込み量が大きいほど、電動機１５の回転速度が速くなる。制御部４は、トリガスイッチ２９を引く操作の引込み量に応じて、電動機１５を回転又は停止させ、また、電動機１５の回転速度を制御する。この電動工具１では、先端工具がチャック２３に取り付けられる。そして、トリガスイッチ２９への操作によって電動機１５の回転速度が制御されることで、先端工具の回転速度が制御される。 The trigger switch 29 is an operation unit that accepts an operation for controlling the rotation of the electric motor 15. By pulling the trigger switch 29, the motor 15 can be switched on and off. Further, the rotation speed (rotation speed) of the output shaft 21, that is, the rotation speed (rotation speed) of the motor 15 can be adjusted by the pull-in amount of the operation of pulling the trigger switch 29. The larger the pull-in amount, the faster the rotation speed of the electric motor 15. The control unit 4 rotates or stops the electric motor 15 according to the pull-in amount of the operation of pulling the trigger switch 29, and also controls the rotation speed of the electric motor 15. In the power tool 1, the tip tool is attached to the chuck 23. Then, the rotation speed of the tip tool is controlled by controlling the rotation speed of the electric motor 15 by operating the trigger switch 29.
　電動工具１は、チャック２３を備えているため、先端工具を用途に応じて交換可能であるが、先端工具が交換可能であることは必須ではない。例えば、電動工具１は、特定の先端工具のみ用いることができる電動工具であってもよい。 Since the power tool 1 is provided with a chuck 23, the tip tool can be replaced according to the application, but it is not essential that the tip tool can be replaced. For example, the power tool 1 may be a power tool that can be used only with a specific tip tool.
　トルク測定部２６は、電動機１５の動作トルクを測定する。トルク測定部２６は、例えば、ねじり歪みの検出が可能な磁歪式歪センサである。磁歪式歪センサは、電動機１５の出力軸１６にトルクが加わることにより発生する歪みに応じた透磁率の変化を、電動機１５の非回転部分に設置したコイルで検出し、歪みに比例した電圧信号を出力する。 The torque measuring unit 26 measures the operating torque of the motor 15. The torque measuring unit 26 is, for example, a magnetostrictive strain sensor capable of detecting torsional strain. The magnetostrictive strain sensor detects a change in the magnetostriction according to the strain generated by applying torque to the output shaft 16 of the motor 15 with a coil installed in the non-rotating portion of the motor 15, and a voltage signal proportional to the strain. Is output.
　ビット回転測定部２５は、出力軸２１の回転角を測定する。ここでは、出力軸２１の回転角は、先端工具（ビット）の回転角に等しい。ビット回転測定部２５としては、例えば、光電式エンコーダ又は磁気式エンコーダを採用することができる。 The bit rotation measuring unit 25 measures the rotation angle of the output shaft 21. Here, the rotation angle of the output shaft 21 is equal to the rotation angle of the tip tool (bit). As the bit rotation measuring unit 25, for example, a photoelectric encoder or a magnetic encoder can be adopted.
　モータ回転測定部２７は、電動機１５の回転角を測定する。モータ回転測定部２７としては、例えば、光電式エンコーダ又は磁気式エンコーダを採用することができる。 The motor rotation measuring unit 27 measures the rotation angle of the electric motor 15. As the motor rotation measuring unit 27, for example, a photoelectric encoder or a magnetic encoder can be adopted.
　（２．２）制御部
　制御部４は、１以上のプロセッサ及びメモリを有するコンピュータシステムを含んでいる。コンピュータシステムのメモリに記録されたプログラムを、コンピュータシステムのプロセッサが実行することにより、制御部４の少なくとも一部の機能が実現される。プログラムは、メモリに記録されていてもよいし、インターネット等の電気通信回線を通して提供されてもよく、メモリカード等の非一時的記録媒体に記録されて提供されてもよい。 (2.2) Control unit The control unit 4 includes a computer system having one or more processors and memories. When the processor of the computer system executes the program recorded in the memory of the computer system, at least a part of the functions of the control unit 4 are realized. The program may be recorded in a memory, provided through a telecommunication line such as the Internet, or may be recorded and provided on a non-temporary recording medium such as a memory card.
　制御部４は、電動機１５の駆動制御を行うように構成される。制御部４は、電動機１５に供給される励磁電流とトルク電流とを（例えば独立に）制御する（ベクトル制御）。ここでは、制御部４の駆動制御は、弱め磁束制御と、通常制御と、を含む。言い換えると、制御部４は、弱め磁束制御のモードとしての第１モード、及び通常制御のモードとしての第２モードを、動作モードとして有している。 The control unit 4 is configured to control the drive of the motor 15. The control unit 4 controls (for example, independently) the exciting current and the torque current supplied to the motor 15 (vector control). Here, the drive control of the control unit 4 includes a weakening magnetic flux control and a normal control. In other words, the control unit 4 has a first mode as a mode of weakening magnetic flux control and a second mode as a mode of normal control as operation modes.
　制御部４は、第１モードでは、後述するインバータ回路部５１（図１参照）から電動機１５のコイル１４１に弱め磁束電流を流させる。すなわち、制御部４は、弱め磁束制御により、永久磁石１３１の磁束（第１磁束）を弱める第２磁束をコイル１４１に発生させるための弱め磁束電流をコイル１４１に流させる。 In the first mode, the control unit 4 causes a weakened magnetic flux current to flow from the inverter circuit unit 51 (see FIG. 1), which will be described later, to the coil 141 of the motor 15. That is, the control unit 4 causes the coil 141 to flow a weakening magnetic flux current for generating a second magnetic flux that weakens the magnetic flux (first magnetic flux) of the permanent magnet 131 in the coil 141 by the weakening magnetic flux control.
　制御部４は、第２モードでは、インバータ回路部５１からコイル１４１に弱め磁束電流を流させない。つまり、通常制御においてコイル１４１に流れる電流は、トルク電流（ｑ軸電流）のみとなる。 In the second mode, the control unit 4 weakens the coil 141 from the inverter circuit unit 51 so that the magnetic flux current does not flow. That is, in normal control, the current flowing through the coil 141 is only the torque current (q-axis current).
　通常制御は、弱め磁束（電流）の指令値（目標値）ｃｉｄ１（図１参照）をゼロ（０）にし、弱め磁束（電流）がこの指令値ｃｉｄ１に収束するように行う制御と言える。一方、弱め磁束制御は、弱め磁束（電流）の指令値ｃｉｄ１をゼロ（０）より大きくし、弱め磁束（電流）がこの指令値ｃｉｄ１に収束するように行う制御と言える。弱め磁束（電流）の指令値ｃｉｄ１がゼロ（０）より大きくなると、電動機１５に弱め磁束電流（マイナスの励磁電流）が流れ、弱め磁束が発生する。 It can be said that the normal control is performed so that the command value (target value) of the weakening magnetic flux (current) (target value) cid1 (see FIG. 1) is set to zero (0) and the weakening magnetic flux (current) converges to this command value cid1. On the other hand, the weakening magnetic flux control can be said to be a control performed so that the command value cid1 of the weakening magnetic flux (current) is made larger than zero (0) and the weakening magnetic flux (current) converges to this command value cid1. When the command value side1 of the weakening magnetic flux (current) becomes larger than zero (0), the weakening magnetic flux current (minus exciting current) flows through the motor 15, and the weakening magnetic flux is generated.
　制御部４は、図１に示すように、指令値生成部４１と、速度制御部４２と、電流制御部４３と、第１の座標変換器４４と、第２の座標変換器４５と、磁束制御部４６と、推定部４７と、脱調検出部４８と、を有している。また電動工具１は、インバータ回路部５１と、複数（図１では２つ）の電流センサ６１、６２と、を更に備えている。制御部４は、インバータ回路部５１と共に用いられ、フィードバック制御により電動機１５の動作を制御する。 As shown in FIG. 1, the control unit 4 includes a command value generation unit 41, a speed control unit 42, a current control unit 43, a first coordinate converter 44, a second coordinate converter 45, and a magnetic flux. It has a control unit 46, an estimation unit 47, and a step-out detection unit 48. Further, the power tool 1 further includes an inverter circuit unit 51 and a plurality of (two in FIG. 1) current sensors 61 and 62. The control unit 4 is used together with the inverter circuit unit 51, and controls the operation of the electric motor 15 by feedback control.
　複数の電流センサ６１、６２はそれぞれ、例えば、ホール素子電流センサ又はシャント抵抗素子を含んでいる。複数の電流センサ６１、６２は、電池３２０からインバータ回路部５１を介して電動機１５に供給される電流を測定する。ここで、電動機１５には、３相電流（Ｕ相電流、Ｖ相電流及びＷ相電流）が供給されており、複数の電流センサ６１、６２は、少なくとも２相の電流を測定する。図１では、電流センサ６１がＵ相電流を測定して電流測定値ｉｕ１を出力し、電流センサ６２がＶ相電流を測定して電流測定値ｉｖ１を出力する。 Each of the plurality of current sensors 61 and 62 includes, for example, a Hall element current sensor or a shunt resistance element. The plurality of current sensors 61 and 62 measure the current supplied from the battery 320 to the motor 15 via the inverter circuit unit 51. Here, a three-phase current (U-phase current, V-phase current, and W-phase current) is supplied to the motor 15, and the plurality of current sensors 61 and 62 measure at least two-phase currents. In FIG. 1, the current sensor 61 measures the U-phase current and outputs the measured current value i u 1, and the current sensor 62 measures the V-phase current and outputs the measured current value i v 1.
　推定部４７は、モータ回転測定部２７で測定された電動機１５の回転角θ１を時間微分して、電動機１５の角速度ω１（出力軸１６の角速度）を算出する。 The estimation unit 47 calculates the angular velocity ω1 (angular velocity of the output shaft 16) of the motor 15 by time-differentiating the rotation angle θ1 of the motor 15 measured by the motor rotation measurement unit 27.
　第２の座標変換器４５は、複数の電流センサ６１、６２で測定された電流測定値ｉｕ１、ｉｖ１を、モータ回転測定部２７で測定された電動機１５の回転角θ１に基づいて座標変換し、電流測定値ｉｄ１、ｉｑ１を算出する。すなわち、第２の座標変換器４５は、３相のうち２相の電流に対応する電流測定値ｉｕ１、ｉｖ１を、磁界成分（ｄ軸電流）に対応する電流測定値ｉｄ１と、トルク成分（ｑ軸電流）に対応する電流測定値ｉｑ１とに変換する。 The second coordinate converter 45 uses the current measured values i u 1 and i v 1 measured by the plurality of current sensors 61 and 62 based on the rotation angle θ1 of the motor 15 measured by the motor rotation measuring unit 27. The coordinates are converted and the current measurement values id1 and iq1 are calculated. That is, the second coordinate converter 45, a current measurement value i u 1, i v 1 corresponding to the two-phase currents of the three phases, the current measurement value id1 corresponding to the magnetic field component (d-axis current), It is converted to the current measured value iq1 corresponding to the torque component (q-axis current).
　指令値生成部４１は、電動機１５の角速度の指令値ｃω１を生成する。指令値生成部４１は、例えば、トリガスイッチ２９（図２参照）を引く操作の引込み量に応じた指令値ｃω１を生成する。指令値生成部４１は、上記引込み量が大きいほど、角速度の指令値ｃω１を大きくする。 The command value generation unit 41 generates the command value cω1 of the angular velocity of the motor 15. The command value generation unit 41 generates, for example, the command value cω1 according to the pull-in amount of the operation of pulling the trigger switch 29 (see FIG. 2). The command value generation unit 41 increases the command value cω1 of the angular velocity as the pull-in amount increases.
　速度制御部４２は、指令値生成部４１で生成された指令値ｃω１と推定部４７で算出された角速度ω１との差分に基づいて、指令値ｃｉｑ１を生成する。指令値ｃｉｑ１は、電動機１５のトルク電流（ｑ軸電流）の大きさを指定する指令値である。速度制御部４２は、指令値ｃω１と角速度ω１との差分を小さくするように指令値ｃｉｑ１を決定する。つまり、制御部４は、電動機１５の回転数がトリガスイッチ２９への操作に対応した目標値に一致するように制御する。 The speed control unit 42 generates the command value ciq1 based on the difference between the command value cω1 generated by the command value generation unit 41 and the angular velocity ω1 calculated by the estimation unit 47. The command value ciq1 is a command value that specifies the magnitude of the torque current (q-axis current) of the motor 15. The speed control unit 42 determines the command value ciq1 so as to reduce the difference between the command value cω1 and the angular velocity ω1. That is, the control unit 4 controls so that the rotation speed of the electric motor 15 matches the target value corresponding to the operation of the trigger switch 29.
　磁束制御部４６は、弱め磁束制御の場合（第１モードの場合）、推定部４７で算出された角速度ω１と、電流制御部４３で生成される指令値ｃｖｑ１（後述する）と、電流測定値ｉｑ１（ｑ軸電流）とに基づいて、指令値ｃｉｄ１を決定する。指令値ｃｉｄ１は、電動機１５の弱め磁束（ｄ軸方向の磁束）の大きさを指定する指令値である。通常制御の場合（第２モードの場合）、磁束制御部４６で生成される指令値ｃｉｄ１は、弱め磁束をゼロ（０）にするための指令値となる。 In the case of weak magnetic flux control (in the case of the first mode), the magnetic flux control unit 46 includes an angular velocity ω1 calculated by the estimation unit 47, a command value cvq1 (described later) generated by the current control unit 43, and a current measurement value. The command value cid1 is determined based on iq1 (q-axis current). The command value cid1 is a command value that specifies the magnitude of the weakening magnetic flux (magnetic flux in the d-axis direction) of the motor 15. In the case of normal control (in the case of the second mode), the command value cid1 generated by the magnetic flux control unit 46 is a command value for setting the weakening magnetic flux to zero (0).
　電流制御部４３は、磁束制御部４６で生成された指令値ｃｉｄ１と第２の座標変換器４５で算出された電流測定値ｉｄ１との差分に基づいて、指令値ｃｖｄ１を生成する。指令値ｃｖｄ１は、電動機１５のｄ軸電圧の大きさを指定する指令値である。電流制御部４３は、指令値ｃｉｄ１と電流測定値ｉｄ１との差分を小さくするように指令値ｃｖｄ１を決定する。 The current control unit 43 generates the command value cvd1 based on the difference between the command value cyd1 generated by the magnetic flux control unit 46 and the current measurement value id1 calculated by the second coordinate converter 45. The command value cvd1 is a command value that specifies the magnitude of the d-axis voltage of the motor 15. The current control unit 43 determines the command value cvd1 so as to reduce the difference between the command value cid1 and the current measurement value id1.
　また、電流制御部４３は、速度制御部４２で生成された指令値ｃｉｑ１と第２の座標変換器４５で算出された電流測定値ｉｑ１との差分に基づいて、指令値ｃｖｑ１を生成する。指令値ｃｖｑ１は、電動機１５のｑ軸電圧の大きさを指定する指令値である。電流制御部４３は、指令値ｃｉｑ１と電流測定値ｉｑ１との差分を小さくするように指令値ｃｖｑ１を生成する。 Further, the current control unit 43 generates the command value cvq1 based on the difference between the command value iq1 generated by the speed control unit 42 and the current measurement value iq1 calculated by the second coordinate converter 45. The command value cvq1 is a command value that specifies the magnitude of the q-axis voltage of the motor 15. The current control unit 43 generates the command value cvq1 so as to reduce the difference between the command value xiq1 and the current measurement value iq1.
　第１の座標変換器４４は、指令値ｃｖｄ１、ｃｖｑ１を、モータ回転測定部２７で測定された電動機１５の回転角θ１に基づいて座標変換し、指令値ｃｖｕ１、ｃｖｖ１、ｃｖｗ１を算出する。すなわち、第１の座標変換器４４は、磁界成分（ｄ軸電圧）に対応する指令値ｃｖｄ１と、トルク成分（ｑ軸電圧）に対応する指令値ｃｖｑ１とを、３相電圧に対応する指令値ｃｖｕ１、ｃｖｖ１、ｃｖｗ１に変換する。指令値ｃｖｕ１はＵ相電圧に、指令値ｃｖｖ１はＶ相電圧に、指令値ｃｖｗ１はＷ相電圧に対応する。 The first coordinate converter 44 converts the command values cvd1 and cvq1 into coordinates based on the rotation angle θ1 of the electric motor 15 measured by the motor rotation measuring unit 27, and converts the command values cv u 1, cv v 1, and cv w. 1 is calculated. That is, the first coordinate converter 44 sets the command value cvd1 corresponding to the magnetic field component (d-axis voltage) and the command value cvq1 corresponding to the torque component (q-axis voltage) to the command value corresponding to the three-phase voltage. Convert to cv u 1, cv v 1, cv w 1. The command value cv u 1 corresponds to the U-phase voltage, the command value cv v 1 corresponds to the V-phase voltage, and the command value cv w 1 corresponds to the W-phase voltage.
　インバータ回路部５１は、指令値ｃｖｕ１、ｃｖｖ１、ｃｖｗ１に応じた３相電圧を電動機１５に供給する。制御部４は、インバータ回路部５１をＰＷＭ制御することにより、電動機１５に供給される電力を制御する。 The inverter circuit unit 51 supplies the three-phase voltage according to the command values cv u 1, cv v 1, and cv w 1 to the motor 15. The control unit 4 controls the electric power supplied to the electric motor 15 by PWM-controlling the inverter circuit unit 51.
　電動機１５は、インバータ回路部５１から供給された電力（３相電圧）により駆動され、回転動力を発生させる。 The motor 15 is driven by the electric power (three-phase voltage) supplied from the inverter circuit section 51 to generate rotational power.
　この結果、制御部４は、電動機１５のコイル１４１に流れる弱め磁束電流が、磁束制御部４６で生成された指令値ｃｉｄ１に対応した大きさとなるように弱め磁束電流を制御する。また、制御部４は、電動機１５の角速度が、指令値生成部４１で生成された指令値ｃω１に対応した角速度となるように電動機１５の角速度を制御する。 As a result, the control unit 4 controls the weakening magnetic flux current so that the weakening magnetic flux current flowing through the coil 141 of the electric motor 15 has a magnitude corresponding to the command value cid1 generated by the magnetic flux control unit 46. Further, the control unit 4 controls the angular velocity of the motor 15 so that the angular velocity of the motor 15 corresponds to the command value cω1 generated by the command value generation unit 41.
　脱調検出部４８は、第２の座標変換器４５から取得した電流測定値ｉｄ１、ｉｑ１と、電流制御部４３から取得した指令値ｃｖｄ１、ｃｖｑ１と、に基づいて、電動機１５の脱調を検出する。脱調が検出された場合は、脱調検出部４８は、インバータ回路部５１に停止信号ｃｓ１を送信して、インバータ回路部５１から電動機１５への電力供給を停止させる。 The step-out detection unit 48 detects the step-out of the motor 15 based on the current measurement values id1 and iq1 acquired from the second coordinate converter 45 and the command values cvd1 and cvq1 acquired from the current control unit 43. To do. When step-out is detected, the step-out detection unit 48 transmits a stop signal cs1 to the inverter circuit unit 51 to stop the power supply from the inverter circuit unit 51 to the motor 15.
　以下、動作モードについて説明する。 The operation mode will be described below.
　制御部４は、切替条件が満たされる場合に、電動機１５のコイル１４１に弱め磁束電流を流す第１モードで動作する。すなわち、切替条件が満たされる場合に、制御部４の制御は、弱め磁束制御となる。 The control unit 4 operates in the first mode in which a weakening magnetic flux current is passed through the coil 141 of the motor 15 when the switching condition is satisfied. That is, when the switching condition is satisfied, the control of the control unit 4 becomes the weak magnetic flux control.
　切替条件は、例えば、電動機１５が高速域で動作しているという高速域条件を含む。電動機１５が高速域で動作しているとは、概略的には、電動機１５の回転速度が比較的大きいということである。「電動機１５が高速域で動作している」という定義は、電動機１５の回転速度が所定の回転速度以上で、かつ、インバータ回路部５１に対する制御部４のＰＷＭ（Pulse Width Modulation）制御のデューティ（変調度）が規定値以上であることである。ＰＷＭ制御のデューティは、ＰＷＭ信号の１周期中のオン期間を１周期の長さで割った値である。電動機１５の回転速度は、デューティに略比例する。上記規定値は、例えば、０．９又は０．９５程度である。 The switching condition includes, for example, a high-speed range condition that the motor 15 is operating in the high-speed range. The fact that the electric motor 15 operates in the high speed range generally means that the rotational speed of the electric motor 15 is relatively high. The definition that "the motor 15 is operating in the high speed range" is defined as the duty of PWM (Pulse Width Modulation) control of the control unit 4 with respect to the inverter circuit unit 51 when the rotation speed of the motor 15 is equal to or higher than a predetermined rotation speed. The degree of modulation) is equal to or higher than the specified value. The duty of the PWM control is a value obtained by dividing the ON period in one cycle of the PWM signal by the length of one cycle. The rotation speed of the electric motor 15 is substantially proportional to the duty. The above-mentioned specified value is, for example, about 0.9 or 0.95.
　また切替条件は、例えば、電動機１５のコイル１４１に流れるトルク電流値（ｑ軸電流値）が所定の電流値以下であるというトルク電流条件を含む。制御部４は、切替条件を満たすか否かを判定するために、トルク電流値として電流測定値ｉｑ１を用いる。ただし、制御部４は、トルク電流値として、トルク電流値の指令値ｃｉｑ１を用いてもよい。 Further, the switching condition includes, for example, a torque current condition that the torque current value (q-axis current value) flowing through the coil 141 of the motor 15 is equal to or less than a predetermined current value. The control unit 4 uses the current measurement value iq1 as the torque current value in order to determine whether or not the switching condition is satisfied. However, the control unit 4 may use the command value iq1 of the torque current value as the torque current value.
　ここでは切替条件は、高速域条件及びトルク電流条件の両方を含むものとするが、いずれか一方のみを含んでもよい。切替条件は例えばトルク電流条件のみを含んでもよい。 Here, the switching condition includes both the high-speed range condition and the torque current condition, but only one of them may be included. The switching condition may include only the torque current condition, for example.
　制御部４は、出力軸２１及び駆動軸２２等を介して電動機１５の出力軸１６が外部から受ける負荷（トルク）が比較的低い（無負荷も含む）低負荷領域において切替条件が満たされて、弱め磁束制御を行う。それにより、電動機１５の最大回転速度（最大回転数）を増加させることができる。つまり、制御部４は、電動機１５の出力軸１６が外部から受ける負荷が所定の大きさよりも小さい場合に、弱め磁束制御を行う。 The control unit 4 satisfies the switching condition in a low load region where the load (torque) received from the outside by the output shaft 16 of the motor 15 via the output shaft 21 and the drive shaft 22 is relatively low (including no load). , Weak magnetic flux control is performed. Thereby, the maximum rotation speed (maximum rotation speed) of the electric motor 15 can be increased. That is, the control unit 4 performs the weakening magnetic flux control when the load received from the outside by the output shaft 16 of the electric motor 15 is smaller than a predetermined magnitude.
　制御部４は、切替条件が満たされない場合、弱め磁束電流を流させない第２モードで動作する。すなわち、切替条件が満たされない場合、制御部４の制御は、通常制御となる。制御部４は、電動機１５に比較的大きなトルク電流が必要となる高負荷領域において、通常制御を行うことで、比較的大きなトルクを得ることができる。 The control unit 4 operates in the second mode in which the weakening magnetic flux current is not passed when the switching condition is not satisfied. That is, when the switching condition is not satisfied, the control of the control unit 4 becomes normal control. The control unit 4 can obtain a relatively large torque by performing normal control in a high load region where the electric motor 15 requires a relatively large torque current.
　なお、弱め磁束制御及び通常制御は、トリガスイッチ２９とは別の操作部への操作により手動で切り替え可能であってもよい。弱め磁束制御及び通常制御は、後述する表示部Ａ３（図１参照）へのタップ操作等によって切り替え可能であってもよい。 Note that the weakening magnetic flux control and the normal control may be manually switched by operating an operation unit different from the trigger switch 29. The weakening magnetic flux control and the normal control may be switched by a tap operation or the like on the display unit A3 (see FIG. 1) described later.
　（２．３）回転数の低下抑制
　ところで、図３は、比較例の電動工具に関する動作特性を説明するためのグラフである。図３の特性Ｃ１は、電動機１５に関するＴ－Ｎカーブ（負荷及び回転数（ｒｐｍ）の関係）を示している。負荷（トルク）の増加に伴い、電動機の最大回転数は低下する。例えば、使用者によるトリガスイッチ２９の引込み量が一定に維持されているとすると、負荷が所定値Ｌ１以下であれば、電動機１５は、現在の引込み量に対応した目標値の回転数Ｎ１となるように制御される（図３中の特性Ｂ１を参照）。しかし、負荷が所定値Ｌ１を超えると、回転数Ｎ１で維持できなくなり、以降は、たとえ引込み量が一定に維持されていても、電動機１５の回転数はＴ－Ｎカーブに沿って減少していく（図３中の特性Ｂ２を参照）。そのため、負荷が増加するにつれて回転が遅くなっているという違和感を使用者に与える（操作感の低下）可能性がある。また使用者の作業効率も低下し得る。 (2.3) Suppression of decrease in rotation speed By the way, FIG. 3 is a graph for explaining the operating characteristics of the power tool of the comparative example. The characteristic C1 in FIG. 3 shows the TN curve (relationship between load and rotation speed (rpm)) with respect to the motor 15. As the load (torque) increases, the maximum rotation speed of the motor decreases. For example, assuming that the pull-in amount of the trigger switch 29 by the user is maintained constant, if the load is a predetermined value L1 or less, the motor 15 becomes the rotation speed N1 of the target value corresponding to the current pull-in amount. (See characteristic B1 in FIG. 3). However, when the load exceeds the predetermined value L1, the rotation speed N1 cannot be maintained, and thereafter, even if the pull-in amount is kept constant, the rotation speed of the motor 15 decreases along the TN curve. Go (see characteristic B2 in FIG. 3). Therefore, there is a possibility that the user feels uncomfortable that the rotation becomes slower as the load increases (decrease in operation feeling). In addition, the work efficiency of the user may be reduced.
　そこで本実施形態の電動工具１の制御部４は、負荷の増加に応じて、励磁電流を増加させるように制御する。ここでは一例として、制御部４は、負荷の増加によって電動機１５の回転数が低下した場合に、弱め磁束電流を励磁電流としてコイル１４１に流させる弱め磁束制御を行う。つまり、制御部４は、一例として、電動機１５の回転数が低下したことを判断することで、負荷が増加したとみなす。 Therefore, the control unit 4 of the power tool 1 of the present embodiment controls so as to increase the exciting current according to the increase in the load. Here, as an example, the control unit 4 performs weakening magnetic flux control in which a weakening magnetic flux current flows through the coil 141 as an exciting current when the rotation speed of the motor 15 decreases due to an increase in load. That is, as an example, the control unit 4 determines that the rotation speed of the electric motor 15 has decreased, and thus considers that the load has increased.
　制御部４の磁束制御部４６は、電動機１５の回転数（ここでは角速度とする）を監視する。磁束制御部４６は、推定部４７から取得した電動機１５の角速度ω１が、トリガスイッチ２９の引込み量に応じた現在の指令値ｃω１（目標角速度）よりも低いか否か（すなわち回転数よりも低いか否か）を判定する。ここでは制御部４は、引込み量が所定の間隔において例えば一定（ただしゼロ（０）より大きい）であるという「トリガ条件」を満たし、かつ負荷の増加によって電動機１５の角速度ω１が低下した場合に、弱め磁束制御を行う。磁束制御部４６は、指令値生成部４１から指令値ｃω１を所定のサンプリング周期で取得しており、上記所定の間隔は、例えば、指令値ｃω１のサンプリング周期の１以上の整数倍を想定するが、特に限定されない。磁束制御部４６は、トリガ条件と、推定部４７から取得した角速度ω１が目標角速度に比べて低いという「角速度条件」の両方を満たせば、第１モード（弱め磁束制御）で動作する。磁束制御部４６は、例えば、第２モード（通常制御）で動作中にトリガ条件と角速度条件との両方が満たされると、第２モードから第１モードに切り替える。 The magnetic flux control unit 46 of the control unit 4 monitors the rotation speed (here, the angular velocity) of the motor 15. The magnetic flux control unit 46 determines whether or not the angular velocity ω1 of the motor 15 acquired from the estimation unit 47 is lower than the current command value cω1 (target angular velocity) according to the pull-in amount of the trigger switch 29 (that is, lower than the rotation speed). Whether or not) is determined. Here, the control unit 4 satisfies the "trigger condition" that the pull-in amount is, for example, constant (however, larger than zero (0)) at a predetermined interval, and the angular velocity ω1 of the motor 15 decreases due to an increase in the load. , Performs weakening magnetic flux control. The magnetic flux control unit 46 acquires the command value cω1 from the command value generation unit 41 at a predetermined sampling cycle, and the predetermined interval is assumed to be, for example, an integral multiple of 1 or more of the sampling cycle of the command value cω1. , Not particularly limited. The magnetic flux control unit 46 operates in the first mode (weak magnetic flux control) if both the trigger condition and the "angular velocity condition" that the angular velocity ω1 acquired from the estimation unit 47 is lower than the target angular velocity are satisfied. For example, the magnetic flux control unit 46 switches from the second mode to the first mode when both the trigger condition and the angular velocity condition are satisfied during operation in the second mode (normal control).
　つまり、本実施形態の弱め磁束制御は、上述した「低負荷領域において切替条件が満たされた」場合に実行される第１弱め磁束制御と、「トリガ条件と角速度条件との両方が満たされた」場合に実行される第２弱め磁束制御とを含む。なお、第１弱め磁束制御が実行される「低負荷領域」は、少なくとも、所定値Ｌ１よりも低い領域を想定する。そして、第１弱め磁束制御により、Ｔ－Ｎカーブの低負荷領域における電動機１５の最大回転数を増加できる。 That is, the weakening magnetic flux control of the present embodiment satisfies both the first weakening magnetic flux control executed when the above-mentioned "switching condition is satisfied in the low load region" and the "trigger condition and angular velocity condition". Includes a second weakening flux control that is performed in the case. The "low load region" in which the first weakening magnetic flux control is executed is assumed to be at least a region lower than the predetermined value L1. Then, the maximum rotation speed of the motor 15 in the low load region of the TN curve can be increased by the first weakening magnetic flux control.
　以下、第２弱め磁束制御について説明する。第２弱め磁束制御において、制御部４は、負荷の変化に伴う電動機１５の回転数の変化量が低減するように、励磁電流の大きさを決定する。磁束制御部４６は、上記変化量が低減するように、例えば、指令値ｃｉｄ１をゼロ（０）より大きくして、弱め磁束電流（マイナスの励磁電流）を流させる。指令値ｃｉｄ１は、負荷の増加に伴って低下した角速度ω１が、現在の目標角速度に復帰するように決定される。指令値ｃｉｄ１は、目標角速度に対する角速度ω１の変化量（ここでは低下量）が大きいほど、大きくなるように調整される。制御部４は、自身のメモリに、複数の指令値ｃｉｄ１と、角速度ω１（回転数でもよい）の複数の低下量とをそれぞれ対応付けした対応データを記憶している。磁束制御部４６は、現在の目標角速度に対する角速度ω１の低下量を算出し、算出した低下量に対応する指令値ｃｉｄ１を対応データの中から選ぶ。なお、指令値ｃｉｄ１は、第２弱め磁束制御において、ゼロ（０）より大きければ、角速度ω１の低下量とは無関係に一定（固定値）でもよい。第２弱め磁束制御において、指令値ｃｉｄ１が固定値である場合であっても、負荷の変化に伴う電動機１５の回転数の変化量は、低減され得る。 Hereinafter, the second weakening magnetic flux control will be described. In the second weakening magnetic flux control, the control unit 4 determines the magnitude of the exciting current so that the amount of change in the rotation speed of the motor 15 due to the change in the load is reduced. The magnetic flux control unit 46 makes the command value cid1 larger than zero (0) so that the amount of change is reduced, and causes a weakening magnetic flux current (minus exciting current) to flow. The command value cid1 is determined so that the angular velocity ω1 that has decreased with the increase in load returns to the current target angular velocity. The command value cid1 is adjusted so that the larger the amount of change (here, the amount of decrease) of the angular velocity ω1 with respect to the target angular velocity, the larger the amount. The control unit 4 stores in its own memory corresponding data in which a plurality of command values cid1 and a plurality of reduction amounts of the angular velocity ω1 (which may be the number of rotations) are associated with each other. The magnetic flux control unit 46 calculates the amount of decrease in the angular velocity ω1 with respect to the current target angular velocity, and selects the command value cid1 corresponding to the calculated amount of decrease from the corresponding data. The command value cid1 may be constant (fixed value) regardless of the amount of decrease in the angular velocity ω1 as long as it is larger than zero (0) in the second weakening magnetic flux control. In the second weakening magnetic flux control, even when the command value id1 is a fixed value, the amount of change in the rotation speed of the motor 15 due to the change in load can be reduced.
　ここで本実施形態の制御部４は、負荷が変化しても、電動機１５の回転数がトリガスイッチ２９（操作部）への操作入力に対応した目標値（ここでは目標角速度に相当）に維持されるように、励磁電流の大きさを決定する。例えば、磁束制御部４６は、負荷が所定値Ｌ１を超えても、電動機１５の回転数が略フラットが維持されるように、指令値ｃｉｄ１を増加させて、弱め磁束電流（マイナスの励磁電流）を大きくする。要するに、磁束制御部４６は、図４に示すように、電動機１５の回転数が回転数Ｎ１に維持されて特性Ｂ１の延長線となる特性Ｄ１に沿うように、指令値ｃｉｄ１を増加させる。図４は、本実施形態の電動工具１に関する動作特性を説明するためのグラフである。なお、図４の特性Ｃ１及び特性Ｂ１は、図３の特性Ｃ１及び特性Ｂ１と共通である。 Here, the control unit 4 of the present embodiment maintains the rotation speed of the motor 15 at the target value (corresponding to the target angular velocity here) corresponding to the operation input to the trigger switch 29 (operation unit) even if the load changes. The magnitude of the exciting current is determined so as to be. For example, the magnetic flux control unit 46 increases the command value cid1 so that the rotation speed of the motor 15 is maintained substantially flat even when the load exceeds the predetermined value L1, and the magnetic flux current (minus exciting current) is weakened. To increase. In short, as shown in FIG. 4, the magnetic flux control unit 46 increases the command value cid1 so that the rotation speed of the motor 15 is maintained at the rotation speed N1 and is in line with the characteristic D1 which is an extension of the characteristic B1. FIG. 4 is a graph for explaining the operating characteristics of the power tool 1 of the present embodiment. The characteristic C1 and the characteristic B1 in FIG. 4 are common to the characteristic C1 and the characteristic B1 in FIG.
　特に制御部４は、励磁電流の大きさを連続的に変化させる。すなわち、制御部４は、負荷の増加に対して励磁電流の大きさを連続的に増加させる。励磁電流の「連続的な変化」によって、電動機１５の回転数が略フラットに維持されやすくなる（図４のカーブＥ１参照）。ただし、制御部４は、励磁電流の大きさを、負荷の増加に対して非連続的（すなわち段階的）に変化（増加）させてもよい。 In particular, the control unit 4 continuously changes the magnitude of the exciting current. That is, the control unit 4 continuously increases the magnitude of the exciting current as the load increases. The "continuous change" of the exciting current makes it easier for the rotation speed of the motor 15 to be kept substantially flat (see curve E1 in FIG. 4). However, the control unit 4 may change (increase) the magnitude of the exciting current discontinuously (that is, stepwise) with respect to the increase in the load.
　なお、本実施形態の制御部４は、電動機１５の回転数（角速度）の低下によって負荷の増加を判断しているため、実際には、電動機１５の回転数は、特性Ｄ１から特性Ｃ１の側へ少しずれたカーブＥ１（図４参照）に沿うように制御され得る。なお、励磁電流の増加によって、電源部３２の電池３２０の消耗が大きくなり得るため、制御部４は、負荷がある閾値（所定値Ｌ１よりも十分に高い値）を超えるほど増加すると、負荷の増加に対する追従を止めることが好ましい。カーブＥ１は、最終的には特性Ｃ１に到達し得る。 Since the control unit 4 of the present embodiment determines the increase in the load by the decrease in the rotation speed (angular velocity) of the electric motor 15, the rotation speed of the electric motor 15 is actually on the side from the characteristic D1 to the characteristic C1. It can be controlled to follow a curve E1 (see FIG. 4) that is slightly offset to. Since the consumption of the battery 320 of the power supply unit 32 may increase due to the increase in the exciting current, when the load increases to the extent that the load exceeds a certain threshold value (a value sufficiently higher than the predetermined value L1), the load becomes large. It is preferable to stop following the increase. The curve E1 can eventually reach the characteristic C1.
　また本実施形態では、磁束制御部４６は、電動機１５の回転数（角速度ω１）が目標値（目標角速度）を超えないように、指令値ｃｉｄ１を増加させて弱め磁束電流を大きくする。ただし、もし第２弱め磁束制御の最中に、例えば負荷が軽減されて、角速度ω１が目角速度よりも大きくなれば、磁束制御部４６は、逆に、弱め磁束電流が減るように指令値ｃｉｄ１を減少させる。 Further, in the present embodiment, the magnetic flux control unit 46 increases the command value cid1 to increase the weakening magnetic flux current so that the rotation speed (angular velocity ω1) of the electric motor 15 does not exceed the target value (target angular velocity). However, if, for example, the load is reduced and the angular velocity ω1 becomes larger than the angular velocity during the second weakening magnetic flux control, the magnetic flux control unit 46 conversely causes the command value side1 to reduce the weakening magnetic flux current. To reduce.
　ところで、本実施形態の制御部４は、図１に示すように、報知部Ａ１及び設定部Ａ２を更に有している。言い換えると、制御部４は、報知部Ａ１としての機能、及び設定部Ａ２としての機能を更に有している。 By the way, as shown in FIG. 1, the control unit 4 of the present embodiment further includes a notification unit A1 and a setting unit A2. In other words, the control unit 4 further has a function as a notification unit A1 and a function as a setting unit A2.
　報知部Ａ１は、例えば、磁束制御部４６が第２弱め磁束制御で動作中であることを、使用者に報知するように構成される。具体的には、報知部Ａ１は、電動工具１に備え付けのタッチパネル式の液晶ディスプレイ（表示部Ａ３：図１参照）上に、第２弱め磁束制御で動作中である旨を示す文字メッセージを表示させて、使用者に報知する。報知部Ａ１は、文字メッセージの代わりに（又は加えて）、電動工具１に備え付けのスピーカから音声メッセージを出力させて報知してもよい。また報知部Ａ１は、電動工具１に備え付けの表示灯の点灯状態等を変更させることで報知してもよい。点灯状態の変更は、消灯から点灯への変更、又は、点灯から点滅への変更等を含み得る。なお、報知部Ａ１は、第２弱め磁束制御以外にも、通常制御又は第１弱め磁束制御で動作中であることも、使用者に報知してもよい。 The notification unit A1 is configured to notify the user, for example, that the magnetic flux control unit 46 is operating in the second weakening magnetic flux control. Specifically, the notification unit A1 displays a character message indicating that the power tool 1 is operating with the second weakening magnetic flux control on the touch panel type liquid crystal display (display unit A3: see FIG. 1). And notify the user. The notification unit A1 may output a voice message from a speaker provided in the power tool 1 instead of (or in addition to) the character message to notify the power tool 1. Further, the notification unit A1 may notify by changing the lighting state of the indicator lamp provided in the power tool 1. The change in the lighting state may include a change from turning off to lighting, a change from lighting to blinking, and the like. In addition to the second weakening magnetic flux control, the notification unit A1 may also notify the user that it is operating under normal control or first weakening magnetic flux control.
　設定部Ａ２は、励磁電流を増加させる制御に関する有効又は無効を設定するように構成される。具体的には、設定部Ａ２は、使用者から表示部Ａ３へのタップ操作等を通じて受け付ける操作入力に応じて、第２弱め磁束制御の「有効」又は「無効」を設定する。設定部Ａ２は、第２弱め磁束制御の有効又は無効に関する設定情報を制御部４のメモリに記憶する。磁束制御部４６は、設定情報が第２弱め磁束制御の「無効」を指定していれば、たとえトリガ条件と角速度条件との両方が満たされても、第２モード（通常制御）を維持する。なお、上記操作入力は、表示部Ａ３以外に、電動工具１に備え付けの押し釦スイッチ又はディップスイッチ等を通じて受け付けられてもよい。 The setting unit A2 is configured to set valid or invalid for control to increase the exciting current. Specifically, the setting unit A2 sets "valid" or "invalid" of the second weakening magnetic flux control according to the operation input received from the user through a tap operation or the like to the display unit A3. The setting unit A2 stores the setting information regarding the validity or invalidity of the second weakening magnetic flux control in the memory of the control unit 4. If the setting information specifies "invalid" for the second weakening magnetic flux control, the magnetic flux control unit 46 maintains the second mode (normal control) even if both the trigger condition and the angular velocity condition are satisfied. .. The operation input may be received through a push button switch, a DIP switch, or the like provided in the power tool 1 in addition to the display unit A3.
　このように制御部４が報知部Ａ１及び設定部Ａ２を有していることで、利便性が向上される。 Since the control unit 4 has the notification unit A1 and the setting unit A2 in this way, the convenience is improved.
　（２．４）第２弱め磁束制御の動作
　以下、電動工具１における第２弱め磁束制御に関する動作について図５を参照しながら説明する。なお、以下では一例として、使用者が電動工具１を使用中であって、さらに電動工具１が、指令値ｃｉｄ１がゼロ（０）である第２モード（通常制御）で動作中である場合を想定する。また第２弱め磁束制御は「有効」に設定されているものとする。 (2.4) Operation of Second Weakened Magnetic Flux Control Hereinafter, an operation related to the second weakened magnetic flux control in the power tool 1 will be described with reference to FIG. In the following, as an example, a case where the user is using the power tool 1 and the power tool 1 is operating in the second mode (normal control) in which the command value cid1 is zero (0). Suppose. Further, it is assumed that the second weakening magnetic flux control is set to "effective".
　制御部４は、第２モード（通常制御）で動作中である（ステップＳ１）。制御部４は、トリガ条件を満たしているか否か、すなわちトリガスイッチ２９の引込み量が所定の間隔において一定であるか否かを判定する（ステップＳ２）。制御部４は、引込み量が一定であると判定すると（ステップＳ２：Ｙｅｓ）、角速度条件を満たしているか否か、すなわち電動機１５の角速度ω１が現在の指令値ｃω１に対応した目標角速度よりも低いか否かを判定する（ステップＳ３）。なお、制御部４は、引込み量が一定でないと判定すると（ステップＳ２：Ｎｏ）、第２モード（通常制御）を継続する。 The control unit 4 is operating in the second mode (normal control) (step S1). The control unit 4 determines whether or not the trigger condition is satisfied, that is, whether or not the pull-in amount of the trigger switch 29 is constant at a predetermined interval (step S2). When the control unit 4 determines that the pull-in amount is constant (step S2: Yes), whether or not the angular velocity condition is satisfied, that is, the angular velocity ω1 of the motor 15 is lower than the target angular velocity corresponding to the current command value cω1. Whether or not it is determined (step S3). When the control unit 4 determines that the pull-in amount is not constant (step S2: No), the control unit 4 continues the second mode (normal control).
　制御部４は、電動機１５の角速度ω１が目標角速度よりも低いと判定すると（ステップＳ３：Ｙｅｓ）、動作モードを第２モードから第１モード（第２弱め磁束制御）に切り替える（ステップＳ４）。なお、制御部４は、電動機１５の角速度ω１が目標角速度に略一致していると判定すると（ステップＳ３：Ｎｏ）、第２モード（通常制御）を継続する。 When the control unit 4 determines that the angular velocity ω1 of the motor 15 is lower than the target angular velocity (step S3: Yes), the control unit 4 switches the operation mode from the second mode to the first mode (second weakening magnetic flux control) (step S4). When the control unit 4 determines that the angular velocity ω1 of the motor 15 substantially matches the target angular velocity (step S3: No), the control unit 4 continues the second mode (normal control).
　制御部４は、第２弱め磁束制御において、目標角速度に対する角速度ω１の低下量を算出し、算出した低下量に対応する指令値ｃｉｄ１を決定する。以降、制御部４は、例えばトリガ条件を満たしている限り（ステップＳ５：Ｙｅｓ）、負荷の増加に追従して電動機１５の回転数が略フラットが維持されるように、指令値ｃｉｄ１を増加させて弱め磁束電流を大きくする。もしその間にトリガ条件を満たさなくなれば（ステップＳ５：Ｎｏ）、制御部４は、第１モード（第２弱め磁束制御）を解除する（ステップＳ６）。なお、第２弱め磁束制御の解除条件は、トリガ条件に限定されない。第２弱め磁束制御は、引込み量がゼロ（０）になると解除されてよい。 In the second weakening magnetic flux control, the control unit 4 calculates the amount of decrease in the angular velocity ω1 with respect to the target angular velocity, and determines the command value cid1 corresponding to the calculated amount of decrease. After that, as long as the trigger condition is satisfied (step S5: Yes), the control unit 4 increases the command value cid1 so that the rotation speed of the motor 15 is kept substantially flat following the increase in the load. To weaken and increase the magnetic flux current. If the trigger condition is not satisfied during that time (step S5: No), the control unit 4 releases the first mode (second weakening magnetic flux control) (step S6). The condition for releasing the second weakening magnetic flux control is not limited to the trigger condition. The second weakening magnetic flux control may be canceled when the pull-in amount becomes zero (0).
　このように本実施形態の制御部４は、電動機１５の出力軸１６が外部から受ける負荷の増加に応じて、励磁電流を増加させるように制御する。そのため、例えば図３の特性Ｂ２とは違って、負荷が増加することで電動機１５の回転数が低下して、電動機の目標回転数が得られなくなる可能性を低減できる（図４のカーブＥ１参照）。そのため、電動機１５の低効率化の抑制を図ることができる。したがって、使用者の作業効率も低下しにくくなる。 As described above, the control unit 4 of the present embodiment controls so that the exciting current is increased according to the increase in the load received from the outside by the output shaft 16 of the electric motor 15. Therefore, unlike the characteristic B2 of FIG. 3, for example, it is possible to reduce the possibility that the rotation speed of the motor 15 decreases due to the increase in the load and the target rotation speed of the motor cannot be obtained (see curve E1 of FIG. 4). ). Therefore, it is possible to suppress the reduction in efficiency of the motor 15. Therefore, the work efficiency of the user is less likely to decrease.
　特に電動機１５の回転数（ここでは角速度ω１）の低下をトリガにして弱め磁束制御を行うため、電動機１５の低効率化を更に抑制できる。 In particular, since the weakening magnetic flux control is performed by triggering the decrease in the rotation speed of the motor 15 (here, the angular velocity ω1), the efficiency reduction of the motor 15 can be further suppressed.
　また制御部４は、負荷の変化に伴う電動機１５の回転数の変化量が低減するように、励磁電流の大きさを決定するため、負荷が増加するにつれて回転が遅くなっているという違和感を使用者に与えにくくすることができる。 Further, since the control unit 4 determines the magnitude of the exciting current so that the amount of change in the rotation speed of the motor 15 due to the change in the load is reduced, the control unit 4 uses a sense of incongruity that the rotation slows down as the load increases. It can be difficult to give to a person.
　（３）変形例
　上記実施形態は、本開示の様々な実施形態の一つに過ぎない。上記実施形態は、本開示の目的を達成できれば、設計等に応じて種々の変更が可能である。また、上記実施形態に係る電動工具１の制御部４と同様の機能は、この制御方法、コンピュータプログラム、又はコンピュータプログラムを記録した非一時的記録媒体等で具現化されてもよい。具体的には、一の態様に係る電動工具１の制御方法は、駆動力伝達機構１８を駆動する電動機１５に供給される励磁電流とトルク電流とを制御するベクトル制御を行う主ステップを含む。主ステップは、少なくとも電動機１５の出力軸１６が外部から受ける負荷の増加に応じて、励磁電流を増加させるように制御する副ステップを含む。 (3) Modified Example The above embodiment is only one of various embodiments of the present disclosure. The above-described embodiment can be changed in various ways depending on the design and the like as long as the object of the present disclosure can be achieved. Further, the same function as the control unit 4 of the power tool 1 according to the above embodiment may be realized by this control method, a computer program, a non-temporary recording medium on which the computer program is recorded, or the like. Specifically, the control method of the electric tool 1 according to one aspect includes a main step of performing vector control for controlling the exciting current and the torque current supplied to the electric motor 15 that drives the driving force transmission mechanism 18. The main step includes at least a sub-step of controlling the output shaft 16 of the motor 15 to increase the exciting current in response to an increase in the load received from the outside.
　以下、上記実施形態の変形例を列挙する。以下に説明する変形例は、適宜組み合わせて適用可能である。以下では、上記実施形態を「基本例」と呼ぶこともある。 The following is a list of modified examples of the above embodiment. The modifications described below can be applied in combination as appropriate. Hereinafter, the above embodiment may be referred to as a “basic example”.
　本開示における電動工具１の制御部４は、コンピュータシステムを含んでいる。コンピュータシステムは、ハードウェアとしてのプロセッサ及びメモリを主構成とする。コンピュータシステムのメモリに記録されたプログラムをプロセッサが実行することによって、本開示における制御部４としての機能が実現される。プログラムは、コンピュータシステムのメモリに予め記録されてもよく、電気通信回線を通じて提供されてもよく、コンピュータシステムで読み取り可能なメモリカード、光学ディスク、ハードディスクドライブ等の非一時的記録媒体に記録されて提供されてもよい。コンピュータシステムのプロセッサは、半導体集積回路（ＩＣ）又は大規模集積回路（ＬＳＩ）を含む１ないし複数の電子回路で構成される。ここでいうＩＣ又はＬＳＩ等の集積回路は、集積の度合いによって呼び方が異なっており、システムＬＳＩ、ＶＬＳＩ（Very Large Scale Integration）、又はＵＬＳＩ（Ultra Large Scale Integration）と呼ばれる集積回路を含む。さらに、ＬＳＩの製造後にプログラムされる、ＦＰＧＡ（Field-Programmable Gate Array）、又はＬＳＩ内部の接合関係の再構成若しくはＬＳＩ内部の回路区画の再構成が可能な論理デバイスについても、プロセッサとして採用することができる。複数の電子回路は、１つのチップに集約されていてもよいし、複数のチップに分散して設けられていてもよい。複数のチップは、１つの装置に集約されていてもよいし、複数の装置に分散して設けられていてもよい。ここでいうコンピュータシステムは、１以上のプロセッサ及び１以上のメモリを有するマイクロコントローラを含む。したがって、マイクロコントローラについても、半導体集積回路又は大規模集積回路を含む１ないし複数の電子回路で構成される。 The control unit 4 of the power tool 1 in the present disclosure includes a computer system. The main configuration of a computer system is a processor and memory as hardware. When the processor executes the program recorded in the memory of the computer system, the function as the control unit 4 in the present disclosure is realized. The program may be pre-recorded in the memory of the computer system, may be provided through a telecommunications line, and may be recorded on a non-temporary recording medium such as a memory card, optical disk, hard disk drive, etc. that can be read by the computer system. May be provided. A processor in a computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large scale integrated circuit (LSI). The integrated circuit such as IC or LSI referred to here has a different name depending on the degree of integration, and includes an integrated circuit called a system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Further, an FPGA (Field-Programmable Gate Array) programmed after the LSI is manufactured, or a logical device capable of reconfiguring the junction relationship inside the LSI or reconfiguring the circuit partition inside the LSI should also be adopted as a processor. Can be done. A plurality of electronic circuits may be integrated on one chip, or may be distributed on a plurality of chips. The plurality of chips may be integrated in one device, or may be distributed in a plurality of devices. The computer system referred to here includes a microprocessor having one or more processors and one or more memories. Therefore, the microprocessor is also composed of one or a plurality of electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.
　また、制御部４における複数の機能が、１つのハウジング内に集約されていることは必須の構成ではない。制御部４の構成要素は、複数のハウジングに分散して設けられていてもよい。反対に、制御部４における複数の機能が、基本例のように、１つのハウジング内に集約されてもよい。さらに、制御部４の少なくとも一部の機能、例えば、制御部４の一部の機能がクラウド（クラウドコンピューティング）等によって実現されてもよい。 Further, it is not an essential configuration that a plurality of functions in the control unit 4 are integrated in one housing. The components of the control unit 4 may be dispersedly provided in a plurality of housings. On the contrary, a plurality of functions in the control unit 4 may be integrated in one housing as in the basic example. Further, at least a part of the functions of the control unit 4, for example, a part of the functions of the control unit 4 may be realized by a cloud (cloud computing) or the like.
　基本例では、制御部４は、負荷が増加した場合に、弱め磁束電流を増加させるように第２弱め磁束制御を実行する。しかし、制御部４は、強め磁束電流を増加させるように制御するモード（強め磁束制御）を更に有してもよい。強め磁束電流は、プラスの励磁電流である。強め磁束制御により、電動機１５の回転数、すなわち出力軸１６（回転軸）の回転数は減少される。磁束制御部４６は、例えば、負荷が更に増大して、所定値Ｌ１よりも十分に大きい閾値を超えた場合に、特性Ｃ１に向かって回転数が急激に低下するように強め磁束電流を流してもよい。 In the basic example, the control unit 4 executes the second weakening magnetic flux control so as to increase the weakening magnetic flux current when the load increases. However, the control unit 4 may further have a mode (strong magnetic flux control) for controlling so as to increase the strong magnetic flux current. The stronger magnetic flux current is a positive exciting current. Due to the strong magnetic flux control, the rotation speed of the electric motor 15, that is, the rotation speed of the output shaft 16 (rotation shaft) is reduced. For example, when the load is further increased and exceeds a threshold value sufficiently larger than the predetermined value L1, the magnetic flux control unit 46 causes a strong magnetic flux current to flow so that the rotation speed sharply decreases toward the characteristic C1. May be good.
　基本例では、弱め磁束制御は、第１弱め磁束制御と第２弱め磁束制御とを含む。しかし、本開示における電動工具１にとって、第１弱め磁束制御は必須の制御ではなく、省略されてもよい。 In the basic example, the weakening magnetic flux control includes the first weakening magnetic flux control and the second weakening magnetic flux control. However, for the power tool 1 in the present disclosure, the first weakening magnetic flux control is not an essential control and may be omitted.
　基本例では、第２弱め磁束制御を実行する条件として、引込み量が所定の間隔において一定であるという「トリガ条件」を満たすことを前提としていた。しかし、本開示における電動工具１にとって、トリガ条件は、必須の条件ではない。例えば制御部４は、引込み量が所定の間隔において増加した場合であっても、角速度条件を満たしているか否か、すなわち電動機１５の角速度ω１が（増加後の）指令値ｃω１に対応した目標角速度よりも低いか否かを判定してもよい。 In the basic example, as a condition for executing the second weakening magnetic flux control, it was premised that the "trigger condition" that the pull-in amount was constant at a predetermined interval was satisfied. However, the trigger condition is not an indispensable condition for the power tool 1 in the present disclosure. For example, the control unit 4 determines whether or not the angular velocity condition is satisfied, that is, the angular velocity ω1 of the motor 15 corresponds to the command value cω1 (after the increase) even when the pull-in amount increases at a predetermined interval. It may be determined whether or not it is lower than.
　基本例では、制御部４は、電動機１５の回転数（角速度）の低下を通じて、負荷の増加を判断している。しかし、電動工具１は、負荷を検出する検出部を更に備えてもよい。制御部４は、検出された負荷が増加した場合に、弱め磁束制御（第２弱め磁束制御）を行ってもよい。この場合一例として、検出部は、基本例における電流センサ６１，６２に相当する。制御部４は、検出部（電流センサ６１，６２）で検出された検出結果（例えば電流測定値ｉｕ１及び電流測定値ｉｖ１）に対応するトルク電流（トルク成分に対応する電流測定値ｉｑ１）に基づいて、負荷が増加したか否かを判定する。この構成によれば、負荷の増加をトリガにして弱め磁束制御を行うため、電動機１５の低効率化を更に抑制できる。また負荷の検出を容易に行える。なお、上記の検出部は、基本例の電流センサ６１，６２とは別に設けられてもよい。 In the basic example, the control unit 4 determines an increase in the load through a decrease in the rotation speed (angular velocity) of the electric motor 15. However, the power tool 1 may further include a detection unit that detects the load. The control unit 4 may perform weakening magnetic flux control (second weakening magnetic flux control) when the detected load increases. In this case, as an example, the detection unit corresponds to the current sensors 61 and 62 in the basic example. The control unit 4 has a torque current (current measurement value corresponding to the torque component) corresponding to the detection result (for example, current measurement value i u 1 and current measurement value i v 1) detected by the detection unit (current sensors 61, 62). Based on iq1), it is determined whether or not the load has increased. According to this configuration, since the weakening magnetic flux control is performed by triggering the increase in the load, it is possible to further suppress the reduction in efficiency of the motor 15. Moreover, the load can be easily detected. The above-mentioned detection unit may be provided separately from the current sensors 61 and 62 of the basic example.
　（４）まとめ
　以上説明したように、第１の態様に係る電動工具（１）は、電動機（１５）と、駆動力伝達機構（１８）と、制御部（４）と、を備える。電動機（１５）は、永久磁石（１３１）及びコイル（１４１）を有する。駆動力伝達機構（１８）は、電動機（１５）によって駆動される。制御部（４）は、電動機（１５）に供給される励磁電流とトルク電流とを制御するベクトル制御を行う。制御部（４）は、少なくとも電動機（１５）の出力軸（１６）が外部から受ける負荷の増加に応じて、励磁電流を増加させるように制御する。第１の態様によれば、電動機（１５）の低効率化の抑制を図ることができる。 (4) Summary As described above, the electric tool (1) according to the first aspect includes an electric motor (15), a driving force transmission mechanism (18), and a control unit (4). The motor (15) has a permanent magnet (131) and a coil (141). The driving force transmission mechanism (18) is driven by the electric motor (15). The control unit (4) performs vector control for controlling the exciting current and the torque current supplied to the electric motor (15). The control unit (4) controls to increase the exciting current at least in response to an increase in the load received from the outside by the output shaft (16) of the electric motor (15). According to the first aspect, it is possible to suppress the reduction in efficiency of the motor (15).
　第２の態様に係る電動工具（１）に関して、第１の態様において、制御部（４）は、負荷の増加によって電動機（１５）の回転数が低下した場合に、永久磁石（１３１）の第１磁束を弱める第２磁束をコイル（１４１）に発生させるための弱め磁束電流を励磁電流としてコイル（１４１）に流させる弱め磁束制御を行う。第２の態様によれば、回転数の低下をトリガにして弱め磁束制御を行うため、電動機（１５）の低効率化を更に抑制できる。 Regarding the electric tool (1) according to the second aspect, in the first aspect, the control unit (4) is a permanent magnet (131) when the rotation speed of the electric motor (15) decreases due to an increase in load. 1 Weak magnetic flux control is performed in which a weakening magnetic flux current for generating a second magnetic flux that weakens the magnetic flux in the coil (141) is passed through the coil (141) as an exciting current. According to the second aspect, since the weakening magnetic flux control is performed by triggering the decrease in the rotation speed, it is possible to further suppress the reduction in efficiency of the motor (15).
　第３の態様に係る電動工具（１）に関して、第１の態様又は第２の態様において、制御部（４）は、負荷の変化に伴う電動機（１５）の回転数の変化量が低減するように、励磁電流の大きさを決定する。第３の態様によれば、電動機（１５）の低効率化を更に抑制でき、また電動工具（１）の使用者に対して負荷の変化によって回転数が変わったといった違和感を与えにくくすることができる。 Regarding the power tool (1) according to the third aspect, in the first aspect or the second aspect, the control unit (4) reduces the amount of change in the rotation speed of the electric motor (15) due to the change in load. In addition, the magnitude of the exciting current is determined. According to the third aspect, it is possible to further suppress the reduction in efficiency of the electric motor (15) and to make it difficult for the user of the electric tool (1) to feel uncomfortable that the rotation speed has changed due to a change in load. it can.
　第４の態様に係る電動工具（１）は、第１の態様～第３の態様のいずれか１つにおいて、電動機（１５）の回転を制御するための操作を受け付ける操作部（トリガスイッチ２９）を更に備える。制御部（４）は、負荷が変化しても、電動機（１５）の回転数が操作部（トリガスイッチ２９）への操作に対応した目標値に維持されるように、励磁電流の大きさを決定する。第４の態様によれば、電動機（１５）の低効率化を更に抑制でき、また電動工具（１）の使用者に対して負荷の変化によって回転数が変わったといった違和感を与えにくくすることができる。 The power tool (1) according to the fourth aspect is an operation unit (trigger switch 29) that receives an operation for controlling the rotation of the electric motor (15) in any one of the first to third aspects. Further prepare. The control unit (4) adjusts the magnitude of the exciting current so that the rotation speed of the motor (15) is maintained at the target value corresponding to the operation of the operation unit (trigger switch 29) even if the load changes. decide. According to the fourth aspect, it is possible to further suppress the reduction in efficiency of the electric motor (15) and make it difficult for the user of the electric tool (1) to feel uncomfortable that the rotation speed has changed due to a change in load. it can.
　第５の態様に係る電動工具（１）に関して、第１の態様～第４の態様のいずれか１つにおいて、制御部（４）は、励磁電流の大きさを連続的に変化させる。第５の態様によれば、励磁電流の大きさを非連続的（すなわち段階的）に変化させる場合に比べて、電動機（１５）の低効率化を更に抑制できる。 Regarding the power tool (1) according to the fifth aspect, in any one of the first to fourth aspects, the control unit (4) continuously changes the magnitude of the exciting current. According to the fifth aspect, it is possible to further suppress the reduction in efficiency of the electric motor (15) as compared with the case where the magnitude of the exciting current is changed discontinuously (that is, stepwise).
　第６の態様に係る電動工具（１）は、第１の態様～第５の態様のいずれか１つにおいて、負荷を検出する検出部（電流センサ６１，６２）を更に備える。制御部（４）は、検出された負荷が増加した場合に、永久磁石（１３１）の第１磁束を弱める第２磁束をコイル（１４１）に発生させるための弱め磁束電流を励磁電流としてコイル（１４１）に流させる弱め磁束制御を行う。第６の態様によれば、負荷の増加をトリガにして弱め磁束制御を行うため、電動機（１５）の低効率化を更に抑制できる。 The power tool (1) according to the sixth aspect further includes detection units (current sensors 61, 62) for detecting a load in any one of the first to fifth aspects. The control unit (4) uses the weakening magnetic flux current for generating the second magnetic flux that weakens the first magnetic flux of the permanent magnet (131) in the coil (141) as the exciting current when the detected load increases. The weakening magnetic flux is controlled to flow in 141). According to the sixth aspect, since the weakening magnetic flux control is performed by triggering the increase in the load, it is possible to further suppress the reduction in efficiency of the motor (15).
　第７の態様に係る電動工具（１）に関して、第６の態様において、制御部（４）は、検出部（電流センサ６１，６２）で検出された検出結果に対応するトルク電流に基づいて、負荷が増加したか否かを判定する。第７の態様によれば、負荷の検出を容易に行える。 Regarding the power tool (1) according to the seventh aspect, in the sixth aspect, the control unit (4) is based on the torque current corresponding to the detection result detected by the detection units (current sensors 61 and 62). Determine if the load has increased. According to the seventh aspect, the load can be easily detected.
　第８の態様に係る電動工具（１）に関して、第１の態様～第７の態様のいずれか１つにおいて、制御部（４）は、励磁電流を増加させる制御に関する有効又は無効を設定する設定部（Ａ２）を更に有する。第８の態様によれば、利便性を向上させつつ、電動機（１５）の低効率化を更に抑制できる。 Regarding the power tool (1) according to the eighth aspect, in any one of the first to seventh aspects, the control unit (4) is set to set valid or invalid for the control for increasing the exciting current. It further has a part (A2). According to the eighth aspect, it is possible to further suppress the reduction in efficiency of the electric motor (15) while improving the convenience.
　第９の態様に係る制御方法は、永久磁石（１３１）及びコイル（１４１）を有した電動機（１５）を備える電動工具（１）の制御方法である。制御方法は、駆動力伝達機構（１８）を駆動する電動機（１５）に供給される励磁電流とトルク電流とを制御するベクトル制御を行う主ステップを含む。主ステップは、少なくとも電動機（１５）の出力軸（１６）が外部から受ける負荷の増加に応じて、励磁電流を増加させるように制御する副ステップを含む。第９の態様によれば、電動機（１５）の低効率化の抑制を図ることが可能な制御方法を提供できる。 The control method according to the ninth aspect is a control method of an electric tool (1) including an electric motor (15) having a permanent magnet (131) and a coil (141). The control method includes a main step of performing vector control for controlling the exciting current and the torque current supplied to the electric motor (15) that drives the driving force transmission mechanism (18). The main step includes at least a sub-step of controlling the output shaft (16) of the motor (15) to increase the exciting current in response to an increase in the load received from the outside. According to the ninth aspect, it is possible to provide a control method capable of suppressing the reduction in efficiency of the motor (15).
　第１０の態様に係るプログラムは、１以上のプロセッサに、第９の態様における制御方法を実行させるためのプログラムである。第１０の態様によれば、電動機（１５）の低効率化の抑制を図ることが可能な機能を提供できる。 The program according to the tenth aspect is a program for causing one or more processors to execute the control method in the ninth aspect. According to the tenth aspect, it is possible to provide a function capable of suppressing the reduction in efficiency of the electric motor (15).
　第２～第８の態様に係る構成については、電動工具（１）に必須の構成ではなく、適宜省略可能である。 The configurations according to the second to eighth aspects are not essential configurations for the power tool (1) and can be omitted as appropriate.
　１　電動工具
　１３１　永久磁石
　１４１　コイル
　１５　電動機
　１６　出力軸
　１８　駆動力伝達機構
　４　制御部
　２９　トリガスイッチ（操作部）
　Ａ２　設定部
　６１，６２　電流センサ（検出部） 1 Power tool 131 Permanent magnet 141 Coil 15 Motor 16 Output shaft 18 Driving force transmission mechanism 4 Control unit 29 Trigger switch (operation unit)
A2 setting unit 61, 62 Current sensor (detection unit)

Claims (10)

  1. 　永久磁石及びコイルを有する電動機と、
    　前記電動機によって駆動される駆動力伝達機構と、
    　前記電動機に供給される励磁電流とトルク電流とを制御するベクトル制御を行う制御部と、
    を備え、
    　前記制御部は、少なくとも前記電動機の出力軸が外部から受ける負荷の増加に応じて、前記励磁電流を増加させるように制御する、
    　電動工具。     Motors with permanent magnets and coils,
    The driving force transmission mechanism driven by the motor and
    A control unit that performs vector control to control the exciting current and torque current supplied to the motor, and
    With
    The control unit controls to increase the exciting current at least in response to an increase in a load received from the outside by the output shaft of the motor.
    Electric tool.
  2. 　前記制御部は、前記負荷の増加によって前記電動機の回転数が低下した場合に、前記永久磁石の第１磁束を弱める第２磁束を前記コイルに発生させるための弱め磁束電流を前記励磁電流として前記コイルに流させる弱め磁束制御を行う、
    　請求項１に記載の電動工具。     The control unit uses the weakening magnetic flux current for generating the second magnetic flux that weakens the first magnetic flux of the permanent magnet in the coil as the exciting current when the rotation speed of the motor decreases due to the increase in the load. Controls the weakening magnetic flux that flows through the coil,
    The power tool according to claim 1.
  3. 　前記制御部は、前記負荷の変化に伴う前記電動機の回転数の変化量が低減するように、前記励磁電流の大きさを決定する、
    　請求項１又は請求項２に記載の電動工具。     The control unit determines the magnitude of the exciting current so that the amount of change in the rotation speed of the electric motor due to the change in the load is reduced.
    The power tool according to claim 1 or 2.
  4. 　前記電動機の回転を制御するための操作を受け付ける操作部を更に備え、
    　前記制御部は、前記負荷が変化しても、前記電動機の回転数が前記操作部への操作に対応した目標値に維持されるように、前記励磁電流の大きさを決定する、
    　請求項１～３のいずれか１項に記載の電動工具。     Further provided with an operation unit that accepts an operation for controlling the rotation of the motor.
    The control unit determines the magnitude of the exciting current so that the rotation speed of the motor is maintained at a target value corresponding to the operation on the operation unit even if the load changes.
    The power tool according to any one of claims 1 to 3.
  5. 　前記制御部は、前記励磁電流の大きさを連続的に変化させる、
    　請求項１～４のいずれか１項に記載の電動工具。     The control unit continuously changes the magnitude of the exciting current.
    The power tool according to any one of claims 1 to 4.
  6. 　前記負荷を検出する検出部を更に備え、
    　前記制御部は、検出された前記負荷が増加した場合に、前記永久磁石の第１磁束を弱める第２磁束を前記コイルに発生させるための弱め磁束電流を前記励磁電流として前記コイルに流させる弱め磁束制御を行う、
    　請求項１～５のいずれか１項に記載の電動工具。     Further provided with a detection unit for detecting the load,
    When the detected load increases, the control unit causes the coil to flow a weakening magnetic flux current for generating a second magnetic flux that weakens the first magnetic flux of the permanent magnet as the exciting current. Perform magnetic flux control,
    The power tool according to any one of claims 1 to 5.
  7. 　前記制御部は、前記検出部で検出された検出結果に対応する前記トルク電流に基づいて、前記負荷が増加したか否かを判定する、
    　請求項６に記載の電動工具。     The control unit determines whether or not the load has increased based on the torque current corresponding to the detection result detected by the detection unit.
    The power tool according to claim 6.
  8. 　前記制御部は、前記励磁電流を増加させる制御に関する有効又は無効を設定する設定部を更に有する、
    　請求項１～７のいずれか１項に記載の電動工具。     The control unit further includes a setting unit for setting valid or invalid for the control for increasing the exciting current.
    The power tool according to any one of claims 1 to 7.
  9. 　永久磁石及びコイルを有した電動機を備える電動工具の制御方法であって、
    　駆動力伝達機構を駆動する前記電動機に供給される励磁電流とトルク電流とを制御するベクトル制御を行う主ステップを含み、
    　前記主ステップは、少なくとも前記電動機の出力軸が外部から受ける負荷の増加に応じて、前記励磁電流を増加させるように制御する副ステップを含む、
    　制御方法。     A method of controlling an electric tool including an electric motor having a permanent magnet and a coil.
    Includes a main step of performing vector control to control the exciting current and torque current supplied to the motor that drives the driving force transmission mechanism.
    The main step includes at least a sub-step that controls the exciting current to increase in response to an increase in load received from the outside by the output shaft of the motor.
    Control method.
  10. 　１以上のプロセッサに請求項９に記載の制御方法を実行させるためのプログラム。 A program for causing one or more processors to execute the control method according to claim 9.
PCT/JP2020/043352 2019-11-22 2020-11-20 Electric tool, control method, and program WO2021100844A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10328952A (en) * 1997-06-02 1998-12-15 Wako Giken:Kk Control method and device of motor, and screw fastening method and device
JP2012065464A (en) * 2010-09-16 2012-03-29 Seiko Epson Corp Motor control device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10328952A (en) * 1997-06-02 1998-12-15 Wako Giken:Kk Control method and device of motor, and screw fastening method and device
JP2012065464A (en) * 2010-09-16 2012-03-29 Seiko Epson Corp Motor control device

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