Motor Drive Unit

Abstract

This motor drive device 1 comprises: a rectification circuit 10 for rectifying a power supply voltage from a single-phase or three-phase alternating-current power supply 100 to a direct-current voltage; an inverter circuit 20 for inverting the direct-current voltage output from the rectification circuit 10 to a motor drive voltage, and outputting the motor drive voltage to a motor; a control unit 30 for controlling the rectification circuit 10 and the inverter circuit 20; and a detection unit 40 for detecting a decrease in the power supply voltage on the basis of the voltage value or the phase of the power supply voltage. When a decrease in the power supply voltage is not detected, the control unit 30 controls the rectification circuit 10 and the inverter circuit 20 such that a motor electric power calculated from a target speed of the motor is output to the motor. When a decrease in the power supply voltage is detected, the control unit 30 uses regenerative power obtained from the motor to control the inverter circuit 20 such that the voltage of a DC link 50 connecting the rectification circuit 10 and the inverter circuit 20 is maintained.

Description

[Technical field]

[0001] The present invention relates to a motor drive device.

[0002] This application claims priority from Japanese Patent Application No. 2021-203116, the contents of which are incorporated herein by reference. [Background technology]

[0003] 2. Description of the Related Art A device that converts AC power from an AC power source into three-phase AC power to drive a motor has been disclosed that includes a rectifier circuit, a smoothing capacitor, and an inverter circuit (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-289769 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, motor drive devices used to drive motors for vehicles such as railways receive power from a power source while the vehicle is running. Such power supply voltages contain various interruptions and noise. Systems used in industries other than railways are also required to operate continuously. In this case, in order to minimize the effects of power interruptions and noise, it is required that the system continue to operate without tripping the power supply and that the torque required by the system be supplied without delay. [Means for solving the problem]

[0006] In order to solve the above problems, a motor drive device according to one embodiment of the present invention includes a rectifier circuit that rectifies a power supply voltage from a single-phase or three-phase AC power supply into a DC voltage, an inverter circuit that converts the DC voltage output from the rectifier circuit into a motor drive voltage and outputs it to a motor, a control unit that controls the rectifier circuit and the inverter circuit, and a detection unit that detects a drop in the power supply voltage based on a voltage value or phase of the power supply voltage. When a drop in the power supply voltage is not detected, the control unit controls the rectifier circuit and the inverter circuit to output motor power calculated from a target speed of the motor to the motor, and when a drop in the power supply voltage is detected, the control unit controls the inverter circuit so that the voltage of a DC link connecting the rectifier circuit and the inverter circuit is maintained by using regenerative power obtained from the motor.

[0007] In one embodiment, the AC power source may be a single-phase power source, and in this case, when a drop in the power source voltage is not detected, the control unit calculates a rectified power based on a target speed of the motor and a current speed of the motor, calculates a capacitor power required to keep the DC link voltage constant, controls a rectifier circuit and an inverter circuit to output the motor power calculated by subtracting the capacitor power from the rectified power to the motor, thereby outputting the pulsation of the single-phase power source to the motor, and when a drop in the power source voltage is detected, sets the rectified power to zero and controls the inverter circuit to supply the capacitor power using regenerative power from the motor, thereby maintaining the DC link voltage.

[0008] In one embodiment, the rectifier circuit may include a PFC circuit that corrects the power factor of the power supply. In this case, the control unit controls the PFC circuit to correct the power factor of the power supply when a drop in the power supply voltage is not detected, and does not control the PFC circuit and does not correct the power factor of the power supply when a drop in the power supply voltage is detected.

[0009] In one embodiment, the AC power supply may be a single-phase power supply. In this case, the control unit converts the power supply voltage into an α-axis voltage, a β-axis voltage, and a peak component, generates a target voltage based on the α-axis voltage, the β-axis voltage, and the peak component, and controls the rectifier circuit and the inverter circuit so that the phase of the current supplied to the motor matches the phase of the target voltage. The detection unit detects a drop in the power supply voltage based on the α-axis voltage, the β-axis voltage, and the peak component converted by the control unit.

[0010] In one embodiment, the detection unit may collect the power supply voltage at start-up to generate a reference voltage, and then compare the reference voltage with the power supply voltage to detect that the power supply voltage has dropped.

[0011] In one embodiment, the detection unit may detect that the power supply voltage has dropped when the amount of change in the power supply voltage is continuously less than a predetermined value for a predetermined period of time.

[0012] In one embodiment, the motor drive device may include a voltage monitoring unit that monitors a history of a DC link voltage value, and may stop the supply of power to the motor when the voltage monitoring unit detects that the DC link voltage value is below a predetermined lower limit, and may restore the supply of power to the motor when the voltage monitoring unit detects that the DC link voltage value is equal to or greater than a predetermined upper limit.

[0013] In addition, any combination of the above components, or mutual substitution of the components or expressions of the present invention among methods, devices, programs, temporary or non-temporary storage media recording programs, systems, etc., are also valid aspects of the present invention. Effect of the Invention

[0014] According to the present invention, even if a temporary drop in the power supply voltage, deviation from the ideal power supply voltage, distortion, or momentary interruption occurs, the motor drive system can continue to operate and can quickly return to the target speed after power is restored. [Brief description of the drawings]

[0015] [Figure 1] 1 is a functional block diagram of a motor drive device according to a first embodiment. [Diagram 2] FIG. 11 is a functional block diagram of a motor drive device according to a second embodiment. [Diagram 3] FIG. 11 is a functional block diagram of a motor drive device according to a third embodiment. [Figure 4] FIG. 13 is a functional block diagram of a motor drive device according to a fourth embodiment. [Diagram 5] FIG. 2 is a functional block diagram of a control unit and a power supply voltage distortion elimination circuit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the invention. All features and combinations described in the embodiments are not necessarily essential to the invention. The same or equivalent components, members, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, the scale and shape of each part shown in each drawing are set for convenience to facilitate explanation, and are not to be interpreted as being limiting unless otherwise specified. In addition, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not represent any order or importance, but are only intended to distinguish one configuration from another. In addition, some of the members that are not important in explaining the embodiment in each drawing are omitted.

[0017] [First embodiment] FIG. 1 is a functional block diagram of a motor drive device 1 according to a first embodiment. The motor drive device 1 receives an input voltage v GBased on this, the motor driving device 1 functions as a system for driving the motor 110. The motor driving device 1 can be used to drive various motors, such as railroad cars, pumps, compressors, electric actuators for ships and airplanes, and robot arms. The three-phase power generated by the motor driving device 1 is output to an external device such as the motor 110. Note that in this specification, along with the flow of power or signals from the AC power source 100 toward the output to the motor 110, the upstream side may be referred to as the previous stage or input, and the downstream side may be referred to as the subsequent stage or output.

[0018] The motor drive device 1 includes a rectifier circuit 10, an inverter circuit 20, a control unit 30, and a detection unit 40. The rectifier circuit 10 and the inverter circuit 20 are electrically connected by a DC link 50. As will be described later, the control unit 30 executes DC link voltage control of the DC link 50, output current control of the inverter circuit 20, and motor control by detecting the rotation angle of the motor 110.

[0019] The AC power source 100 may be, for example, a commercial power source or a generator. The AC power source 100 outputs an input voltage to the rectifier circuit 10.

[0020] The rectifier circuit 10 converts the power supply voltage v input from the AC power supply 100 into G After full-wave rectification, the DC link voltage v DC The rectifier circuit 10 generates a DC link voltage v DC to the inverter circuit 20. Such a rectifier circuit 10 may be realized using known technology.

[0021] The inverter circuit 20 is disposed after the rectifier circuit 10 and is connected to the DC link voltage v DC Based on the three-phase AC voltage, the motor drive voltage v M The three-phase AC voltage may be, for example, a U-phase, a V-phase, and a W-phase, alternating with a phase difference of 2π / 3. Such an inverter circuit 20 may be realized using a known technique.

[0022] The control unit 30 controls the rectifier circuit 10 and the inverter circuit 20. Specifically, the control unit 30 detects the power supply voltage v G When a decrease in the power supply voltage v is not detected, the rectifier circuit 10 and the inverter circuit 20 are controlled so that the motor power calculated from the target speed of the motor is output to the motor 110. G When a drop in the DC link voltage v of the DC link 50 is detected, the control unit 30 uses the regenerative power obtained from the motor 110 to DC The inverter circuit 20 is controlled so that the voltage Vcc is maintained.

[0023] The detection unit 40 detects the power supply voltage v G Based on the voltage value or phase of this power supply voltage v G Detects a decrease in

[0024] The motor 110 is driven by the motor drive voltage v supplied from the inverter circuit 20. M The motor 110 transmits the obtained power to an external load 120 to cause the load 120 to move.

[0025] The load 120 is a load such as a flywheel that is moved by the motor 110 and has a predetermined inertia J TOT (e.g. moment of inertia).

[0026] According to this embodiment, the motor drive device continues to output motor power calculated from the motor's target speed to motor 110 during normal times when there is no drop in the power supply voltage, while when a drop in the power supply voltage occurs, the DC link voltage is maintained by regenerative power from the motor. This allows the motor drive system to continue operating even if a power supply trip occurs due to a momentary interruption or the like, and allows the motor to quickly return to the target speed after power is restored.

[0027] In one embodiment, the AC power supply 100 is a single-phase power supply. The control unit 30 detects the power supply voltage v GIf no decrease in speed is detected, the power supply P G , and then calculates the DC link voltage v based on the target voltage and the current voltage of the DC link voltage. DC The capacitor power p required to keep constant C Calculate the power supply power P G From the capacitor power p C The motor power p calculated by subtracting M The rectifier circuit 10 and the inverter circuit 20 are controlled so that the pulsation of the single-phase power supply 100 is output to the motor 110. This pulsation is generated by the inertia J of the load 120 connected to the motor 110. TOT On the other hand, the power supply voltage v G When a drop in the power supply P G is set to zero, and the inverter circuit 20 is controlled so that the capacitor power is supplied by the regenerative power from the motor 110. As a result, the DC link voltage v DC is retained.

[0028] According to this embodiment, when there is no drop in the power supply voltage, the pulsation of the single-phase power supply is output to the motor, and can be absorbed by the inertia of the load connected to the motor. This control was originally devised by the present inventors. The present inventors have named this control MPPB (Machine-Integrated Power Pulsation Buffer) control.

[0029] [Second embodiment] 2 is a functional block diagram of a motor drive device 2 according to a second embodiment. A rectifier circuit 10 of the motor drive device 2 includes a PFC circuit 11 that improves the power factor of the power supply. The PFC circuit 11 improves the power factor reduction caused by a phase shift between the AC power supply voltage and the current flowing therethrough, and brings the power factor closer to 1. The PFC circuit 11 may use an existing method such as a passive method in which a reactor is inserted in series with the power supply, a partial switching method in which a switch is added to a reactor insertion section of the passive method, or a switching method in which a boost chopper circuit is inserted between a diode bridge and a load, and a switch is used to control the current to match the phase with the input voltage.

[0030] The control unit 30 detects the power supply voltage v G When a drop in the power supply voltage v is not detected, the PFC circuit 11 is controlled to improve the power factor of the power supply. G When a decrease in the power factor is detected, the control unit 30 does not control the PFC circuit 11 and does not improve the power factor of the power supply.

[0031] According to this embodiment, while the power factor can be improved during normal operation, when a temporary drop in the power supply voltage occurs, the power supply current does not follow the power supply voltage, preventing disturbance of the power supply current waveform and suppressing the generation of harmonic noise.

[0032] [Third embodiment] 3 is a functional block diagram of a motor drive device 3 according to a third embodiment. In this embodiment, the AC power supply 100 is a single-phase power supply. The motor drive device 3 includes a rectifier circuit 10, an inverter circuit 20, a control unit 30, a detection unit 40, and a power supply voltage distortion elimination circuit 60. That is, the motor drive device 3 differs from the motor drive device 1 of FIG. 1 in that it additionally includes the power supply voltage distortion elimination circuit 60. The other configuration of the motor drive device 3 is the same as the configuration of the motor drive device 1.

[0033] The power supply voltage distortion elimination circuit 60 has a second-order generalized integrator 61 and a phase-locked loop 62. In general, when there is distortion in the power supply voltage, this distortion can be eliminated by a low-pass filter. However, a low-pass filter causes a phase shift, and therefore power factor = 1 control cannot be achieved. In response to this, the power supply voltage can be reconstructed by using a phase-locked loop (PLL) instead of a low-pass filter. However, while a PLL can be easily implemented for a three-phase power supply, a different approach is required for a single-phase power supply. A second-order generalized integrator (SOGI) calculates the power supply voltage v measured at the input stage by G Based on this, the quadrature voltage v generated from the single-phase input voltage α and v β can be provided to the PLL, which can then calculate the phase angle to generate the target voltage.

[0034] According to this embodiment, even in the case of a single-phase power supply, distortion of the power supply voltage can be removed while maintaining power factor=1 control.

[0035] [Fourth embodiment] Fig. 4 is a functional block diagram of a motor drive device 4 according to a fourth embodiment. Motor drive device 4 includes a rectifier circuit 10, an inverter circuit 20, a control unit 30, a detection unit 40, and a voltage monitoring unit 70. That is, motor drive device 3 differs from motor drive device 1 of Fig. 1 in that it additionally includes a voltage monitoring unit 70. The other configuration of motor drive device 4 is the same as that of motor drive device 1.

[0036] The voltage monitoring unit 70 detects the voltage value v of the DC link. DC The control unit 30 monitors the history of the voltage value v of the DC link. DCWhen the voltage monitoring unit 70 detects that the DC link voltage value is below a predetermined lower limit, the control unit 30 stops the supply of power to the motor 110. When the voltage monitoring unit 70 detects that the DC link voltage value is equal to or greater than a predetermined upper limit, the control unit 30 restores the supply of power to the motor 110. The lower limit may be set to, for example, 10% of the normal voltage value, and the upper limit may be set to, for example, 30% of the normal voltage value.

[0037] According to this embodiment, the DC link voltage value v DC The system can be safely shut down when the DC link voltage value v falls below a certain lower limit before it reaches 0. DC The system can be quickly restored when the load reaches or exceeds a predetermined upper limit before the load recovers and reaches a normal value.

[0038] [Control method] The control method of the embodiment will be described below mainly with reference to Fig. 5. Fig. 5 is a functional block diagram of the control unit 30 and the power supply voltage distortion eliminating circuit 60.

[0039] The control unit 30 includes a speed control unit 31, a DC link voltage control unit 32, a power supply current control unit 33, a motor current control unit , a first switch 35, and a second switch .

[0040] The power supply voltage distortion elimination circuit 60 includes a second order generalized integrator (SOGI) 61, a phase locked loop (PLL) 62, and a PLL ON / OFF control unit 63.

[0041] [Power supply voltage distortion elimination circuit] The second-order generalized integrator 61 operates on the supply voltage v G to the quadrature component of the voltage v α and v β and the peak component v pk The second-order generalized integrator 61 generates v α , v β and v pk to the phase locked loop 62. The phase locked loop 62 outputs v α , v β and v pkBased on the power supply voltage frequency f PLL and feeds this back to the second-order generalized integrator 61. The phase-locked loop 62 also calculates the phase angle θ=2πf G t is calculated and used to calculate the target voltage v G * Generate the target voltage v G * is input to the power supply current control section 33 and used for power supply feedforward.

[0042] [First switch] The first switch 35 of the control unit 30 is controlled to be turned on and off by the PLL ON / OFF control unit 63 of the power supply voltage distortion elimination circuit 60. G v generated from α and v β and peak component v pk and based on the power supply voltage v G The detection unit 40 detects a drop in the power supply voltage v G When a drop in the power supply voltage v is not detected, the PLL ON / OFF control unit 63 turns on the first switch 35. G When a drop in the power supply voltage v is detected, the PLL ON / OFF control unit 63 turns off the first switch 35. G When there is no drop in the power supply voltage v, the PFC circuit 11 improves the power factor of the power supply. G When there is a drop in the power factor, the PFC circuit 11 does not improve the power factor of the power supply.

[0043] [Second switch] The second switch 36 of the control unit 30 is connected to the DC link voltage value v DC That is, the voltage monitor 70 controls the DC link voltage v DC When it is detected that the DC link voltage value v is less than the predetermined lower limit, the second switch 36 is turned OFF. This stops the power supply to the motor 110. On the other hand, the voltage monitor 70 monitors the DC link voltage value v DCWhen it is detected that the current flow rate is equal to or greater than a predetermined upper limit, the second switch 36 is turned ON, thereby restoring the power supply to the motor 110.

[0044] [Speed ​​control section] The input terminal of the speed control unit 31 is connected to a target motor speed ω * The speed control unit 31 receives the target motor speed ω * From target motor power p M * When the first switch 35 is ON, the target motor power p M * is used for power supply voltage control and motor current control. On the other hand, when the first switch 35 is OFF, the target motor power p M * is not used to control the motor drive. The speed controller continues to run calculations, but the results are not used. This allows for a smooth recovery of the system when power is restored.

[0045] [DC link voltage control unit] The input terminal of the DC link voltage control unit 32 is connected to a target DC link voltage v DC * The DC link voltage control unit 32 receives the target DC link voltage v DC * to the target DC link capacitor power p c * When the second switch 36 is ON, the target DC link capacitor power p c * is used for motor current control. On the other hand, when the second switch 36 is OFF, the target DC link capacitor power p c * is not used for motor current control. That is, at this time, the function of the DC link voltage control unit 32 is stopped.

[0046] [Power supply current control section] The input terminal of the power supply current control unit 33 is connected to the target motor power p M *The target average power supply current I is calculated from G * and the phase angle θ from the phase locked loop 62. The power supply current control unit 33 receives the target power supply voltage v G * When this control unit returns from a stop, it performs all the initial startup sequences.

[0047] [Motor current control section] The motor current control unit 34 receives the target DC link capacitor power p c * and the target power supply voltage v from the power supply current control unit 33 G * The target power supply p is calculated from G * The motor current control unit 34 controls the motor current based on these.

[0048] The above description is based on the embodiments of the present invention. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification should be treated as illustrative rather than restrictive.

[0049] The method by which the detection unit detects a drop in the power supply voltage is not limited to the method described with reference to FIG. [Variation 1] It is assumed that this motor drive device is applied to a motor that drives a compressor or the like inside a railway vehicle. In this case, when the device is started, the vehicle is not running, and power trips such as momentary power outages are unlikely to occur. Therefore, the detection unit may collect power supply voltages for a predetermined time (e.g., one minute) after the device is started, generate a reference voltage, and after the predetermined time has elapsed, compare this reference voltage with the newly collected power supply voltage to detect whether a drop in power supply voltage has occurred. This makes it possible to detect a drop in power supply voltage with greater accuracy. Note that this method is not limited to railway vehicle applications, and since it can generally be said that momentary power outages are unlikely to occur when the device is started, it can be applied to any application. [Variation 2] The detection unit may detect that the power supply voltage has dropped (that a momentary interruption has occurred) when the amount of fluctuation in the power supply voltage remains less than a predetermined value (e.g., less than 0.1 mV) continuously for a predetermined period of time (e.g., one minute). [Industrial Applicability]

[0050] The present invention can be used to drive various motors for railroad cars, pumps, compressors, electric actuators for ships and airplanes, robot arms, and the like. [Explanation of symbols]

[0051] 1··motor drive device, 2··motor drive device, 3··motor drive device, 4··motor drive device, 10··rectifier circuit, 20··inverter circuit, 30··control section, 31··speed control section, 32··DC link voltage control section, 33··power supply current control section, 34··motor current control section, 35··first switch, 36··second switch, 40··detection section, 50··DC link, 60··power supply voltage distortion elimination circuit, 61··second order generalized integrator (SOGI), 62··phase locked loop (PLL), 63··PLL ON / OFF control section, 70··voltage monitoring section, 100··AC power supply, 110··motor, 120··load.

Claims

1. a rectifier circuit that rectifies a power supply voltage from a single-phase or three-phase AC power supply into a DC voltage; an inverter circuit that converts the DC voltage output from the rectifier circuit into a motor drive voltage and outputs the motor drive voltage to the motor; A control unit that controls the rectifier circuit and the inverter circuit; a detection unit that detects a drop in the power supply voltage based on a voltage value or a phase of the power supply voltage; Equipped with The control unit is When a drop in the power supply voltage is not detected, the rectifier circuit and the inverter circuit are controlled so as to output to the motor a motor power calculated from a target speed of the motor; when a drop in the power supply voltage is detected, the inverter circuit is controlled using regenerative power obtained from the motor so that a voltage of a DC link connecting the rectifier circuit and the inverter circuit is maintained; the AC power source is a single-phase power source; The control unit is when a drop in the power supply voltage is not detected, a rectified power is calculated based on a target speed of the motor and a current speed of the motor, a capacitor power required to keep the voltage of the DC link constant is calculated, and the rectifier circuit and the inverter circuit are controlled so that the motor power calculated by subtracting the capacitor power from the rectified power is output to the motor, thereby outputting the pulsation of the single-phase power supply to the motor; a motor drive device which maintains a voltage of the DC link by setting the rectified power to zero and controlling the inverter circuit so that the capacitor power is supplied using regenerative power from the motor when a drop in the power supply voltage is detected.

2. the rectifier circuit includes a PFC circuit that corrects a power factor of the power supply; The control unit is When a drop in the power supply voltage is not detected, the PFC circuit is controlled to improve a power factor of the power supply; 2. The motor drive device according to claim 1, wherein when a drop in the power supply voltage is detected, the PFC circuit is not controlled and the power factor of the power supply is not improved.

3. the AC power source is a single-phase power source; the control unit converts the power supply voltage into an α-axis voltage, a β-axis voltage, and a peak component, generates a target voltage based on the α-axis voltage, the β-axis voltage, and the peak component, and controls the rectifier circuit and the inverter circuit so that a phase of a current supplied to the motor matches a phase of the target voltage; 2. The motor drive device according to claim 1, wherein the detection unit detects a drop in the power supply voltage based on the α-axis voltage, the β-axis voltage, and the peak component converted by the control unit.

4. 2. The motor drive device according to claim 1, wherein the detection unit collects the power supply voltage at startup to generate a reference voltage, and then compares the reference voltage with the power supply voltage to detect that the power supply voltage has dropped.

5. 2. The motor drive device according to claim 1, wherein the detection unit detects that the power supply voltage has dropped when a fluctuation amount of the power supply voltage is continuously less than a predetermined value for a predetermined time.

6. a voltage monitoring unit that monitors a history of a voltage value of the DC link; When the voltage monitoring unit detects that the voltage value of the DC link is below a predetermined lower limit value, the supply of power to the motor is stopped.

2. The motor drive device according to claim 1, wherein the voltage monitoring unit restores the supply of power to the motor when the voltage value of the DC link reaches or exceeds a predetermined upper limit.

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