CN114600360A - Converter and motor control system - Google Patents

Abstract

The converter (1) is provided with a power module (21), a smoothing capacitor (22), a bus current detection unit (25), and a control unit (26). A power module (21) rectifies an AC voltage supplied from an AC power supply (3) and outputs the rectified voltage from a DC power supply terminal (14). A bus current detection unit (25) detects a bus current, which is a current flowing between the DC power supply terminal (14) and the smoothing capacitor (22). The control unit (26) controls the plurality of switching elements (Q1-Q6) on the basis of the voltage phase of the AC power supply (3) and outputs the regenerative power of the motor (5) to the AC power supply (3). The control unit (26) has a power failure detection unit (33) that determines whether or not a power failure has occurred in the AC power supply (3) during at least either the powering operation of the motor (5) or the regeneration operation of the motor (5), based on the absolute value of the bus current detected by the bus current detection unit (25).

Description

Converter and motor control system

Technical Field

The present invention relates to a converter and a motor control system that are arranged between an ac power supply and a motor drive device and perform power conversion.

Background

The converter disposed between an AC power supply and a motor drive device includes: a power module including a bridge rectifier circuit that bridge-connects a plurality of rectifier elements; and a smoothing capacitor that smoothes an output voltage of the power module. An ac voltage supplied from an ac power supply to the converter is rectified by a power module, and the rectified voltage is smoothed by a smoothing capacitor.

A motor driven by a motor driving device usually consumes power during acceleration and generates induced electromotive force during deceleration. Therefore, the motor drive device operates the motor as a generator. In the following description, the acceleration operation of the motor is referred to as "motor power running" or "power running", and the deceleration operation of the motor is referred to as "motor regeneration" or "regeneration".

When the motor is in power running, the voltage smoothed by the converter is applied to the motor drive device. The motor drive device converts a dc voltage supplied from the converter into an ac voltage by dc-ac conversion, and applies the converted ac voltage to the motor to drive the motor.

When the motor is regenerated, the induced electromotive force generated by the motor is converted into a dc voltage by ac-dc conversion performed by the motor driving device, and the converted dc voltage is supplied to the smoothing capacitor of the converter. When the voltage applied from the motor to the motor drive device is large, the dc voltage applied from the motor drive device to the converter may exceed the allowable voltage of the smoothing capacitor or the power module of the converter. In this case, since there is a possibility that a failure may occur in the smoothing capacitor or the power module of the converter, the converter has a function of processing the regenerative power, which is the power generated by the induced electromotive force of the motor, so that the smoothing capacitor or the power module is not damaged.

The regenerative power processing method includes a resistance regeneration method in which regenerative power is heat-dissipated by a resistor, and a power regeneration method in which regenerative power is returned to an ac power supply. In recent years, in industrial machines such as machine tools and robots, the use of converters to which a power regeneration method is applied has been increasing from the viewpoint of energy saving. A converter to which a power supply regeneration method is applied has a power module including a circuit in which a switching element and each rectifying element are connected in parallel, and supplies regenerative power to an ac power supply by controlling on/off of each switching element.

When a power failure occurs in a converter to which the power regeneration method is applied, such as when the power supply from the ac power supply is stopped during the motor powering operation or during the motor regeneration operation, an overcurrent may flow through the power module at the time of the power failure start or the power restoration start, and the power module may deteriorate or fail. In an industrial machine such as a machine tool and a robot to which the converter is applied, when an ac power supply fails during power running or regeneration, the feed shaft, the main shaft, and the like may be excessively rotated, and the tool, the workpiece, and the like may be damaged.

Patent document 1 discloses a converter control device capable of detecting that a power failure occurs in an ac power supply during regeneration. The converter control device connects a regeneration resistor between terminals of the smoothing capacitor via a chopper, and shares the regenerative power by the coordinated control of the voltage-type pwm (pulse Width modulation) converter and the chopper. In addition, the converter control device detects that a power failure has occurred in the ac power supply based on a ratio between the bus current and the chopper current flowing through the regeneration resistor during motor regeneration.

Patent document 1: japanese laid-open patent publication No. 6-205586

Disclosure of Invention

However, the technique described in patent document 1 has a problem of complicated configuration because a plurality of current detection units are required to detect the occurrence of a power failure in the ac power supply, and the occurrence of a power failure in the ac power supply is detected based on the outputs of the plurality of current detection units.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a converter capable of detecting occurrence of a power failure in an ac power supply with a simple configuration.

In order to solve the above problems, a converter according to the present invention is a converter disposed between an ac power supply and a motor drive device that controls a motor, and includes a power module, a smoothing capacitor, a bus current detection unit, and a control unit. The power module has: a plurality of rectifier elements that rectify an alternating-current voltage supplied from an alternating-current power supply; a plurality of switching elements connected in parallel to each of the plurality of rectifying elements; and two DC power supply terminals which output voltages rectified by the plurality of rectifying elements. The smoothing capacitor is connected to the two dc power supply terminals and smoothes the voltage rectified by the power module. The bus current detection unit detects a bus current, which is a current flowing between 1 of the two dc power supply terminals and the smoothing capacitor. The control unit controls the plurality of switching elements based on a voltage phase of the ac power supply, thereby causing the power module to output regenerative power of the motor to the ac power supply. The control unit includes a power failure detection unit that determines whether or not a power failure has occurred in the ac power supply in either of the motor powering operation and the motor regenerating operation, based on an absolute value of the bus current detected by the bus current detection unit.

ADVANTAGEOUS EFFECTS OF INVENTION

The converter according to the present invention has an effect of detecting the occurrence of a power failure in an ac power supply with a simple configuration.

Drawings

Fig. 1 is a diagram showing an example of the configuration of a motor control system according to embodiment 1.

Fig. 2 is a timing chart showing operations of the power supply phase detecting unit and the base drive signal generating unit according to embodiment 1.

Fig. 3 is a diagram for explaining an operation in the motor power running mode of the motor control system according to embodiment 1.

Fig. 4 is a diagram showing a relationship between a power supply voltage of an ac power supply and a current flowing through a converter in a motor powering operation of the motor control system according to embodiment 1.

Fig. 5 is a diagram for explaining a power supply regeneration operation by the on/off operation of the converter according to embodiment 1.

Fig. 6 is a diagram showing a relationship between a power supply voltage of an ac power supply and a current flowing through a converter at the time of motor regeneration in the motor control system according to embodiment 1.

Fig. 7 is a diagram showing a state of a motor control system in a case where the motor control system according to embodiment 1 drives a motor.

Fig. 8 is a diagram showing a state of the motor control system in a case where a power failure occurs in the ac power supply in the motor power running section shown in fig. 7.

Fig. 9 is a diagram showing a state of the motor control system in a case where a power failure occurs in the motor regeneration section ac power supply shown in fig. 7.

Fig. 10 is a flowchart showing an example of a processing flow of the power failure detection unit of the converter according to embodiment 1.

Fig. 11 is a flowchart showing an example of a process flow of the regeneration control unit of the converter according to embodiment 1.

Fig. 12 is a flowchart showing an example of a processing flow of the motor control unit of the motor drive device according to embodiment 1.

Fig. 13 is a diagram showing an example of the configuration of a motor control system according to embodiment 2.

Fig. 14 is a flowchart showing an example of a flow of a counting process of the power failure detection unit of the converter according to embodiment 2.

Fig. 15 is a flowchart showing an example of a failure prediction processing flow of the failure prediction unit of the host control device according to embodiment 2.

Fig. 16 is a diagram showing another example of the configuration of the motor control system according to embodiment 2.

Detailed Description

Hereinafter, a converter and a motor control system according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment mode 1

The configuration of the motor control system according to embodiment 1 will be described. Fig. 1 is a diagram showing an example of the configuration of a motor control system according to embodiment 1. As shown in fig. 1, a motor control system 100 according to embodiment 1 controls a motor 5 using a 3-phase ac voltage output from an ac power supply 3. The motor control system 100 includes: a converter 1 that converts an ac voltage output from an ac power supply 3 into a dc voltage; and a motor drive device 4 for controlling the motor 5 using the dc voltage output from the converter 1.

The ac power supply 3 is a 3-phase ac power supply, and includes, for example, a power generation device and a power transmission device. The 3-phase ac voltage supplied from the ac power supply 3 is an R-phase ac voltage, i.e., an R-phase voltage V_RS-phase AC voltage, i.e. S-phase voltage V_SAnd a T-phase voltage V as an alternating voltage of the T phase_T. Hereinafter, the R-phase voltage V may be referred to_RVoltage V of S phase_SAnd T-phase voltage V_TGenerally referred to as supply voltage V_RST. The motor 5 is a motor constituting an industrial machine such as a machine tool or a robot, for example, but may be a motor other than a motor constituting an industrial machine.

Converter 1 is connected to an ac power supply 3 as an input power supply via reactor 2. The converter 1 converts an ac voltage supplied from an ac power supply 3 into a dc voltage, and supplies the converted dc voltage to a motor drive device 4. The motor drive device 4 includes: a power conversion unit 40 that performs power conversion; and a motor control unit 41 that controls the power conversion unit 40. The motor control unit 41 performs variable speed control of the motor 5 by converting the dc voltage supplied from the converter 1 into an ac voltage corresponding to the control speed of the motor 5 by the power conversion unit 40, and supplying the converted ac voltage from the power conversion unit 40 to the motor 5.

The converter 1 has a power supply regeneration function of outputting an induced electromotive force generated by the motor 5 at the time of deceleration of the motor 5 to the ac power supply 3 as a regenerative power. The induced electromotive force generated by the motor 5 is converted from ac power to dc power by the motor drive device 4, and the dc power converted by the motor drive device 4 is supplied to the converter 1. The converter 1 converts dc power supplied from the motor drive device 4 into ac power, and outputs the converted ac power to the ac power supply 3. Hereinafter, an operation at the time of regeneration of the motor control system 100 may be referred to as a power source regeneration operation, and an operation at the time of powering of the motor control system 100 may be referred to as a powering operation. In addition, the induced electromotive force generated by the motor 5 during the power supply regeneration operation may be referred to as regenerative power.

The control method of the converter having the power regeneration function includes a PWM control method and a 120-degree conduction regeneration method. The converter 1 is a 120-degree conduction regenerative converter, and is also referred to as a power regenerative converter.

As shown in fig. 1, converter 1 includes power module 21, smoothing capacitor 22, bus voltage detection unit 23, power supply phase detection unit 24, bus current detection unit 25, control unit 26, and drive circuit 27.

The power module 21 includes ac power supply terminals 11 to 13, a positive dc power supply terminal 14, a negative dc power supply terminal 15, a plurality of rectifier elements D1 to D6, and a plurality of switching elements Q1 to Q6. Ac power supply terminal 11 is connected to an R-phase power supply terminal of ac power supply 3 via reactor 2, ac power supply terminal 12 is connected to an S-phase power supply terminal of ac power supply 3 via reactor 2, and ac power supply terminal 13 is connected to a T-phase power supply terminal of ac power supply 3 via reactor 2. The plurality of rectifier devices D1 to D6 are connected in a bridge manner to form a bridge rectifier circuit.

Between the dc power supply terminal 14 and the dc power supply terminal 15, the switching elements Q1 and Q2 connected in series, the switching elements Q3 and Q4 connected in series, and the switching elements Q5 and Q6 connected in series are connected in parallel with each other. The collector terminals of the switching elements Q1, Q3, and Q5 constituting the upper arm are connected to the dc power supply terminal 14, and the emitter terminals of the switching elements Q2, Q4, and Q6 constituting the lower arm are connected to the dc power supply terminal 15. The dc power supply terminal 14 is connected to a positive-side dc power supply terminal 17 of the motor drive device 4, and the dc power supply terminal 15 is connected to a negative-side dc power supply terminal 18 of the motor drive device 4.

The emitter terminal of the switching element Q1 and the collector terminal of the switching element Q2 are connected to the alternating-current power supply terminal 11. The emitter terminal of the switching element Q3 and the collector terminal of the switching element Q4 are connected to the ac power supply terminal 12. The emitter terminal of the switching element Q5 and the collector terminal of the switching element Q6 are connected to the alternating-current power supply terminal 13.

The switching elements Q1 to Q6 are connected in parallel to the corresponding ones of the rectifier elements D1 to D6, respectively. The rectifier elements D1 to D6 each have an anode terminal connected to the emitter terminal of the corresponding one of the switching elements Q1 to Q6, and a cathode terminal connected to the collector terminal of the corresponding one of the switching elements Q1 to Q6.

The rectifier device D1 and the switching device Q1 constitute a positive power device of the R phase, and the rectifier device D2 and the switching device Q2 constitute a negative power device of the R phase. The rectifier device D3 and the switching device Q3 constitute a positive power device of the S phase, and the rectifier device D4 and the switching device Q4 constitute a negative power device of the S phase. Further, the rectifier device D5 and the switching device Q5 constitute a positive power device of the T phase, and the rectifier device D6 and the switching device Q6 constitute a negative power device of the T phase. The power module 21 shown in fig. 1 is an example of a configuration in the case where the ac power supply 3 is a 3-phase ac power supply, but the ac power supply 3 may be a single-phase power supply. In this case, the power module 21 of the converter 1 is composed of 4 sets of power elements.

The switching elements Q1 to Q6 are Semiconductor switching elements typified by MOSFETs (Metal-Oxide-Semiconductor Field-Effect transistors) and igbts (insulated Gate Bipolar transistors). The rectifier devices D1 to D6 are diodes. Hereinafter, the switching element Q may be referred to as the switching element Q when the switching elements Q1 to Q6 are not individually shown, and the rectifying elements D may be referred to as the rectifying elements D when the rectifying elements D1 to D6 are not individually shown.

Smoothing capacitor 22 is disposed between dc power supply terminal 14 and dc power supply terminal 15, and smoothes the voltage rectified by power module 21. Bus voltage detection unit 23 detects inter-terminal voltage V of smoothing capacitor 22_DCI.e. the bus voltage V, which is the instantaneous value of the voltage between the dc supply terminal 14 and the dc supply terminal 15_PNAnd (6) detecting. The bus voltage detecting unit 23 will show the bus voltage V_PNThe information (2) is outputted to the control unit 26.

The power phase detection unit 24 detects the power supply voltage V of the AC power supply 3_RSTThe voltage phase of the ac power supply 3 is detected. Further, the power supply phase detecting section 24 detects the phase of the ac power supply 3 based on the power supply voltage V between the reactor 2 and the ac power supply 3_RSTThe voltage phase of ac power supply 3 is detected, but it may be arranged so as to be based on power supply voltage V of reactor 2 and ac power supply terminals 11, 12, and 13_RSTThe voltage phase of the ac power supply 3 is detected.

The power phase detection unit 24 outputs a power phase detection signal θ indicating the voltage phase of the ac power supply 3 to the control unit 26. The power supply phase detection signal θ output from the power supply phase detection unit 24 includes an R-S line phase detection signal θ_R-SS-R line phase detection signal theta_S-RS-T line phase detection signal theta_S-TPhase detection signal theta between T-S lines_T-ST-R line phase detection signal theta_T-RR-T line phase detection signal theta_R-T。

Phase detection signal theta between R-S lines_R-SRepresents the potential difference of the R phase relative to the S phase, namely the voltage V between the R and S lines_R-SPhase of (1), S-R line phase detection signal theta_S-RRepresents the potential difference of S phase relative to R phase, i.e. the voltage V between S-R lines_S-RThe phase of (c). R-S line voltage V_R-SAnd a voltage V between S and R lines_S-RAre both voltages between the R and S phases, but due to the reference phaseThis is different and therefore the phases are shifted by 180 degrees from each other.

Phase detection signal theta between S-T lines_S-TRepresents the potential difference of S phase relative to T phase, i.e. the voltage V between S and T lines_S-TPhase of (1), phase detection signal theta between T-S lines_T-SRepresents the potential difference of the T phase relative to the S phase, i.e. the voltage V between the T-S lines_T-SThe phase of (c). Voltage V between S-T lines_S-TAnd a voltage V between T and S lines_T-SThe voltage is between the S phase and the T phase, but the phases are shifted by 180 degrees from each other because the phases serving as the reference are different from each other.

Phase detection signal theta between T-R lines_T-RRepresents the potential difference of the T phase relative to the R phase, i.e. the voltage V between the T-R lines_T-RPhase of (a), R-T line phase detection signal theta_R-TRepresents the potential difference of the R phase relative to the T phase, namely the voltage V between the R-T lines_R-TThe phase of (c). Voltage V between T-R lines_T-RAnd a voltage V between R and T lines_R-TAll of the R and T phases are voltages, but the phases are shifted by 180 degrees from each other because the phases serving as the reference are different from each other.

The bus current detection unit 25 is disposed between the dc power supply terminal 14 of the power module 21 and the positive terminal of the smoothing capacitor 22, and detects a bus current I, which is an instantaneous value of a current flowing through the dc bus between the dc power supply terminal 14 of the power module 21 and the smoothing capacitor 22_PNAnd (6) detecting. Note that, instead of being disposed between the dc power supply terminal 14 of the power module 21 and the positive terminal of the smoothing capacitor 22, the bus current detection unit 25 may be disposed between the dc power supply terminal 15 of the power module 21 and the negative terminal of the smoothing capacitor 22.

Next, the control unit 26 will be explained. The control unit 26 includes a base drive signal generation unit 31, a regeneration control unit 32, a power failure detection unit 33, and a condition setting unit 34. The control unit 26 includes a processor, a memory, an AD (Analog-to-Digital) converter, and the like. The processor, the memory, and the AD converter can transmit and receive data to and from each other through a bus, for example. The processor reads out and executes the program stored in the memory, thereby executing the functions of the base drive signal generation unit 31, the regeneration control unit 32, the power failure detection unit 33, and the condition setting unit 34.

The processor is an example of a Processing circuit, and includes one or more of a cpu (central Processing unit), a dsp (digital Signal processor), and a system lsi (large Scale integration). The Memory includes 1 or more of ram (random Access Memory), rom (Read Only Memory), flash Memory, eprom (Erasable Programmable Read Only Memory), and EEPROM (registered trademark). The base drive signal generation unit 31, the regeneration control unit 32, the power failure detection unit 33, and the condition setting unit 34 may be partly or entirely configured by hardware such as an asic (application Specific Integrated circuit) or an fpga (field Programmable Gate array). The control unit 26 may include a part or all of the power phase detection unit 24.

The base drive signal generation unit 31 generates the base drive signal S for driving the switching elements Q1 to Q6 based on the power supply phase detection signal θ_RP、S_RN、S_SP、S_SN、S_TP、S_TN. The base drive signal generating section 31 generates the base drive signal S_RP、S_RN、S_SP、S_SN、S_TP、S_TNAnd outputs the result to the regeneration control unit 32.

Base drive signal S_RPIs a signal for driving the switching element Q1, a base drive signal S_RNIs a signal for driving the switching element Q2. Base drive signal S_SPIs a signal for driving the switching element Q3, a base drive signal S_SNIs a signal for driving the switching element Q4. Base drive signal S_TPIs a signal for driving the switching element Q5, a base drive signal S_TNIs a signal for driving the switching element Q6.

The regeneration control unit 32 controls the regeneration of the battery based on the bus current I_PNAnd bus voltage V_PNA base drive signal S_RP、S_RN、S_SP、S_SN、S_TP、S_TNAnd outputs the signal to the drive circuit 27 as an output signal. The driving circuit 27 will drivePolar drive signal S_RP、S_RN、S_SP、S_SN、S_TP、S_TNAmplified and outputted to the bases of the switching elements Q1 to Q6. By base drive signal S_RP、S_RN、S_SP、S_SN、S_TP、S_TNThe switching elements Q1 to Q6 are switched on and off, thereby performing a power supply regeneration operation in the converter 1. The regenerative power is output from the converter 1 to the ac power supply 3 by this power supply regenerative operation.

The regeneration control unit 32 is set to the power supply voltage V of the ac power supply 3, for example_RSTAnd bus voltage V_PNIn the case where the difference is greater than or equal to a predetermined value, or at bus current I_PNIs less than or equal to a predetermined value, the base drive signal S is applied_RP、S_RN、S_SP、S_SN、S_TP、S_TNAnd outputs the output signal to the drive circuit 27. The regeneration control unit 32 is set to the power supply voltage V of the ac power supply 3, for example_RSTAnd bus voltage V_PNThe difference is less than a predetermined value and the bus current I_PNDoes not output the base drive signal S to the drive circuit 27 when the absolute value of (d) exceeds a predetermined value_RP、S_RN、S_SP、S_SN、S_TP、S_TN. In this case, in the converter 1, all of the switching elements Q1 to Q6 are turned off, and the power supply regeneration operation is not performed.

Next, the operation of the power phase detection unit 24 and the base drive signal generation unit 31 will be described with reference to fig. 2. Fig. 2 is a timing chart showing operations of the power supply phase detecting unit and the base drive signal generating unit according to embodiment 1. FIG. 2 shows line-to-line voltage and R-S line-to-line phase detection signal θ during motor regeneration_R-SS-R line phase detection signal theta_S-RS-T line phase detection signal theta_S-TPhase detection signal theta between T-S lines_T-ST-R line phase detection signal theta_T-RR-T line phase detection signal theta_R-TBase driving signal S_RP、S_RN、S_SP、S_SN、S_TP、S_TNAnd the change of the current flowing in the R phase, the T phase and the S phase with time respectively.

Power supply phase detection unit 24 detects voltage V based on voltage of R phase_RVoltage V of S phase_SAnd T-phase voltage V_TFor R-S line voltage V_R-SVoltage V between S-R lines_S-RVoltage V between S-T lines_S-TVoltage V between T-S lines_T-SVoltage V between T-R lines_T-RAnd a voltage V between R-T lines_R-TAnd (6) detecting. Next, the voltage V between the R-S lines is not independently controlled_R-SVoltage V between S-R lines_S-RVoltage V between S-T lines_S-TVoltage V between T-S lines_T-SVoltage V between T-R lines_T-RAnd a voltage V between R-T lines_R-TWhen they are expressed separately, they may be simply referred to as line-to-line voltages.

The power supply phase detecting section 24 detects a zero cross point of each line voltage to generate an R-S line phase detection signal θ_R-SS-R line phase detection signal theta_S-RS-T line phase detection signal theta_S-TPhase detection signal theta between T-S lines_T-ST-R line phase detection signal theta_T-RAnd a phase detection signal theta between R-T lines_R-T. Next, the phase detection signal θ is detected between the R-S lines without individually aligning the R-S lines_R-SS-R line phase detection signal theta_S-RS-T line phase detection signal theta_S-TPhase detection signal theta between T-S lines_T-ST-R line phase detection signal theta_T-RAnd a phase detection signal theta between R-T lines_R-TWhen the signals are expressed separately, they may be described as line-to-line phase detection signals.

In the example shown in fig. 2, the power supply phase detecting unit 24 generates line-to-line phase detection signals for the line-to-line voltages so that the line-to-line voltage becomes a High (High) level in a phase interval in which the line-to-line voltage is a positive value and becomes a Low (Low) level in a phase interval in which the line-to-line voltage is a negative value. Since the waveform of the line-to-line voltage of the ac power supply 3, which is a 3-phase ac power supply, is a sine wave, the line-to-line voltage is the largest at the center of the phase section where the line-to-line phase detection signal is at a high level, and the line-to-line voltage is the smallest at the center of the phase section where the line-to-line phase detection signal is at a low level. The base drive signal generator 31 can calculate the phase indicating the maximum voltage and the phase indicating the minimum voltage from the line-to-line phase detection signals generated by the power supply phase detector 24.

Next, the operation of the base drive signal generating unit 31 will be described. The base drive signal generating section 31 generates the base drive signal S based on the 6 line-to-line phase detection signals output from the power supply phase detecting section 24_RP、S_RN、S_SP、S_SN、S_TP、S_TN。

Hereinafter, switching between on and off of the switching element Q is referred to as an on-off operation, and a current flowing through the switching element Q during a regenerative operation of the converter 1 is referred to as a regenerative current. Fig. 1 shows an R-phase current I indicated by an arrow indicating a direction from the ac power supply 3 to the converter 1_RS phase current I_SAnd T-phase current I_TThe current flowing in the direction indicated by the arrow is regarded as a positive current, and the current flowing in the opposite direction is regarded as a negative current. As the current in the converter 1, the current flowing from the converter 1 to the motor drive device 4 is regarded as a positive current, and the current in the opposite direction is regarded as a negative current.

Base drive signal generating section 31 generates voltage V between T-S lines_T-SIn the 1 st section from the time t0 to t2 when the instantaneous value is maximum, the base drive signal S is set_SN、S_TPThe base drive signal is set to high level, and the remaining base drive signal is set to low level. Thus, in the 1 st section, the positive-side switching element Q5 of the T-phase and the negative-side switching element Q4 of the S-phase are kept on, and the remaining switching elements are kept off. In this case, the positive electrode terminal and the negative electrode terminal of the smoothing capacitor 22 are connected to the T-phase and S-phase of the ac power supply 3 via the power supply impedance of the ac power supply 3. Therefore, a current flows through the switching elements Q5 and Q4 which are turned on to the T phase and the S phase. In interval 1, T-phase regenerative current Ir, which is a current flowing in T-phase_TS-phase regenerative current Ir which is a current flowing in the negative direction and flowing in the S-phase_STo the positive directionAnd (4) flowing.

Base drive signal generating section 31 generates voltage V between R-S lines_R-SIn the 2 nd interval from t2 to t4, where the instantaneous value is the maximum, the base drive signal S is set_RP、S_SNThe base drive signal is set to high level, and the remaining base drive signal is set to low level. Thus, in the 2 nd section, the R-phase positive side switching element Q1 and the S-phase negative side switching element Q4 are maintained on, and the remaining switching elements are maintained off. Therefore, a current flows through the switching elements Q1 and Q4 which are turned on to the R phase and the S phase. In interval 2, R-phase regenerative current Ir which is the current flowing in R-phase_RFlows in the negative direction, and the S-phase regenerative current Ir_SFlows in the positive direction.

Base drive signal generating section 31 generates voltage V between R-T lines_R-TIn the 3 rd section from t4 to t6, where the instantaneous value is the maximum, the base drive signal S is set_RP、S_TNThe base drive signal is set to high level, and the remaining base drive signal is set to low level. Thus, in the 3 rd section, the R-phase positive side switching element Q1 and the T-phase negative side switching element Q6 are kept on, and the remaining switching elements are kept off. Therefore, a current flows through the switching elements Q1 and Q6 which are turned on to the R phase and the T phase. In the 3 rd interval, R-phase regenerative current Ir_RFlows in the negative direction, and T-phase regenerative current Ir_TFlows in the positive direction.

Base drive signal generating section 31 generates voltage V between S-T lines_S-TIn the 4 th interval from t6 to t8, where the instantaneous value of the base drive signal S is the maximum value_SP、S_TNThe base drive signal is set to high level, and the remaining base drive signal is set to low level. Thus, in the 4 th section, the S-phase positive side switching element Q3 and the T-phase negative side switching element Q6 are kept on, and the remaining switching elements are kept off. Therefore, a current flows through the switching elements Q3 and Q6 which are turned on to the S phase and the T phase. In the 4 th interval, the S-phase regenerative current Ir_SFlows in the negative direction, and T-phase regenerative current Ir_TFlows in the positive direction.

Base drive signal generating section 31 generates voltage V between S-R lines_S-RIn the 5 th interval from t8 to t10, where the instantaneous value is the maximum, the base is setPolar drive signal S_SP、S_RNThe base drive signal is set to high level, and the remaining base drive signal is set to low level. Thus, in the 5 th section, the S-phase positive side switching element Q3 and the R-phase negative side switching element Q2 are kept on, and the remaining switching elements are kept off. Therefore, a current flows through the switching elements Q3 and Q2 which are turned on to the S phase and the R phase. In the 5 th interval, the S-phase regenerative current Ir_SFlows in the negative direction, and R-phase regenerative current Ir_RFlows in the positive direction.

Base drive signal generating section 31 generates voltage V between T-R lines_T-RIn the 6 th interval from t10 to t12, where the instantaneous value of the base drive signal S is the maximum value_TP、S_RNThe base drive signal is set to high level, and the remaining base drive signal is set to low level. Thus, in the 6 th section, the switching element Q5 on the positive side of the T-phase and the switching element Q2 on the negative side of the R-phase are maintained on, and the remaining switching elements are maintained off. Therefore, a current flows through the switching elements Q5 and Q2 which are turned on to the T-phase and the R-phase. In the 6 th interval, the T-phase regenerative current Ir_TFlows in the negative direction, and R-phase regenerative current Ir_RFlows in the positive direction.

Further, the regenerative current flowing between the converter 1 and the ac power supply 3 is limited by the impedance of the reactor 2. Even when the switching elements Q1 to Q6 are turned on and off, the voltage V between the terminals of the smoothing capacitor 22_DCIs less than or equal to the supply voltage V of the AC power supply 3_RSTIn the case of (2), the regenerative current does not flow either. The regenerative current is obtained by using the inter-terminal voltage V of the smoothing capacitor 22_DCAnd the supply voltage V of the AC power supply 3_RSTThe voltage difference therebetween.

In this way, since the converter 1 performs the power supply regeneration operation by the 120-degree conduction regeneration method, the on/off operation of each switching element Q is only required at the start and end of the 120-degree interval. Therefore, converter 1 can significantly reduce the on-off loss of each switching element Q as compared with a PWM regenerative converter. In addition, since the number of on/off operations of the converter 1 is smaller than that of the converter of the PWM regeneration system, the on/off noise is also small, and the converter can be configured at low cost. In addition, while the PWM regenerative converter needs to constantly perform the on-off operation, the converter 1 can reduce the on-off loss of the switching element Q because the power supply regeneration operation by the on-off operation is stopped and the ac/dc conversion is performed by the rectifier bridge circuit of the power module 21 during the motor power running. The converter 1 may be a PWM regeneration converter.

Next, the power running operation of the motor control system 100 will be described. The motor drive device 4 of the motor control system 100 converts the dc voltage output from the converter 1 into an ac voltage during motor power running, and supplies the converted ac voltage to the motor 5 to perform variable speed control of the motor 5. In this case, if the motor drive device 4 converts the dc voltage output from the converter 1 to an ac voltage, the voltage of the smoothing capacitor 22 of the converter 1 decreases. If the inter-terminal voltage V of the smoothing capacitor 22 is set_DCSupply voltage V to AC power supply 3_RSTLarge, the supply voltage V from the AC power supply 3_RSTAnd is input to the power module 21 via the reactor 2. The rectifier devices D1 to D6 of the power module 21 supply the power supply voltage V input from the ac power supply 3 via the reactor 2_RSTRectified and the rectified voltage is output to the smoothing capacitor 22.

Fig. 3 is a diagram for explaining an operation in the motor power running mode of the motor control system according to embodiment 1. In the example shown in fig. 3, the switching elements Q1 and Q4 are turned on, and the R-phase regenerative current Ir is obtained_RFlows in the direction from the AC power supply 3 to the motor drive device 4, and the S-phase regenerative current Ir_SFlows in the direction from the motor drive device 4 to the ac power supply 3. In the following, the current flowing between the ac power supply 3 and the converter 1 is referred to as a powering current.

Fig. 4 is a diagram showing a relationship between a power supply voltage of an ac power supply and a current flowing through a converter in a motor powering operation of the motor control system according to embodiment 1. Fig. 4 shows a line-to-line voltage and an R-phase power running current Ip during motor power running of the motor control system_RS-phase power running current Ip_ST-phase power running current Ip_TAnd a current I flowing through the rectifier elements D1, D2, D3, D4, D5, and D6_D1、I_D2、I_D3、I_D4、I_D5、I_D6And bus current I_PNChange over time.

R-phase power running current Ip_RIs a current flowing between the R phase of the ac power supply 3 and the converter 1 when the motor is in power running. S-phase power running current Ip_SIs a current flowing between the S-phase of the ac power supply 3 and the converter 1 when the motor is in power running. T-phase power running current Ip_TIs a current flowing between the T-phase of the ac power supply 3 and the converter 1 when the motor is in power running. R-phase power running current Ip_RS-phase power running current Ip_SAnd a T-phase power running current Ip_TThe ac power source 3 and the smoothing capacitor 22 flow through the rectifier elements D1 to D6.

As shown in fig. 4, during the motor power running mode, the converter 1 operates as follows. In the interval from time t0 to time t2, the rectifier elements D5 and D4 are turned on, and the current flows in the direction from the ac power supply 3 to the smoothing capacitor 22 in the rectifier element D5 and flows in the direction from the smoothing capacitor 22 to the ac power supply 3 in the rectifier element D4. In the interval from time t2 to time t4, the rectifier elements D1 and D4 are turned on, and the current flows in the direction from the ac power supply 3 to the smoothing capacitor 22 in the rectifier element D1 and flows in the direction from the smoothing capacitor 22 to the ac power supply 3 in the rectifier element D4. In the interval from time t4 to time t6, the rectifier device D1 is turned on, and the current flows in the direction from the ac power supply 3 to the smoothing capacitor 22 in the rectifier devices D1 and D6, and the current flows in the direction from the smoothing capacitor 22 to the ac power supply 3 in the rectifier device D6.

In the interval from time t6 to time t8, the rectifier elements D3 and D6 are turned on, and the current flows in the direction from the ac power supply 3 to the smoothing capacitor 22 in the rectifier element D3 and flows in the direction from the smoothing capacitor 22 to the ac power supply 3 in the rectifier element D6. In the interval from time t8 to time t10, the rectifier elements D3 and D2 are turned on, and the current flows in the direction from the ac power supply 3 to the smoothing capacitor 22 in the rectifier element D3 and flows in the direction from the smoothing capacitor 22 to the ac power supply 3 in the rectifier element D2. In the interval from time t10 to time t12, the rectifier elements D5 and D2 are turned on, and the current flows in the direction from the ac power supply 3 to the smoothing capacitor 22 in the rectifier element D5 and flows in the direction from the smoothing capacitor 22 to the ac power supply 3 in the rectifier element D2.

As shown in fig. 4, each of the rectifier devices D in the power module 21 is turned on and a current flows only during 1/3 of the power cycle of the ac power supply 3. In addition, during half of the period, that is, during 1/6 of the power supply cycle of the ac power supply 3, the line-to-line voltage having the largest voltage value is switched, and therefore the combination of the rectifier elements D that are in the on state is switched. For example, in the interval from time t2 to t4 among the intervals from time t2 to t6, the rectifier device D1 and the rectifier device D4 are turned on and a current flows, but in the interval from time t4 to t6, the rectifier device D1 and the rectifier device D6 are turned on and a current flows.

Next, a power supply regeneration operation of the converter 1 during motor regeneration will be described. Fig. 5 is a diagram for explaining a power supply regeneration operation by the on/off operation of the converter according to embodiment 1. When the motor is regenerated, the motor drive device 4 converts the regenerative power of the motor 5 from ac power to dc power, and supplies the regenerative power converted into ac power to the smoothing capacitor 22. Thereby, the inter-terminal voltage V of the smoothing capacitor 22_DCThe voltage V between the terminals of the smoothing capacitor 22 rises_DCBecomes higher than the power supply voltage V of the ac power supply 3_RSTIs large.

The regeneration control unit 32 of the converter 1 determines if the power supply voltage V of the AC power supply 3 is high_RSTAnd bus voltage V_PNIf the difference is greater than or equal to a predetermined value, the base drive signal S is applied_RP、S_RN、S_SP、S_SN、S_TP、S_TNThe output is outputted to the drive circuit 27, and the power regeneration operation by the on/off operation of the power module 21 is started. In the converter 1, if the power regeneration is realized by the on-off actionWhen the operation starts, the dc power of the smoothing capacitor 22 is converted into ac power by the switching elements Q of the power module 21, and the converted ac power is output as regenerative power to the ac power supply 3 via the reactor 2.

Fig. 6 is a diagram showing a relationship between a power supply voltage of an ac power supply and a current flowing through a converter at the time of motor regeneration in the motor control system according to embodiment 1. Fig. 6 shows a line-to-line voltage and an R-phase regenerative current Ir during motor regeneration_RS-phase regenerative current Ir_ST-phase regenerative current Ir_TAnd a current I flowing through the switching elements Q1, Q2, Q3, Q4, Q5, and Q6_Q1、I_Q2、I_Q3、I_Q4、I_Q5、I_Q6And bus current I_PNChange over time.

As shown in fig. 6, when the power source of the converter 1 is regenerated, a current I flows through the switching elements Q1, Q2, Q3, Q4, Q5, and Q6_Q1、I_Q2、I_Q3、I_Q4、I_Q5、I_Q6So that R-phase regenerative current Ir flows between converter 1 and AC power supply 3_RS-phase regenerative current Ir_SAnd T-phase regenerative current Ir_TThe converter 1 outputs regenerative power to the ac power supply 3.

As shown in fig. 6, each switching element Q in the power module 21 is turned on only during 1/3 of the power supply cycle of the ac power supply 3 and a regenerative current flows. In addition, during half of the period, that is, during 1/6 of the power supply cycle of the ac power supply 3, the line-to-line voltage having the largest voltage value is switched, and therefore, the combination of the switching elements Q that are turned on is switched. For example, in the interval from time t2 to t4 among the intervals from time t2 to t6, the switching element Q1 and the switching element Q4 are turned on and the regenerative current flows, but in the interval from time t4 to t6, the switching element Q1 and the switching element Q6 are turned on and the regenerative current flows.

Then, the bus current I flowing through the converter 1 during the motor power running and the motor regeneration is measured_PNThe description is given. Fig. 7 is a diagram showing a case where the motor control system according to embodiment 1 drives a motorA state of the motor control system of (1). Fig. 7 shows motor speed N and motor torque T_outMotor output power P_outThe inter-terminal voltage V of the smoothing capacitor 22_DCBus current I_PNAnd a supply voltage V_RSTChange over time. The motor speed N is the rotational speed of the rotating shaft provided to the motor 5. Motor torque T_outIs the torque of the motor 5. Output power P of motor_outIs the output power of the motor 5.

First, the motor power operation section shown in fig. 7 will be described. The motor power running section is a section from time t20 to time t23, and is a section in which the motor control system 100 performs the power running operation. The time t20 is the time when the motor 5 starts accelerating, and the time t23 is the time when the motor speed N reaches the target speed. In the motor power running region, the motor torque T is passed_outThe motor speed N becomes larger and, in addition, the motor output P becomes larger_outIncreased, bus current I_PNAnd also becomes larger. If the motor torque T_outWhen the output power P of the motor becomes smaller_outConstant, bus current I_PNThe peak value of (a) is also constant.

Next, the motor constant speed section will be described. The motor constant speed section is a section from time t23 to t24, and the motor speed N is a constant speed section. In the motor constant speed section, the motor output power P is different from the motor power operation section_outLow, and therefore hardly flowing bus current I_PN。

Next, the motor regeneration section will be described. The motor regeneration section is a section from time t24 to t27, and is a section in which the motor control system 100 performs a power regeneration operation. The time t24 is when the motor 5 starts decelerating, and the time t27 is when the motor 5 stops. If the motor 5 starts to decelerate, the regenerative power of the motor 5 flows into the smoothing capacitor 22, and therefore the inter-terminal voltage V of the smoothing capacitor 22_DCAnd (4) rising.

If the voltage between terminals V_DCIf the predetermined value is exceeded, the converter1 starts the power regeneration operation. When the power supply regeneration operation is started, a regenerative current flows from the smoothing capacitor 22 to the power module 21, and the inter-terminal voltage V of the smoothing capacitor 22_DCAnd becomes smaller. At time t24, the motor output P is reduced due to the motor deceleration_outLarge in absolute value of (b), and therefore a large regenerative current flows, but as the motor speed N decreases, the motor output P decreases_outThe absolute value of (a) becomes small and the regenerative current also becomes small.

Next, a case where a power failure occurs in the ac power supply 3 will be described. When a power failure occurs in which the supply of electric power from the ac power supply 3 to the motor control system 100 is stopped during motor powering operation, motor constant speed operation, or motor regeneration, a large current flows through the rectifier device D or the switching device Q in the power module 21. Therefore, the converter 1 includes a power failure detection unit 33, and the power failure detection unit 33 detects that a power failure has occurred in the ac power supply 3.

First, a case where a power failure occurs in the ac power supply 3 during the motor powering operation will be described. Fig. 8 is a diagram showing a state of the motor control system in a case where a power failure occurs in the ac power supply in the motor power running section shown in fig. 7. In fig. 8, the period from time t21 to time t22 is a power failure period. Time t21 is a time at which the supply of electric power from ac power supply 3 to converter 1 is stopped, i.e., a power stop start time. In fig. 8, time t22 is a time when the power failure by the ac power supply 3 ends, that is, a power supply return start time.

As shown in fig. 8, if the ac power supply 3 is stopped during the motor power running, no power is supplied to the converter 1, and therefore no bus current I flows_PN. During this period, the electric power is continuously supplied from the motor drive device 4 to the motor 5, and therefore the electric power stored in the smoothing capacitor 22 is supplied from the converter 1 to the motor drive device 4. As a result, the inter-terminal voltage V of the smoothing capacitor 22_DCAnd sharply decreases.

Thereafter, at time t22, if ac power supply 3 recovers from a power failure, power supply voltage V of ac power supply 3_RSTBecomes more than the inter-terminal electricity of the smoothing capacitor 22Pressure V_DCTherefore, a large current flows from the ac power supply 3 into the smoothing capacitor 22 through the rectifier devices D1 to D6. Due to the inter-terminal voltage V of the smoothing capacitor 22_DCSince it is smaller than the case shown in fig. 7, a bus current I in a larger positive direction flows than the case shown in fig. 7_PN. Supply voltage V of ac power supply 3_RSTAnd the inter-terminal voltage V of the smoothing capacitor 22_DCThe larger the potential difference is, the bus current I_PNThe larger.

Thus, the supply voltage V of the AC power supply 3_RSTAnd the inter-terminal voltage V of the smoothing capacitor 22_DCThe larger the potential difference of (a), the larger the current flows through the rectifier devices D1 to D6. In the motor constant speed section, similarly, the motor output P is used_outIn the state of (3), a large current may flow through the rectifier devices D1 to D6 on the same principle as in the case of the motor power running.

Next, a case where a power failure occurs during motor regeneration will be described. Fig. 9 is a diagram showing a state of the motor control system in a case where a power failure occurs in the motor regeneration section ac power supply shown in fig. 7. In fig. 9, the period from time t25 to time t26 is a power failure period. Time t25 is a power outage start time, and time t26 is a power supply return start time. When the motor is regenerated, the inter-terminal voltage V of the smoothing capacitor 22 is made by the regenerated energy_DCHowever, if the ac power supply 3 stops, the inter-terminal voltage V of the smoothing capacitor 22 rises as shown in fig. 9_DCSupply voltage V to AC supply 3_RSTBecomes larger than the case shown in fig. 7, and therefore a larger negative bus current I flows than the case shown in fig. 7_PN。

Supply voltage V of ac power supply 3_RSTAnd the inter-terminal voltage V of the smoothing capacitor 22_DCThe larger the potential difference is, the larger the bus current I_PNThe larger. Thus, the supply voltage V of the AC power supply 3_RSTAnd the inter-terminal voltage V of the smoothing capacitor 22_DCThe larger the potential difference of (3), the larger the current flows through the switching elements Q1 to Q6. In addition, the switching elements Q1E are determined in accordance with the voltage phase of the AC power supply 3Which combination of switching elements of Q6 flows a current.

In this way, when the ac power supply 3 is powered or the motor is at a constant speed and a power failure occurs, a large current flows through the rectifier elements D1 to D6 at the start of power restoration. When a power failure occurs in the ac power supply 3 during motor regeneration, a large current flows through the switching elements Q1 to Q6 at the start of the power failure.

The power failure detection unit 33 detects the bus current I detected by the bus current detection unit 25 during motor regeneration_PNIs greater than or equal to a preset 1 st threshold Ith 1. The power failure detection unit 33 generates a bus current I during motor regeneration_PNWhen the absolute value of (a) is greater than or equal to the 1 st threshold Ith1, it is determined that a power failure has occurred in the ac power supply 3, the power supply regeneration operation is determined to be stopped, and a regeneration stop command for stopping the power supply regeneration operation is output to the regeneration control unit 32 and the motor control unit 41.

The power failure detection unit 33 also detects the bus current I detected by the bus current detection unit 25 during motor regeneration_PNIs determined whether or not the absolute value of (b) is less than or equal to the 2 nd threshold value Ith2 during the preset 1 st time Tth 1. When the power failure detection unit 33 determines that the motor is regenerating, the bus current I_PNWhen the absolute value of (d) is less than or equal to the 2 nd threshold Ith2 during the 1 st time Tth1, it is determined that a power failure has occurred in the ac power supply 3, the power supply regeneration operation is determined to be stopped, and a regeneration stop command for stopping the power supply regeneration operation is output to the regeneration control unit 32 and the motor control unit 41.

When the power failure detection unit 33 outputs the regeneration stop command, the regeneration control unit 32 stops outputting the base drive signal S to the drive circuit 27_RP、S_RN、S_SP、S_SN、S_TP、S_TNAnd the power regeneration operation by the power module 21 is stopped. This allows the converter 1 to suppress the malfunction of the switching elements Q1 to Q6. The 1 st threshold Ith1 is set to, for example, a value of a rated current of the power module 21.

When the regeneration stop command is output from the power failure detection unit 33, the motor control unit 41 controls the power conversion unit 40 to stop the output of the ac power from the power conversion unit 40 to the motor 5. This allows the converter 1 to suppress the malfunction of the switching elements Q1 to Q6.

The power failure detection unit 33 detects the bus current I detected by the bus current detection unit 25 during the motor power running_PNIs greater than or equal to the 1 st threshold Ith 1. Bus current I of power failure detection unit 33 during motor power running_PNWhen the absolute value of (d) is greater than or equal to 1 st threshold Ith1, it is determined that a power failure has occurred in ac power supply 3, and the power running operation is stopped. If the power failure detection unit 33 determines to stop the power running operation, it outputs a power running stop command for stopping the power running operation to the motor control unit 41. When the motor is in power running, the power failure detection part 33 detects the bus current I_PNThe determination that a power failure has occurred in the ac power supply 3 when the absolute value of (a) is greater than or equal to the 1 st threshold Ith1 is detected at the timing (timing) when the power supply from the ac power supply 3 is restarted after the power failure has occurred in the ac power supply 3. Therefore, in this case, the determination of the occurrence of the power failure by the power failure detection unit 33 includes the determination of the start of the power supply recovery.

The power failure detection unit 33 detects the bus current I detected by the bus current detection unit 25 during the motor power running_PNIs less than or equal to the 2 nd threshold value Ith2 during the 1 st time Tth 1. When the power failure detection unit 33 determines that the motor is in the power running mode, the bus current I is determined_PNWhen the absolute value of (d) is less than or equal to the 2 nd threshold Ith2 during the 1 st time Tth1, it is determined that a power failure has occurred in the ac power supply 3, and the power running operation is stopped. If the power failure detection unit 33 determines to stop the power running operation, it outputs a power running stop command for stopping the power running operation to the motor control unit 41.

When the power failure detection unit 33 outputs the power running stop command, the motor control unit 41 controls the power conversion unit 40 to stop the output of the ac power from the power conversion unit 40 to the motor 5. Thus, the motor drive device 4 can suppress the failure of the rectifier elements D1 to D6. Further, the motor drive device 4 can prevent damage to a tool or a workpiece caused by excessive rotation of a feed shaft or a main shaft of an industrial machine, for example.

The power failure detection unit 33 may be configured only for the bus current I_PNIs greater than or equal to the 1 st threshold Ith1, it is determined that a power failure has occurred in the ac power supply 3 or that only the bus current I has occurred_PNIs less than or equal to the 2 nd threshold Ith2 during the 1 st time Tth1, it is determined that a power failure has occurred in the ac power supply 3.

Further, the power failure detection unit 33 may not output the regeneration stop command to the motor control unit 41 when the motor is regenerated. Thus, for example, when the power failure time is short while the ac power supply 3 is powered off, the regenerative power of the motor 5 can be stored in the smoothing capacitor 22. In this case, the power failure detection unit 33 may be configured to detect the bus current I_PNIs equal to or less than 2 nd threshold value Ith2 for a period of 2 nd time Tth2 longer than 1 st time Tth1, the regeneration stop command is output to motor control unit 41. This prevents excessive accumulation of regenerative power in the smoothing capacitor 22 when the power failure time of the ac power supply 3 is long.

The condition setting unit 34 receives the power outage determination condition adopted by the power outage detection unit 33, and sets the received determination condition in the power outage detection unit 33. For example, the condition setting unit 34 receives determination condition information transmitted to the converter 1 by wire or wirelessly from an input device or a terminal device, not shown, and sets the determination condition for power outage, adopted by the power outage detection unit 33, to the power outage detection unit 33 based on the received determination condition information. The determination condition information includes, for example, information indicating each of the 1 st threshold value Ith1, the 2 nd threshold value Ith2, the 1 st time Tth1, and the 2 nd time Tth 2. The condition setting unit 34 can change the 1 st threshold Ith1, the 2 nd threshold Ith2, the 1 st time Tth1, and the 2 nd time Tth2 set in the power failure detection unit 33.

FIG. 10 shows a converter according to embodiment 1The flowchart of an example of the processing flow of the power failure detection unit is repeatedly executed at a predetermined cycle, for example. As shown in fig. 10, the power failure detection unit 33 obtains the bus current I detected by the bus current detection unit 25_PNIs detected (step S10). The power failure detection unit 33 obtains the bus current I_PNInformation of (2) to bus current I_PNIs calculated (step S11).

Then, the power failure detection unit 33 detects the bus current I_PNIs greater than or equal to the 1 st threshold Ith1 (step S12). The power failure detection unit 33 determines that the bus current I is_PNIs not greater than or equal to the 1 st threshold value Ith1 (step S12: No), the bus current I is measured_PNIs less than or equal to the 2 nd threshold Ith2 for a predetermined 1 st time Tth1 (step S13).

The power failure detection unit 33 determines that the bus current I is_PNIs greater than or equal to the 1 st threshold value Ith1 (step S12: Yes), or when it is determined that the bus current I is_PNWhen the absolute value of (b) is less than or equal to the 2 nd threshold value Ith2 (step S13: Yes) during the 1 st time Tth1, it is determined whether or not the motor is being regenerated (step S14). In step S14, the power failure detection unit 33 acquires a state signal including information indicating whether or not the power regeneration operation is being performed, for example, from the regeneration control unit 32, and determines whether or not the motor regeneration operation is being performed based on the acquired state signal.

When it is determined that the motor regeneration is not being performed (No in step S14), the power failure detection unit 33 determines whether or not the motor is in the motor power running mode (step S15). In step S15, the power failure detection unit 33 acquires a state signal including information indicating whether or not the power running operation is being performed, for example, from the motor control unit 41, and determines whether or not the power running operation is being performed based on the acquired state signal.

When the power failure detection unit 33 determines that the motor regeneration is underway (Yes in step S14), it determines to stop the power regeneration operation (step S16), and outputs a regeneration stop command to the regeneration control unit 32 and the motor control unit 41 (step S17). In step S17, the power outage detection unit 33 may output the regeneration stop command to only one of the regeneration control unit 32 and the motor control unit 41.

When the power failure detection unit 33 determines that the motor is in the powering operation (Yes in step S15), it determines to stop the powering operation (step S18), and outputs a power operation stop command to the motor control unit 41 (step S19). The power failure detection unit 33 determines that the bus current I is_PNIf the absolute value of (b) is not less than or equal to 2 nd threshold Ith2 during time 1 Tth1 (step S13: No), if it is determined that the motor is not in the powering operation (step S15: No), if the process of step S17 is finished, or if the process of step S19 is finished, the process shown in fig. 10 is finished.

Fig. 11 is a flowchart showing an example of a process flow of the regeneration control unit of the converter according to embodiment 1, and is repeatedly executed at a predetermined cycle, for example. As shown in fig. 11, the regeneration control unit 32 determines whether or not a regeneration stop command is received from the power failure detection unit 33 (step S20).

When it is determined that the regeneration stop command is received from the power failure detection unit 33 (Yes in step S20), the regeneration control unit 32 stops the power regeneration operation (step S21). In step S21, the regeneration control unit 32 stops outputting the base drive signal S to the drive circuit 27_RP、S_RN、S_SP、S_SN、S_TP、S_TNThe plurality of switching elements Q1 to Q6 are turned off to stop the power supply regeneration operation. If it is determined that the regeneration stop command has not been received from the power outage detection unit 33 (No at step S20), or if the process of step S21 has ended, the regeneration control unit 32 ends the process shown in fig. 11.

Fig. 12 is a flowchart showing an example of a processing flow of the motor control unit of the motor drive device according to embodiment 1, and is repeatedly executed at a predetermined cycle, for example. As shown in fig. 12, the motor control unit 41 determines whether or not the power failure detection unit 33 has received the powering-off stop command (step S30). When determining that the powering stop command is received from the power failure detection unit 33 (step S30: Yes), the motor control unit 41 controls the power conversion unit 40 to stop the supply of electric power from the power conversion unit 40 to the motor 5 and to stop the powering operation by the power conversion unit 40 (step S31).

When determining that the powering-on stop command is not obtained from the power failure detection unit 33 (No in step S30), the motor control unit 41 determines whether or not the regeneration stop command is obtained from the power failure detection unit 33 (step S32). When determining that the regeneration stop command has been received from the power failure detection unit 33 (Yes at step S32), the motor control unit 41 controls the power conversion unit 40 to stop the power regeneration operation by the power conversion unit 40 (step S33).

If it is determined that the regeneration stop command has not been received from the power failure detection unit 33 (No at step S32), the motor control unit 41 ends the processing shown in fig. 12 when the processing of step S31 ends or when the processing of step S33 ends.

As described above, the converter 1 according to embodiment 1 is disposed between the ac power supply 3 as an input power supply and the motor drive device 4 that performs variable speed control of the motor 5, and the converter 1 includes the power module 21, the smoothing capacitor 22, the bus current detection unit 25, and the control unit 26. The power module 21 includes: a plurality of rectifier elements D1 to D6 that rectify an ac voltage supplied from the ac power supply 3; a plurality of switching elements Q1 to Q6 connected in parallel with the corresponding ones of the plurality of rectifying elements D1 to D6, respectively; and two dc power supply terminals 14 and 15 that output voltages rectified by the plurality of rectifying elements D1 to D6. The smoothing capacitor 22 is connected to the two dc power supply terminals 14 and 15, and smoothes the voltage rectified by the power module 21. The bus current detection unit 25 detects a bus current I, which is a current flowing between the dc power supply terminal 14 or the dc power supply terminal 15 and the smoothing capacitor 22_PNAnd (6) detecting. The controller 26 controls the plurality of switching elements Q1 to Q6 based on the voltage phase of the ac power supply 3, thereby outputting the regenerative power of the motor 5 to the ac power supply 3. The control unit 26 detects the bus current based on the bus current detected by the bus current detection unit 25Stream I_PNThe absolute value of (a) is used to determine whether or not a power failure has occurred in the ac power supply 3 in at least either the powering operation of the motor 5 or the regenerating operation of the motor 5. This allows converter 1 to detect the occurrence of a power failure in ac power supply 3 with a simple configuration. For example, since the converter 1 does not need to be provided with a current detection unit other than the bus current detection unit 25 for power failure detection, the manufacturing cost of the converter 1 can be reduced as compared with a converter using a plurality of current detection units for power failure detection. Further, a normal converter having a power regeneration function includes a conversion means for monitoring an input current input from an input power source to the converter and converting the input current into a direct current based on a monitoring result, but the converter 1 may not use this conversion means, and therefore, the configuration can be simplified as compared with a normal converter. In addition, the converter 1 is based on the bus current I_PNSince the occurrence of a power failure is detected as the absolute value of (2), the occurrence of a power failure in the ac power supply 3 can be detected without using different thresholds for powering and regeneration.

In addition, the power failure detection unit 33 detects the bus current I_PNWhen the absolute value of (b) exceeds the 1 st threshold Ith1, it is determined that a power failure has occurred in the ac power supply 3. Thus, the converter 1 can detect the occurrence of a power failure in the ac power supply 3 with high accuracy without using different thresholds at the powering time and the regeneration time. The 1 st threshold Ith1 is an example of a preset value.

In addition, the power failure detection unit 33 detects the bus current I_PNWhen the absolute value of (d) is less than or equal to the 2 nd threshold Ith2 for the preset 1 st time Tth1, it is determined that a power failure has occurred in the ac power supply 3. Thus, the converter 1 can detect the occurrence of a power failure in the ac power supply 3 with high accuracy without using different thresholds at the powering time and the regeneration time. The 2 nd threshold Ith2 is an example of a preset value.

The converter 1 further includes a condition setting unit 34, and the condition setting unit 34 receives the power failure determination condition adopted by the power failure detection unit 33, and determines the received power failure determination conditionThe predetermined condition is set in the power failure detection unit 33. The power failure detection unit 33 detects the bus current I detected by the bus current detection unit 25_PNWhen the absolute value of (b) satisfies the determination condition, it is determined that the power failure has occurred in the ac power supply 3. The determination condition is, for example, at least one of the 1 st threshold value Ith1, the 2 nd threshold value Ith2, the 1 st time Tth1, and the 2 nd time Tth 2. This enables the user of the converter 1 to change the sensitivity of the power failure detection. For example, it is possible to use the case where a user who intends to focus on protection of the converter 1 sets the 1 st threshold Ith1 and the 2 nd threshold Ith2 to values lower than the rated current of the power module 21, and a user who intends to avoid erroneous detection of a power failure in order to improve the operation efficiency of the industrial machine sets the 1 st threshold Ith1 and the 2 nd threshold Ith2 to values higher than the rated current of the power module 21.

The control unit 26 includes a regeneration control unit 32, and the regeneration control unit 32 controls the plurality of switching elements Q1 to Q6 during motor regeneration. When determining that the ac power supply 3 has a power failure, the power failure detection unit 33 outputs a regeneration stop command to the regeneration control unit 32. When the power failure detection unit 33 outputs a regeneration stop command, the regeneration control unit 32 stops the control of the plurality of switching elements Q1 to Q6. This allows the converter 1 to suppress the malfunction of the switching elements Q1 to Q6.

When it is determined that the ac power supply 3 has failed, the power failure detection unit 33 outputs a power running stop command to the motor drive device 4, and stops the supply of electric power from the motor drive device 4 to the motor 5 in response to the motor stop command. Thus, when a power failure occurs during motor power running, the converter 1 can stop the operation of the motor drive device 4, and can suppress a failure of the rectifier elements D1 to D6.

Embodiment mode 2

The motor control system according to embodiment 2 is different from the motor control system according to embodiment 1 in that a failure prediction of a power module is further performed. Hereinafter, components having the same functions as those in embodiment 1 are denoted by the same reference numerals, and description thereof is omitted, and differences from the motor control system 100 in embodiment 1 will be mainly described.

Fig. 13 is a diagram showing an example of the configuration of a motor control system according to embodiment 2. As shown in fig. 13, a motor control system 100A according to embodiment 2 includes a converter 1A, a motor drive device 4, and a host control device 6. Converter 1A differs from converter 1 in that a control unit 26A is provided instead of control unit 26 having power failure detection unit 33, and that control unit 26A has power failure detection unit 33A.

The power failure detection unit 33A has a function of generating count information and transmitting the generated count information to the higher-level control device 6, in addition to the function of the power failure detection unit 33. The count information includes a 1 st count value N1 and a 2 nd count value N2. The 1 st count value N1 indicates the number of times of the power failure of the ac power supply 3 during the motor powering operation, and the 2 nd count value N2 indicates the number of times of the power failure of the ac power supply 3 during the motor regeneration operation.

Since an overcurrent flows through the rectifier device D when the ac power supply 3 fails during the motor powering operation, the 1 st count value N1 can also be referred to as an overcurrent count value of the rectifier device D. In addition, since an overcurrent flows through the switching element Q when the ac power supply 3 fails during motor regeneration, the 2 nd count value N2 can also be referred to as an overcurrent count value of the switching element Q.

The power failure detection unit 33A detects the bus current I detected by the bus current detection unit 25_PNIs greater than or equal to the 1 st threshold Ith 1. The power failure detection unit 33A detects the bus current I_PNIs greater than or equal to the 1 st threshold value Ith1, the bus current I is measured_PNIs determined to be positive. The power failure detection unit 33A determines that the bus current I is_PNIf the sign of (1) is positive, the 1 st count value N1 is incremented. The power failure detection unit 33A determines that the bus current I is_PNIf the sign of (2) is not positive, the 2 nd count value N2 is incremented. The power failure detection unit 33A outputs count information including the 1 st count value N1 and the 2 nd count value N2 to the higher-level control device 6. The power failure detection unit 33A may output the first count value N1 and the second count value N1 to the upper-stage control device 6The 2 nd counter value N2 is count information including the incremented counter value.

The upper control device 6 transmits a motor operation command and a motor stop command to the motor drive device 4 to control the motor drive device 4. The motor drive device 4 starts control of the motor 5 if receiving the motor operation command, and stops control of the motor 5 if receiving the motor stop command.

The upper control device 6 includes a failure prediction unit 60, and the failure prediction unit 60 determines whether or not there is a possibility of failure occurrence in the power module 21 based on the count information output from the converter 1A. When the 1 st count value N1 is greater than or equal to the 1 st count threshold Nth1, the failure prediction unit 60 determines that the rectifier device D of the power module 21 is highly likely to fail. When the 2 nd count value N2 is greater than or equal to the 2 nd count threshold Nth2, the failure prediction unit 60 determines that the switching element Q of the power module 21 is highly likely to fail. The 1 st count threshold Nth1 and the 2 nd count threshold Nth2 may be set arbitrarily, and may be determined by, for example, the lifetime characteristics presented by the manufacturer of the power module 21.

When there is a high possibility that the rectifying element D or the switching element Q of the power module 21 is malfunctioning, the malfunction prediction unit 60 notifies a user of the motor control system 100A of a power module malfunction warning. The power module failure warning is information indicating that the power module 21 has a possibility of generating a failure. The failure prediction unit 60 can display failure warning information on a display device not shown, or can transmit the failure warning information to a terminal device of a user via a communication unit not shown, for example.

Fig. 14 is a flowchart showing an example of a flow of a counting process of the power failure detection unit of the converter according to embodiment 2, and is repeatedly executed at a predetermined cycle, for example. As shown in fig. 14, the power failure detection unit 33A obtains the bus current I detected by the bus current detection unit 25_PNIs detected (step S40). The power failure detection unit 33A obtains the bus current I_PNInformation of (2) to bus current I_PNIs calculated (step S41).

Then, the power failure detection unit 33A detects the bus current I_PNIs greater than or equal to the 1 st threshold Ith1 (step S42). The power failure detection unit 33A determines that the bus current I is_PNIs greater than or equal to the 1 st threshold value Ith1 (step S42: Yes), the bus current I is measured_PNWhether or not the sign of (b) is positive is determined (step S43). In addition, the bus current I_PNIs a sign of a bus current I_PNOf (c) is used.

The power failure detection unit 33A determines that the bus current I is_PNIf (1) is positive (step S43: Yes), the 1 st count value N1 is incremented by adding 1 to the 1 st count value N1 (step S44). The power failure detection unit 33A determines that the bus current I is_PNIf (1) is not positive (No in step S43), the 2 nd count value N2 is incremented by adding 1 to the 2 nd count value N2.

When the process of step S44 or the process of step S45 ends, power outage detection unit 33A outputs count information including 1 st count value N1 and 2 nd count value N2 to higher-order control device 6 (step S46). When the processing of step S46 is finished, or when the power failure detection unit 33A determines that the bus current I is_PNIs not greater than or equal to the 1 st threshold Ith1 (step S42: No), the process shown in fig. 14 ends.

Fig. 15 is a flowchart showing an example of a failure prediction processing flow of the failure prediction unit of the host control device according to embodiment 2, and is repeatedly executed at a predetermined cycle, for example. As shown in fig. 15, failure prediction unit 60 determines whether or not count information is acquired from converter 1A (step S50).

When determining that the count information is acquired (Yes in step S50), failure prediction unit 60 determines whether or not the 1 st count value N1 included in the count information is greater than or equal to the 1 st count threshold Nth1 (step S51). When determining that the 1 st count value N1 is not greater than or equal to the 1 st count threshold Nth1 (step S51: No), failure prediction unit 60 determines whether or not the 2 nd count value N2 included in the count information is greater than or equal to the 2 nd count threshold Nth2 (step S52).

When it is determined that the 1 st count value N1 is greater than or equal to the 1 st count threshold Nth1 (step S51: Yes), or when it is determined that the 2 nd count value N2 is greater than or equal to the 2 nd count threshold Nth2 (step S52: Yes), failure prediction unit 60 notifies the user of motor control system 100A of a power module failure warning (step S53). In step S53, the failure prediction unit 60 may display failure warning information on a display device not shown, or may transmit the failure warning information to a terminal device of a user via a communication unit not shown, for example.

When it is determined that the count information is not acquired (No at step S50), when it is determined that the 2 nd count value N2 is not greater than or equal to the 2 nd count threshold Nth2 (No at step S52), or when the process at step S53 is completed, failure prediction unit 60 ends the process shown in fig. 15.

In the above example, the failure prediction unit 60 is provided in the higher-level control device 6, but the failure prediction unit 60 may be provided in the converter 1A. Fig. 16 is a diagram showing another example of the configuration of the motor control system according to embodiment 2. As shown in fig. 16, control unit 26A of converter 1A includes failure prediction unit 60 in addition to the configuration shown in fig. 13.

Like the failure prediction unit 60 shown in fig. 13, the failure prediction unit 60 shown in fig. 16 determines whether or not there is a possibility of failure occurrence in the power module 21 based on the count information output from the power failure detection unit 33A. Specifically, the failure prediction unit 60 determines that the switching element Q of the power module 21 is likely to fail when the 1 st count value N1 is greater than or equal to the 1 st count threshold Nth1 and when the 2 nd count value N2 is greater than or equal to the 2 nd count threshold Nth 2. When there is a possibility that a failure may occur in rectifying element D or switching element Q of power module 21, failure prediction unit 60 notifies a power module failure warning to a user of motor control system 100A.

The timing of incrementing the 1 st count value N1 and the 2 nd count value N2 by the power failure detection unit 33A is not limited to the above timing. For example, the power failure detection unit 33A detects the bus current I_PNIs not greater than or equal to the 1 st threshold value Ith1, for the bus current I_PNIs less than or equal to the 2 nd threshold value Ith2 during the 1 st time Tth 1. The power failure detection unit 33A detects the bus current I_PNIs less than or equal to the 2 nd threshold value Ith2 during the 1 st time Tth1, if the bus current I_PNIs positive, the 1 st count value N1 is incremented if the bus current I_PNA negative sign of (d) increments the 2 nd count value N2.

The hardware configuration of the control unit 26A is the same as that of the control unit 26. The function of the power failure detection unit 33A is executed by the processor reading and executing a program stored in the memory. The power failure detection unit 33A may be partially or entirely configured by hardware such as an ASIC or FPGA. The hardware configuration of failure prediction unit 60 is the same as that of control unit 26. The function of the failure prediction unit 60 is executed by the processor reading and executing a program stored in the memory. The failure prediction unit 60 may be partially or entirely configured by hardware such as an ASIC or FPGA.

As described above, the motor control system 100A according to embodiment 2 includes the converter 1A, the motor drive device 4, and the host control device 6 that controls the motor drive device 4. When it is determined that a power failure has occurred, power failure detection unit 33A of converter 1A compares the 1 st count value N1 with the 2 nd count value N2 to determine a bus current I_PNThe count value corresponding to the polarity of (1) is incremented, and count information including at least the count value incremented from the 1 st count value N1 and the 2 nd count value N2 is output. Failure prediction unit 60 of upper control device 6 predicts the failure of power module 21 based on the count information output from power failure detection unit 33A. Thus, before the power module 21 of the converter 1A fails and the industrial machine is stopped, the user can be notified of information indicating that there is a possibility of failure occurring in the power module 21.

Converter 1A further includes failure prediction unit 60, and failure prediction unit 60 predicts a failure of power module 21 based on the determination result of the occurrence of the power outage obtained by power outage detection unit 33A. When the power failure detection unit 33A determines that a power failure has occurred, the 1 st counter value N1 and the 2 nd counter value N2 are compared with the parentLine current I_PNThe count value corresponding to the polarity of (d) is incremented. The failure prediction unit 60 predicts the failure of the power module 21 based on the 1 st count value N1 and the 2 nd count value N2. Thus, before the power module 21 of the converter 1A fails and the industrial machine is stopped, the user can be notified of information indicating that there is a possibility that the power module 21 fails.

The configuration shown in the above embodiment is an example of the contents of the present invention, and may be combined with other known techniques, and a part of the configuration may be omitted or modified within a range not departing from the gist of the present invention.

Description of the reference numerals

1. 1A converter, 2 reactors, 3 ac power supply, 4 motor drive devices, 5 motors, 6 host control devices, 11, 12, 13 ac power supply terminals, 14, 15 dc power supply terminals, 21 power modules, 22 smoothing capacitors, 23 bus voltage detection units, 24 power supply phase detection units, 25 bus current detection units, 26A control units, 27 drive circuits, 31 base drive signal generation units, 32 regeneration control units, 33A power failure detection units, 34 condition setting units, 40 power conversion units, 41 motor control units, 60 failure prediction units, 100A motor control systems, D, D1, D2, D3, D4, D5, D6 rectifier elements, i.e., motor control units, 60 failure prediction units, 100A motor control systems, D, D1, D2, D3, D4, D5, D6 rectifier elements_PNThe bus current, N1 1 st count value, N2 2 nd count value, Q, Q1, Q2, Q3, Q4, Q5, Q6 switching elements.

Claims (9)

1. A converter is arranged between an AC power supply and a motor drive device for controlling a motor,

the converter is characterized by comprising:

a power module including a plurality of rectifier elements that rectify an ac voltage supplied from the ac power supply, a plurality of switching elements that are connected in parallel to each of the plurality of rectifier elements, and two dc power supply terminals that output a voltage rectified by the plurality of rectifier elements;

a smoothing capacitor connected to the two dc power supply terminals, and configured to smooth a voltage rectified by the power module;

a bus current detection unit that detects a bus current that is a current flowing between 1 of the two dc power supply terminals and the smoothing capacitor; and

a control unit that controls the plurality of switching elements based on a voltage phase of the AC power supply to cause the power module to output regenerative power of the motor to the AC power supply,

the control unit includes a power failure detection unit that determines whether or not a power failure has occurred in the ac power supply in either one of a powering operation of the motor and a regenerating operation of the motor, based on an absolute value of the bus current detected by the bus current detection unit.

2. The converter according to claim 1,

the power failure detection unit determines that the power failure has occurred when an absolute value of the bus current exceeds a preset value at least at either the powering operation or the regeneration operation.

3. The converter according to claim 1 or 2,

the power failure detection unit determines that the power failure has occurred when an absolute value of the bus current is less than or equal to a predetermined value for a predetermined time period at least during either the powering operation or the regeneration operation.

4. The converter according to any one of claims 1 to 3,

a condition setting unit that receives the power outage determination condition employed by the power outage detection unit and sets the received determination condition to the power outage detection unit,

the power failure detection unit determines that the power failure has occurred when an absolute value of the bus current satisfies the determination condition at least either one of the power running time and the regeneration time.

5. The converter according to any one of claims 1 to 4,

the control unit includes a regeneration control unit that controls the plurality of switching elements during the regeneration,

the power failure detection unit outputs a regeneration stop command to the regeneration control unit when it is determined that the power failure has occurred during the regeneration,

the regeneration control unit stops control of the plurality of switching elements when the power failure detection unit outputs the regeneration stop command.

6. The converter according to any one of claims 1 to 5,

the power failure detection unit outputs a motor stop command to the motor drive device when it is determined that the power failure has occurred during a powering operation of the motor, and stops the supply of electric power from the motor drive device to the motor by the motor stop command.

7. The converter according to any one of claims 1 to 6,

a failure prediction unit that predicts a failure of the power module based on a determination result of the occurrence of the power outage obtained by the power outage detection unit,

the power failure detection unit increments a count value corresponding to the polarity of the bus current out of a 1 st count value and a 2 nd count value when it is determined that the power failure has occurred,

the failure prediction unit predicts a failure of the power module based on the 1 st count value and the 2 nd count value.

8. The converter according to any one of claims 1 to 6,

the power failure detection unit increments a count value corresponding to the polarity of the bus current, out of a 1 st count value and a 2 nd count value, and outputs count information including at least one of the 1 st count value and the 2 nd count value, when it is determined that the power failure has occurred.

9. A motor control system, comprising:

the converter of claim 8;

the motor drive device; and

a higher-level control device that controls the motor drive device,

the converter outputs the count information to the upper control device,

the higher-level control device performs failure prediction of the power module based on the count information.

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