WO2020241366A1

WO2020241366A1 - Power conversion device and power conversion device control method

Info

Publication number: WO2020241366A1
Application number: PCT/JP2020/019719
Authority: WO
Inventors: 遼一稲田; 圭介早坂; 哲重田
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2019-05-24
Filing date: 2020-05-19
Publication date: 2020-12-03
Also published as: JPWO2020241366A1; CN113875143A; DE112020002128T5; JP7124218B2

Abstract

Conventionally, it is impossible to specify which location of a power semiconductor constituting an upper arm circuit and a lower arm circuit is failed. In the present invention, a simulated DC current calculation unit 451 in a power semiconductor diagnosis unit 45 calculates a first failure occasion simulated DC current value of each phase on the basis of the duty values Du, Dv, Dw and AC current sensor values Ius, Ivs, Iws of respective phases and outputs the first failure occasion simulated DC current value to a failure determination unit 452. The failure determination unit 452 determines, using the first failure occasion simulated DC current value of each phase, a DC current sensor value Idcs, the duty values Du, Dv, Dw of the respective phases, and a target torque, which location of a power semiconductor in a power conversion circuit 60 is failed and outputs a failure notification signal according to the failed location to a failure notification device 30 and a PWM signal generation unit 44. The failure determination unit 452 discriminates the target torque and identifies whether the failure has occurred in powering time or regenerative time.

Description

Power converter and control method of power converter

The present invention relates to a power conversion device and a control method for the power conversion device.

Hybrid vehicles and electric vehicles are equipped with a power conversion device to drive the motor. The power conversion device converts the direct current supplied from the battery into an alternating current by switching the power semiconductors constituting the upper arm circuit and the lower arm circuit corresponding to each phase of the motor, and drives the motor. There is.

In recent years, there has been an increasing need to detect abnormalities and failures in power converters based on functional safety standards for automobiles. Therefore, it is necessary to carry out a diagnosis that can detect an abnormality or failure even in a power semiconductor.

Patent Document 1 has a drive circuit for switching ON / OFF of the power semiconductor for each power semiconductor, and when it is determined that a failure has occurred inside the power conversion device, an abnormality notification is sent to an external abnormality notification device. A device that outputs a signal is disclosed.

JP-A-2017-208893

With the device described in Patent Document 1, it was not possible to identify which part of the power semiconductor constituting the upper arm circuit and the lower arm circuit is out of order.

The power conversion device according to the present invention is composed of an upper arm circuit and a lower arm circuit corresponding to each phase of a multi-phase motor, and has a power conversion circuit that converts a direct current into a multi-phase alternating current and the upper arm circuit. When one of the plurality of phases fails based on the control circuit that outputs the PWM signal to the lower arm circuit and the direct current output from the power conversion circuit and the duty ratio of the PWM signal. To the simulated DC current calculation unit that calculates the simulated DC current at the time of the first failure based on the AC current value of the remaining phases, and the DC current input to the power conversion circuit or the AC current value output from the power conversion circuit. Based on the DC current, the duty ratio of the PWM signal, and the simulated DC current at the time of the first failure, the failure determination unit that detects the failure of the upper arm circuit or the lower arm circuit of any phase. Be prepared.
In the control method of the power conversion device according to the present invention, a power conversion circuit is formed by an upper arm circuit and a lower arm circuit corresponding to each phase of a multi-phase motor, and a direct current is converted into a multi-phase alternating current. When a PWM signal is output to the upper arm circuit and the lower arm circuit, and one of the plurality of phases fails based on the direct current output from the power conversion circuit and the duty ratio of the PWM signal. The simulated DC current at the time of the first failure is calculated based on the AC current value of the remaining phases, and the DC current input to the power conversion circuit or the DC current based on the AC current value output from the power conversion circuit and the above Based on the duty ratio of the PWM signal and the simulated DC current at the time of the first failure, the failure of the upper arm circuit or the lower arm circuit of any phase is detected.

According to the present invention, it is possible to identify which part of the power semiconductor constituting the upper arm circuit and the lower arm circuit is out of order.

It is a circuit block diagram of the power conversion apparatus which concerns on 1st Embodiment. It is a circuit block diagram of a power conversion circuit. It is a flowchart which shows the failure determination process which concerns on 1st Embodiment. It is a flowchart which shows the failure handling process. (A) (B) (C) It is a graph of AC current, duty, and direct current when a failure of OFF sticking occurs in the U-phase upper arm circuit during power running. It is a circuit block diagram of the power conversion apparatus which concerns on 2nd Embodiment. It is a flowchart which shows the failure determination process which concerns on 2nd Embodiment. It is a circuit block diagram of the power conversion apparatus which concerns on 3rd Embodiment. It is a flowchart which shows the failure determination process which concerns on 3rd Embodiment. It is a flowchart which shows the failure determination process which concerns on 4th Embodiment. It is a flowchart which shows the failure determination process which concerns on 5th Embodiment.

[First Embodiment]
FIG. 1 is a circuit configuration diagram of the power conversion device 100 according to the first embodiment.
The power conversion device 100 converts the DC power obtained from the DC power supply 10 into AC power to drive the motor 20 during power running. The DC power supply 10 is a power supply for driving the motor 20. Further, the power conversion device 100 converts the power of the motor 20 into DC power to charge the DC power supply 10 at the time of regeneration.

The motor 20 is a three-phase electric motor having three windings inside. Further, the motor 20 is equipped with an angle sensor (not shown) for measuring the rotation angle of the motor 20, and the angle sensor outputs the measured rotation angle as an angle sensor value to the power conversion device 100. .. The power conversion device 100 detects a failure described later and notifies the failure notification device 30 of the failure.

The power conversion device 100 includes a control circuit 40, a driver circuit 50, and a power conversion circuit 60. The control circuit 40 includes a motor speed calculation unit 41, a target current calculation unit 42, a duty calculation unit 43, a PWM signal generation unit 44, and a power semiconductor diagnosis unit 45. The power semiconductor diagnosis unit 45 includes a simulated direct current calculation unit 451 and a failure determination unit 452.
The voltage sensor 70 is a sensor that measures the output voltage of the DC power supply 10, and outputs the measured voltage value as a voltage sensor value to the target current calculation unit 42 in the control circuit 40.

The DC current sensor 80 measures the DC current flowing between the DC power supply 10 and the power conversion circuit (inverter circuit) 60, and outputs the measured current value as the DC current sensor value Idcs to the failure determination unit 452. In the present embodiment, the DC current sensor 80 is installed so as to measure the current flowing from the DC power supply 10 into the power conversion circuit 60 as a positive current value, but the reverse current value is used as a positive current value. A DC current sensor 80 may be installed to measure.

The AC current sensor 90 is a sensor for measuring the AC current flowing through each phase (U phase, V phase, W phase) of the motor 20. Specifically, the AC current Iu flowing through the U phase is measured, and the AC current sensor value Ius is output to the duty calculation unit 43 and the simulated DC current calculation unit 451. Similarly, the AC current Iv flowing through the V phase is measured, and the AC current sensor value Ivs is output to the duty calculation unit 43 and the simulated DC current calculation unit 451. Similarly, the AC current Iw flowing through the W phase is measured, and the AC current sensor value Iws is output to the duty calculation unit 43 and the simulated DC current calculation unit 451.

The motor speed calculation unit 41 calculates the motor speed value from the change in the angle sensor value in the motor 20, and outputs the calculated motor speed value to the target current calculation unit 42.
The control circuit 40 communicates with an electronic control device (not shown) provided outside the power conversion device 100, receives a target torque of the motor 20 from the external electronic control device, and inputs the target torque to the target current calculation unit 42.

The target current calculation unit 42 calculates the current value to be passed through the motor 20 by using the target torque, the voltage sensor value, and the motor speed value output by the motor speed calculation unit 41, and calculates the duty using this current value as the target current value. Output to unit 43. This target current value is expressed, for example, in the form of a d-axis target current value and a q-axis target current value.

The duty calculation unit 43 calculates the U-phase duty value Du, the V-phase duty value Dv, and the W-phase duty value Dw based on the target current value output by the target current calculation unit 42 and the AC current sensor values Ius, Ivs, and Iws. , Output to the PWM signal generation unit 44 and the simulated DC current calculation unit 451.

In the present embodiment, the U-phase duty value Du indicates the ON time ratio of the U-phase upper arm circuit power semiconductor, and the ON time ratio of the U-phase lower arm circuit power semiconductor is indicated by 1-Du. Similarly, the V-phase duty value Dv indicates the ON time ratio of the V-phase upper arm circuit power semiconductor, and the ON time ratio of the V-phase lower arm circuit power semiconductor is indicated by 1-Dv. The W-phase duty value Dw indicates the ON time ratio of the W-phase upper arm circuit power semiconductor, and the ON time ratio of the W-phase lower arm circuit power semiconductor is indicated by 1-Dw.

The PWM signal generation unit 44 has a timer (not shown) inside, and based on this timer value, U-phase duty value Du, V-phase duty value Dv, and W-phase duty value Dw, PWM (Pulse Wide Modulation). ) Generates a signal and outputs it to the driver circuit 50.

The PWM signal generation unit 44 controls the PWM signal so that the motor 20 is not driven when an abnormality notification signal is output from the power semiconductor diagnosis unit 45. The state in which the motor 20 is not driven includes, for example, a state in which all six power semiconductors in the power conversion circuit 60 are turned off (referred to as a freewheel state in the present embodiment). As another example, of the six power semiconductors, three power semiconductors in the upper arm circuit are turned on and three power semiconductors in the lower arm circuit are turned off (in this embodiment, the upper arm active short state and the state). (Called), conversely, a state in which three power semiconductors in the upper arm circuit are turned off and three power semiconductors in the lower arm circuit are turned on (referred to as a lower arm active short state in this embodiment) can be mentioned.

The driver circuit 50 receives the PWM signal output by the PWM signal generation unit 44 and outputs a drive signal for switching ON / OFF of the power semiconductor to the power conversion circuit 60.
The power conversion circuit 60 has a smoothing capacitor and six power semiconductors inside, and converts the DC power obtained from the DC power supply 10 into AC power to drive the motor 20 at the time of power running. Further, at the time of regeneration, the power of the motor 20 is converted into DC power to charge the DC power supply 10.

The power semiconductor diagnosis unit 45 diagnoses the failure of the power semiconductor in the power conversion circuit 60. The simulated DC current calculation unit 451 in the power semiconductor diagnostic unit 45 calculates the simulated DC current value at the time of the first failure of each phase based on the duty values Du, Dv, Dw of each phase and the AC current sensor values Ius, Ivs, Iws. It is calculated and output to the failure determination unit 452.

The failure determination unit 452 uses the simulated DC current value at the time of the first failure of each phase, the DC current sensor value Idcs, the duty values Du, Dv, Dw of each phase, and the target torque of the power semiconductor in the power conversion circuit 60. It is determined which part has failed, and a failure notification signal corresponding to the failed part is output to the failure notification device 30 and the PWM signal generation unit 44. The failure determination unit 452 determines the target torque and identifies whether it is during power running or regeneration. Specifically, when the target torque is positive, it means that it is in power running, and when the target torque is negative, it means that it is in regeneration. As another identification method, if the DC current sensor value Idcs is positive, it may be identified as power running, and if the DC current sensor value Idcs is negative, it may be identified as regenerative.

FIG. 2 is a circuit configuration diagram of the power conversion circuit 60.
The power conversion circuit 60 has a UVW phase upper and lower arm series circuit. The U-phase upper and lower arm series circuit 61 includes a U-phase upper arm power semiconductor Tu and a U-phase upper arm diode Du, and a U-phase lower arm power semiconductor Tu and a U-phase lower arm diode Du. The V-phase upper and lower arm series circuit 62 includes a V-phase upper arm power semiconductor Tv and a V-phase upper arm diode Dvu, and a V-phase lower arm power semiconductor Tvl and a V-phase lower arm diode Dvl. The W-phase upper and lower arm series circuit 63 includes a W-phase upper arm power semiconductor Tww and a W-phase upper arm diode Dwoo, and a W-phase lower arm power semiconductor Twl and a W-phase lower arm diode Dwl.

The upper arm circuit 64 includes a U-phase upper arm power semiconductor Tu and a U-phase upper arm diode Du, a V-phase upper arm power semiconductor Tv and a V-phase upper arm diode Dv, and a W-phase upper arm power semiconductor Tww and a W-phase upper arm. It has a diode Dwoo. The lower arm circuit 65 includes a U-phase lower arm power semiconductor Tul and a U-phase lower arm diode Dul, a V-phase lower arm power semiconductor Tvl and a V-phase lower arm diode Dvl, and a W-phase lower arm power semiconductor Twl and a W-phase lower arm. It has a diode Dwl. The power semiconductor is, for example, a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor).

The smoothing capacitor 66 smoothes the current generated by ON / OFF of the power semiconductor and suppresses the ripple of the DC current supplied from the DC power supply 10 to the power conversion circuit 60. For the smoothing capacitor 66, for example, an electrolytic capacitor or a film capacitor is used.

FIG. 3 is a flowchart showing a failure determination process of the power semiconductor in the power semiconductor diagnosis unit 45.
As shown in step S10 of FIG. 3, the power semiconductor diagnostic unit 45 acquires the AC current sensor values Ius, Ivs, Iws and the DC current sensor value Idcs.

In step S11, the simulated DC current calculation unit 451 uses the duty values Du, Dv, Dw of each phase and the AC current sensor values Ius, Ivs, and Iws based on the following equations (1) to (3). 1 The simulated DC current value Idcu at the time of failure, the simulated DC current value Idcv at the time of the first failure of the V phase, and the simulated DC current value Idcw at the time of the first failure of the W phase are calculated and output to the failure determination unit 452.
Simulated DC current at the time of U-phase first failure Idcu = Dv × Ivs + Dw × Iws (1)
Simulated DC current at the time of V-phase first failure Idcv = Du × Ius + Dw × Iws (2)
Simulated DC current at the time of W phase 1st failure Idcw = Du × Ius + Dv × Ivs (3)

In step S12, the failure determination unit 452 determines that a failure has occurred in the U-phase power semiconductor when the difference between the DC current sensor value Idcs and the simulated DC current value Idcu at the time of the first U-phase failure is less than the threshold value 1. To do. When an OFF sticking failure of a power semiconductor occurs, the simulated DC current at the time of the first failure of the phase concerned becomes substantially equal to the actual DC current value during the time period when a current is to be passed through the failed power semiconductor. The threshold value 1 is set to a value at which this relationship holds. This makes it possible to determine in which phase the failure occurred.
In step S13, the failure determination unit 452 determines whether the motor 20 is in the power running state or the regenerative state based on the input target torque or the like.

If it is determined to be in the power running state, the process proceeds to step S14, and in step S14, the failure determination unit 452 determines whether the U-phase duty value Du is larger than the threshold value 2. When the U-phase duty value Du is larger than the threshold value 2, it is determined in step S16 that the U-phase upper arm circuit power semiconductor has an OFF sticking failure. If the U-phase duty value Du is not larger than the threshold value 2, it is determined in step S17 that the U-phase lower arm circuit power semiconductor has an OFF sticking failure. If the U-phase duty value Du is in the range of 0 to 1, the threshold value 2 is set to, for example, 0.5. As a result, it is determined whether the current is going to flow through the upper arm circuit or the lower arm circuit.

If it is determined in step S13 that the state is regenerated, the process proceeds to step S15, and in step S15, the failure determination unit 452 determines whether the U-phase duty value Du is equal to or less than the threshold value 2. If the U-phase duty value Du is a threshold value of 2 or less, it is determined in step S16 that the U-phase upper arm circuit power semiconductor has an OFF sticking failure. If the U-phase duty value Du is not equal to or less than the threshold value 2, it is determined in step S17 that the U-phase lower arm circuit power semiconductor has an OFF sticking failure.
In step S18, the failure determination unit 452 outputs a failure notification signal corresponding to the failure location to the PWM signal generation unit 44 and the failure notification device 30.

As described above, since no current flows through the failed power semiconductor, the DC current becomes substantially equal to the simulated DC current at the time of the first failure of the failure phase when the current is tried to flow to the failure location. At this time, since it is possible to know which of the upper and lower arms is mainly ON by the duty value of the failure phase, the failure location of the upper and lower arms can be determined by the duty. Since the phases of the voltage (that is, the duty) and the current are the same during power running, the time zone in which the duty is larger than the threshold value 0.5 and the time zone in which the current is to be passed through the upper arm match. On the other hand, during regeneration, the phases of the voltage (that is, the duty) and the current are shifted by 180 °, so that the time zone when the duty is smaller than the threshold value 0.5 and the time zone when the current is to be passed through the upper arm coincide.
Steps S22 to S27 indicate a V-phase failure determination process, and steps S32 to S37 indicate a W-phase failure determination process.

If the difference between the DC current sensor value Idcs and the simulated DC current value Idcu at the time of the first U-phase failure is not less than the threshold value 1 in step S12, the process proceeds to step S22. In step S22, the failure determination unit 452 determines that a failure has occurred in the V-phase power semiconductor when the difference between the DC current sensor value Idcs and the simulated DC current value Idcv at the time of the first failure of the V phase is less than the threshold value 1. To do. Hereinafter, since steps S22 to S27 are the same as steps S12 to S17 which are U-phase failure determination processes, the description thereof will be omitted.

If the difference between the DC current sensor value Idcs and the simulated DC current value Idcv at the time of the first failure of the V phase is not less than the threshold value 1 in step S22, the process proceeds to step S32. In step S32, the failure determination unit 452 determines that a failure has occurred in the W-phase power semiconductor when the difference between the DC current sensor value Idcs and the simulated DC current value Idcw at the time of the first W-phase failure is less than the threshold value 1. To do. Hereinafter, steps S32 to S37 are the same as steps S12 to S17, which are U-phase failure determination processes, and thus the description thereof will be omitted.

In step S32, the failure determination unit 452 proceeds to step S39 if the difference between the DC current sensor value Idcs and the simulated DC current value Idcw at the time of the first W phase failure is not less than the threshold value 1. In step S39, it is determined that there is no OFF sticking failure in the power semiconductor.

FIG. 4 is a flowchart showing a failure handling process of the PWM signal generation unit 44.
The PWM signal generation unit 44 receives the failure notification signal from the failure determination unit 452 and starts the failure handling process. When the failure notification signal is received in step S18 of FIG. 3 and it is determined in step S40 of FIG. 4 that an upper arm OFF sticking failure of any of the U phase, V phase, and W phase has occurred, the step is taken. Proceed to S41.
In step S41, a PWM signal is generated so as to be in the freewheel state or the lower arm active short state. Since the power semiconductor of the upper arm circuit cannot be turned on due to a failure, the upper arm circuit is not put into the active short state.

If it is determined in step S42 that the lower arm OFF sticking failure of any of the U phase, V phase, and W phase has occurred, the process proceeds to step S43.
In step S43, a PWM signal is generated so as to be in the freewheel state or the upper arm active short state. Since the power semiconductor of the lower arm circuit cannot be turned on due to a failure, the lower arm circuit is not put into the active short state.

If neither failure corresponds to step S40 or step S42, the process proceeds to step S44. In step S44, since no failure has occurred, the PWM signal generation unit 44 continues the PWM operation, generates a PWM signal corresponding to the duty values Du, Dv, and Dw of each phase, and outputs the PWM signal to the driver circuit 50.

5 (A), 5 (B), and 5 (C) are graphs of alternating current, duty, and direct current when a failure of OFF sticking occurs in the U-phase upper arm circuit during power running. ..
FIG. 5A shows an alternating current, FIG. 5B shows a duty, FIG. 5C shows a direct current, and the horizontal axis of each graph is time. At time t, a case where a failure of OFF sticking occurs in the U-phase upper arm circuit during power running is shown.

As shown in FIG. 5 (A), since the failure of OFF sticking occurred in the U-phase upper arm circuit at time t, the AC current sensor value Ius flowing through the U-phase becomes zero. As shown in FIG. 5C, a time zone in which the simulated DC current value Idcu at the time of the first U-phase failure is close to the DC current sensor value Idcs occurs, and in this time zone, as shown in step S13 of FIG. It is determined that the difference between the DC current sensor value Idcs and the simulated DC current value Idcu at the time of the first U-phase failure is less than the threshold value 1. Then, in this time zone, as shown in FIG. 5 (B), the duty value Du of the U phase exceeds 0.5. Therefore, as shown in step S14 of FIG. 3, it is determined that the U-phase duty value Du is larger than the threshold value 2. As a result, in step S16 of FIG. 3, it is determined that the U-phase upper arm circuit power semiconductor has an OFF sticking failure.

[Second Embodiment]
FIG. 6 is a circuit configuration diagram of the power conversion device 200 according to the second embodiment.
The power conversion device 200 according to the second embodiment does not include the DC current sensor 80 as compared with the power conversion device 100 according to the first embodiment shown in FIG. 1, and the power semiconductor diagnostic unit 46 It is different. The same parts as those of the power conversion device 100 according to the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and the different parts will be described below.

The simulated DC current calculation unit 461 of the power semiconductor diagnostic unit 46 calculates the simulated DC current at the time of the first failure of each phase based on the equations (1) to (3) shown in the first embodiment. Furthermore, the simulated DC current value at normal time is calculated using the phase duty Du, Dv, Dw and the AC current sensor values Ius, Ivs, and Iws of each phase. That is, since the DC current in the normal state can be calculated by the following equation (4), the value calculated by this equation (4) is used instead of the DC current sensor.
DC current = (Du x Ius) + (Dv x Ivs) + (Dv x Iws) (4)
Here, Du: U phase duty ratio, Dv: V phase duty ratio, Dw: W phase duty ratio, Ius: U phase AC current sensor value, Ivs: V phase AC current sensor value, Iws: W phase AC current sensor value Is.

The simulated DC current calculation unit 461 outputs the calculated DC current to the failure determination unit 462. The failure determination unit 462 uses the simulated DC current value at the time of the first failure of each phase, the simulated DC current value at the time of normal operation, the duty values Du, Dv, Dw of each phase, and the target torque, and uses the power semiconductor in the power conversion circuit 60. It is determined which part of the device is out of order, and a failure notification signal corresponding to the failure part is output to the failure notification device 30 and the PWM signal generation unit 44. The failure determination unit 462 determines the target torque to determine whether it is during power running or regeneration. Specifically, when the target torque is positive, it means that it is in power running, and when the target torque is negative, it means that it is in regeneration. As another identification method, when the simulated DC current calculated by the simulated DC current calculation unit 461 during normal operation is positive, it is assumed to be during power running, and when the simulated DC current calculated by the simulated DC current calculation unit 461 during normal operation is negative, it is assumed that it is during power running. It may be identified as being regenerated.

FIG. 7 is a flowchart showing a failure determination process of the power semiconductor in the power semiconductor diagnosis unit 46.
The failure determination process in the power semiconductor diagnostic unit 46 according to the second embodiment is described by assigning the same reference numerals to the same parts as the flowchart showing the failure determination process according to the first embodiment shown in FIG. Will be omitted, and the different parts will be described below.
As shown in step S10'in FIG. 7, the power semiconductor diagnostic unit 46 acquires the AC current sensor values Ius, Ivs, and Iws.

In step S11', the simulated DC current calculation unit 461 uses the duty values Du, Dv, Dw of each phase and the AC current sensor values Ius, Ivs, and Iws based on the equations (1) to (3), and the U phase phase. 1 The simulated DC current value Idcu at the time of failure, the simulated DC current value Idcv at the time of the first failure of the V phase, and the simulated DC current value Idcw at the time of the first failure of the W phase are calculated and output to the failure determination unit 462. Further, the normal simulated DC current Idce, which is the normal DC current, is calculated based on the equation (4) and output to the failure determination unit 462.

In step S12', when the difference between the normal simulated DC current Idce and the U-phase first fault simulated DC current value Idcu is less than the threshold value 1, the fault determination unit 462 has failed in the U-phase power semiconductor. Is determined. When an OFF sticking failure of a power semiconductor occurs, the simulated DC current at the time of the first failure of the phase concerned becomes substantially equal to the actual DC current value during the time period when a current is to be passed through the failed power semiconductor. The threshold value 1 is set to a value at which this relationship holds. This makes it possible to determine in which phase the failure occurred.

In step S13, the failure determination unit 462 determines whether the motor 20 is in the power running state or the regenerative state based on the input target torque or the like. Hereinafter, it is the same as the flowchart showing the failure determination process according to the first embodiment shown in FIG.

If the difference between the normal simulated DC current Idce and the U-phase first failure simulated DC current value Idcu is not less than the threshold value 1 in step S12', the process proceeds to step S22'. In step S22', when the difference between the normal simulated DC current Idce and the V-phase first fault simulated DC current value Idcv is less than the threshold value 1, the fault determination unit 462 has failed in the V-phase power semiconductor. Is determined. Hereinafter, since steps S23 to S27 are the same as the U-phase failure determination processing steps S13 to S17, the description thereof will be omitted.

In step S22', if the difference between the normal simulated DC current Idce and the V-phase first fault simulated DC current value Idcv is not less than the threshold value 1, the process proceeds to step S32'. In step S32', when the difference between the normal simulated DC current Idce and the W-phase first fault simulated DC current value Idcw is less than the threshold value 1, the failure determination unit 462 has failed in the W-phase power semiconductor. Is determined. Hereinafter, since steps S33 to S37 are the same as the U-phase failure determination processing steps S13 to S17, the description thereof will be omitted.

In step S32', the failure determination unit 462 proceeds to step S39 if the difference between the normal simulated DC current Idce and the W-phase first fault simulated DC current value Idcw is not less than the threshold value 1. In step S39, it is determined that there is no OFF sticking failure in the power semiconductor.

[Third Embodiment]
FIG. 8 is a circuit configuration diagram of the power conversion device 300 according to the third embodiment.
The power conversion device 300 according to the third embodiment is different from the power semiconductor diagnostic unit 47 in the power conversion device 100 according to the first embodiment shown in FIG. The same parts as those of the power conversion device 100 according to the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and the different parts will be described below.

The simulated DC current calculation unit 471 of the power semiconductor diagnostic unit 47 calculates the simulated DC current at the time of the first failure of each phase based on the equations (1) to (3) shown in the first embodiment. Further, the simulated DC current at the time of the second failure of each phase is calculated based on the following equations (5) to (7).
Simulated DC current at the time of U-phase second failure Idcu2 = K × Ius + Dv × Ivs + Dw × Iws (5)
Simulated DC current at the time of V-phase second failure Idcv2 = Du × Ius + K × Ivs + Dw × Iws (6)
Simulated DC current at the time of W phase second failure Idcw2 = Du × Ius + Dv × Ivs + K × Iws (7)
Here, Du: U phase duty ratio, Dv: V phase duty ratio, Dw: W phase duty ratio, Ius: U phase AC current sensor value, Ivs: V phase AC current sensor value, Iws: W phase AC current sensor value , K is a coefficient. The coefficient K is set in the range of 0 <K ≦ 1. The simulated DC current at the time of the first failure of the equations (1) to (3) shown in the first embodiment corresponds to the case where the equations (5) to (7) are calculated with K = 0. To avoid false positives during normal operation, it is desirable to set K to a value that differs significantly from 0 (for example, K = 1).

The simulated DC current at the time of the first failure and the simulated DC current at the time of the second failure of each phase calculated by the simulated DC current calculation unit 471 are output to the failure determination unit 472.

The failure determination unit 472 determines the simulated DC current value at the time of the first failure of each phase, the simulated DC current value at the time of the second failure of each phase, the DC current sensor value Idcs, the duty values Du, Dv, Dw of each phase, and the target torque. It is used to determine which part of the power semiconductor in the power conversion circuit 60 has failed, and outputs a failure notification signal corresponding to the failed part to the failure notification device 30 and the PWM signal generation unit 44.

In the present embodiment, the failure determination unit 472 has a difference between the DC current sensor value Idcs and the simulated DC current value at the time of the first failure less than the threshold value 1, and the DC current sensor value Idcs and the simulated DC current value at the time of the second failure are It is determined whether the difference between the and is less than the threshold value 1.

Since no current flows through the failed power semiconductor, the simulated DC current at the time of the second failure using the AC current of all three phases and the DC current are also equal. Therefore, it is possible to identify the faulty part even if the simulated DC current at the time of the second fault is additionally used. When only the difference between the DC current sensor value Idcs and the simulated DC current value at the time of the first failure is judged, the simulated DC current value at the time of the first failure and the DC current other than the failure phase at the timing when the duty is small (duty ≈ 0) Is close to each other, which may induce false detection of failure. On the other hand, in the present embodiment, the difference between the DC current sensor value Idcs and the simulated DC current value at the time of the first failure is less than the threshold value 1, and the DC current sensor value Idcs and the simulated DC current value at the time of the second failure are By determining whether the difference between the current and the current is less than the threshold value 1, the false detection of the failure can be eliminated.

FIG. 9 is a flowchart showing a failure determination process of the power semiconductor in the power semiconductor diagnosis unit 47.

The failure determination process in the power semiconductor diagnostic unit 47 according to the third embodiment is described by assigning the same reference numerals to the same parts as the flowchart showing the failure determination process according to the first embodiment shown in FIG. Will be omitted, and the different parts will be described below.

In step S10 of FIG. 9, the power semiconductor diagnostic unit 45 acquires the AC current sensor values Ius, Ivs, Iws and the DC current sensor value Idcs, and in step S11'', the simulated DC current calculation unit 471 obtains the duty value Du. , Dv, Dw and AC current sensor values Ius, Ivs, Iws, U phase, simulated DC current value at the time of the first failure, Idcu, V phase, based on the equations (1) to (3) described in the first embodiment. The simulated DC current value Idcv at the time of the first failure and the W phase simulated DC current value Idcw at the time of the first failure are calculated and output to the failure determination unit 472. Further, the simulated DC current calculation unit 471 is based on the equations (5) to (7), the simulated DC current value Idcu2 at the time of the U-phase second failure, the simulated DC current value Idcv2 at the time of the V-phase second failure, and the W-phase second. The simulated DC current value Idcw2 at the time of failure is calculated and output to the failure determination unit 472.

In step S12'', the failure determination unit 472 simulates that the difference between the DC current sensor value Idcs and the U-phase first failure simulated DC current value Idcu is less than the threshold value 1 and the DC current sensor value Idcs and the U-phase second failure. When the difference between the DC current values Idcu2 is less than the threshold value 1, it is determined that the U-phase power semiconductor has a failure.

In step S13, the failure determination unit 462 determines whether the motor 20 is in the power running state or the regenerative state based on the input target torque or the like. Hereinafter, steps S13 to S18 are the same as the flowchart showing the failure determination process according to the first embodiment shown in FIG.

In step S12'', the failure determination unit 472 simulates that the difference between the DC current sensor value Idcs and the U-phase first failure simulated DC current value Idcu is less than the threshold value 1 and the DC current sensor value Idcs and the U-phase second failure. If the condition that the difference between the DC current values Idcu2 is less than the threshold value 1 is not satisfied, the process proceeds to step S22''. In step S22'', the failure determination unit 472 simulates that the difference between the DC current sensor value Idcs and the V-phase first failure simulated DC current value Idcv is less than the threshold value 1 and the DC current sensor value Idcs and the V-phase second failure. When the difference between the DC current values Idcv2 is less than the threshold value 1, it is determined that the V-phase power semiconductor has a failure. Hereinafter, since steps S23 to S27 are the same as the U-phase failure determination processing steps S13 to S17, the description thereof will be omitted.

In step S22'', the difference between the DC current sensor value Idcs and the simulated DC current value Idcv at the time of the first failure of the V phase is less than the threshold value 1, and the difference between the DC current sensor value Idcs and the simulated DC current value Idcv2 at the time of the second failure of the V phase. If does not satisfy the condition of less than the threshold value 1, the process proceeds to step S32''. In step S32'', the failure determination unit 472 simulates that the difference between the DC current sensor value Idcs and the W-phase first failure simulated DC current value Idcw is less than the threshold value 1 and the DC current sensor value Idcs and the W-phase second failure. When the difference between the DC current values Idcw2 is less than the threshold value 1, it is determined that the W-phase power semiconductor has a failure. Hereinafter, since steps S33 to S37 are the same as the U-phase failure determination processing steps S13 to S17, the description thereof will be omitted.

In step S32'', the failure determination unit 462 simulates that the difference between the DC current sensor value Idcs and the W-phase first failure simulated DC current value Idcw is less than the threshold value 1, and the DC current sensor value Idcs and the W-phase second failure simulation. If the difference between the DC current values Idcw2 does not satisfy the condition of less than the threshold value 1, the process proceeds to step S39. In step S39, it is determined that there is no OFF sticking failure in the power semiconductor.

[Fourth Embodiment]
Since the power conversion device 100 according to the fourth embodiment is the same as the power conversion device 100 according to the first embodiment shown in FIG. 1, the same reference numerals are given to the same parts and the description thereof will be omitted. ..

FIG. 10 is a flowchart showing a failure determination process of the power semiconductor in the present embodiment. In this embodiment, there is a part in which the failure determination process is different from the flowchart showing the failure determination process according to the first embodiment shown in FIG. The same parts as those in the flowchart showing the failure determination process according to the first embodiment shown in FIG. 3 are designated by the same reference numerals, the description thereof will be omitted, and the different parts will be described below.

In the first embodiment, in step S12 of FIG. 3, it was determined whether the difference between the DC current sensor value Idcs and the simulated DC current value Idcu at the time of the first U-phase failure is less than the threshold value 1. In the present embodiment, in step S12 ″ of FIG. 10, it is determined whether the difference between the DC current sensor value Idcs and the simulated DC current value Idcu at the time of the first U-phase failure continues to be less than the threshold value 1 for a certain period of time or longer. .. Even if the power semiconductor has not failed, when the AC current of a certain phase is 0, the DC current sensor value and the simulated DC current value at the time of the first failure of the corresponding phase match, so there is a risk of false detection of failure. is there. Therefore, in the present embodiment, the failure is detected by detecting the failure when the difference between the DC current sensor value Idcs and the simulated DC current value Idcu at the time of the first U-phase failure is less than the threshold value 1 for a certain period of time or longer. Avoid false positives.

In step S22'''' in FIG. 10, it is determined whether the state in which the difference between the DC current sensor value Idcs and the simulated DC current value Idcv at the time of the first failure of the V phase is less than the threshold value 1 continues for a certain period of time or more.
In step S32'''in FIG. 10, it is determined whether the state in which the difference between the DC current sensor value Idcs and the simulated DC current value Idcw at the time of the first W phase failure is less than the threshold value 1 continues for a certain period of time or more.

[Fifth Embodiment]
Since the power conversion device 300 according to the fifth embodiment is the same as the power conversion device 300 according to the third embodiment shown in FIG. 8, the same reference numerals are given to the same parts and the description thereof will be omitted. ..

FIG. 11 is a flowchart showing a failure determination process of the power semiconductor in the present embodiment. In the present embodiment, there is a part in which the failure determination process is different from the flowchart showing the failure determination process according to the third embodiment shown in FIG. The same parts as those in the flowchart showing the failure determination process according to the third embodiment shown in FIG. 9 are designated by the same reference numerals, the description thereof will be omitted, and the different parts will be described below.

In the third embodiment, in step S12 ″ of FIG. 9, the difference between the DC current sensor value Idcs and the simulated DC current value Idcu at the time of the first U-phase failure is less than the threshold value 1, and the DC current sensor values Idcs and the U-phase first. 2 It was determined whether the difference between the simulated DC current values Idcu2 at the time of failure was less than the threshold value 1. In the present embodiment, in step S12'''' of FIG. 11, it is determined whether the difference between the simulated DC current value Idcu at the time of the first U-phase failure and the simulated DC current value Idcu2 at the time of the second U-phase failure is less than the threshold value 1. To do. In the third embodiment, the difference between the DC current sensor value Idcs and the U-phase first failure simulated DC current value Idcu is less than the threshold value 1, and the DC current sensor value Idcs and the U-phase second failure simulated DC current value Idcu2. When the condition that the difference is less than the threshold value 1 is satisfied, the difference between the simulated DC current value Idcu at the time of the first U-phase failure and the simulated DC current value Idcu2 at the time of the second U-phase failure also falls within a certain range. Therefore, by setting the determination conditions of the present embodiment, it is possible to perform a determination equivalent to the determination conditions of the third embodiment while simplifying the determination conditions as compared with the third embodiment.

In step S22'''' in FIG. 11, it is determined whether the difference between the simulated DC current value Idcv at the time of the first failure of the V phase and the simulated DC current value Idcv2 at the time of the second failure of the V phase is less than the threshold value 1.
In step S32'''' of FIG. 11, it is determined whether the difference between the simulated DC current value Idcw at the time of the first failure of the W phase and the simulated DC current value Idcw2 at the time of the second failure of the W phase is less than the threshold value 1.

According to the embodiment described above, the following effects can be obtained.
(1) The power conversion device 100 is composed of an upper arm circuit and a lower arm circuit corresponding to each phase of the multi-phase motor 20, and includes a power conversion circuit 60 that converts a direct current into a multi-phase alternating current. When one of the plurality of phases fails based on the control circuit 40 that outputs the PWM signal to the arm circuit and the lower arm circuit, and the direct current output from the power conversion circuit 60 and the duty ratio of the PWM signal. The simulated DC current calculation unit 451 that calculates the simulated DC current at the time of the first failure based on the AC current value of the remaining phases, the DC current input to the power conversion circuit 60, or the AC current value output from the power conversion circuit 60. Based on the DC current based on the above, the duty ratio of the PWM signal, and the simulated DC current at the time of the first failure, the failure determination unit 452 for detecting the failure of the upper arm circuit or the lower arm circuit of either phase is provided. Thereby, it is possible to identify which part of the power semiconductor constituting the upper arm circuit and the lower arm circuit is out of order.

(2) In the control method of the power conversion device 100, a power conversion circuit 60 is configured by an upper arm circuit and a lower arm circuit corresponding to each phase of the multi-phase motor 20, and a direct current is converted into a multi-phase alternating current. Then, a PWM signal is output to the upper arm circuit and the lower arm circuit, and the remainder when one of the plurality of phases fails based on the AC current output from the power conversion circuit 60 and the duty ratio of the PWM signal. The simulated DC current at the time of the first failure is calculated based on the AC current value of the phase, and the DC current input to the power conversion circuit 60 or the DC current based on the AC current value output from the power conversion circuit 60 and the PWM signal. The failure of the upper arm circuit or the lower arm circuit of either phase is detected based on the duty ratio of the above and the simulated DC current at the time of the first failure. Thereby, it is possible to identify which part of the power semiconductor constituting the upper arm circuit and the lower arm circuit is out of order.

(Modification example)
The present invention can be implemented by modifying the first to fifth embodiments described above as follows.
(1) Although the motor 20 has been described with the example of three phases having three windings inside, the motor 20 is not limited to the three phases and may be a multi-phase motor. In this case as well, a failure of the upper arm circuit or the lower arm circuit of either phase can be detected.

(2) The power conversion device 100 has an AC current sensor 90 for three phases inside, but may have only two phases. In this case, the remaining one-phase alternating current can be calculated by utilizing the fact that the sum of the three-phase alternating currents becomes 0, as in the case of having the three-phase alternating current sensors 90. Failure of the upper arm circuit or lower arm circuit of either phase can be detected.

The present invention is not limited to the above-described embodiment, and other embodiments considered within the scope of the technical idea of the present invention are also included within the scope of the present invention as long as the features of the present invention are not impaired. .. Further, the configuration may be a combination of the above-described embodiments.

10 DC power supply 20 Motor 40 Control circuit 41 Motor speed calculation unit 42 Target current calculation unit 43 Duty calculation unit 44 PWM signal generation unit 45 Power semiconductor diagnostic unit 50 Driver circuit 60 Power conversion circuit 100 Power conversion device 451 Simulated DC current calculation unit 452 Failure judgment unit

Claims

A power conversion circuit that is composed of an upper arm circuit and a lower arm circuit corresponding to each phase of a multi-phase motor and converts a direct current into a multi-phase alternating current.
A control circuit that outputs a PWM signal to the upper arm circuit and the lower arm circuit,
Based on the AC current output from the power conversion circuit and the duty ratio of the PWM signal, a simulated direct current at the time of the first failure based on the AC current value of the remaining phase when one of the plurality of phases fails. A simulated DC current calculation unit that calculates the current,
Based on the DC current input to the power conversion circuit or the DC current based on the AC current value output from the power conversion circuit, the duty ratio of the PWM signal, and the simulated DC current at the time of the first failure. A power conversion device including a failure determination unit for detecting a failure of the upper arm circuit or the lower arm circuit of any phase.
In the power conversion device according to claim 1,
A DC current sensor that measures the DC current input to the power conversion circuit is provided.
The failure determination unit is a power conversion device that detects a failure of the upper arm circuit or the lower arm circuit of any phase based on the DC current measured by the DC current sensor.
In the power conversion device according to claim 1,
The simulated DC current calculation unit calculates the DC current based on the AC current value output from the power conversion circuit based on the AC current value output from the power conversion circuit and the duty ratio of the PWM signal. ,
The failure determination unit is a power conversion device that detects a failure of the upper arm circuit or the lower arm circuit of any phase based on the calculated direct current.
In the power conversion device according to any one of claims 1 to 3.
The simulated DC current calculation unit calculates a simulated DC current at the time of a second failure based on all the AC current values of the plurality of phases, and is based on the simulated DC current at the time of the first failure and the simulated DC current at the time of the second failure. , A power conversion device that detects a failure of the upper arm circuit and the lower arm circuit in any phase.
In the power conversion device according to any one of claims 1 to 3.
When the difference between the DC current and the simulated DC current at the time of the first failure of a certain phase is a certain value or less, the failure determination unit determines that the duty ratio of the phase is equal to or more than the threshold value or the motor of the motor during power running. A power conversion device that determines that the upper arm circuit of the phase has failed if the duty ratio of the phase is equal to or less than a threshold value during regeneration.
In the power conversion device according to claim 5,
When the difference between the DC current and the simulated DC current at the time of the first failure of a certain phase is equal to or less than a certain value for a certain period of time or more, the failure determination unit determines the duty ratio of the phase during power running of the motor. A power conversion device for determining that the upper arm circuit of the phase has failed if the duty ratio of the phase is equal to or higher than the threshold value or the duty ratio of the phase is equal to or lower than the threshold value when the motor is regenerated.
In the power conversion device according to claim 5,
When the failure determination unit determines that the upper arm circuit has failed, the control circuit turns off all the power semiconductors constituting the upper arm circuit and the lower arm circuit of the power conversion circuit. A power conversion device that outputs the PWM signal that turns on all the power semiconductors constituting the lower arm circuit of the power conversion circuit.
In the power conversion device according to any one of claims 1 to 3.
When the difference between the DC current and the simulated DC current at the time of the first failure of a certain phase is a certain value or less, the failure determination unit determines that the duty ratio of the phase is equal to or less than the threshold value or the motor of the motor during power running of the motor. A power conversion device that determines that the lower arm circuit of the phase has failed if the duty ratio of the phase is equal to or greater than the threshold value during regeneration.
In the power conversion device according to claim 8,
When the difference between the DC current and the simulated DC current at the time of the first failure of a certain phase is equal to or less than a certain value for a certain period of time or more, the failure determination unit determines the duty ratio of the phase during power running of the motor. A power conversion device that determines that the lower arm circuit of the phase has failed if is equal to or less than the threshold value, or if the duty ratio of the phase is equal to or greater than the threshold value during regeneration of the motor.
In the power conversion device according to claim 8,
When the failure determination unit determines that the lower arm circuit has failed, the control circuit turns off all the power semiconductors constituting the upper arm circuit and the lower arm circuit of the power conversion circuit. A power conversion device that outputs the PWM signal that turns on the PWM signal or all the power semiconductors constituting the upper arm circuit of the power conversion circuit.
A power conversion circuit is composed of an upper arm circuit and a lower arm circuit corresponding to each phase of a multi-phase motor, and a direct current is converted into a multi-phase alternating current.
A PWM signal is output to the upper arm circuit and the lower arm circuit,
Based on the AC current output from the power conversion circuit and the duty ratio of the PWM signal, the simulated DC at the time of the first failure based on the AC current value of the remaining phase when one of the plurality of phases fails. Calculate the current and
Based on the DC current input to the power conversion circuit or the DC current based on the AC current value output from the power conversion circuit, the duty ratio of the PWM signal, and the simulated DC current at the time of the first failure. A method for controlling a power converter that detects a failure of the upper arm circuit or the lower arm circuit of any phase.
In the control method of the power conversion device according to claim 11,
A DC current sensor that measures the DC current input to the power conversion circuit is provided.
A control method for a power conversion device that detects a failure of the upper arm circuit or the lower arm circuit of any phase based on the direct current measured by the direct current sensor.
In the control method of the power conversion device according to claim 11,
Based on the AC current value output from the power conversion circuit and the duty ratio of the PWM signal, the DC current based on the AC current value output from the power conversion circuit is calculated.
A control method for a power conversion device that detects a failure of the upper arm circuit or the lower arm circuit of any phase based on the calculated direct current.
The method for controlling a power conversion device according to any one of claims 11 to 13.
A second failure simulated DC current is calculated based on all the AC current values of the plurality of phases, and based on the first failure simulated DC current and the second failure simulated DC current, the above of any phase. A method for controlling a power conversion device that detects a failure of an arm circuit and the lower arm circuit.
The method for controlling a power conversion device according to any one of claims 11 to 13.
When the difference between the DC current and the simulated DC current at the time of the first failure of a certain phase is equal to or less than a certain value, the duty ratio of the phase is equal to or more than the threshold value when the motor is running, or the phase is said to regenerate. A control method for a power conversion device that determines that the upper arm circuit of the relevant phase has failed if the duty ratio is equal to or less than a threshold value.
In the control method of the power conversion device according to claim 15,
When the difference between the DC current and the simulated DC current at the time of the first failure of a certain phase is equal to or less than a certain value for a certain period of time or more, the duty ratio of the phase is equal to or more than the threshold value or the said. A control method for a power conversion device that determines that the upper arm circuit of the phase is out of order if the duty ratio of the phase is equal to or less than a threshold value when the motor is regenerated.
In the control method of the power conversion device according to claim 15,
When it is determined that the upper arm circuit is out of order, all the power semiconductors constituting the upper arm circuit and the lower arm circuit of the power conversion circuit are turned off, or the lower part of the power conversion circuit is turned off. A method for controlling a power conversion device that outputs a PWM signal that turns on all power semiconductors constituting an arm circuit.
The method for controlling a power conversion device according to any one of claims 11 to 13.
When the difference between the DC current and the simulated DC current at the time of the first failure of a certain phase is equal to or less than a certain value, the duty ratio of the phase is equal to or less than the threshold value during power running of the motor, or the said phase of the phase is regenerated. A control method for a power conversion device that determines that the lower arm circuit of the relevant phase has failed if the duty ratio is equal to or greater than a threshold value.
In the control method of the power conversion device according to claim 18,
When the difference between the DC current and the simulated DC current at the time of the first failure of a certain phase is equal to or less than a certain value for a certain period of time or more, the duty ratio of the phase is equal to or less than the threshold value or the said. A control method for a power conversion device that determines that the lower arm circuit of the phase is out of order if the duty ratio of the phase is equal to or greater than a threshold value when the motor is regenerated.
In the control method of the power conversion device according to claim 18,
When it is determined that the lower arm circuit is out of order, the PWM signal that turns off the upper arm circuit of the power conversion circuit and all the power semiconductors constituting the lower arm circuit, or the power conversion. A method for controlling a power conversion device that outputs a PWM signal that turns on all power semiconductors constituting the upper arm circuit of the circuit.