Electric motor control device

Abstract

An electric motor control device controls an electric motor (30) having multiple coils in multiple phases. The electric motor control device includes: an inverter comprising multiple switching elements driven by pulse width modulation to control the voltage applied to each coil of the multiple coils in the multiple phases; a smoothing capacitor (C2) that smooths the voltage applied to the multiple coils in the multiple phases via the inverter; a controller (14, 15) that outputs a pulse width modulation drive signal having a duty cycle set to rotate the electric motor according to a target value to the multiple switching elements; a detection unit (23, 25) that detects the voltage applied to at least one coil of the multiple coils; and an anomaly determination unit (24, 26) that, when the voltage detected by the detection unit exceeds a threshold while the multiple switching elements are driven by pulse width modulation, determines an anomaly of the smoothing capacitor for determining the lifespan of the smoothing capacitor.

Description

Technical Field

[0001] This disclosure relates to an electric motor control device for controlling an electric motor (also known as an electric motor) having multiphase coils. Background Technology

[0002] For example, Patent Document 1 discloses an electric motor control device capable of estimating the lifespan of a main circuit capacitor used as a smoothing capacitor. The electric motor control device in Patent Document 1 estimates the ripple current flowing into the main circuit capacitor based on data calculated from the output power to the electric motor, system impedance, carrier frequency, and ripple current. Furthermore, the electric motor control device estimates the internal temperature of the capacitor and its lifespan data based on the direct voltage detected by a voltage detector and applied to the main circuit capacitor, the ambient temperature of the main circuit capacitor detected by an ambient temperature sensor, and the estimated ripple current. In addition, the electric motor control device estimates the lifespan of the main circuit capacitor and calculates the capacitor life integration time based on the estimated lifespan. When the capacitor life integration time is substantially equal to a predetermined basic lifespan, the main circuit capacitor is determined to have reached the end of its lifespan.

[0003] Related technical documents

[0004] Patent documents

[0005] Patent Document 1: JP 5197897 B1 Summary of the Invention

[0006] However, when the lifespan of the flat capacitor is determined by a method such as that of the electric motor controller in Patent Document 1, many additional components and configurations are required, such as a voltage detector, an ambient temperature sensor, a system impedance setting unit, a ripple current calculation and data storage device, a ripple current estimation unit, a capacitor lifespan data storage device, and a capacitor lifespan estimation unit.

[0007] Furthermore, methods for electric motor control devices, such as those in Patent Document 1, do not directly measure lifespan but rather estimate it. Moreover, variations exist in aspects such as the capacitance of the main circuit capacitors. Therefore, a margin must be added to the lifespan setting, potentially resulting in low accuracy in determining the lifespan.

[0008] One object of this disclosure is to provide an electric motor control device that can determine the life of a flat capacitor with high accuracy without having many additional components and many additional configurations.

[0009] According to this disclosure, an electric motor control device controls an electric motor having multiple phases and multiple coils. The electric motor control device includes: an inverter comprising multiple switching elements driven by pulse width modulation (PWM) to control the voltage applied to each of the multiple coils in the multiple phases; a smoothing capacitor that smooths the voltage applied to the multiple coils in the multiple phases via the inverter; a controller that outputs a PWM drive signal having a duty cycle set to rotate the electric motor according to a target value to the multiple switching elements; a detection unit that detects the voltage applied to at least one of the multiple coils; and an anomaly determination unit that, when the multiple switching elements are driven by the PWM, determines an anomaly of the smoothing capacitor when the voltage detected by the detection unit exceeds a threshold value, for determining the lifespan of the smoothing capacitor.

[0010] As the lateral capacitor approaches the end of its lifespan, its capacitance decreases sharply. The electric motor control device of this disclosure detects this decrease in capacitance based on the magnitude of the switching noise caused by the switching element driven by the pulse width modulation. When the lateral capacitor capacitance remains at its normal value, it can prevent voltage changes, i.e., switching noise, when the switching element is turned on or off. However, when the second lateral capacitor approaches the end of its lifespan and its capacitance decreases, voltage changes caused by the switching element, i.e., switching noise, increase. In other words, the switching noise generated when the switching element is turned on or off increases. This switching noise appears in the voltage applied to the coil.

[0011] Therefore, according to this disclosure, the electric motor control device includes: an anomaly determination unit that, when the plurality of switching elements are driven by the pulse width modulation, determines an anomaly of the current-delay capacitor when the voltage applied to the coil and detected by the detection unit exceeds a threshold, for determining the lifespan of the current-delay capacitor. In this way, by determining a current-delay capacitor anomaly, including a decrease in the capacitance of the current-delay capacitor, based on the magnitude of the switching noise during PWM driving, the electric motor control device of this disclosure can determine the lifespan of the current-delay capacitor with high accuracy without requiring complex configuration. Attached Figure Description

[0012] The above and other objects, features, and advantages of this disclosure will become more apparent from the following detailed description with reference to the accompanying drawings.

[0013] Figure 1 This is a configuration diagram showing the overall configuration of an electric motor control system including an electric motor control device according to the first embodiment;

[0014] Figure 2A This is a waveform diagram illustrating an example of the change in drain-source voltage of a switching element when the capacitance of the flat capacitor is normal.

[0015] Figure 2B This is a waveform diagram illustrating an example of the change in drain-source voltage of a switching element as the capacitance of a flat capacitor decreases due to its lifetime.

[0016] Figure 3 This is a configuration diagram illustrating an example of the configuration of the noise detection circuit and the anomaly determination circuit;

[0017] Figure 4A This is a waveform diagram illustrating an example of the change in drain-source voltage of a switching element as the capacitance of a flat capacitor decreases due to its lifetime, and an example of the switching noise generated by the PWM drive when the duty ratio of the PWM drive signal is less than 100%.

[0018] Figure 4B This is a waveform diagram illustrating an example of the change in drain-source voltage of a switching element as the capacitance of a flat capacitor decreases due to its lifetime, and an example of the switching noise generated by the PWM drive when the duty cycle of the PWM drive signal is equal to 100%.

[0019] Figure 5 This is a waveform diagram illustrating an example of the anomaly determination circuit outputting an anomaly determination signal and the estimated lifetime determination unit outputting a lifetime determination signal, and thus the lifetime extension control is performed by the efflux capacitor.

[0020] Figure 6 This is a configuration diagram showing the overall configuration of an electric motor control system including an electric motor control device according to the second embodiment;

[0021] Figure 7A This is a waveform diagram illustrating an example of the change in drain-source voltage of a switching element when the capacitance of the flat capacitor is normal.

[0022] Figure 7B This is a waveform diagram illustrating an example of the change in the neutral point voltage of an electric motor when the capacitance of the collimating capacitor is normal.

[0023] Figure 8A This is a waveform diagram illustrating an example of the change in drain-source voltage of a switching element as the capacitance of a flat capacitor decreases due to its lifetime; and

[0024] Figure 8B This is a waveform diagram illustrating an example of the change in the neutral point voltage of an electric motor as the capacitance of the flat capacitor decreases due to its lifetime. Detailed Implementation

[0025] In the following description, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0026] (First Embodiment)

[0027] Figure 1 The overall configuration of an electric motor control system including an electric motor control device 10 according to the first embodiment is shown. (As...) Figure 1 As shown, the electric motor control system includes a higher-level system 4, an electric motor control unit 10, and an electric motor 30. The higher-level system 4 calculates target values ​​(such as target rotational speed or target torque) for the electric motor 30 based on the detection values ​​of various sensors and outputs these target values ​​to the electric motor control unit 10. The electric motor control unit 10 sets the duty cycle of the PWM drive signal to rotate the electric motor 30 according to the target value, and drives each of the switching elements 20 and 22 forming the inverter by the PWM drive signal with the set duty cycle. Thus, three-phase AC power corresponding to the duty cycle of the PWM drive signal is supplied to each coil of the U-phase, V-phase, and W-phase of the electric motor 30, and the electric motor 30 rotates according to the target value.

[0028] The higher-level system 4 and the electric motor control device 10 can be integrated, and the electric motor control device 10 can calculate the target value of the electric motor 30. The electric motor 30 is preferably used as a motor for various purposes, such as for use in vehicles (e.g., radiator fan motor, air conditioner fan motor, water pump motor for cooling the engine, etc.).

[0029] Next, the configuration of the electric motor control device 10 in this embodiment will be described in detail. Figure 1 The electric motor control device 10 shown includes a power terminal connected to the positive electrode side of the battery 2 as an external connection terminal, a ground terminal connected to the negative electrode side, and input and output terminals for transmitting signals to and receiving signals from the higher-level system 4. The power terminal is connected to a high-potential power line in the electric motor control device 10, and the ground terminal is connected to a low-potential power line. The electric motor control device 10 receives direct current supplied by the battery 2, which serves as a DC power source, via the power terminal and the ground terminal.

[0030] The electric motor control device 10 includes an input-output (I / F) circuit 12, a control circuit 14, switching elements 20 and 22, a snubber circuit 23, a noise detection circuit 24, an anomaly determination circuit 26, an AND circuit 28, a first current-limiting capacitor C1, an inductor L1, a second current-limiting capacitor C2, etc. In the accompanying drawings, the noise detection circuit 24 may also be referred to as "noise detection," and the anomaly determination circuit 26 may also be referred to as "anomaly determination."

[0031] The input-output (I / F) circuit 12 receives the target value from the higher-level system 4 via the input terminal of the electric motor control device 10 and outputs the target value to the control circuit 14. When the control circuit 14 receives a determination that the lifespan of the second balancing capacitor C2 is nearing its end, the input-output (I / F) circuit 12 outputs the result to the higher-level system 4 via the output terminal.

[0032] A first smoothing capacitor C1 is connected in parallel to battery 2 between the high-potential and low-potential power lines, smoothing the direct current (DC) voltage supplied by battery 2. A second smoothing capacitor C2 is connected to the first smoothing capacitor C1 via inductor L1. Inductor L1 and the second smoothing capacitor C2 form an LC filter, which blocks noise, for example, from another device sharing the battery 2. The second smoothing capacitor C2 is connected in parallel to an inverter including switching elements 20 and 22 between the high-potential and low-potential power lines. Therefore, the DC voltage smoothed by the second smoothing capacitor C2 is supplied to the inverter.

[0033] For example, electrolytic capacitors with large capacitance are used as the first shunt capacitor C1 and the second shunt capacitor C2. The first shunt capacitor C1 and the second shunt capacitor C2 assist in supplying power to the inverter by stabilizing the voltage supplied to the inverter and storing charge. In this embodiment, based on the control signal from the control circuit 14, according to the drive 15 (see...) Figure 3 The output PWM drive signal drives each of the switching elements 20 and 22 that form the inverter. Through PWM drive, each of the switching elements 20 and 22 is turned on and off. This results in voltage variations between the drain and source of the switching elements 20 and 22, i.e., switching noise. This switching noise appears in the voltage applied to each coil of the U-phase, V-phase, and W-phase. The second lateral capacitor C2 further prevents this switching noise.

[0034] With the capacitance of the second lateral capacitor C2 remaining normal, it can effectively suppress voltage variations between the drain and source of switching elements 20 and 22, i.e., switching noise. For example, Figure 2AAs shown, the switching noise is suppressed to approximately the power supply voltage through the second balancing capacitor C2. However, when the lifespan of the second balancing capacitor C2 is nearing its end and its capacitance decreases, it becomes difficult to suppress the voltage changes caused by the switching of switching elements 20 and 22, i.e., switching noise. For example, when the lifespan of the second balancing capacitor C2 is nearing its end, as... Figure 2B As shown, the peak value of the switching noise may exceed three times the power supply voltage. Therefore, the electromagnetic noise generated by the switching noise degrades EMC performance and may adversely affect other products. For example, when sensorless control of the electric motor 30 is performed, the induced voltage of the non-energized phase cannot be read, and the electric motor 30 cannot be driven.

[0035] Semiconductor elements such as MOSFETs or IGBTs can be used as switching elements 20 and 22. Switching elements 20 and 22 have freewheeling diodes that return current due to transient high voltages generated during interruptions. Although in Figure 1 Only the switching elements 20 and 22, which are placed in the upper and lower arm circuits for the U-phase coil, are shown in the diagram. However, upper and lower arm circuits with switching elements are provided for each of the V-phase and W-phase coils. The switching elements placed in the upper and lower arm circuits of these phases form an inverter.

[0036] A series circuit of capacitor C3 and resistor R1 is connected in parallel to switching element 20. A series circuit of capacitor C4 and resistor R2 is connected in parallel to switching element 22. Each of the series circuits of capacitors and resistors serves as an RC snubber circuit, which absorbs transient high voltages generated when switching elements 20 and 22 are interrupted. Furthermore, the snubber circuit 23, including capacitor C4 and resistor R2, serves as a detection unit that divides and detects the voltage applied to the U-phase coil.

[0037] As described above, switching noise during the PWM drive of switching elements 20 and 22 occurs in the voltage applied to the coil of each phase. When the lifespan of the second shunt capacitor C2 is nearing its end and its capacitance decreases, the switching noise may significantly exceed the power supply voltage supplied from battery 2. Therefore, by detecting the applied voltage of the voltage divider in the U-phase coil through buffer circuit 23, switching noise exceeding the power supply voltage in noise detection circuit 24 can be accurately detected, as will be described later. Furthermore, by using buffer circuit 23 as the detection unit, it is unnecessary to add components for dividing and detecting the voltage applied to the U-phase coil.

[0038] although Figure 1Only a configuration for detecting switching noise from the voltage applied to the U-phase coil is shown, but configurations for detecting switching noise from the voltages applied to the V-phase and W-phase coils can be added. By providing a configuration for detecting switching noise for each phase coil, switching noise indicating that the lifespan of the second lateral capacitor C2 is nearing its end can be accurately detected regardless of variations in the inductance value of each phase coil. However, it is not always necessary to provide a configuration for detecting switching noise for all three phase coils. A configuration for detecting switching noise can be provided for at least one phase coil.

[0039] The noise detection circuit 24 detects the magnitude of switching noise appearing in the voltage divided by the buffer circuit 23, detected, and applied to the U-phase coil. For example, the noise detection circuit 24 can be configured as follows: Figure 3 The peak hold circuit is shown. When the input voltage divided by the buffer circuit 23 is higher than the output voltage of the peak hold circuit, the peak hold circuit outputs a high voltage to the amplifier 32. When the amplifier 32 outputs a high voltage, capacitor C5 is charged via diode D1. The voltage charged in capacitor C5 becomes the output voltage of the peak hold circuit via the voltage follower formed by the amplifier 34. When the output voltage of the peak hold circuit becomes higher than the input voltage divided by the buffer circuit 23 due to the charging of capacitor C5, the amplifier 32 stops outputting a high voltage. Through this operation, the voltage corresponding to the maximum value of the peak of the switching noise is held by capacitor C5 of the peak hold circuit.

[0040] The anomaly determination circuit 26 determines the anomaly of the second collimating capacitor C2 based on the output voltage of the noise detection circuit 24, including a decrease in capacitance due to the lifetime of the second collimating capacitor C2. For example, as... Figure 3 As shown, the anomaly determination circuit 26 can be configured as a comparator 36, which compares the output voltage of the noise detection circuit 24 with a threshold voltage set by resistors R4 and R5. When the output voltage of the noise detection circuit 24 becomes higher than the threshold voltage set by resistors R4 and R5, the anomaly determination circuit 26 outputs an anomaly determination signal, indicating an anomaly in the second lateral capacitor C2. The noise detection circuit 24 and the anomaly determination circuit 26 can correspond to an abnormality determination portion.

[0041] Control circuit 14 operates to set the duty cycle according to target values ​​(such as target speed or target torque) given by the higher-level system 4m, and outputs a control signal indicating the duty cycle to driver 15 (see [link]). Figure 3The driver 15 generates a PWM drive signal with a set duty cycle and outputs the PWM drive signal to the control terminal of the switching element 22. The control circuit 14 and the driver 15 may correspond to a controller.

[0042] The control circuit 14 includes an energization time integration portion 16, which serves as a calculation unit, and calculates the cumulative energization time obtained by accumulating the energization time of the electric motor 30. When the control circuit 14 drives the electric motor 30, the energization time integration portion 16 measures the time period from start to finish as one energization time of the electric motor 30. Once the energization time has been measured, the energization time integration portion 16 updates the cumulative energization time by adding the measured energization time to the cumulative energization time, which is the cumulative value of the energization time up to that point. In the accompanying drawings, the energization time integration portion 16 may also be referred to as "EN time integration".

[0043] Furthermore, the control circuit 14 includes an estimated lifespan determination unit 18, which serves as a setting time determination unit. This unit determines the likelihood that the lifespan of the second ducting capacitor C2 will reach its end based on the cumulative energizing time calculated by the energizing time accumulation unit 16. For example, when the cumulative energizing time exceeds a predetermined time (such as the time corresponding to the required lifespan of the product), the estimated lifespan determination unit 18 outputs a lifespan determination signal indicating the likelihood that the lifespan of the second ducting capacitor C2 will reach its end.

[0044] The AND circuit 28 receives the output signal from the estimated lifetime determination unit 18 and the output signal from the anomaly determination circuit 26. When it receives the lifetime determination signal from the estimated lifetime determination unit 18 and the anomaly determination signal from the anomaly determination circuit 26, the AND circuit 28 outputs an anomaly signal to the control circuit 14 indicating that the lifetime of the second lateral capacitor C2 is nearing its end.

[0045] When an abnormal signal indicating that the lifespan of the second ducting capacitor C2 is nearing its end is received from the AND circuit 28, the control circuit 14 notifies the higher-level system 4 via the input-output I / F circuit 12 and executes lifespan extension control to extend the lifespan of the second ducting capacitor C2. Then, the control circuit 14 or the higher-level system 4 may display a warning light to notify the user that the lifespan of the second ducting capacitor C2 is nearing its end. The control circuit 14 and the AND circuit 28 may correspond to an abnormality decision portion.

[0046] In lifetime extension control, for example, control circuit 14 outputs a PWM drive signal with a duty cycle of 100%. This lifetime extension control can be executed by instructions from higher-level system 4, or it can be actively executed by control circuit 14. In either case, higher-level system 4 can apply a target value corresponding to a 100% duty cycle to control circuit 14 along with the execution of lifetime extension control.

[0047] like Figure 4A As shown, when the duty cycle of the PWM drive signal is less than 100%, switching elements 20 and 22 are switched on and off for each PWM cycle, resulting in switching noise. The switching noise and fluctuations in the applied voltage to the coil continue to apply a load to the second flat capacitor C2, which is nearing the end of its lifespan.

[0048] On the other hand, such as Figure 4B As shown, when the duty cycle of the PWM drive signal is 100%, switching elements 20 and 22 are neither turned on nor off for each PWM cycle. Therefore, the number of voltage fluctuations and noise generated in the coil can be reduced. This, in turn, extends the lifespan of the second flat capacitor C2, which is nearing the end of its lifespan.

[0049] like Figure 5 As shown in (d) and (e), in the electric motor control device 10 of this embodiment, when an anomaly determination signal is output from the anomaly determination circuit 26 and a lifespan determination signal is output from the estimated lifespan determination unit 18, it is determined that the lifespan of the second lateral capacitor C2 is nearing its end and an anomaly has occurred. Therefore, for example, it can prevent surge voltages from another device sharing the battery 2 (such as a higher system) from being identified as an increase in switching noise, and it can prevent the incorrect determination that the lifespan of the second lateral capacitor C2 is nearing its end and thus an anomaly has occurred.

[0050] In addition, such as Figure 5 As shown in (a) to (c) and (f), in the lifespan extension control, the device driven by the electric motor 30 can operate at maximum capacity by setting the duty cycle of the PWM drive signal to 100%. Therefore, situations where the target set by the higher-level system 4 cannot be achieved can be avoided. For example, the system can be operated in a safer state because the cooling capacity is maximized when, for example, the electric motor 30 is used as a radiator fan motor, an air conditioner fan motor, or a water pump motor for cooling an engine.

[0051] However, the lifespan extension control of the second ducting capacitor C2 is not limited to the control described above, which sets the duty cycle of the PWM drive signal to 100%. For example, in the lifespan extension control, when the PWM cycle of the PWM drive signals output to the multiple switching elements 20 and 22 forming the inverter can be extended, the PWM drive of each of the switching elements 20 and 22 can be executed based on the PWM drive signal with a duty cycle according to the target value set by the higher-level system 4. By extending the PWM cycle, the number of switching times of each switching element 20 and 22 can be reduced. Therefore, the lifespan of the second ducting capacitor C2 can be extended. Furthermore, by setting the duty cycle according to the target value set by the higher-level system 4, the electric motor 30 can be controlled according to the target value set by the higher-level system 4.

[0052] As described above, according to this embodiment, the electric motor control device 10 determines the abnormal decrease in capacitance of the second lateral capacitor C2 based on the magnitude of the switching noise during PWM driving. Therefore, regardless of the tolerance of capacitance changes in the second lateral capacitor C2, the lifespan of the second lateral capacitor C2 can be determined with high accuracy. Furthermore, in the electric motor control device 10 of this embodiment, it is unnecessary to add components such as an ambient temperature sensor or a configuration for estimating ripple current or the internal temperature of the lateral capacitor. Therefore, a complex configuration is not required.

[0053] (Second Embodiment)

[0054] Next, an electric motor control system including an electric motor control device 10 according to a second embodiment of the present disclosure will be described. Figure 6 The overall configuration of the electric motor control system is shown. For example... Figure 6 As shown, the electric motor control system of this disclosure differs from the electric motor control system of the first embodiment, and detects the voltage at the neutral point of the three-phase coil of the electric motor 30 as the voltage applied to the coil. Although in Figure 6 The buffer circuit described in the first embodiment is omitted, but a buffer circuit may be provided for each switching element 20 and 22.

[0055] like Figure 6 As shown, the neutral point of the three-phase coil is connected to the low-potential power line via a neutral point filter 25 formed by capacitors C6 and C7. The neutral point filter 25 suppresses potential fluctuations at the neutral point and reduces radiation noise from the electric motor 30. In this embodiment, the voltage at the neutral point is divided and detected using the neutral point filter 25. That is, as... Figure 6As shown, the neutral point voltages of capacitors C6 and C7 are detected as the voltage applied to the coil and input to the noise detection circuit 24. The remaining configuration is similar to that according to the first embodiment, and therefore will not be described again.

[0056] Figure 7A and Figure 7B This illustrates an example of the voltage changes between the drain and source of switching elements 20 and 22, as well as the neutral point voltage, when the capacitance of the second lateral capacitor C2 is normal. Figure 7B As shown, the switching noise generated when each of the switching elements 20 and 22 is turned on and off also appears in the neutral point voltage.

[0057] Figure 8A and Figure 8B This illustrates an example of how the voltage between the drain and source of switching elements 20 and 22, as well as the neutral point voltage, changes as the capacitance of the second lateral capacitor C2 decreases due to its lifetime. Figure 8A As shown, when the capacitance of the second parallel capacitor C2 decreases, the voltage change between the drain and source of switching elements 20 and 22, i.e., the switching noise, significantly exceeds the power supply voltage. This switching noise also appears in the neutral point voltage of the electric motor 30, such as... Figure 8B As shown. Therefore, when the neutral point voltage is detected and the maximum value of the peak exceeds the threshold voltage, it can be determined that the second collimating capacitor C2, whose capacitance has decreased due to its lifetime, is abnormal.

[0058] Embodiments of this disclosure have been described. However, this disclosure is not limited to the above embodiments, and various modifications can be made within the spirit and scope of this disclosure.

[0059] For example, Figure 3 An example of an analog circuit, where the noise detection circuit 24 is an analog circuit serving as a peak hold circuit, is shown. However, the noise detection circuit 24 may include digital circuitry. For example, the voltage detected by the buffer circuit 23 is sampled and converted into a digital value, and the maximum value at the peak can be calculated. Alternatively, instead of calculating the maximum value, the average value over a predetermined period can be calculated. Furthermore, the anomaly determination circuit 26 may be provided in a digital configuration and may determine anomalies in the second shunt capacitor C2 based on the frequency or number of times the sampled voltage exceeds a threshold.

[0060] The control circuitry 14 and method described in this disclosure can be implemented by a special-purpose computer configured with memory and a processor programmed to perform one or more specific functions embodied in a computer program stored in memory. Alternatively, the control circuitry 14 and method described in this disclosure can be implemented by a special-purpose computer provided by configuring a processor having one or more dedicated hardware logic circuits. Alternatively, the control circuitry 14 and method described in this disclosure can be implemented by one or more special-purpose computers configured as a combination of a processor and memory, the combination of which executes a computer program and is programmed to perform one or more functions, the processor being configured with one or more hardware logic circuits. The computer program can be stored as instructions to be executed by a computer in a tangible, non-transitory computer-readable storage medium.

Claims

1. An electric motor control device configured to control an electric motor having multiple phases and multiple coils, the electric motor control device comprising: An inverter comprising a plurality of switching elements driven by pulse width modulation to control the voltage applied to each of a plurality of coils in the plurality of phases; A smoothing capacitor, configured to smooth the voltage applied to the plurality of coils of the plurality of phases via the inverter; A controller configured to output a pulse width modulation drive signal to the plurality of switching elements, the pulse width modulation drive signal having a duty cycle set to rotate the electric motor according to a target value; A detection unit configured to detect the voltage applied to at least one of the plurality of coils; as well as An anomaly determination unit is configured to determine an anomaly in the current-delay capacitor when the voltage detected by the detection unit exceeds a threshold when the plurality of switching elements are driven by the pulse width modulation, thereby determining the lifespan of the current-delay capacitor. The energizing time accumulator is configured to calculate the cumulative energizing time obtained by accumulating the energizing time of the electric motor; as well as The lifespan estimation and determination unit is configured to determine that the cumulative energization time exceeds a set time that is set as the lifespan of the ducting capacitor.

2. The electric motor control device according to claim 1 further includes: An anomaly determination unit is configured to determine that an anomaly has occurred in the current-flow capacitor when the anomaly determination unit determines that the current-flow capacitor is abnormal and the estimated lifespan determination unit determines that the cumulative energization time exceeds the set time.

3. The electric motor control device according to claim 1, wherein, The controller is configured to set the duty cycle of the PWM drive signal output to the plurality of switching elements to 100% when the current capacitor is abnormal.

4. The electric motor control device according to claim 3, wherein, The controller is configured to extend the period of the PWM drive signal output to the plurality of switching elements when the current-carrying capacitor is abnormal.

5. The electric motor control device according to any one of claims 1 to 4, wherein, The detection unit is configured to detect the voltage divided by the buffer circuit of each of the plurality of switching elements, which is connected in parallel, as the voltage applied to the at least one coil.

6. The electric motor control device according to any one of claims 1 to 4, wherein, The detection unit is configured to detect the voltage divided by the neutral point filter connected to the neutral point of the plurality of switching elements as the voltage applied to the at least one coil.

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