JP6689478B1 - Converter and motor control system - Google Patents

Abstract

The converter (1) includes a power module (21), a smoothing capacitor (22), a bus current detector (25), and a controller (26). The power module (21) rectifies the AC voltage supplied from the AC power supply (3) and outputs the rectified voltage from the DC power supply terminal (14). The bus current detector (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 to Q6) based on 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), based on the absolute value of the bus current detected by the bus current detection unit (25), is at least one of power running of the motor (5) and regeneration of the motor (5). A power failure detection unit (33) for determining whether or not a power failure has occurred in the AC power supply (3).

Description

  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 to convert electric power.

  The converter arranged between the AC power supply and the motor drive device includes a power module including a bridge rectifier circuit in which a plurality of rectifier elements are bridge-connected, and a smoothing capacitor that smoothes an output voltage of the power module. The AC voltage supplied from the AC power supply to the converter is rectified by the power module, and the rectified voltage is smoothed by the smoothing capacitor.

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

  During motor power running, the voltage smoothed by the converter is applied to the motor drive device. The motor drive device drives the motor by converting the DC voltage supplied from the converter into an AC voltage by DC / AC conversion and applying the converted AC voltage to the motor.

  During motor regeneration, the induced electromotive force generated in the motor is converted into DC voltage by AC-DC conversion by the motor drive 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 the smoothing capacitor or the power module of the converter may fail, the converter has a function of processing regenerative electric power that is power generated by the induced electromotive force of the motor so as not to damage the smoothing capacitor or the power module.

  The regenerative power processing method includes a resistance regenerative method in which regenerative power is consumed by a resistor by heat and a power source regenerative method in which regenerative power is returned to an AC power source. In recent years, converters to which a power regeneration system is applied are increasing in industrial machines such as machine tools and robots from the viewpoint of energy saving. A converter that applies the power regeneration method has a power module that includes a circuit in which a switching element is connected in parallel to each rectifying element, and by controlling the on / off of each switching element, regenerative power is supplied to an AC power source. Supplied.

  A converter that applies the power regeneration system has a power module that generates an overcurrent at the start of a power failure or power recovery when a power failure occurs when the power supply from the AC power supply stops during motor power running or motor regeneration. May deteriorate or malfunction. Also, in industrial machines such as machine tools and robots to which such converters are applied, if a power failure occurs in the AC power supply during power running or regeneration, the feed axis or spindle may rotate excessively, and tools or workpieces may be damaged. There is.

  Patent Document 1 discloses a converter control device that can detect occurrence of a power failure in an AC power supply during regeneration. In such a converter control device, a regenerative resistor is connected between the terminals of the smoothing capacitor via a chopper, and the regenerative electric power is shared by cooperative control of a voltage-type PWM (Pulse Width Modulation) converter and the chopper. Then, this converter control device detects that a power failure has occurred in the AC power supply from the ratio of the bus current and the chopper current flowing through the regenerative resistor during motor regeneration.

JP-A-6-205586

  However, the technique described in Patent Document 1 requires a plurality of current detection means to detect that a power failure has occurred in the AC power supply, and the power failure has occurred in the AC power supply from the outputs of the plurality of current detection means. Therefore, there is a problem that the configuration is complicated.

  The present invention has been made in view of the above, and an object thereof is to obtain a converter that can detect occurrence of a power failure in an AC power supply with a simple configuration.

  In order to solve the above-mentioned problems and to achieve the object, a converter of the present invention is a converter arranged between an AC power supply and a motor drive device that controls a motor, and includes a power module and a smoothing capacitor. A busbar current detection unit and a control unit are provided. The power module includes a plurality of rectifying elements that rectify an AC voltage supplied from an AC power source, a plurality of switching elements that are respectively connected in parallel to corresponding rectifying elements among the plurality of rectifying elements, and a plurality of rectifying elements. And two DC power supply terminals for outputting the generated voltage. The smoothing capacitor is connected to the two DC power supply terminals and smoothes the voltage rectified by the power module. The bus current detector detects a bus current, which is a current flowing between one of the two DC power supply terminals and the smoothing capacitor. The control unit causes the power module to output the regenerative power of the motor to the AC power supply by controlling the plurality of switching elements based on the voltage phase of the AC power supply. The control unit determines, based on the absolute value of the busbar current detected by the busbar current detection unit, whether or not a power failure has occurred in the AC power supply when the motor is running or when the motor is regenerating. Equipped with a power failure detection unit.

  The converter according to the present invention has the effect of being able to detect the occurrence of a power failure in the AC power supply with a simple configuration.

FIG. 3 is a diagram showing an example of a configuration of a motor control system according to the first embodiment. Time chart showing operations of the power supply phase detection unit and the base drive signal generation unit according to the first embodiment FIG. 3 is a diagram for explaining an operation during power running of the motor in the motor control system according to the first embodiment. FIG. 3 is a diagram showing the relationship between the power supply voltage of the AC power supply and the current flowing in the converter during power running of the motor of the motor control system according to the first embodiment. FIG. 6 is a diagram for explaining a power regeneration operation by a switching operation of the converter according to the first embodiment. FIG. 3 is a diagram showing the relationship between the power supply voltage of the AC power supply and the current flowing in the converter during motor regeneration of the motor control system according to the first embodiment. FIG. 3 is a diagram showing a state of the motor control system when the motor control system according to the first embodiment drives a motor. The figure which shows the state of the motor control system when a power failure occurs in AC power supply in the motor power running section shown in FIG. FIG. 7 is a diagram showing a state of the motor control system when an AC power failure occurs in the motor regeneration section shown in FIG. The flowchart which shows an example of the processing procedure by the power failure detection part of the converter concerning Embodiment 1. The flowchart which shows an example of the processing procedure by the regeneration control part of the converter concerning Embodiment 1. The flowchart which shows an example of the processing procedure by the motor control part of the motor drive device concerning Embodiment 1. The figure which shows an example of a structure of the motor control system concerning Embodiment 2. The flowchart which shows an example of the counter processing procedure by the power failure detection part of the converter concerning Embodiment 2. The flowchart which shows an example of the failure prediction processing procedure by the failure prediction unit of the host controller according to the second embodiment. The figure which shows the other example of a structure of the motor control system concerning Embodiment 2.

  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 1.
The configuration of the motor control system according to the first embodiment will be described. FIG. 1 is a diagram illustrating an example of a configuration of a motor control system according to the first embodiment. As shown in FIG. 1, the motor control system 100 according to the first embodiment controls the motor 5 using the three-phase AC voltage output from the AC power supply 3. The motor control system 100 includes a converter 1 that converts the AC voltage output from the AC power supply 3 into a DC voltage, and a motor drive device 4 that controls the motor 5 using the DC voltage output from the converter 1.

The AC power supply 3 is a three-phase AC power supply, and includes, for example, a power generator and power transmission equipment. The three-phase AC voltage supplied from the AC power source 3 is an R-phase voltage V _R that is an R-phase AC voltage, an S-phase voltage V _S that is an S-phase AC voltage, and a T-phase that is a T-phase AC voltage. The voltage is V _T. In the following, the R-phase voltage V _R , the S-phase voltage V _S , and the T-phase voltage V _T may be collectively referred to as the power supply voltage V _RST . The motor 5 is, for example, a motor that constitutes an industrial machine such as a machine tool and a robot, but may be a motor other than the motor that constitutes the industrial machine.

  The converter 1 is connected to an AC power supply 3 which is an input power supply via a reactor 2. The converter 1 converts the AC voltage supplied from the AC power supply 3 into a DC voltage, and supplies the converted DC voltage to the motor drive device 4. The motor drive device 4 includes a power converter 40 that performs power conversion, and a motor controller 41 that controls the power converter 40. The motor control unit 41 causes the power conversion unit 40 to convert the DC voltage supplied from the converter 1 into an AC voltage according to the control speed of the motor 5, and causes the converted AC voltage to be supplied from the power conversion unit 40 to the motor 5. Thus, the motor 5 is controlled at a variable speed.

  The converter 1 has a power regeneration function that outputs the induced electromotive force generated in the motor 5 as regenerative power to the AC power source 3 when the motor 5 decelerates. The induced electromotive force generated in 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 the 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, the operation during regeneration in the motor control system 100 may be referred to as a power regeneration operation, and the operation during power running in the motor control system 100 may be referred to as a power running operation. Further, the induced electromotive force generated in the motor 5 during the power regeneration operation may be referred to as regenerative power.

  There are a PWM control method and a 120-degree energization regeneration method as a control method for a converter having a power regeneration function. The converter 1 is a 120-degree energization regeneration converter and is also called a power regeneration converter.

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

  The power module 21 includes AC power supply terminals 11 to 13, a DC power supply terminal 14 on the positive electrode side, a DC power supply terminal 15 on the negative electrode side, a plurality of rectifying elements D1 to D6, and a plurality of switching elements Q1 to Q6. . The AC power supply terminal 11 is connected to the R-phase power supply terminal of the AC power supply 3 via the reactor 2, the AC power supply terminal 12 is connected to the S-phase power supply terminal of the AC power supply 3 via the reactor 2, and the AC power supply terminal 13 Is connected to the T-phase power supply terminal of the AC power supply 3 via the reactor 2. The plurality of rectifying elements D1 to D6 are bridge-connected to form a bridge rectifying circuit.

  Between the DC power supply terminal 14 and the DC power supply terminal 15, switching elements Q1 and Q2 connected in series, switching elements Q3 and Q4 connected in series, and switching elements Q5 and Q6 connected in series, Are connected in parallel with each other. The DC power supply terminal 14 is connected to the collector terminals of the switching elements Q1, Q3, Q5 forming the upper arm, and the DC power supply terminal 15 is connected to the emitter terminals of the switching elements Q2, Q4, Q6 forming the lower arm. To be done. The DC power supply terminal 14 is connected to the DC power supply terminal 17 on the positive side of the motor drive device 4, and the DC power supply terminal 15 is connected to the DC power supply terminal 18 on the negative side 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 AC 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 AC power supply terminal 13.

  A corresponding rectifying element among the rectifying elements D1 to D6 is connected in parallel to each of the switching elements Q1 to Q6. Each of the rectifying elements D1 to D6 has an anode terminal connected to an emitter terminal of a corresponding switching element among the switching elements Q1 to Q6 and a cathode terminal connected to a collector terminal of a corresponding switching element among the switching elements Q1 to Q6. It

  The rectifying element D1 and the switching element Q1 form a positive-side power element in the R phase, and the rectifying element D2 and the switching element Q2 form a negative-side power element in the R phase. The rectifying element D3 and the switching element Q3 form a positive power element in the S phase, and the rectifying element D4 and the switching element Q4 form a negative power element in the S phase. Further, the rectifying element D5 and the switching element Q5 form a positive power element in the T phase, and the rectifying element D6 and the switching element Q6 form a negative power element in the T phase. Note that the power module 21 shown in FIG. 1 is an example of a configuration in which the AC power supply 3 is a three-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 four sets of power elements.

  The switching elements Q1 to Q6 are semiconductor switching elements represented by a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor). The rectifying elements D1 to D6 are diodes. In the following, when each of the switching elements Q1 to Q6 is shown without distinction, it is referred to as a switching element Q, and when each of the rectifying elements D1 to D6 is shown without individually distinguishing, it is referred to as a rectifying element D. There are cases.

The smoothing capacitor 22 is arranged between the DC power supply terminal 14 and the DC power supply terminal 15, and smoothes the voltage rectified by the power module 21. The bus voltage detector 23 detects the instantaneous value of the inter-terminal voltage V _DC of the smoothing capacitor 22, that is, the bus voltage V _PN which is the instantaneous value of the voltage between the DC power supply terminal 14 and the DC power supply terminal 15. The bus voltage detector 23 outputs information indicating the bus voltage V _PN to the controller 26.

The power supply phase detector 24 detects the voltage phase of the AC power supply 3 from the power supply voltage V _RST of the AC power supply 3. Although the power supply phase detection unit 24 detects the voltage phase of the AC power supply 3 from the power supply voltage V _RST between the AC power supply 3 and the reactor 2, the power supply voltage V of the reactor 2 and the AC power supply terminals 11, 12, 13 is detected. _It may be arranged so as to detect the voltage phase of the AC power supply 3 from the _RST .

The power supply phase detection unit 24 outputs a power supply 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 RS phase line detection signal θ _RS , SR line phase detection signal θ _SR, and ST line The phase detection signal θ _S-T , the T-S line phase detection signal θ _T-S , the T-R line phase detection signal θ _T-R, and the R-T line phase detection signal θ _R-T included.

The R-S line phase detection signal θ _R-S indicates the phase of the R-S line voltage V _R-S that is the potential difference between the _R phase and the S phase, and the S-R line phase detection signal θ _S-R Indicates the phase of the S-R line voltage V _S-R , which is the potential difference between the S phase and the R phase. The R-S line voltage V _R-S and the S-R line voltage V _S-R are both voltages between the R phase and the S phase, but since the reference phases are different from each other, the phases are different. 180 degrees from each other.

The S-T line phase detection signal θ _S-T indicates the phase of the S-T line voltage V _S-T , which is the potential difference between the _S phase and the T phase, and the T-S line phase detection signal θ _T-S. Indicates the phase of the T-S line voltage V _T-S , which is the potential difference between the T phase and the S phase. The S-T line voltage V _S-T and the T-S line voltage V _T-S are both voltages between the S phase and the T phase, but since the reference phases are different from each other, the phases are different. 180 degrees from each other.

The T-R line phase detection signal θ _T-R indicates the phase of the T-R line voltage V _T-R which is the potential difference between the _T phase and the R phase, and the R-T line phase detection signal θ _R-T indicates the phase of a potential difference across the T-phase of the R-phase R-T line voltage V _R-T. The T-R line voltage V _T-R and the R-T line voltage V _R-T are both voltages between the R phase and the T phase, but since the reference phases are different from each other, the phases are different. 180 degrees from each other.

The busbar current detector 25 is arranged between the DC power supply terminal 14 of the power module 21 and the positive electrode terminal of the smoothing capacitor 22, and the current flowing through the DC busbar between the DC power supply terminal 14 of the power module 21 and the smoothing capacitor 22. detecting the bus current I _PN an instantaneous value. The bus current detector 25 is provided between the DC power supply terminal 14 of the power module 21 and the positive electrode terminal of the smoothing capacitor 22 instead of between the DC power supply terminal 14 of the power module 21 and the positive electrode terminal of the smoothing capacitor 22. It may be arranged.

  Next, the control unit 26 will be described. 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 send and receive data to and from each other by, for example, a bus. The processor executes 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 by reading and executing the program stored in the memory.

  The processor is, for example, 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 at least one of a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), and an EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory). . It should be noted that the base drive signal generation unit 31, the regeneration control unit 32, the power failure detection unit 33, and the condition setting unit 34 are each partly or wholly hardware such as ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array). It may be configured with wear. Further, the control unit 26 may be configured to include a part or all of the power supply phase detection unit 24.

The base drive signal generation unit 31 generates base drive signals S _RP , S _RN , S _SP , S _SN , S _TP , S _TN for driving the switching elements Q1 to Q6 based on the power supply phase detection signal θ. . The base drive signal generation unit 31 outputs the generated base drive signals S _RP , S _RN , S _SP , S _SN , S _TP , and S _TN to the regeneration control unit 32.

The base drive signal S _RP is a signal for driving the switching element Q1, and the base drive signal S _RN is a signal for driving the switching element Q2. The base drive signal S _SP is a signal for driving the switching element Q3, and the base drive signal S _SN is a signal for driving the switching element Q4. The base drive signal S _TP is a signal for driving the switching element Q5, and the base drive signal S _TN is a signal for driving the switching element Q6.

The regenerative controller 32 outputs the base drive signals S _RP , S _RN , S _SP , S _SN , S _TP , and S _TN to the drive circuit 27 as output signals based on the bus current I _PN and the bus voltage V _PN . The drive circuit 27 amplifies the base drive signals S _RP , S _RN , S _SP , S _SN , S _TP and S _TN and outputs them to the bases of the switching elements Q1 to Q6. By switching the switching elements Q1 to Q6 on and off by the base drive signals S _RP , S _RN , S _SP , S _SN , S _TP , and S _TN , the converter 1 performs the power regeneration operation. By such a power regeneration operation, regenerative power is output from converter 1 to AC power source 3.

The regenerative control unit 32, for example, when the difference between the power supply voltage V _RST of the AC power supply 3 and the bus voltage V _PN exceeds a preset value, or the absolute value of the bus current I _PN is a preset value. When the following cases occur, the base drive signals S _RP , S _RN , S _SP , S _SN , S _TP and S _TN are output to the drive circuit 27 as output signals. Further, the regeneration control unit 32 sets, for example, the difference between the power supply voltage V _RST of the AC power supply 3 and the bus voltage V _PN to be less than a preset value and the absolute value of the bus current I _PN to be a preset value. If it exceeds, the base drive signals S _RP , S _RN , S _SP , S _SN , S _TP and S _TN are not output to the drive circuit 27. In this case, in the converter 1, all the switching elements Q1 to Q6 are off, and the power regeneration operation is not performed.

Next, the operations of the power supply phase detector 24 and the base drive signal generator 31 will be described with reference to FIG. FIG. 2 is a time chart showing the operations of the power phase detector and the base drive signal generator according to the first embodiment. In FIG. 2, line voltage, RS line phase detection signal θ _RS , SR line phase detection signal θ _S-R , S-T line phase detection signal θ _S during motor regeneration. _-T , T-S line phase detection signal θ _T-S , T-R line phase detection signal θ _T-R , R-T line phase detection signal θ _R-T , base drive signals S _RP , S _RN , S _SP , S _SN , S _TP , S _TN , and time changes of the currents flowing in the R phase, the T phase, and the S phase.

The power supply phase detection unit 24, based on the R-phase voltage V _R , the S-phase voltage V _S , and the T-phase voltage V _T , the R-S line voltage V _R-S and the S-R line voltage V _S-R. , S-T line voltage V _S-T , T-S line voltage V _T-S , T-R line voltage V _T-R , and R-T line voltage V _R-T are detected. Hereinafter, R-S line voltage V _R-S , S-R line voltage V _S-R , S-T line voltage V _S-T , T-S line voltage V _T-S , T-R line When each of the inter-voltage V _T-R and the R-T line voltage V _R-T is shown without distinction, it may be simply referred to as a line voltage.

The power supply phase detection unit 24 detects the zero-cross point of each line voltage, and detects the R-S line phase detection signal θ _R-S , S-R line phase detection signal θ _S-R , S-T line phase. The detection signals θ _S-T , the T-S line phase detection signal θ _T-S , the T-R line phase detection signal θ _T-R , and the R-T line phase detection signal θ _R-T are generated. Hereinafter, R-S line phase detection signal θ _R-S , S-R line phase detection signal θ _S-R , S-T line phase detection signal θ _S-T , T-S line phase detection signal θ _{When each of the T-S} , T-R line-to-line phase detection signal θ _T-R , and R-T line-to-line phase detection signal θ _R-T is shown without distinction, it is described as a line-to-line phase detection signal. There are cases.

  In the example illustrated in FIG. 2, the power supply phase detection unit 24 sets each line so that the line voltage becomes High level in a phase section in which the line voltage has a positive value and becomes Low level in a phase section in which the line voltage has a negative value. A line phase detection signal for the line voltage is generated. Since the waveform of the line voltage of the AC power supply 3 which is a three-phase AC power supply is a sine wave, the line voltage becomes maximum at the center of the phase section where the line phase detection signal is at the high level, and the line phase detection is performed. The line voltage becomes minimum at the center of the low-level phase section of the signal. The base drive signal generation unit 31 can calculate the phase indicating the maximum voltage and the phase indicating the minimum voltage based on each line phase detection signal generated by the power supply phase detection unit 24.

Next, the operation of the base drive signal generator 31 will be described. The base drive signal generation unit 31 generates base drive signals S _RP , S _RN , S _SP , S _SN , S _TP , and S _TN based on the six line phase detection signals output from the power supply phase detection unit 24. To do.

Hereinafter, switching on and off of the switching element Q will be described as a switching operation, and a current flowing through the switching element Q during the regenerative operation of the converter 1 will be referred to as a regenerative current. Further, FIG. 1 shows the R-phase current I _R , the S-phase current I _S , and the T-phase current I _T , which are indicated by the arrows pointing from the AC power supply 3 to the converter 1, and flow in the directions indicated by the arrows. The current is treated as a positive current and the current in the opposite direction is treated as a negative current. Further, as the current in the converter 1, the current flowing from the converter 1 toward the motor drive device 4 is treated as a plus current, and the current in the opposite direction is treated as a minus current.

The base drive signal generation unit 31 sets the base drive signals S _SN and S _TP to the High level in the first section from time t0 to t2 in which the instantaneous value of the T-S line voltage V _T-S is the highest, and the remaining bases. Set the drive signal to Low level. As a result, in the first section, the T-phase positive-side switching element Q5 and the S-phase negative-side switching element Q4 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 the S phase of the AC power supply 3 via the power supply impedance of the AC power supply 3. Therefore, a current flows in the T phase and the S phase through the switching elements Q5 and Q4 which are in the ON state. In the first section, the T-phase regenerative current Ir _{T that} is a current flowing in the T phase flows in the negative direction, and the S-phase regenerative current Ir _{S that} is a current flowing in the S phase flows in the positive direction.

The base drive signal generation unit 31 sets the base drive signals S _RP and S _SN to the High level in the second section from the time t2 to the time t4 when the instantaneous value of the R-S line voltage V _R-S is the highest, and the remaining bases. Set the drive signal to Low level. As a result, in the second section, the switching element Q1 on the positive side of the R phase and the switching element Q4 on the negative side of the S phase are kept on and the remaining switching elements are kept off. Therefore, current flows in the R phase and the S phase via the switching elements Q1 and Q4 that are in the ON state. In the second section, the R-phase regenerative current Ir _{R, which} is the current flowing in the R-phase, flows in the negative direction, and the S-phase regenerative current Ir _S flows in the positive direction.

The base drive signal generation unit 31 sets the base drive signals S _RP and S _TN to the High level in the third section from the time t4 to the time t6 when the instantaneous value of the RT line voltage V _R-T is the largest, and sets the remaining bases. Set the drive signal to Low level. As a result, in the third section, the switching element Q1 on the positive side of the R phase and the switching element Q6 on the negative side of the T phase are kept on and the remaining switching elements are kept off. Therefore, current flows in the R phase and the T phase through the switching elements Q1 and Q6 that are in the ON state. In the third section, the R-phase regenerative current Ir _R flows in the negative direction and the T-phase regenerative current Ir _T flows in the positive direction.

The base drive signal generation unit 31 sets the base drive signals S _SP and S _TN to the High level in the fourth section from the time t6 to the time t8 when the instantaneous value of the ST line voltage V _S-T is the largest, and sets the remaining bases to the high level. Set the drive signal to Low level. As a result, in the fourth section, the switching element Q3 on the positive side of the S phase and the switching element Q6 on the negative side of the T phase are kept on and the remaining switching elements are kept off. Therefore, current flows in the S phase and the T phase via the switching elements Q3 and Q6 which are in the ON state. In the fourth section, the S-phase regenerative current Ir _S flows in the negative direction and the T-phase regenerative current Ir _T flows in the positive direction.

The base drive signal generation unit 31 sets the base drive signals S _SP and S _RN to the High level in the fifth section from the time t8 to the time t10 when the instantaneous value of the S-R line voltage V _S-R is the largest, and sets the remaining bases. Set the drive signal to Low level. As a result, in the fifth section, the switching element Q3 on the positive side of the S phase and the switching element Q2 on the negative side of the R phase are kept on and the remaining switching elements are kept off. Therefore, a current flows in the S phase and the R phase via the switching elements Q3 and Q2 that are in the ON state. In the fifth section, the S-phase regenerative current Ir _S flows in the negative direction and the R-phase regenerative current Ir _R flows in the positive direction.

The base drive signal generation unit 31 sets the base drive signals S _TP and S _RN to the High level in the sixth section of the time t10 to t12 where the instantaneous value of the T-R line voltage V _T-R is the highest, and the remaining bases. Set the drive signal to Low level. As a result, in the sixth section, the T-phase positive-side switching element Q5 and the R-phase negative-side switching element Q2 are kept on and the remaining switching elements are kept off. Therefore, a current flows in the T phase and the R phase via the switching elements Q5 and Q2 that are in the ON state. In the sixth section, the T-phase regenerative current Ir _T flows in the negative direction and the R-phase regenerative current Ir _R flows in the positive direction.

The regenerative current flowing between converter 1 and AC power supply 3 is limited by the impedance of reactor 2. Further, even if the switching operation of the switching element Q1~Q6 is being performed, if the inter-terminal voltage V _DC of the smoothing capacitor 22 is equal to or less than the supply voltage V _RST of the AC power source 3, the regenerative current does not flow. The regenerative current flows by utilizing the voltage difference between the voltage _VDC between the terminals of the smoothing capacitor 22 and the power supply voltage _VRST of the AC power supply 3.

  As described above, since the converter 1 performs the power regeneration operation by the 120-degree energization regeneration method, the switching operation of each switching element Q is required only at the start and end of the 120-degree section. Therefore, the converter 1 can significantly reduce the switching loss of each switching element Q as compared with the PWM regenerative converter. Further, since the converter 1 has a smaller number of switching operations than a PWM regenerative converter, it can be reduced in switching noise and can be constructed at low cost. Further, while the PWM regenerative converter requires constant switching operation, the converter 1 stops the power regeneration operation by switching operation during motor powering, and performs AC / DC conversion in the rectifying bridge circuit of the power module 21. The switching loss of the switching element Q can be reduced. The converter 1 may be a PWM regenerative converter.

Next, the power running operation in 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 control the motor 5 at a variable speed. In this case, when the motor drive device 4 converts the DC voltage output from the converter 1 into an AC voltage, the voltage of the smoothing capacitor 22 of the converter 1 decreases. When the terminal voltage _{V DC} of the smoothing capacitor 22 is larger than the power supply voltage _{V RST} of the AC power source 3, the power supply voltage _{V RST} from the AC power supply 3 is input to the power module 21 via a reactor 2. The rectifying elements D1 to D6 of the power module 21 rectify the power supply voltage V _RST input from the AC power supply 3 via the reactor 2 and output the rectified voltage to the smoothing capacitor 22.

FIG. 3 is a diagram for explaining an operation during power running of the motor in the motor control system according to the first embodiment. In the example shown in FIG. 3, the switching elements Q1 and Q4 are on, the R-phase regenerative current Ir _R flows in the direction from the AC power supply 3 to the motor driving device 4, and the S-phase regenerative current Ir _S is flowing from the motor driving device 4. It flows in the direction toward the AC power supply 3. In addition, below, the electric current which flows between the alternating current power supply 3 and the converter 1 is described as a power running current.

FIG. 4 is a diagram showing a relationship between the power supply voltage of the AC power supply and the current flowing in the converter during the motor power running of the motor control system according to the first embodiment. In FIG. 4, the line voltage, the R-phase powering current Ip _R , the S-phase powering current Ip _S , the T-phase powering current Ip _T , the rectifying elements D1, D2, D3, D4, D5 during the motor powering of the motor control system. Time changes of the currents I _D1 , I _D2 , I _D3 , I _D4 , I _D5 , I _D6 flowing through _D6 , and the bus current I _PN are shown.

The R-phase power running current Ip _R is a current flowing between the R phase of the AC power supply 3 and the converter 1 during power running of the motor. The S-phase power running current Ip _S is a current that flows between the S phase of the AC power supply 3 and the converter 1 during motor power running. The T-phase power running current Ip _T is a current flowing between the T phase of the AC power supply 3 and the converter 1 during power running of the motor. The R-phase power running current Ip _R , the S-phase power running current Ip _S , and the T phase power running current Ip _T flow between the AC power supply 3 and the smoothing capacitor 22 via the rectifying elements D1 to D6.

  As shown in FIG. 4, during power running of the motor, the converter 1 operates as follows. In the period from time t0 to t2, the rectifying elements D5 and D4 are in a conductive state, a current flows in the rectifying element D5 in the direction from the AC power supply 3 to the smoothing capacitor 22, and the rectifying element D4 is from the smoothing capacitor 22 to the AC power supply. Current flows in the direction of 3. In the section from time t2 to t4, the rectifying elements D1 and D4 become conductive, current flows in the rectifying element D1 in the direction from the AC power source 3 to the smoothing capacitor 22, and the rectifying element D4 moves from the smoothing capacitor 22 to the AC power source. Current flows in the direction of 3. In the section from time t4 to t6, the rectifying element D1 is in a conductive state, current flows in the rectifying elements D1 and D6 in the direction from the AC power source 3 to the smoothing capacitor 22, and the rectifying element D6 is switched from the smoothing capacitor 22 to the AC power source. Current flows in the direction of 3.

  During the period from time t6 to time t8, the rectifying elements D3 and D6 are in a conductive state, a current flows in the rectifying element D3 in the direction from the AC power source 3 to the smoothing capacitor 22, and the rectifying element D6 moves from the smoothing capacitor 22 to the AC power source. Current flows in the direction of 3. In the section from time t8 to t10, the rectifying elements D3 and D2 are in a conductive state, a current flows in the rectifying element D3 in the direction from the AC power supply 3 to the smoothing capacitor 22, and the rectifying element D2 flows from the smoothing capacitor 22 to the AC power supply. Current flows in the direction of 3. In the section from time t10 to time t12, the rectifying elements D5 and D2 are in a conductive state, a current flows in the rectifying element D5 in the direction from the AC power supply 3 to the smoothing capacitor 22, and the rectifying element D2 flows from the smoothing capacitor 22 to the AC power supply. Current flows in the direction of 3.

  As shown in FIG. 4, each rectifying element D in the power module 21 becomes conductive only during a period of ⅓ of the power supply cycle of the AC power supply 3, and a current flows. In addition, since the line voltage having the maximum voltage value is switched in this half period, that is, in a period of 1/6 of the power supply cycle of the AC power supply 3, the combination of the rectifying elements D which are in the conductive state is switched. For example, in the section from time t2 to t6, the rectifying element D1 and the rectifying element D4 are conducting and the current flows in the section from time t2 to t4, but the section from time t4 to t6 is the rectifying element D1 and the rectifying element. D6 is conducting and current is flowing.

Next, the power regeneration operation of the converter 1 during motor regeneration will be described. FIG. 5 is a diagram for explaining the power regeneration operation by the switching operation of the converter according to the first embodiment. During motor regeneration, the motor drive device 4 converts the regenerative power of the motor 5 from AC power to DC power and supplies the regenerated power converted to AC power to the smoothing capacitor 22. As a result, the voltage _VDC between the terminals of the smoothing capacitor 22 rises, and the voltage _VDC between the terminals of the smoothing capacitor 22 becomes higher than the power supply voltage _VRST of the AC power supply 3.

When the difference between the power supply voltage V _RST of the AC power supply 3 and the bus voltage V _PN becomes a predetermined value or more, the regeneration control unit 32 of the converter 1 outputs the base drive signals S _RP , S _RN , S _SP , S _SN , S _TP and S _TN are output to the drive circuit 27 to start the power regeneration operation by the switching operation of the power module 21. When the power regeneration operation by the switching operation is started in the converter 1, the DC power of the smoothing capacitor 22 is converted into AC power by each switching element Q of the power module 21, and the converted AC power is used as the regenerative power. It is output to the AC power supply 3 via 2.

FIG. 6 is a diagram showing the relationship between the power supply voltage of the AC power supply and the current flowing in the converter during motor regeneration of the motor control system according to the first embodiment. In FIG. 6, during motor regeneration, the line voltage, the R-phase regenerative current Ir _R , the S-phase regenerative current Ir _S , the T-phase regenerative current Ir _T , and the currents flowing through the switching elements Q1, Q2, Q3, Q4, Q5, Q6. Time changes of I _Q1 , I _Q2 , I _Q3 , I _Q4 , I _Q5 , I _Q6 , and the bus current I _PN are shown.

As shown in FIG. 6, during regeneration of the power supply of the converter 1, currents I _Q1 , I _Q2 , I _Q3 , I _Q4 , I _Q5 , and I _Q6 flow through the switching elements Q1, Q2, Q3, Q4, Q5, Q6. Then, the R-phase regenerative current Ir _R , the S-phase regenerative current Ir _S , and the T-phase regenerative current Ir _T flow between the converter 1 and the AC power supply 3, and regenerative power is output from the converter 1 to the AC power supply 3.

  As shown in FIG. 6, each switching element Q in the power module 21 is turned on for a period of 1/3 of the power supply cycle of the AC power supply 3 to flow a regenerative current. Further, in the half period, that is, in the period of 1/6 of the power supply cycle of the AC power supply 3, the line voltage having the maximum voltage value is switched, so that the combination of the switching elements Q to be turned on is switched. For example, in the period from time t2 to t6, the switching element Q1 and the switching element Q4 are turned on and regenerative current flows in the period from time t2 to t4, but the period from time t4 to t6 is the same as the switching element Q1. The switching element Q6 is turned on and the regenerative current is flowing.

Next, the bus current I _PN flowing through the converter 1 during motor power running and motor regeneration will be described. FIG. 7 is a diagram showing a state of the motor control system when the motor control system according to the first embodiment drives a motor. FIG. 7 shows changes over time in motor speed N, motor torque T _out , motor output P _out , inter-terminal voltage _VDC of smoothing capacitor 22, bus current _IPN , and power supply voltage V _RST . The motor speed N is the rotation speed of the rotating shaft provided in the motor 5. The motor torque T _out is the torque of the motor 5. The motor output P _out is the output of the motor 5.

First, the motor power running section shown in FIG. 7 will be described. The motor powering section is a section from time t20 to t23, and is a section in which the motor control system 100 is performing a powering operation. Time t20 is the time when the motor 5 starts to accelerate, and time t23 is the time when the motor speed N reaches the target speed. In the motor running section, the motor torque T _out increases the motor speed N, and as the motor output P _out increases, the bus current I _PN increases. When the motor torque T _out becomes smaller, the motor output P _out becomes constant and the peak value of the bus current I _PN also becomes constant.

Next, the motor constant speed section will be described. The motor constant speed section is a section from time t23 to t24, and is a section in which the motor speed N is a constant speed. In the motor constant speed section, unlike the motor power running section, the motor output P _out is low, and therefore the bus current _IPN hardly flows.

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 is performing the power regeneration operation. Time t24 is the time when the motor 5 starts decelerating, and time t27 is the time when the motor 5 is stopped. When the motor 5 starts decelerating, the regenerative power of the motor 5 flows into the smoothing capacitor 22, so that the voltage _VDC between the terminals of the smoothing capacitor 22 increases.

When inter-terminal voltage _VDC exceeds a predetermined value, converter 1 starts the power regeneration operation. When the power regeneration operation is started, a regenerative current flows from the smoothing capacitor 22 to the power module 21, and the voltage _VDC between the terminals of the smoothing capacitor 22 becomes small. At time t24, a large regenerative current flows because the absolute value of the motor output P _out during motor deceleration is large, but as the motor speed N decreases, the absolute value of the motor output P _out decreases and the regenerative current also decreases. .

  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 power supply from the AC power supply 3 to the motor control system 100 is stopped during the power running of the motor, the constant speed of the motor, or the regeneration of the motor, the rectifying element D or the switching element Q in the power module 21 is large. An electric current flows. Therefore, converter 1 includes a power failure detection unit 33 that detects that a power failure has occurred in AC power supply 3.

  First, a case where a power failure occurs in the AC power supply 3 during power running of the motor will be described. FIG. 8 is a diagram showing a state of the motor control system when 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 t22 is a power failure period. Time t21 is a time when the power supply from the AC power supply 3 to the converter 1 is stopped, that is, a power failure start time. Further, in FIG. 8, time t22 is the time at which the power failure that has occurred in the AC power supply 3 ends, that is, the power recovery start time.

As shown in FIG. 8, when the AC power supply 3 is stopped during the power running of the motor, the power is not supplied to the converter 1, and the bus current I _PN stops flowing. Electric power continues to be supplied from the motor driving device 4 to the motor 5 during this period, so that the electric power accumulated in the smoothing capacitor 22 is supplied from the converter 1 to the motor driving device 4. As a result, the voltage _VDC between the terminals of the smoothing capacitor 22 drops sharply.

After that, at time t22, when the AC power supply 3 recovers from the power failure, the power supply voltage V _RST of the AC power supply 3 becomes larger than the inter-terminal voltage _VDC of the smoothing capacitor 22, so the AC power supply 3 passes through the rectifying elements D1 to D6. Current flows into the smoothing capacitor 22. Since the voltage _VDC between the terminals of the smoothing capacitor 22 is smaller than that shown in FIG. 7, a larger positive-direction bus current I _PN flows as compared with the case shown in FIG. The bus current I _PN increases as the potential difference between the power supply voltage V _RST of the AC power supply 3 and the inter-terminal voltage V _DC of the smoothing capacitor 22 increases.

Therefore, as the potential difference between the power supply voltage V _RST of the AC power supply 3 and the voltage _VDC between the terminals of the smoothing capacitor 22 is larger, a larger current flows through the rectifying elements D1 to D6. Also in the constant motor speed section, depending on the state of the motor output P _out , a large current may flow through the rectifying elements D1 to D6 according to the same principle as in the case of 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 when a power failure occurs in the AC power supply in the motor regeneration section shown in FIG. 7. In FIG. 9, the period from time t25 to t26 is a power failure period. Time t25 is the power failure start time, and time t26 is the power recovery start time. When the motor is regenerative, but inter-terminal voltage V _DC of the smoothing capacitor 22 is increased by the regenerative energy, when the AC power source 3 stops, as shown in FIG. 9, the power supply of the terminal voltage V _DC and the AC power source 3 of the smoothing capacitor 22 Since the potential difference from the voltage V _RST becomes larger than that in the case shown in FIG. 7, a larger negative-direction bus current I _PN flows as compared with the case shown in FIG.

The bus current I _PN increases as the potential difference between the power supply voltage V _RST of the AC power supply 3 and the inter-terminal voltage V _DC of the smoothing capacitor 22 increases. Therefore, the larger the potential difference between the power supply voltage V _RST of the AC power supply 3 and the terminal voltage V _DC of the smoothing capacitor 22, the larger the current flows through the switching elements Q1 to Q6. In addition, which combination of switching elements Q1 to Q6 the current flows through is determined depending on the voltage phase of the AC power supply 3.

  In this way, when a power failure occurs in the AC power supply 3 during power running of the motor or at a constant motor speed, a large current flows through the rectifying elements D1 to D6 at the start of power recovery. 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 determines whether or not the absolute value of the bus current I _PN detected by the bus current detection unit 25 during motor regeneration is equal to or greater than a preset first threshold value Ith1. Power failure detecting section 33, when the motor regenerative, when the absolute value of the bus current I _PN is the first threshold value Ith1 or more, determines that power failure occurs to the AC power source 3, to determine the stop of the power source regeneration operation, power regeneration A regeneration stop command for stopping the operation is output to regeneration control unit 32 and motor control unit 41.

In addition, during the motor regeneration, the power failure detection unit 33 determines whether or not the absolute value of the bus current I _PN detected by the bus current detection unit 25 is equal to or less than the second threshold value Ith2 during the preset first time Tth1. To judge. When the power failure detection unit 33 determines that the absolute value of the bus current I _PN is the second threshold value Ith2 or less during the first time Tth1 during motor regeneration, it determines that a power failure has occurred in the AC power supply 3, The stop of the regenerative operation is determined, and a regenerative stop command for stopping the power regenerative operation is output to the regenerative control unit 32 and the motor control unit 41.

The regenerative control unit 32 stops the output of the base drive signals S _RP , S _RN , S _SP , S _SN , S _TP , and S _{TN to} the drive circuit 27 when the regenerative stop command is output from the power failure detection unit 33. The power regeneration operation by the power module 21 is stopped. Thereby, converter 1 can suppress the failure of switching elements Q1-Q6. The first threshold value Ith1 described above is set to the value of the rated current of the power module 21, for example.

  When the power failure detection unit 33 outputs the regeneration 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. Thereby, converter 1 can suppress the failure of switching elements Q1-Q6.

Further, the power failure detection unit 33 determines whether or not the absolute value of the bus current I _PN detected by the bus current detection unit 25 is equal to or more than the first threshold value Ith1 during the motor power running. The power failure detection unit 33 determines that a power failure has occurred in the AC power supply 3 and determines to stop the power running operation when the absolute value of the bus current I _PN is the first threshold value Ith1 or more during the power running of the motor. When the power outage detection unit 33 determines to stop the powering operation, it outputs a powering stop command for stopping the powering operation to the motor control unit 41. When the motor powering is performed, the power failure detection unit 33 determines that the AC power supply 3 has a power failure when the absolute value of the bus current I _PN is equal to or greater than the first threshold value Ith1. It is detected when the power supply from the power supply 3 is restarted. Therefore, in this case, the determination by the power failure detection unit 33 that the power failure has occurred includes the determination of the power recovery start.

Further, the power failure detection unit 33 determines whether or not the absolute value of the bus current I _PN detected by the bus current detection unit 25 is equal to or less than the second threshold value Ith2 during the first time Tth1 during the motor power running. Power failure detecting unit 33 determines when the motor power running, and if the absolute value of the bus current I _PN is determined to be the second threshold value Ith2 less during the first hour Tth1, power failure to the AC power source 3 is generated, powering Decide to stop the operation. When the power outage detection unit 33 determines to stop the powering operation, it outputs a powering stop command for stopping the powering operation to the motor control unit 41.

  When a power running 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 AC power from the power conversion unit 40 to the motor 5. Thereby, the motor drive device 4 can suppress the failure of the rectifying elements D1 to D6. Further, the motor drive device 4 can prevent damage to the tool or the work due to excessive rotation of the feed shaft or the main shaft of the industrial machine, for example.

Incidentally, the power failure detector 33, the bus current or determines that the absolute value of I _PN power failure only to the AC power source 3 to the case where the first threshold value Ith1 or more occurs, the bus current I _PN of absolute value first hour It is also possible to determine that a power failure has occurred in the AC power supply 3 only when it is equal to or less than the second threshold value Ith2 during Tth1.

The power failure detection unit 33 can also not output a regeneration stop command to the motor control unit 41 during motor regeneration. Thereby, for example, the regenerative power of the motor 5 can be stored in the smoothing capacitor 22 when the power failure time, which is a period during which the AC power supply 3 is in a power failure, is short. In this case, the power failure detection unit 33 issues a regeneration stop command to the motor control unit 41 when the absolute value of the bus current I _PN becomes the second threshold value Ith2 or less during the second time Tth2 longer than the first time Tth1. You can also output to. As a result, it is possible to prevent the regenerative power from excessively accumulating 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 failure determination condition by the power failure detection unit 33, and sets the received determination condition in the power failure detection unit 33. For example, the condition setting unit 34 receives determination condition information transmitted to the converter 1 in a wired or wireless manner from an input device or a terminal device (not shown), and determines a power failure by the power failure detection unit 33 based on the received determination condition information. The condition is set in the power failure detection unit 33. The determination condition information includes, for example, information indicating each of the above-described first threshold value Ith1, second threshold value Ith2, first time Tth1, and second time Tth2. The condition setting unit 34 can change the first threshold Ith1, the second threshold Ith2, the first time Tth1, and the second time Tth2 set in the power failure detection unit 33.

FIG. 10 is a flowchart showing an example of a processing procedure by the power failure detection unit of the converter according to the first embodiment, and is repeatedly executed, for example, in a preset cycle. As illustrated in FIG. 10, the power failure detection unit 33 acquires information on the bus current I _PN detected by the bus current detection unit 25 (step S10). Power failure detecting section 33 calculates the absolute value of the bus current _{I PN} on the basis of the acquired bus current _{I PN} information (step S11).

Next, the power failure detection unit 33 determines whether or not the absolute value of the bus current I _PN is greater than or equal to the first threshold value Ith1 (step S12). Power failure detecting unit 33, when the absolute value of the bus current _{I PN} is determined not to be the first threshold value Ith1 or more (step S12: No), during the first hour Tth1 the absolute value of the bus current _{I PN} is set in advance In, it is determined whether or not it is equal to or less than the second threshold value Ith2 (step S13).

Power failure detecting unit 33, when the absolute value of the bus current _{I PN} is determined to be the first threshold value Ith1 or more (step S12: Yes), or the second between the absolute value of the bus current _{I PN} is first hour Tth1 When it determines with it being below threshold value Ith2 (step S13: Yes), it is determined whether it is during motor regeneration (step S14). In step S14, the power failure detection unit 33 acquires, for example, a status signal including information indicating whether or not the power regeneration operation is in progress from the regeneration control unit 32, and motor regeneration is in progress based on the acquired status signal. Or not.

  When the power outage detection unit 33 determines that the motor regeneration is not being performed (step S14: No), the power outage detection unit 33 determines whether or not the motor is being powered (step S15). In step S15, the power outage detection unit 33 acquires, for example, a state signal including information indicating whether or not the powering operation is in progress from the motor control unit 41, and determines whether the powering operation is in progress based on the acquired state signal. Determine whether or not.

  When the power failure detection unit 33 determines that the motor regeneration is in progress (step S14: Yes), it determines to stop the power regeneration operation (step S16), and issues a regeneration stop command to the regeneration control unit 32 and the motor control unit 41. Output (step S17). In step S17, the power failure detection unit 33 can also output a regeneration stop command to only one of the regeneration control unit 32 and the motor control unit 41.

When it is determined that the motor is in the power running state (step S15: Yes), the power failure detecting section 33 determines to stop the power running operation (step S18) and outputs a power running stop command to the motor control section 41 (step S19). . When the power failure detection unit 33 determines that the absolute value of the bus current I _PN is not less than or equal to the second threshold value Ith2 during the first time Tth1 (step S13: No), it is determined that the motor is not running (step S15). : No), if the process of step S17 ends, or if the process of step S19 ends, the process illustrated in FIG. 10 ends.

  FIG. 11 is a flowchart showing an example of a processing procedure performed by the regeneration control unit of the converter according to the first embodiment, and is repeatedly executed, for example, in a preset cycle. As shown in FIG. 11, the regeneration control unit 32 determines whether or not the regeneration stop command is acquired from the power failure detection unit 33 (step S20).

When it is determined that the regeneration stop command is acquired from the power failure detection unit 33 (step S20: Yes), the regeneration control unit 32 stops the power regeneration operation (step S21). In step S21, the regeneration control unit 32 stops the output of the base drive signals S _RP , S _RN , S _SP , S _SN , S _TP and S _{TN to} the drive circuit 27, and turns off the plurality of switching elements Q1 to Q6. By doing so, the power regeneration operation is stopped. When it is determined that the regenerative stop command has not been acquired from the power failure detection unit 33 (step S20: No), or when the process of step S21 ends, the regenerative control unit 32 ends the process illustrated in FIG. 11.

  FIG. 12 is a flowchart showing an example of a processing procedure by the motor control unit of the motor drive device according to the first embodiment, and is repeatedly executed, for example, in a preset cycle. As shown in FIG. 12, the motor control unit 41 determines whether or not a power running stop command has been acquired from the power failure detection unit 33 (step S30). When the motor control unit 41 determines that the power running stop command has been acquired from the power failure detection unit 33 (step S30: Yes), it controls the power conversion unit 40 to stop the power supply from the power conversion unit 40 to the motor 5. Then, the power running operation by the power converter 40 is stopped (step S31).

  When determining that the power running stop command has not been acquired from the power failure detection unit 33 (step S30: No), the motor control unit 41 determines whether or not the regeneration stop command has been acquired from the power failure detection unit 33 (step S32). ). When the motor control unit 41 determines that the regenerative stop command is acquired from the power failure detection unit 33 (step S32: Yes), it controls the power conversion unit 40 to stop the power regeneration operation by the power conversion unit 40 (step S33). ).

  When the motor control unit 41 determines that the regenerative stop command has not been acquired from the power failure detection unit 33 (step S32: No), the process of step S31 ends, or the process of step S33 ends, the The process shown in 12 ends.

As described above, the converter 1 according to the first embodiment is arranged between the AC power supply 3 that is an input power supply and the motor drive device 4 that controls the motor 5 at a variable speed, and includes the power module 21 and the smoothing capacitor 22. A bus current detector 25 and a controller 26 are provided. The power module 21 includes a plurality of rectifying elements D1 to D6 that rectify the AC voltage supplied from the AC power source 3, and a plurality of switching elements that are connected in parallel to the corresponding rectifying elements among the plurality of rectifying elements D1 to D6. It is provided with Q1 to Q6 and two DC power supply terminals 14 and 15 that output the voltage 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. Bus current detector 25 detects the bus current I _PN is the current flowing between a DC power supply terminal 14 or a DC power supply terminal 15 and the smoothing capacitor 22. The control unit 26 controls the plurality of switching elements Q1 to Q6 based on the voltage phase of the AC power supply 3 and outputs the regenerative power of the motor 5 to the AC power supply 3. Based on the absolute value of the bus current I _PN detected by the bus current detection unit 25, the control unit 26 causes a power failure to the AC power supply 3 when the motor 5 is running at least and when the motor 5 is regenerating. Is determined. Thereby, converter 1 can detect the occurrence of a power failure in AC power supply 3 with a simple configuration. For example, 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, so that the manufacturing cost of the converter 1 is lower than that of a converter using a plurality of current detection units for power failure detection. It can be reduced. In addition, a general converter having a power regeneration function has a conversion unit that monitors an input current input from the input power source to the converter and converts the input current into a DC current based on the monitoring result. Since it is not necessary to use such a conversion means, the configuration can be simplified as compared with a general converter. Further, since the converter 1 detects that a power failure has occurred based on the absolute value of the bus current _IPN , that the AC power source 3 has a power failure without using different thresholds during power running and during regeneration. Can be detected.

Also, the power failure detection unit 33 determines that when the absolute value of the bus current I _PN exceeds a first threshold value Ith1, power failure to the AC power supply 3 has occurred. Thereby, converter 1 can accurately detect that a power failure has occurred in AC power supply 3 without using different thresholds during power running and during regeneration. The first threshold value Ith1 is an example of a preset value.

Also, the power failure detecting unit 33 judges that the absolute value of the bus current I _PN is the second threshold Ith2 less during the first hour Tth1 previously set, power failure in the AC power source 3 has occurred. Thereby, converter 1 can accurately detect that a power failure has occurred in AC power supply 3 without using different thresholds during power running and during regeneration. The second threshold Ith2 is an example of a preset value.

Further, the converter 1 includes a condition setting unit 34 that receives the determination condition of the power failure by the power failure detection unit 33 and sets the received determination condition in the power failure detection unit 33. Power failure detecting unit 33 judges that the absolute value of the bus current I _PN detected by the bus current detection unit 25 when the determination condition is satisfied, the power failure to the AC power source 3 is generated. The determination condition is, for example, at least one of the first threshold value Ith1, the second threshold value Ith2, the first time Tth1, and the second time Tth2 described above. Thereby, the user of converter 1 can change the sensitivity of power failure detection. For example, a user who wants to emphasize the protection of the converter 1 sets the first threshold value Ith1 and the second threshold value Ith2 to a value lower than the rated current of the power module 21, and erroneously detects a power failure in order to improve the operating efficiency of the industrial machine. The user who wants to avoid the problem can set the first threshold value Ith1 and the second threshold value Ith2 to values higher than the rated current of the power module 21.

  The control unit 26 also includes a regeneration control unit 32 that controls the plurality of switching elements Q1 to Q6 during motor regeneration. When determining that a power failure has occurred in the AC power supply 3, the power failure detection unit 33 outputs a regeneration stop command to the regeneration control unit 32. The regenerative control unit 32 stops the control of the plurality of switching elements Q1 to Q6 when the power failure detection unit 33 outputs the regenerative stop command. Thereby, converter 1 can suppress the failure of switching elements Q1-Q6.

  When the power failure detection unit 33 determines that a power failure has occurred in the AC power supply 3, the power failure detection unit 33 outputs a power running stop command to the motor drive device 4 and stops the power supply from the motor drive device 4 to the motor 5 by the motor stop command. Let As a result, the converter 1 can stop the operation of the motor drive device 4 when a power failure occurs during the power running of the motor, and can suppress the failure of the rectifying elements D1 to D6.

Embodiment 2.
The motor control system according to the second embodiment is different from the motor control system according to the first embodiment in that failure prediction of the power module is further performed. In the following, components having the same functions as those in the first embodiment will be designated by the same reference numerals and description thereof will be omitted, and the description will focus on the points different from the motor control system 100 of the first embodiment.

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

  In addition to the function of the power failure detection unit 33, the power failure detection unit 33A has a function of generating counter information and transmitting the generated counter information to the host controller 6. The counter information includes the first counter value N1 and the second counter value N2. The first counter value N1 indicates the number of times the AC power source 3 has a power failure during the power running of the motor, and the second counter value N2 indicates the number of times the AC power source 3 has a power failure during the motor regeneration.

  When a power failure occurs in the AC power supply 3 during power running of the motor, an overcurrent flows through the rectifying element D, so the first counter value N1 can also be referred to as an overcurrent counter value of the rectifying element D. Further, when a power failure occurs in the AC power supply 3 during motor regeneration, an overcurrent flows in the switching element Q, so the second counter value N2 can also be referred to as an overcurrent counter value of the switching element Q.

The power failure detection unit 33A determines whether or not the absolute value of the bus current I _PN detected by the bus current detection unit 25 is equal to or greater than the first threshold value Ith1. Power failure detecting unit 33A determines if the absolute value of the bus current _{I PN} is the first threshold value Ith1 or more, whether the sign of the bus current _{I PN} is positive. Power failure detecting section 33A, when the sign of the bus current I _PN is determined to be positive, counts up the first counter value N1. In addition, the power failure detection unit 33A counts up the second counter value N2 when it determines that the sign of the bus current _IPN is not positive. The power failure detection unit 33A outputs counter information including the first counter value N1 and the second counter value N2 to the higher-level controller 6. Note that the power outage detection unit 33A can also output counter information including the counted-up counter value of the first counter value N1 and the second counter value N2 to the higher-level control device 6.

  The host controller 6 controls the motor drive device 4 by transmitting a motor operation command and a motor stop command to the motor drive device 4. The motor drive device 4 starts controlling the motor 5 when receiving the motor operation command, and stops controlling the motor 5 when receiving the motor stop command.

  The host controller 6 includes a failure prediction unit 60 that determines whether or not a failure of the power module 21 may occur based on the counter information output from the converter 1A. The failure prediction unit 60 determines that there is a high possibility that the rectifying element D of the power module 21 will fail if the first counter value N1 is greater than or equal to the first counter threshold Nth1. Further, the failure prediction unit 60 determines that there is a high possibility that the switching element Q of the power module 21 will fail if the second counter value N2 is greater than or equal to the second counter threshold Nth2. The first counter threshold value Nth1 and the second counter threshold value Nth2 can be set arbitrarily, and are determined by, for example, the life 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 will fail, the failure prediction unit 60 notifies the user of the motor control system 100A of a power module failure warning. The power module failure warning is information indicating that the power module 21 may fail. The failure prediction unit 60 can, for example, display failure warning information on a display device (not shown) or transmit the failure warning information to a user's terminal device via a communication unit (not shown).

FIG. 14 is a flowchart showing an example of a counter processing procedure by the power failure detection unit of the converter according to the second embodiment, which is repeatedly executed, for example, in a preset cycle. As shown in FIG. 14, the power failure detection unit 33A acquires information on the bus current I _PN detected by the bus current detection unit 25 (step S40). Power failure detecting unit 33A calculates the absolute value of the bus current _{I PN} on the basis of the acquired bus current _{I PN} information (step S41).

Next, the power failure detection unit 33A determines whether or not the absolute value of the bus current I _PN is equal to or greater than the first threshold value Ith1 (step S42). Power failure detecting section 33A, when the absolute value of the bus current _{I PN} is determined to be the first threshold value Ith1 or more (step S42: Yes), (determining whether the sign of the bus current _{I PN} is positive S43). Incidentally, the sign of the bus current _{I PN} indicates the polarity of the bus current _{I PN.}

Power failure detecting section 33A, when the sign of the bus current _{I PN} is determined to be positive (step S43: Yes), and counts up the first counter value N1 by adding 1 to the first counter value N1 (step S44). In addition, when the power failure detection unit 33A determines that the sign of the bus current _IPN is not positive (step S43: No), it increments the second counter value N2 by adding 1 to the second counter value N2. (Step S45).

When the process of step S44 or the process of step S45 ends, the power failure detection unit 33A outputs counter information including the first counter value N1 and the second counter value N2 to the higher-level control device 6 (step S46). Power failure detecting section 33A, when the processing in step S46 is completed, or if the absolute value of the bus current _{I PN} is determined not to be the first threshold value Ith1 or more (step S42: No), ends the processing shown in FIG. 14 .

  FIG. 15 is a flowchart showing an example of a failure prediction processing procedure by the failure prediction unit of the host controller according to the second embodiment, which is repeatedly executed at a preset cycle, for example. As illustrated in FIG. 15, the failure prediction unit 60 determines whether or not the counter information has been acquired from the converter 1A (step S50).

  When the failure prediction unit 60 determines that the counter information has been acquired (step S50: Yes), the failure prediction unit 60 determines whether the first counter value N1 included in the counter information is greater than or equal to the first counter threshold Nth1 (step S51). ). When the failure prediction unit 60 determines that the first counter value N1 is not greater than or equal to the first counter threshold Nth1 (step S51: No), the second counter value N2 included in the counter information is greater than or equal to the second counter threshold Nth2. It is determined whether or not (step S52).

  When the failure prediction unit 60 determines that the first counter value N1 is greater than or equal to the first counter threshold Nth1 (step S51: Yes), or determines that the second counter value N2 is greater than or equal to the second counter threshold Nth2. (Step S52: Yes), the power module failure warning is notified to the user of the motor control system 100A (step S53). In step S53, the failure prediction unit 60 can, for example, display failure warning information on a display device (not shown) or transmit the warning information to the user's terminal device via a communication unit (not shown).

  The failure prediction unit 60 determines that the counter information has not been acquired (step S50: No), determines that the second counter value N2 is not greater than or equal to the second counter threshold Nth2 (step S52: No), or When the process of step S53 ends, the process illustrated in FIG. 15 ends.

  In the example described above, the host control device 6 includes the failure prediction unit 60, but the converter 1A may include the failure prediction unit 60. FIG. 16 is a diagram showing another example of the configuration of the motor control system according to the second embodiment. As shown in FIG. 16, the control unit 26A of the converter 1A includes a failure prediction unit 60 in addition to the configuration shown in FIG.

  Similar to the failure prediction unit 60 illustrated in FIG. 13, the failure prediction unit 60 illustrated in FIG. 16 determines whether or not a failure of the power module 21 may occur based on the counter information output from the power failure detection unit 33A. To determine. Specifically, the failure prediction unit 60, when the first counter value N1 is the first counter threshold Nth1 or more and the second counter value N2 is the second counter threshold Nth2 or more, the switching element Q of the power module 21. Determine that there is a possibility of failure. The failure prediction unit 60 notifies the user of the motor control system 100A of a power module failure warning when the rectifying element D or the switching element Q of the power module 21 may fail.

In addition, the timing of upsampling of the first counter value N1 and the second counter value N2 by the power failure detection unit 33A is not limited to the above-described timing. For example, the power failure detecting section 33A, when the absolute value of the bus current _{I PN} is not the first threshold value Ith1 or more, whether the absolute value of the bus current _{I PN} is the second threshold Ith2 less during the first hour Tth1 judge. Power failure detecting section 33A, when the absolute value of the bus current _{I PN} is the second threshold Ith2 less during the first hour Tth1, the first counter value N1 is counted up if the sign of the bus current _{I PN} positive If the sign of the bus current I _PN is negative, the second counter value N2 is incremented.

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

As described above, the motor control system 100A according to the second embodiment includes the converter 1A, the motor drive device 4, and the host control device 6 that controls the motor drive device 4. Failure detection unit 33A of converter 1A, when determining that power failure has occurred, the counter value corresponding to the polarity of the bus current I _PN of the first counter value N1 and the second counter value N2 is counted up, the first counter The counter information including at least the counted-up counter value out of the value N1 and the second counter value N2 is output. The failure prediction unit 60 of the host controller 6 performs failure prediction of the power module 21 based on the counter information output from the power failure detection unit 33A. As a result, it is possible to notify the user of information indicating that the power module 21 may fail before the power module 21 of the converter 1A fails and the industrial machine stops.

The converter 1A also includes a failure prediction unit 60 that predicts a failure of the power module 21 based on the determination result of the power failure occurrence by the power failure detection unit 33A. When determining that a power failure has occurred, the power failure detection unit 33A counts up the counter value of the first counter value N1 and the second counter value N2 that corresponds to the polarity of the bus current _IPN . The failure prediction unit 60 performs failure prediction of the power module 21 based on the first counter value N1 and the second counter value N2. As a result, it is possible to notify the user of information indicating that the power module 21 may fail before the power module 21 of the converter 1A fails and the industrial machine stops.

  The configurations shown in the above embodiments show an example of the content of the present invention, and can be combined with other known techniques, and the configurations of the configurations are possible without departing from the gist of the present invention. It is also possible to omit or change parts.

1, 1A converter, 2 reactor, 3 AC power supply, 4 motor drive device, 5 motor, 6 upper control device, 11, 12, 13 AC power supply terminal, 14, 15 DC power supply terminal, 21 power module, 22 smoothing capacitor, 23 Bus voltage detection unit, 24 power supply phase detection unit, 25 bus current detection unit, 26, 26A control unit, 27 drive circuit, 31 base drive signal generation unit, 32 regeneration control unit, 33, 33A power failure detection unit, 34 condition setting unit , 40 power conversion unit, 41 motor control unit, 60 failure prediction unit, 100, 100A motor control system, D, D1, D2, D3 , D4, D5, D6 rectifying _{element, I PN} bus current, N1 first counter value, N2 Second counter value, Q, Q1, Q2, Q3, Q4, Q5, Q6 Switching element.

Claims (9)

A converter arranged between an AC power supply and a motor drive device for controlling a motor,
A plurality of rectifying elements that rectify the AC voltage supplied from the AC power source, a plurality of switching elements that are respectively connected in parallel to the corresponding rectifying elements of the plurality of rectifying elements, and rectified by the plurality of rectifying elements. A power module having two DC power supply terminals for outputting a fixed voltage,
A smoothing capacitor that is connected to the two DC power supply terminals and smoothes the voltage rectified by the power module;
A bus current detector that detects a bus current that is a current flowing between one of the two DC power supply terminals and the smoothing capacitor;
A control unit that causes the power module to output regenerative power of the motor to the AC power supply by controlling the plurality of switching elements based on the voltage phase of the AC power supply,
The control unit is
Based on the absolute value of the bus current detected by the bus current detection unit, it is determined whether a power failure has occurred in the AC power supply when the motor is running or when the motor is regenerating. A converter that is equipped with a power failure detection unit. The power failure detection unit,
The power failure is determined to occur when the absolute value of the bus bar current exceeds a preset value in at least one of the power running time and the regenerative time. The converter described. The power failure detection unit,
When the absolute value of the bus current is equal to or less than a preset value at a preset time in at least one of the power running and the regenerative, it is determined that the power failure has occurred. The converter according to claim 1 or 2 characterized by the above-mentioned. A condition setting unit that receives the determination condition of the power failure by the power failure detection unit and sets the received determination condition in the power failure detection unit,
The power failure detection unit,
The power failure is determined to have occurred when the absolute value of the busbar current satisfies the determination condition in at least one of the power running time and the regenerative time. The converter described in any one. The control unit is
A regeneration control unit that controls the plurality of switching elements during the regeneration,
The power failure detection unit,
If it is determined that the power failure has occurred during the regeneration, output a regeneration stop command to the regeneration control unit,
The regeneration control unit,
The converter according to any one of claims 1 to 4, wherein when the regenerative stop command is output from the power failure detection unit, control of the plurality of switching elements is stopped. The power failure detection unit,
When it is determined that the power failure has occurred during powering of the motor, a motor stop command is output to the motor drive device, and power supply from the motor drive device to the motor is stopped by the motor stop command. The converter according to any one of claims 1 to 5. Based on the determination result of the occurrence of the power failure by the power failure detection unit, a failure prediction unit that performs failure prediction of the power module,
The power failure detection unit,
When it is determined that the power failure has occurred, the counter value of the first counter value and the second counter value corresponding to the polarity of the bus current is counted up,
The failure prediction unit,
The failure prediction of the power module is performed based on the 1st counter value and the 2nd counter value. The converter according to any one of claims 1 to 6 characterized by things. The power failure detection unit,
When it is determined that the power failure has occurred, a counter value corresponding to the polarity of the bus current in the first counter value and the second counter value is counted up, and at least the first counter value and the second counter value The converter according to any one of claims 1 to 6, wherein counter information including one is output. The converter according to claim 8,
The motor drive device;
A host controller for controlling the motor drive device,
The converter is
Outputting the counter information to the host controller,
The upper control device,
A motor control system, which predicts a failure of the power module based on the counter information.

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