Motor drive system, control program for motor system, and generator drive system

Abstract

This motor drive system for operating a motor unit comprises: a power supply unit; an inverter unit that converts an input voltage received from the power supply unit into an output voltage to be applied to the motor unit; and a controller that applies a signal based on a pulse width modulation method to the inverter unit. The controller includes a state determination unit that determines that an abnormality has occurred in a measurement value of the input voltage when a modulation factor defined by the amplitude of a carrier wave and the amplitude of a voltage command value in the pulse width modulation method indicates an overmodulation state.

Description

Motor drive system, motor system control program, and generator drive system

[0001] The present disclosure relates to a motor drive system, a control program for the motor system, and a generator drive system.

[0002] A motor, which is a rotating machine that uses electromagnetism, may not be able to be driven by directly receiving the voltage output from a power supply. In order to control the motor to a desired torque and rotation speed, the voltage supplied to the motor may be adjusted. In such cases, the voltage output by the power supply is converted to the voltage to be supplied to the motor using an inverter. Patent Documents 1, 2, and 3 disclose technologies related to systems equipped with a motor and an inverter.

[0003] JP 2011-211839 A JP 2010-213525 A JP 2020-137408 A

[0004] In systems that include an electromagnetic rotating machine and an inverter, it is desirable to quickly stop operation when an abnormality occurs in either the rotating machine or the inverter. For example, Patent Document 1 discloses a technique for accurately detecting an open circuit fault in a switching element of an inverter connected to a motor. Patent Document 2 discloses a technique for detecting an abnormality in a control system regardless of the magnitude of the torque output by the motor.

[0005] To detect an abnormality, measurement values ​​indicating the system status are obtained and a process for detecting the abnormality is performed using the measurement values. However, the measurement values ​​obtained from a system including an electromagnetic rotating machine and an inverter contain noise due to various factors. Therefore, it is difficult to determine whether fluctuations in the measurement values ​​are due to an abnormality in the system to be detected or due to superimposed noise in a normal system. Therefore, it has been difficult to quickly determine whether system operation should be stopped.

[0006] The present disclosure describes a motor drive system, a control program for the motor system, and a generator drive system that can easily determine whether or not the system operation should be stopped.

[0007] One aspect of the present disclosure is a motor drive system for operating a motor unit. The motor drive system includes a power supply unit, an inverter unit that converts an input voltage received from the power supply unit into an output voltage that is supplied to the motor unit, and a controller that supplies a signal based on pulse width modulation to the inverter unit. The controller includes a state determination unit that determines that an abnormality has occurred in a measured value of the input voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in the pulse width modulation indicates an overmodulation state.

[0008] The motor drive system determines whether the input voltage received by the inverter unit is abnormal based on whether the modulation rate, which is defined by the amplitude of the carrier wave in the pulse width modulation system and the amplitude of the voltage command value, indicates an overmodulation state. This determination method makes it easy to determine whether fluctuations in the input voltage received by the inverter unit are caused by a system abnormality to be detected, or by superimposed noise in a normal system.

[0009] In the motor drive system, the controller may stop the output of the output voltage from the inverter unit based on the result of determining that an abnormality has occurred in the measured value of the input voltage. According to this operation, the operation of the motor unit can be stopped based on the determination of the abnormality.

[0010] In the above motor drive system, the motor unit may include a first motor and a second motor sharing an output shaft. The inverter unit may include a first inverter circuit generating a first output voltage to be provided to the first motor and a second inverter circuit generating a second output voltage to be provided to the second motor. The state determination unit may determine whether an abnormality has occurred in a measured value of a first input voltage received by the first inverter circuit based on the relationship between the amplitude of a first carrier wave for generating a first pulse-width modulated signal to be provided to the first inverter circuit and the amplitude of a first voltage command value. The controller may further include a torque distribution unit that distributes a required torque required for the output shaft into a first torque to be borne by the first motor and a second torque to be borne by the second motor. The torque distribution unit may distribute the required torque between the first torque and the second torque when a result of the state determination unit indicates that no abnormality has occurred in the measured value of the first input voltage, and may distribute all of the required torque to the second torque and set the first torque to zero when a result of the state determination unit indicates that an abnormality has occurred in the measured value of the first input voltage. According to this operation, even if an abnormality occurs in the system including the first motor, the operation of the system including the second motor allows the operation of the entire system to continue.

[0011] In the above motor drive system, the motor unit may include at least one motor receiving three-phase AC including U-phase, V-phase, and W-phase. The state determination unit may determine whether or not an abnormality has occurred in the measured value of the input voltage using two current values ​​selected from three current values ​​applied to each of the U-phase, V-phase, and W-phase. This operation can reduce the calculation load required to determine whether or not an overmodulation state has occurred.

[0012] In the above motor drive system, the motor unit may include at least one motor receiving three-phase AC including U-phase, V-phase, and W-phase. The state determination unit may determine whether or not an abnormality has occurred in the measured value of the input voltage using all three current values ​​applied to the U-phase, V-phase, and W-phase. This operation can improve the accuracy of determining whether or not an overmodulation state has occurred.

[0013] The motor drive system may further include a voltmeter unit that obtains a measured value of the input voltage. The controller may also include an abnormality factor determination unit that, when it determines that an abnormality has occurred in the measured value of the input voltage, determines whether the abnormality in the measured value of the input voltage is caused by an abnormality in the power supply unit or an abnormality in the voltmeter unit. This operation makes it possible to determine the cause of the abnormality.

[0014] In the motor drive system described above, the state determination unit may determine that an overmodulation state has occurred and that an abnormality has occurred in the measured value of the input voltage when the amplitude of the voltage command value exceeds a threshold value determined based on the measured value of the input voltage. According to this operation, whether or not an overmodulation state has occurred can be determined by the simple process of comparing the amplitude with the threshold value.

[0015] In the motor drive system described above, the state determination unit may determine that an overmodulation state exists and that an abnormality has occurred in the measured input voltage value when the amplitude of the voltage command value exceeds a threshold determined based on the measured input voltage value. The threshold may be a value obtained by multiplying the measured input voltage value by √6 / 4. This operation makes it possible to determine whether or not an overmodulation state exists in motor control employing triangular wave comparison pulse width modulation drive.

[0016] In the motor drive system described above, the state determination unit determines that an overmodulation state has occurred and that an abnormality has occurred in the measured value of the input voltage when the amplitude of the voltage command value exceeds a threshold value determined based on the measured value of the input voltage, and the threshold value may be a value obtained by multiplying the measured value of the input voltage by √2 / 2. This operation makes it possible to determine whether or not an overmodulation state has occurred in control of a motor that employs a third harmonic superposition method.

[0017] Another aspect of the present disclosure is a control program for a motor system including a motor unit including at least one motor, a power supply unit, an inverter unit that converts an input voltage received from the power supply unit into an output voltage to be provided to the motor unit, and a controller that provides a signal based on pulse width modulation to the inverter unit. The control program for the motor system causes a computer to operate as a state determination unit that determines that an abnormality has occurred in the measured value of the input voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in the pulse width modulation indicates an overmodulation state. This control program for the motor system makes it easy to determine whether or not to stop operation of the system.

[0018] Yet another aspect of the present disclosure is a generator driving system for operating a generator unit that generates a voltage to be supplied to a load unit. The generator driving system includes the generator unit, an inverter unit that converts the voltage generated by the generator unit into an output voltage to be supplied to the load unit, and a controller that supplies a signal based on pulse width modulation to the inverter unit. The controller includes a state determination unit that determines that an abnormality has occurred in the measured value of the output voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in pulse width modulation indicates an overmodulation state. This generator driving system makes it easy to determine whether or not to stop operation of the system.

[0019] According to the motor drive system, motor system control program, and generator drive system of the present disclosure, it is possible to easily determine whether or not the operation of the system should be stopped.

[0020] FIG. 1 is a diagram showing a motor system according to a first embodiment. FIG. 2 is a diagram showing an example of the physical configuration of a controller provided in the motor system. FIG. 3 is a flowchart showing a first control operation of the motor system. FIG. 4 is a flowchart showing a second control operation of the motor system. FIG. 5(a) is a diagram showing an example of a power supply unit according to a first embodiment. FIG. 5(b) is a diagram showing an example of a power supply unit according to a second embodiment. FIG. 6 is a control block diagram of a controller according to the first embodiment. FIG. 7 is a control block diagram of a controller according to a second embodiment. FIG. 8 is a diagram showing a motor drive system according to a first example. FIG. 9 is a diagram showing a motor drive system according to a second example. FIG. 10 is a diagram showing a motor drive system according to a third example. FIG. 11 is a diagram showing a motor drive system according to a fourth example. FIG. 12 is a diagram showing a generator drive system according to the second embodiment. FIG. 13 is a diagram showing a generator drive system according to a fifth example. FIG. 14 is a diagram showing a generator drive system according to a sixth example. FIG. 15 is a diagram showing a generator drive system according to a seventh example. FIG. 16 is a diagram showing a generator drive system according to an eighth example. FIG. 17 is a diagram showing a motor system according to a modified example. FIG. 18 is a flowchart showing a first control operation of the modified motor system.

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicated explanations will be omitted.

[0022] 1, the motor drive system 1A includes a power supply unit 2, an inverter unit 3, and a controller 5. The motor drive system 1A supplies a voltage to a motor unit 4. The motor drive system 1A and the motor unit 4 are collectively referred to as a motor system 10A.

[0023] The power supply unit 2 outputs a first supply voltage and a second supply voltage. The power supply unit 2 outputs first voltage data D22 and second voltage data D23. More specifically, the power supply unit 2 has a power supply module 21, a first DC voltage sensor 22 (voltmeter side), and a second DC voltage sensor 23 (voltmeter side). The power supply module 21 outputs the first supply voltage and the second supply voltage. The first DC voltage sensor 22 outputs first voltage data D22 related to the first supply voltage. The second DC voltage sensor 23 outputs second voltage data D23 related to the second supply voltage.

[0024] The inverter unit 3 receives a first supply voltage and a first PWM signal C54A and outputs a first output voltage converted based on the first supply voltage using the first PWM signal C54A. The inverter unit 3 receives a second supply voltage and a second PWM signal C54B and outputs a second output voltage converted based on the second supply voltage using the second PWM signal C54B. More specifically, the inverter unit 3 includes a first inverter circuit 31 and a second inverter circuit 32. The first inverter circuit 31 receives the first supply voltage and the first PWM signal C54A. The first inverter circuit 31 converts the first supply voltage to the first output voltage by operating in accordance with the first PWM signal C54A. The first inverter circuit 31 outputs the first output voltage. The second inverter circuit 32 receives the second supply voltage and a second PWM signal C54B. The second inverter circuit 32 converts the second supply voltage to the second output voltage by operating in accordance with the second PWM signal C54B. The second inverter circuit 32 outputs a second output voltage.

[0025] The motor unit 4 receives the first output voltage and the second output voltage and outputs a combined torque. More specifically, the motor unit 4 has a first motor 41, a second motor 42, and a common output shaft 43. The first motor 41 receives the first output voltage and provides a first torque to the common output shaft 43. The second motor 42 receives the second output voltage and provides a second torque to the common output shaft 43. The first motor 41 and the second motor 42 may be, for example, a dual three-phase motor. The common output shaft 43 outputs a combined torque of the first torque and the second torque. Therefore, in the motor unit 4, the rotation direction of the first motor 41 and the rotation direction of the second motor 42 are the same.

[0026] The first motor 41 and the second motor 42 are not limited to being connected by a single common output shaft 43. For example, the first motor 41 has a first output shaft, and the second motor 42 has a second output shaft. The first output shaft and the second output shaft may be connected to each other by one or more gears.

[0027] The controller 5 outputs a first PWM signal C54A and a second PWM signal C54B for operating the inverter unit 3. The controller 5 receives first voltage data D22, second voltage data D23, first current data D81, and second current data D82. In the examples of FIGS. 1 and 6 , the first current data D81 is the value of the current supplied to each U phase, and the second current data D82 is the value of the current supplied to the W phase. The controller 5 uses the values ​​of the currents supplied to the U phase and the W phase selected from the currents supplied to each of the U phase, V phase, and W phase to determine whether or not overmodulation has occurred. In other words, the controller 5 determines whether or not overmodulation has occurred without using any one of the currents supplied to each of the U phase, V phase, and W phase.

[0028] The combinations of current values ​​used by the controller 5 to determine whether or not overmodulation has occurred are not limited to the combinations mentioned above. The combinations of current values, including the combinations mentioned above, are listed as follows: First combination: U phase is used. V phase is used. W phase is not used. Second combination: U phase is used. V phase is not used. W phase is used. Third combination: U phase is not used. V phase is used. W phase is used. The controller 5 may use all current values ​​to determine whether or not overmodulation has occurred, as shown in the fourth combination below. Fourth combination: U phase is used. V phase is used. W phase is used.

[0029] The controller 5 generates a first PWM signal C54A and a second PWM signal C54B using the first voltage data D22, the second voltage data D23, the first current data D81, and the second current data D82. Specifically, the controller 5 outputs the first PWM signal C54A to the first inverter circuit 31. The controller 5 outputs the second PWM signal C54B to the second inverter circuit 32.

[0030] The controller 5 has, as functional components, a voltage command value calculation unit 51, a state determination unit 52, a distribution unit 53, and a PWM signal calculation unit 54. The controller 5 receives first voltage data D22 and second voltage data D23 from the power supply unit 2. In particular, the controller 5 receives the first voltage data D22 from the first DC voltage sensor 22. The controller 5 receives the second voltage data D23 from the second DC voltage sensor 23. The controller 5 receives first current data D81 and second current data D82. The controller 5 receives drive data C500.

[0031] More specifically, the voltage command value calculation unit 51 receives first current data D81 and second current data D82. The voltage command value calculation unit 51 receives the first current data D81 from the first ammeter 81 and the second current data D82 from the second ammeter 82. These values ​​are used to obtain a motor line voltage command value C51. The state determination unit 52 receives the motor line voltage command value C51 and the first voltage data D22. The state determination unit 52 compares the motor line voltage command value C51 with a threshold C52 obtained from the first voltage data D22. The distribution unit 53 determines a first torque to be distributed to the first motor 41 and a second torque to be distributed to the second motor 42 based on the comparison result of the state determination unit 52. The PWM signal calculation unit 54 obtains a first PWM signal C54A based on the first torque determined by the distribution unit 53 and the first current data D81. Furthermore, the PWM signal calculation unit 54 obtains a second PWM signal C54B based on the second torque determined by the distribution unit 53 and the second current data D82.

[0032] The controller 5 may implement the above-described functional components by executing a control program PG for the motor drive system 1A on a processor. The control program PG for the motor drive system 1A causes a computer 550 having the configuration shown in FIG. 2 to execute the control operations for the motor drive system 1A.

[0033] The processor 551 executes an operating system, application programs, etc. The memory 552 stores various data for obtaining the control program PG of the motor drive system 1A and PWM signals. The memory 552 passes data to the processor 551 in response to a request from the processor 551. Data is written to the memory 552 by the processor 551. The memory 552 may be configured with a read-only memory (ROM) and a random access memory (RAM). The computer 550 may include various elements for executing the control program PG of the motor drive system 1A. For example, the computer 550 may include a communication control unit 553, an input unit 554, and an output unit 555. The input unit 554 may include a keyboard, a mouse, a touch panel, a microphone for audio input, etc. The output unit 555 may include a display, a printer, etc. For example, the output unit 555 may display the execution results of the control program PG of the motor drive system 1A. The control program PG of the motor drive system 1A may be provided in the form of a recording medium such as a CD-ROM, a DVD-ROM, or a semiconductor memory. The control program PG of the motor drive system 1A may also be provided as a data signal via a communication network.

[0034] The processor 551 reads out the control program PG of the motor drive system 1A from the memory 552. The control program PG of the motor drive system 1A executed by the processor 551 causes the processor 551 to operate as a voltage command value calculation unit 51, a state determination unit 52, a distribution unit 53, and a PWM signal calculation unit 54.

[0035] 3 shows a first control operation executed by the controller 5. First, the controller 5 calculates a motor line voltage command value C51 (S11). This operation S11 is executed by the voltage command value calculation unit 51. The motor line voltage command value C51 may be obtained, for example, by the following equation (1): v ＊ ｍ＿Ａ : Motor line voltage command value v＊ ｄ＿Ａ : d-axis component of the output value of the first current controller 542A v ＊ ｑ＿Ａ : q-axis component of the output value of the first current controller 542A

[0036] Next, the controller 5 obtains a threshold value C52 (S12). This operation S12 is executed by the state determination unit 52. The threshold value C52 can be set depending on the control method adopted by the controller 5. For example, when PWM drive, which is a triangular wave comparison type in a two-level inverter, is adopted as the control method, the threshold value may be obtained using the following equation (2). V ＴＨ : Threshold V ＤＣ＿Ａ When a third harmonic superposition method intended to increase the motor line voltage is adopted as the first voltage data control method, the threshold value may be obtained using the following equation (3). V ＴＨ : Threshold V ＤＣ＿Ａ : First voltage data

[0037] Next, the controller 5 determines whether or not the motor line voltage command value C51 is greater than a threshold value C52 (S13). This operation S13 is executed by the state determination unit 52. The state determination unit 52 determines whether or not the motor line voltage command value C51 is greater than the threshold value C52 based on the following equation (4). If the motor line voltage command value C51 is smaller than the threshold value C52, the state determination unit 52 determines that a so-called overmodulation state does not exist. If the motor line voltage command value C51 is greater than the threshold value C52, the state determination unit 52 determines that a so-called overmodulation state exists.

[0038] Next, the controller 5 sets a torque command value based on the determination result of the state determination unit 52. This operation is executed by the distribution unit 53. If it is determined that the power supply unit 2 is not in an overmodulation state (S13: NO), the power supply unit 2 is operating normally. Therefore, the distribution unit 53 distributes the total torque required for the motor unit 4 into a first torque borne by the first motor 41 and a second torque borne by the second motor 42 (S14A). As an example, the distribution unit 53 may distribute half of the total torque as the first torque and the remaining half as the second torque. Then, the controller 5 generates a first PWM signal C54A and a second PWM signal C54B (S15). This operation S15 is executed by the PWM signal calculation unit 54. Specific examples of the PWM signal calculation unit 54 are a first PWM signal calculation module 54M1 and a second PWM signal calculation module 54M2, which will be described in detail later.

[0039] On the other hand, if it is determined that the motor system is in an overmodulation state (S13: YES), an abnormality may be occurring in the power supply unit 2. An abnormality in the power supply unit 2 here refers to an abnormality occurring in the power supply module 21, such as when the desired voltage is not being output from the power supply module 21. For example, the output voltage of the power supply module 21 becomes zero or becomes lower than the desired voltage. An abnormality in the power supply unit 2 refers to an abnormality occurring in the first DC voltage sensor 22, such as when the desired voltage is being output from the power supply module 21 but the first DC voltage sensor 22 does not output appropriate first voltage data D22. If any of these abnormalities occurs, it will impede the normal operation of the motor system 10A, and some kind of action should be taken.

[0040] In the first control operation, the entire operation of the motor system 10A is stopped. More specifically, the distributor 53 sets the first torque borne by the first motor 41 to zero, and also sets the second torque borne by the second motor 42 to zero (S16A). The controller 5 generates a first PWM signal C54A and a second PWM signal C54B (S17). As a result, both the first motor 41 and the second motor 42 are stopped, and the entire operation of the motor system 10A is stopped.

[0041] <Second Control Operation in Motor Drive System> The flowchart shown in Figure 4 shows the second control operation executed by the controller 5. The second control operation differs from the first control operation in the processing when it is determined that the motor is in an overmodulation state (S13: YES). The other operations are the same as the first control operation, and therefore detailed description will not be repeated.

[0042] When it is determined that the motor system is not in an overmodulation state (S13: NO), the distributor 53 divides the total torque required of the motor unit 4 equally into a first torque borne by the first motor 41 and a second torque borne by the second motor 42 (S14B), as in the first control operation. On the other hand, when it is determined that the motor system is in an overmodulation state (S13: YES), the distributor 53 executes a process different from the first control operation. More specifically, when it is determined that the motor system is in an overmodulation state (S13: YES), the distributor 53 sets the first torque of the first motor 41 to zero. The distributor 53 assigns the entire total torque required of the motor unit 4 to the second motor 42 (S16B). The second torque borne by the second motor 42 is equal to the total torque. In the first control operation, the motor system 10A is stopped, whereas in the second control operation, the motor system 10A is not stopped. In this way, the second control operation makes it possible to realize a redundant system that does not cause the entire system to lose its function even if an abnormality occurs in one of the two systems.

[0043] <Operation and Effect> The motor drive system 1A for operating the motor unit 4 includes a power supply unit 2, an inverter unit 3 that converts an input voltage received from the power supply unit 2 into an output voltage that is supplied to the motor unit 4, and a controller 5 that supplies a signal based on pulse width modulation to the inverter unit 3. The controller 5 includes a state determination unit 52 that determines that an abnormality has occurred in the measured value of the input voltage when a modulation rate defined by the amplitude of the carrier wave and the amplitude of the voltage command value in the pulse width modulation indicates an overmodulation state.

[0044] Motor drive system 1A determines whether the input voltage received by inverter unit 3 is abnormal based on whether the modulation rate, which is defined by the amplitude of the carrier wave in pulse width modulation and the amplitude of the voltage command value, indicates an overmodulation state. This determination method makes it easy to determine whether fluctuations in the input voltage received by inverter unit 3 are caused by an abnormality in the system to be detected, or by superimposed noise in a normal system.

[0045] Based on the result of determining that an abnormality has occurred in the measured value of the input voltage, the controller 5 stops the output of the output voltage from the inverter unit 3. According to this operation, the operation of the motor unit 4 can be stopped based on the determination of an abnormality.

[0046] The motor unit 4 includes a first motor 41 and a second motor 42 that share an output shaft. The inverter unit 3 includes a first inverter circuit 31 that generates a first output voltage to be provided to the first motor 41 and a second inverter circuit 32 that generates a second output voltage to be provided to the second motor 42. The state determination unit 52 determines whether or not an abnormality has occurred in the measured value of the first input voltage received by the first inverter circuit 31, based on the relationship between the amplitude of a first carrier wave for generating a first pulse-width modulated signal to be provided to the first inverter circuit 31 and the amplitude of a first voltage command value. The controller 5 further includes a distribution unit 53 that distributes the required torque required of the output shaft into a first torque to be borne by the first motor 41 and a second torque to be borne by the second motor 42. When the result of the state determination unit 52 indicates that no abnormality has occurred in the measured value of the first input voltage, the distribution unit 53 distributes the required torque to the first torque and the second torque, and when the result of the state determination unit 52 indicates that an abnormality has occurred in the measured value of the first input voltage, the distribution unit 53 distributes the entire required torque to the second torque and sets the first torque to zero. According to this operation, even if an abnormality occurs in the system including the first motor 41, the operation of the system including the second motor 42 allows the operation of the entire system to continue.

[0047] The state determination unit 52 determines whether or not an abnormality has occurred in the measured value of the input voltage using two current values ​​selected from the three current values ​​applied to each of the U, V, and W phases. This operation can reduce the calculation load required to determine whether or not an overmodulation state has occurred.

[0048] The state determination unit 52 determines whether or not an abnormality has occurred in the measured value of the input voltage using all three current values ​​applied to the U-phase, V-phase, and W-phase, respectively. This operation can improve the accuracy of determining whether or not an overmodulation state has occurred.

[0049] When the amplitude of the voltage command value exceeds a threshold determined based on the measured value of the input voltage, the state determination unit 52 determines that the state is overmodulation and that an abnormality has occurred in the measured value of the input voltage. According to this operation, it is possible to determine whether or not the state is overmodulation by the simple process of comparing with the threshold.

[0050] When the amplitude of the voltage command value exceeds a threshold value determined based on the measured value of the input voltage, the state determination unit 52 determines that an overmodulation state has occurred and that an abnormality has occurred in the measured value of the input voltage, the threshold value being the measured value of the input voltage multiplied by √6 / 4. This operation makes it possible to determine whether or not an overmodulation state has occurred in the control of a motor that employs triangular wave comparison pulse width modulation drive.

[0051] When the amplitude of the voltage command value exceeds a threshold value determined based on the measured value of the input voltage, the state determination unit 52 determines that an overmodulation state has occurred and that an abnormality has occurred in the measured value of the input voltage, the threshold value being the measured value of the input voltage multiplied by √2 / 2. This operation makes it possible to determine whether or not an overmodulation state has occurred in control of a motor that employs the third harmonic superposition method.

[0052] The control program PG of the motor system 10A causes the computer 550 to operate as a state determination unit 52 that determines that an abnormality has occurred in the measured value of the input voltage when the modulation rate, which is defined by the amplitude of the carrier wave in the pulse width modulation method and the amplitude of the voltage command value, indicates an overmodulation state. The control program PG of the motor system 10A makes it easy to determine whether or not to stop the operation of the system.

[0053] <Examples> In the embodiments, the power supply unit 2 and the controller 5 were not described in detail. The control methods described in the embodiments can be applied to a variety of systems. In the following description, two variations of the power supply unit 2 are exemplified. Furthermore, two variations of the controller 5 are exemplified. Therefore, by combining two variations of the power supply unit 2 and two variations of the controller 5, four specific system configurations can be exemplified. Below, variations of the power supply unit 2 and variations of the controller 5 are described, followed by a description of first to fourth examples.

[0054] 5A, the power supply module 21A of the power supply unit 2A of the first embodiment has a single power supply element 211. The power supply module 21A of the power supply unit 2A of the first embodiment supplies voltage to each of the first motor 41 and the second motor 42 from one single power supply element 211.

[0055] 5B, the power supply module 21B of the power supply unit 2B of the second embodiment has a first power supply element 212 and a second power supply element 213. The power supply module 21B of the power supply unit 2B of the second embodiment supplies voltage to the first motor 41 from the first power supply element 212 and supplies voltage to the second motor 42 from the second power supply element 213. Unlike the first embodiment, the first system including the first power supply element 212 and the first motor 41 is an independent system from the second system including the second power supply element 213 and the second motor 42. According to the second embodiment, for example, even if an abnormality occurs in the first power supply element 212, the second system including the second power supply element 213 can continue to operate.

[0056] <First embodiment of controller 5A> As shown in FIG. 6, the first embodiment of the controller 5A has a first distribution control module 50M, a state determination module 51M, a first distribution module 53M, a first PWM signal calculation module 54M1, and a second PWM signal calculation module 54M2.

[0057] The first distribution control module 50M includes a distribution controller 501. The distribution controller 501 obtains a total torque command value C50 indicating the total torque based on drive data C500. Examples of the drive data C500 include a rotation speed command value / sensor value, a DC voltage command value / sensor value, and a phase current command value / sensor value. The distribution controller 501 outputs the total torque command value C50 to the first distribution module 53M.

[0058] The state determination module 51M includes a voltage command value calculator 511 and a state determiner 512. The voltage command value calculator 511 corresponds to the voltage command value calculation unit 51 shown in FIG. 1. The state determiner 512 corresponds to the state determination unit 52 shown in FIG. 1. The state determination module 51M receives first voltage data D22 and first current data D81. The state determination module 51M outputs a determination signal C51A to the first distribution module 53M using the first voltage data D22 and the first current data D81. The determination signal C51A includes information indicating either "an overmodulation state is occurring" or "an overmodulation state is not occurring."

[0059] The first distribution module 53M corresponds to the distribution unit 53 shown in Fig. 1. The first distribution module 53M obtains a first torque command value C53A for the first PWM signal calculation module 54M1 and a second torque command value C53B for the second PWM signal calculation module 54M2. The first distribution module 53M then outputs the first torque command value C53A to the first PWM signal calculation module 54M1 and the second torque command value C53B to the second PWM signal calculation module 54M2.

[0060] More specifically, the first distribution module 53M includes a distributor 531, a first limiter 532A, and a second limiter 532B. The first distributor 531 obtains a first torque command value C53A and a second torque command value C53B based on the total torque command value C50. As described above, the distributor 531 equally divides the torque value indicated by the total torque command value C50 into a torque value indicated by the first torque command value C53A and a torque value indicated by the second torque command value C53B. The first torque command value C53A is output to the first PWM signal calculation module 54M1 via the first limiter 532A. The first limiter 532A limits the maximum and minimum torque values. Similarly, the second torque command value C53B is output to the second PWM signal calculation module 54M2 via the second limiter 532B.

[0061] The first PWM signal calculation module 54M1 corresponds to the PWM signal calculation unit 54 shown in FIG. 1. The first PWM signal calculation module 54M1 generates a first PWM signal C54A based on the first current data D81 and the first torque command value C53A. The first PWM signal calculation module 54M1 outputs the first PWM signal C54A to the first inverter circuit 31.

[0062] More specifically, the first PWM signal calculation module 54M1 includes a first torque current calculator 541A, a first current controller 542A, a first voltage calculator 543A, and a first current calculator 544A.

[0063] The first torque current calculator 541A receives the first torque command value C53A to obtain a first current command value C541 (q axis), which is then output to the first current controller 542A.

[0064] The first current calculator 544A obtains first current data D81 (U-phase, W-phase) from a voltage line connecting the first inverter circuit 31 and the first motor 41. The first current calculator 544A obtains first current command values ​​C544 (d-axis, q-axis) based on the first current data D81 (U-phase, W-phase). The first current calculator 544A outputs the first current command values ​​C544 (d-axis, q-axis) to the first current controller 542A.

[0065] The first current controller 542A receives a first current command value C541 (d-axis, q-axis) and also receives a first current command value C544 (d-axis, q-axis) from the first current calculator 544A. The first current controller 542A obtains a first voltage command value C542 (d-axis, q-axis) based on these command values. The first current controller 542A outputs the first voltage command value C542 (d-axis, q-axis) to the first voltage calculator 543A.

[0066] The first voltage calculator 543A receives the first voltage command value C542 (d-axis, q-axis) and obtains the first voltage command value (U-phase, V-phase, W-phase) as the first PWM signal C54A. The first voltage calculator 543A outputs the first voltage command value (U-phase, V-phase, W-phase) to the first inverter circuit 31.

[0067] The second PWM signal calculation module 54M2 corresponds to the PWM signal calculation unit 54 shown in Fig. 1. The second PWM signal calculation module 54M2 includes a second torque current calculator 541B, a second current controller 542B, a second voltage calculator 543B, and a second current calculator 544B. The operations of these components are similar to those of the first PWM signal calculation module 54M1, and therefore detailed description thereof will not be repeated.

[0068] 7, the controller 5B of the second embodiment includes a state determination module 51M, a first distribution control module 50M1, a second distribution control module 50M2, a second distribution module 53N, a first PWM signal calculation module 54M1, and a second PWM signal calculation module 54M2. Here, the first PWM signal calculation module 54M1 and the second PWM signal calculation module 54M2 are the same as those of the first embodiment, and therefore detailed description thereof will be omitted.

[0069] The controller 5A of the first embodiment monitors only the voltage input to the first inverter circuit 31. The controller 5B of the second embodiment monitors not only the voltage input to the first inverter circuit 31 but also the voltage input to the second inverter circuit 32.

[0070] The state determination module 51M of the second embodiment has a configuration similar to that of the state determination module 51M of the first embodiment and monitors the voltage input to the first inverter circuit 31. As a result, the state determination module 51M obtains a first determination result C51A regarding the first system. The state determination module 51M of the second embodiment receives second voltage data D23 and second current data D82 and determines whether the second system is in an overmodulation state based on these data. As a result, the state determination module 51M obtains a second determination result C51B regarding the second system. The state determination module 51M outputs a first determination signal C52A to the first divider 531A and outputs a second determination signal C52B to the second divider 531B.

[0071] The controller 5A of the first embodiment has only a first distribution control module 50M including a first distribution controller 501A for the first system. The controller 5B of the second embodiment has, in addition to the first distribution control module 50M, a second distribution control module 50M2 including a second distribution controller 501B for the second system. The first distribution controller 501A outputs a total torque command value C50 to the first distributor 531A. The second distribution controller 501B outputs a total torque command value C50 to the second distributor 531B.

[0072] The second distribution module 53N includes a second distributor 531B in addition to the first distributor 531A. The first distributor 531A uses the total torque command value C50 output from the first distribution controller 501A and the first determination result C51A output from the state determination module 51M to obtain a command to be provided to the first PWM signal calculation module 54M1. When the first determination result C51A indicates that the vehicle is not in an overmodulation state, the first distributor 531A provides half of the torque value indicated by the total torque command value C50 as the first torque command value C53A to the first PWM signal calculation module 54M1. When the first determination result C51A indicates that the vehicle is in an overmodulation state, the first distributor 531A sets the first torque command value C53A to zero. Similarly, when the second determination result C51B indicates that the motor is not in an overmodulation state, the second distributor 531B provides half of the torque value indicated by the combined torque command value C50 as the second torque command value C53B to the second PWM signal calculation module 54M2. When the second determination result C51B indicates that the motor is in an overmodulation state, the second distributor 531B sets the second torque command value C53B to zero.

[0073] The first divider 531A cannot directly know whether the second system is in an overmodulation state. The second divider 531B cannot directly know whether the first system is in an overmodulation state. The first divider 531A and the second divider 531B may share the determination result received from the state determination module 51M with each other. For example, the first divider 531A may pass the first determination result C51A to the second divider 531B. The second divider 531B may pass the second determination result C51B to the first divider 531A.

[0074] The motor drive system 1A can be exemplified by the following four embodiments.

[0075] As shown in Figure 8, the motor drive system 1A1 of the first embodiment for the motor system 10A1 includes a power supply unit 2A of the first configuration (see Figure 5(a)) and a controller 5A of the first configuration (see Figure 6). The power supply unit 2A has a single power supply element 211, and if there is a possibility that an abnormality has occurred in the single power supply element 211, the entire system must be stopped. Therefore, the motor drive system 1A1 of the first embodiment executes a first control operation (see Figure 3).

[0076] 9, a motor drive system 1A2 of the second embodiment for a motor system 10A2 includes a power supply unit 2A of the first embodiment (see FIG. 5(a)) and a controller 5B of the second embodiment (see FIG. 7). The motor drive system 1A2 of the second embodiment executes the first control operation (see FIG. 3).

[0077] As shown in Figure 10, a motor drive system 1A3 of the third embodiment for a motor system 10A3 includes a power supply unit 2B of the second configuration (see Figure 5(b)) and a controller 5A of the first configuration (see Figure 6). The power supply unit 2B has a first power supply element 212 and a second power supply element 213, and even if there is a possibility that an abnormality has occurred in the first power supply element 212, the second power supply element 213 can continue to operate the second motor 42. The motor drive system 1A3 of the third embodiment executes a second control operation (see Figure 4).

[0078] 11, a motor drive system 1A4 of the fourth embodiment for a motor system 10A4 includes a power supply unit 2B (see FIG. 5(b)) of the second embodiment and a controller 5B (see FIG. 7) of the second embodiment. The motor drive system 1A4 of the fourth embodiment executes the second control operation (see FIG. 4).

[0079] Second Embodiment In the first embodiment, a system including a motor (electric motor) as a rotating machine utilizing electromagnetism was exemplified. The technique for detecting an abnormality described in the first embodiment can also be applied to a system including a generator as a rotating machine utilizing electromagnetism. In this case, the generator may be a so-called generator that converts external energy provided by steam or the like into electrical energy. The generator may also be a motor that performs regenerative operation. In other words, the technique for detecting an abnormality described in the first embodiment can be applied to a powering operation in which electrical energy is provided to obtain kinetic energy in a system including a motor, and can also be applied to a regenerative operation in which the kinetic energy of a rotor is converted into electrical energy. In the following explanation, a system including a so-called generator will be described as an example.

[0080] As shown in Figure 12, the generator driving system 1B supplies voltage to a load device unit 6. The generator driving system 1B has an inverter unit 3, a generator unit 7, and a controller 5. The generator driving system 1B is connected to the load device unit 6 to form a load device system 10B. The voltage output by the generator unit 7 is converted to a desired voltage by the inverter unit 3 and supplied to the load device unit 6. If an abnormality occurs in the load device unit 6, a change occurs in the voltage supplied to the load device unit 6. In this case, too, it is necessary to stop the operation of the generator driving system 1B.

[0081] The generator driving system 1B of the second embodiment uses supply current data sent from the generator unit 7 to the inverter unit 3 and input voltage data received by the load device unit 6 to determine whether or not an abnormality has occurred in the input voltage received by the load device unit 6. Here, the state in which "an abnormality has occurred in the input voltage received by the load device unit 6" is assumed to be a case in which an abnormality has occurred in the first DC voltage sensor 22 or the second DC voltage sensor 23 that measures the input voltage given to the load device unit 6.

[0082] As in the first embodiment, in the second embodiment, two configurations of the load device unit 6 can be exemplified. Two configurations of the controllers 5A and 5B can also be exemplified. Therefore, four examples can be presented in the second embodiment. The two configurations of the controllers 5A and 5B are the same as in the first embodiment, so detailed description will not be repeated.

[0083] Fig. 13 shows a generator driving system 1B1 connected to a load device unit 6A of the first embodiment. The load device module 61A of the load device unit 6A includes one load device 61. Fig. 15 shows a generator driving system 1B3 connected to a load device unit 6B of the second embodiment. The load device module 61B of the load device unit 6B includes a first load device 612 and a second load device 613.

[0084] The second embodiment can be exemplified by the following four examples.

[0085] As shown in Fig. 13, the generator driving system 1B1 of the fifth embodiment for the load device system 10B1 includes a load device unit 6A of the first configuration and a controller 5A of the first configuration. The load device unit 6A has one load device 61, and if there is a possibility that an abnormality has occurred in that one load device 61, the entire system must be shut down. Therefore, the generator driving system 1B1 of the fifth embodiment executes the first control operation (see Fig. 3).

[0086] 14, a generator driving system 1B2 of the sixth embodiment for a load device system 10B2 includes a load device unit 6A of the first embodiment and a controller 5B of the second embodiment. The generator driving system 1B2 of the sixth embodiment executes the first control operation (see FIG. 3).

[0087] As shown in Fig. 15, the generator driving system 1B3 of the seventh embodiment for the loading device system 10B3 includes a loading device unit 6B of the second configuration and a controller 5A of the first configuration. The loading device unit 6B has a first loading device 612 and a second loading device 613, and can continue to operate the second loading device 613 even if there is a possibility that an abnormality has occurred in the first loading device 612. The generator driving system 1B3 of the seventh embodiment executes the second control operation (see Fig. 3).

[0088] 16, a generator driving system 1B4 of the eighth embodiment for a load device system 10B4 includes a load device unit 6B of the second configuration and a controller 5B of the second configuration. The generator driving system 1B4 of the eighth embodiment executes the second control operation (see FIG. 3).

[0089] <Operation and Effect> The second embodiment is a generator driving system 1B for operating a generator unit 7 that generates a voltage to be supplied to a load device unit 6. The generator driving system 1B includes the generator unit 7, an inverter unit 3 that converts the voltage generated by the generator unit 7 into an output voltage to be supplied to the load device unit 6, and a controller 5 that supplies a signal based on pulse width modulation to the inverter unit 3. The controller 5B includes a state determination unit 52 that determines that an abnormality has occurred in the measured value of the output voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in pulse width modulation indicates an overmodulation state. This generator driving system 1B makes it easy to determine whether or not to stop system operation.

[0090] <Modifications> The motor drive system, motor system control program, and generator drive system of the present disclosure are not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0091] For example, as shown in Fig. 17 , a controller 5C of a motor drive system 1C included in a motor system 10C that is a modified example may include an abnormality factor determination unit 56. As shown in the flowchart of Fig. 18 , when it is determined that the motor line voltage command value is greater than the threshold value (S13: YES), the controller 5C may further include step S18 of determining the factor that determined that the motor line voltage command value is greater than the threshold value, in addition to steps S16A and S17 for generating control signals for the first motor 41 and the second motor 42. This step S18 is executed by the abnormality factor determination unit 56.

[0092] As already mentioned, there are two possible reasons why overmodulation is occurring, that is, why the measured value of the input voltage is abnormal. First reason: The voltage output by power supply unit 2 is abnormal, and an abnormal voltage value is being output from first DC voltage sensor 22 based on normal measurement by first DC voltage sensor 22. Second reason: The voltage output by power supply unit 2 is normal, but an abnormal voltage value is being output from first DC voltage sensor 22 based on abnormal operation of first DC voltage sensor 22.

[0093] Examples of methods for determining whether the factor causing the value of the first DC voltage sensor 22 to be abnormal are the first factor, such as a determination by comparison with a threshold value, a determination by comparison with an estimated value, and a determination by comparison with a measurement value from another system.

[0094] Examples of methods for determining whether the second factor is the cause of an abnormal value of the first DC voltage sensor 22 include determining by comparison with an estimated value, determining by comparison with a measured value from another system, and determining whether the upper and lower values ​​are stuck.

[0095] The motor drive system 1C includes a DC voltage sensor 22 that measures the input voltage. The controller 5C may include an abnormality factor determination unit 56 that, when it determines that an abnormality has occurred in the measured input voltage, determines whether the abnormality is due to an abnormality in the power supply unit or an abnormality in the voltmeter. This operation makes it possible to determine the cause of the abnormality.

[0096] <Additional Notes> The present disclosure includes the following configurations.

[0097] The present disclosure is [1] "A motor drive system for operating a motor unit, comprising: a power supply unit; an inverter unit that converts an input voltage received from the power supply unit into an output voltage to be provided to the motor unit; and a controller that provides a signal based on a pulse width modulation method to the inverter unit, wherein the controller includes a state determination unit that determines that an abnormality has occurred in the measured value of the input voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in the pulse width modulation method indicates an overmodulation state."

[0098] The present disclosure is [2] "The motor drive system described in [1] above, wherein the controller stops the output of the output voltage from the inverter unit based on the result of determining that an abnormality has occurred in the measured value of the input voltage."

[0099] The present disclosure further provides a method for controlling a power supply voltage Vcc of a first motor and a second motor, the method comprising: (a) determining whether an abnormality has occurred in a measured value of a first input voltage received by the first inverter circuit based on a relationship between an amplitude of a first carrier wave for generating a first pulse width modulation signal to be provided to the first inverter circuit and an amplitude of a first voltage command value; (b) determining whether an abnormality has occurred in a measured value of a first input voltage received by the first inverter circuit based on a relationship between an amplitude of a first carrier wave for generating a first pulse width modulation signal to be provided to the first inverter circuit and an amplitude of a first voltage command value; (c) determining whether an abnormality has occurred in a measured value of a first input voltage received by the first inverter circuit based on a relationship between an amplitude of a first carrier wave for generating a first pulse width modulation signal to be provided to the first inverter circuit and an amplitude of a first voltage command value; and (d) determining whether an abnormality has occurred in a measured value of a first input voltage received by the first inverter circuit based on a relationship between an amplitude of a first carrier wave for generating a first pulse width modulation signal to be provided to the first inverter circuit and an amplitude of a first voltage command value; and (e) determining whether an abnormality has occurred in a measured value of a first input voltage received by the first inverter circuit based on a relationship between an amplitude of a first carrier wave for generating a first pulse width modulation signal to be provided to the first inverter circuit and an amplitude of a first voltage command value; and (f) determining whether an abnormality has occurred in a measured value of a first input voltage received by the first inverter circuit based on a relationship between an amplitude of a first carrier wave for generating a first pulse width modulation signal to be provided to ... The motor drive system according to the above [1] or [2], wherein, when the result of the state determination unit indicates that an abnormality has occurred in the measured value of the first input voltage, the entire required torque is distributed to the second torque, and the first torque is set to zero.

[0100] The present disclosure is [4] "the motor drive system according to any one of the above [1] to [3], wherein the motor unit includes at least one motor receiving three-phase AC including U-phase, V-phase, and W-phase, and the state determination unit determines whether or not an abnormality has occurred in the measured value of the input voltage using two of the current values ​​selected from three current values ​​applied to each of the U-phase, V-phase, and W-phase."

[0101] The present disclosure is [5] "the motor drive system according to any one of the above [1] to [3], wherein the motor unit includes at least one motor receiving three-phase AC including U-phase, V-phase, and W-phase, and the state determination unit determines whether or not an abnormality has occurred in the measured value of the input voltage using all three current values ​​applied to the U-phase, V-phase, and W-phase, respectively."

[0102] The present disclosure is [6] "the motor drive system according to any one of the above [1] to [5], further comprising a voltmeter side unit that obtains a measurement value of the input voltage, wherein the controller includes an abnormality factor determination unit that, when it is determined that an abnormality has occurred in the measurement value of the input voltage, determines whether the abnormality in the measurement value of the input voltage is caused by an abnormality in the power supply unit or an abnormality in the voltmeter side unit."

[0103] The present disclosure is [7] "the motor drive system described in any one of [1] to [6] above, wherein the state determination unit determines that an overmodulation state exists and that an abnormality has occurred in the measurement value of the input voltage when the amplitude of the voltage command value exceeds a threshold value determined based on the measurement value of the input voltage."

[0104] The present disclosure is [8] "the motor drive system described in any one of the above [1] to [6], wherein the state determination unit determines that an overmodulation state has occurred and that an abnormality has occurred in the measured value of the input voltage when the amplitude of the voltage command value exceeds a threshold determined based on the measured value of the input voltage, and the threshold is a value obtained by multiplying the measured value of the input voltage by √6 / 4."

[0105] The present disclosure is [9] "the motor drive system described in any one of the above [1] to [6], wherein the state determination unit determines that an overmodulation state has occurred and that an abnormality has occurred in the measured value of the input voltage when the amplitude of the voltage command value exceeds a threshold determined based on the measured value of the input voltage, and the threshold is a value obtained by multiplying the measured value of the input voltage by √2 / 2."

[0106] The present disclosure is

[10] "A control program for a motor system including a motor unit including at least one motor, a power supply unit, an inverter unit that converts an input voltage received from the power supply unit into an output voltage to be given to the motor unit, and a controller that gives a signal based on a pulse width modulation method to the inverter unit, the control program for the motor system causing a computer to operate as a state determination unit that determines that an abnormality has occurred in the measured value of the input voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in the pulse width modulation method indicates an overmodulation state."

[0107] The present disclosure is

[11] "A generator driving system for operating a generator unit that generates a voltage to be supplied to a load unit, comprising: a generator unit; an inverter unit that converts the voltage generated by the generator unit into an output voltage to be supplied to the load unit; and a controller that supplies a signal based on a pulse width modulation method to the inverter unit, wherein the controller includes a state determination unit that determines that an abnormality has occurred in the measured value of the output voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in the pulse width modulation method indicates an overmodulation state."

[0108] 1A, 1A1, 1A2, 1A3, 1A4, 1C Motor drive system 1B, 1B1, 1B2, 1B3, 1B4 Generator drive system 2 Power supply unit 3 Inverter unit 4 Motor unit 5, 5A, 5B Controller 7 Generator unit 10A, 10A1, 10A2, 10A3, 10A4, 10C Motor system 22, 23 DC voltage sensor (voltage measurement unit) 31 First inverter circuit 32 Second inverter circuit 41 First motor 42 Second motor 52 State determination unit 53 Distribution unit (torque distribution unit) 550 Computer 56 Abnormality factor determination unit PG Control program

Claims

1. A motor drive system for operating a motor unit, comprising: a power supply unit; an inverter unit that converts an input voltage received from the power supply unit into an output voltage to be supplied to the motor unit; and a controller that supplies a signal based on a pulse width modulation method to the inverter unit, wherein the controller includes a state determination unit that determines that an abnormality has occurred in the measured value of the input voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in the pulse width modulation method indicates an overmodulation state.

2. The motor drive system according to claim 1, wherein the controller stops the output of the output voltage from the inverter unit based on the result of determining that an abnormality has occurred in the measured value of the input voltage.

3. The motor drive system of claim 1, wherein the motor unit includes a first motor and a second motor sharing an output shaft, the inverter unit includes a first inverter circuit that generates a first output voltage to be provided to the first motor and a second inverter circuit that generates a second output voltage to be provided to the second motor, the state determination unit determines whether or not an abnormality has occurred in the measured value of the first input voltage received by the first inverter circuit based on the relationship between the amplitude of a first carrier wave for generating a first pulse width modulation signal to be provided to the first inverter circuit and the amplitude of a first voltage command value, the controller further has a torque distribution unit that distributes a required torque required of the output shaft into a first torque to be borne by the first motor and a second torque to be borne by the second motor, and the torque distribution unit distributes the required torque into the first torque and the second torque when the result of the state determination unit indicates that no abnormality has occurred in the measured value of the first input voltage, and distributes all of the required torque to the second torque and sets the first torque to zero when the result of the state determination unit indicates that an abnormality has occurred in the measured value of the first input voltage.

4. The motor drive system according to claim 1, wherein the motor unit includes at least one motor receiving three-phase AC including U-phase, V-phase, and W-phase, and the state determination unit determines whether or not an abnormality has occurred in the measured value of the input voltage using two of the three current values ​​applied to each of the U-phase, V-phase, and W-phase.

5. The motor drive system according to claim 1, wherein the motor unit includes at least one motor receiving three-phase AC including U-phase, V-phase, and W-phase, and the state determination unit determines whether or not an abnormality has occurred in the measured value of the input voltage using all three current values ​​applied to each of the U-phase, V-phase, and W-phase.

6. The motor drive system of claim 1, further comprising a voltmeter side section for obtaining a measurement value of the input voltage, wherein the controller includes an abnormality factor determination section for, when it is determined that an abnormality has occurred in the measurement value of the input voltage, determining whether the abnormality in the measurement value of the input voltage is caused by an abnormality in the power supply unit or an abnormality in the voltmeter side section.

7. The motor drive system of claim 1, wherein the state determination unit determines that an overmodulation state exists and that an abnormality has occurred in the measured value of the input voltage when the amplitude of the voltage command value exceeds a threshold determined based on the measured value of the input voltage.

8. The motor drive system of claim 1, wherein the state determination unit determines that an overmodulation state has occurred and that an abnormality has occurred in the measured value of the input voltage when the amplitude of the voltage command value exceeds a threshold determined based on the measured value of the input voltage, and the threshold is a value obtained by multiplying the measured value of the input voltage by √6 / 4.

9. The motor drive system of claim 1, wherein the state determination unit determines that an overmodulation state has occurred and that an abnormality has occurred in the measured value of the input voltage when the amplitude of the voltage command value exceeds a threshold determined based on the measured value of the input voltage, and the threshold is a value obtained by multiplying the measured value of the input voltage by √2 / 2.

10. A control program for a motor system comprising a motor unit including at least one motor, a power supply unit, an inverter unit that converts an input voltage received from the power supply unit into an output voltage to be supplied to the motor unit, and a controller that supplies a signal based on a pulse width modulation method to the inverter unit, the control program causing a computer to operate as a state determination unit that determines that an abnormality has occurred in the measured value of the input voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in the pulse width modulation method indicates an overmodulation state.

11. A generator driving system for operating a generator unit that generates a voltage to be supplied to a load unit, comprising: a generator unit; an inverter unit that converts the voltage generated by the generator unit into an output voltage to be supplied to the load unit; and a controller that supplies a signal based on a pulse width modulation system to the inverter unit, wherein the controller includes a state determination unit that determines that an abnormality has occurred in the measured value of the output voltage when a modulation rate defined by the amplitude of a carrier wave and the amplitude of a voltage command value in the pulse width modulation system indicates an overmodulation state.

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