JP2019170057A - Motor control device - Google Patents

Abstract

To provide a motor control device capable of identifying one-phase short circuit and a plurality-phase short circuit without being influenced by an off-set deviation caused by a variance of a current sensor and a noise.SOLUTION: A phase current peak-value acquiring section 44 acquires a maximum current and a minimum current of each phase on the basis of a detected value or an estimated value of a phase current in a period of one electricity cycle or more of MG80. When a short-circuit occurrence of an inverter 60 is detected by a short-circuit occurrence detection section 43, a short-circuit phase number determination section 45 executes a short-circuit phase number determination processing for identifying whether the short-circuit of the inverter is one-phase short circuit or two-phase or three-phase short circuit on the basis of the maximum current and the minimum current of each phase. When the minimum current of the specific phase, being one arbitrary phase among three phases, is larger than the maximum current of the other two phases or the maximum current of the specific phase is smaller than the minimum current of the other two phases, the short-circuit phase number determination section 45 determines that the short circuit is one-phase short circuit of a specific phase in the short-circuit phase number determination processing. Except the one-phase short circuit, it determines that the short circuit is a plurality-phase short circuit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor control device.

  Conventionally, in a motor control device that supplies power to a three-phase AC motor with an inverter, the number of short-circuited phases is determined when a short-circuit fault occurs in one or more switching elements of the inverter, and an abnormal action is selected based on the number of short-circuited phases The technology to do is known.

  For example, the short-circuit phase specifying method disclosed in Patent Document 1 takes an absolute value of a signal obtained by smoothing processing, and always defines a value taken out as a positive current value as an “annealed absolute value”. A value obtained by smoothing and extracting a signal used for smoothing processing as an absolute value is defined as an “absolute smoothing value”. And 1 phase short circuit, 2 phase short circuit, and 3 phase short circuit are determined with a current level using the difference electric current value of "absolute annealing value" and "abnormal annealing absolute value".

  In addition, the electric motor system disclosed in Patent Document 2 determines that a three-phase short circuit occurs when all of the three-phase AC current generated by the back electromotive force of the three-phase AC motor crosses zero, and the two-phase AC current zero-crosses. In this case, it is determined as a two-phase short circuit, and it is determined as a one-phase short circuit when all of the three-phase alternating currents do not cross zero.

Japanese Patent No. 5003589 JP, 2006-123141, A

  In the technique of Patent Document 1, there is a risk of erroneously identifying whether it is a one-phase short circuit or a two-phase or three-phase multi-phase short circuit due to the effect of offset deviation due to variations in current sensors. Further, in the technique of Patent Document 2, there is a possibility that the zero cross determination may be erroneous due to the effect of offset deviation due to variations in current sensors and noise superimposed on the current detection value.

  The present invention has been created in view of the above points, and its purpose is to distinguish between a single-phase short-circuit and a multi-phase short-circuit without being affected by offset deviation or noise due to variations in current sensors. The object is to provide a motor control device.

  The present invention converts DC power from a DC power source into three-phase AC power and supplies it to a motor (80) by an inverter (60) in which a plurality of switching elements (61-66) of three-phase upper and lower arms are bridge-connected. This is a motor control device. The motor control device includes a short-circuit occurrence detection unit (43), a phase current peak value acquisition unit (44), and a short-circuit phase number determination unit (45).

  A short circuit generation | occurrence | production detection part detects that the short circuit of the switching element of 1 phase or more generate | occur | produced in the inverter. The phase current peak value acquisition unit acquires the current maximum value and the current minimum value of each phase based on the detected value or estimated value of the phase current in a period of one or more electrical cycles of the motor. When the short circuit occurrence detection unit detects the occurrence of a short circuit of the inverter, the short circuit phase number determination unit determines whether the short circuit of the inverter is a one-phase short circuit based on the maximum current value and the minimum current value of each phase. “Short-circuited phase number determination processing” for identifying whether the phase is a three-phase multi-phase short circuit is executed.

  In the short-circuit phase number determination process, the short-circuit phase number determination unit determines whether the current value of a specific phase, which is an arbitrary one of the three phases, is larger than the current maximum value of the other two phases, or the current maximum of a specific phase When the value is smaller than the minimum current value of the other two phases, it is determined that the single phase is short-circuited for a specific phase.

  The present invention pays attention to the fact that the current amplitude range of a specific phase and the current amplitude range of the other two phases are separated from each other without overlapping each other when one phase is short-circuited, and the current maximum value and current minimum value of each phase are compared. Distinguish one-phase short-circuit and multi-phase short-circuit. In the prior arts of Patent Documents 1 and 2 that involve the calculation of the absolute value and the zero-cross determination, there is a possibility that the number of short-circuit phases may be erroneously identified due to the offset deviation of the zero reference value and the influence of noise. On the other hand, in the present invention, by comparing the magnitude relationship between the current values of each phase without using the comparison with the reference value, the one-phase short circuit can be achieved without being affected by offset deviation or noise due to variations in current sensors. A multi-phase short circuit can be properly identified.

1 is an overall configuration diagram of a motor drive system to which a motor control device according to each embodiment is applied. The current path figure at the time of a U-phase upper arm 1 phase short circuit. The figure which shows the electric current behavior at the time of (a) U-phase upper arm 1 phase short circuit, (b) Upper arm 2 phase short circuit, (c) Upper arm 3 phase short circuit. The figure which shows the current behavior at the time of (a) U-phase lower arm 1-phase short circuit, (b) lower arm 2-phase short circuit, and (c) lower arm 3-phase short circuit. The flowchart of the process at the time of the short circuit occurrence by 1st Embodiment. The time chart of the control switching at the time of the 1-phase short circuit detection by 1st Embodiment. The flowchart of the process at the time of the short circuit occurrence by 2nd Embodiment. The flowchart of the process at the time of the short circuit occurrence by 3rd Embodiment. The figure which shows the relationship between MG rotation speed and the electric current peak space | interval at the time of 1 phase short circuit. The flowchart of the process at the time of the short circuit occurrence by 4th Embodiment.

  Hereinafter, a plurality of embodiments of a motor control device will be described based on the drawings. The first to fourth embodiments are collectively referred to as “this embodiment”. The motor control device of the present embodiment is a device that controls energization of MG in a system that drives a motor generator (hereinafter “MG”) that is a power source of a hybrid vehicle or an electric vehicle. “MG” and “MG control device” in the embodiment correspond to “motor” and “motor control device”.

[System configuration]
First, an overall configuration of an MG drive system to which the MG control device of each embodiment is applied will be described with reference to FIG. The MG drive system 90 is a system that converts the DC power of the battery 11, which is a chargeable / dischargeable secondary battery, into three-phase AC power by the inverter 60 and supplies it to the MG 80. The MG control device 40 may be applied to a motor drive system that includes a converter that boosts the voltage of the battery 11 and outputs the boosted voltage to the inverter 60.

  The battery 11 is configured by a chargeable / dischargeable secondary battery such as a nickel metal hydride battery or a lithium ion battery. The positive electrode of the battery 11 is connected to the high potential line Lp, and the negative electrode of the battery 11 is connected to the low potential line Ln. Between the battery 11 and the inverter 60, the power supply relay 20 which can interrupt | block an electric power path is provided. The power supply relay 20 in FIG. 1 includes a relay 21 that can cut off the high potential line Lp and a relay 22 that can cut off the low potential line Ln. A capacitor 15 for smoothing the input voltage is provided on the battery 11 side of the inverter 60.

  In the inverter 60, six switching elements 61-66 of three-phase upper and lower arms are bridge-connected. Switching elements 61, 62, and 63 are U-phase, V-phase, and W-phase upper arm switching elements, respectively, and switching elements 64, 65, and 66 are U-phase, V-phase, and W-phase lower arm switching elements, respectively. It is an element. The switching elements 61-66 are composed of, for example, IGBTs, and freewheeling diodes that allow current flowing from the low potential side to the high potential side are connected in parallel. During normal control, in the inverter 60, the switching elements 61-66 operate according to the switching signal (“SW signal” in the figure) commanded from the inverter operation unit 41 of the MG control device 40, and the DC power from the battery 11 is three-phased. Convert to AC power.

  In the present embodiment, a situation is assumed in which a short-circuit failure has occurred in one or more switching elements 61-66. Hereinafter, a short circuit of the switching element of the one-phase upper arm or lower arm is referred to as “one-phase short circuit”, and a short circuit of the switching element of the two-phase or three-phase upper arm or lower arm is referred to as “multi-phase short circuit”. A short circuit of the switching element of the upper arm of one phase is referred to as “one-phase short circuit of the upper arm”, and a short circuit of the switching element of the lower arm of one phase is referred to as “one-phase short circuit of the lower arm”.

  The MG 80 is, for example, a permanent magnet type synchronous three-phase AC motor. The MG 80 functions as an electric motor that generates torque by a power running operation, and a generator that generates regenerative power by torque transmitted from the engine of the drive wheels or the hybrid vehicle. Although FIG. 1 illustrates a configuration in which the three-phase windings 81, 82, and 83 of the MG 80 are star-connected, a delta connection may be used.

  A current sensor 70 for detecting a phase current is provided in an energization path connected to two or more phases of the three-phase windings 81, 82, 83. When the current sensor is provided in three phases, the MG control device 40 acquires three-phase phase current values Iu, Iv, and Iw. When the current sensor is provided in two phases, the MG control device 40 acquires a two-phase phase current value and estimates the other one-phase phase current value based on Kirchoff's law. The electrical angle sensor 85 is a resolver, for example, and detects the electrical angle θ of the MG 80.

  The MG control device 40 is configured by a microcomputer or the like, and includes a CPU, a ROM, an I / O (not shown), a bus line that connects these configurations, and the like. The microcomputer executes control by software processing by executing a program stored in advance by the CPU or hardware processing by a dedicated electronic circuit.

The MG control device 40 of this embodiment includes an inverter operation unit 41, a relay operation unit 42, a short circuit occurrence detection unit 43, a phase current peak value acquisition unit 44, a short circuit phase number determination unit 45, a rotation speed calculation unit 46, and the like. The inverter operation unit 41 commands a switching signal to each switching element 61-66 of the inverter 60. During normal control, the inverter operation unit 41 performs “MG control” for calculating an output voltage command to the inverter 60 so that the MG 80 outputs torque according to the torque command Trq ^* . For example, the inverter operation unit 41 performs current feedback control using the input phase currents Iu, Iv, Iw and the electrical angle θ. Since current feedback control is a well-known technique, description thereof is omitted.

  As described above, the MG control device 40 of the present embodiment has a unique configuration that assumes a situation in which a short circuit failure has occurred in the switching elements 61-66 of the inverter 60. The relay operation unit 42 opens and closes the power supply relay 20 when the system is started or stopped, and in the third embodiment, turns off the power supply relay 20 when a short circuit is detected, as indicated by a broken line. The short-circuit occurrence detection unit 43 generates a short circuit of one or more switching elements based on information on the phase currents Iu, Iv, Iw and other abnormal information (inverter input current, inverter power, element temperature, etc.). Detect that

  When the occurrence of a short circuit in the inverter 60 is detected by the short circuit occurrence detection unit 43, the phase current peak value acquisition unit 44 determines the current of each phase based on the detected value or estimated value of the phase current in a period of one or more electrical cycles of the MG 80. The maximum values Iu_max, Iv_max, Iw_max and the minimum current values Iu_min, Iv_min, Iw_min are acquired and output to the short-circuit phase number determination unit 45.

  Specifically, the phase current peak value acquisition unit 44 holds the phase current detection value for a phase for which a detection value is acquired from the current sensor 70 during a period of one electrical cycle or more. In the configuration in which the current value of the other one phase is estimated from the detected current value of the two phases, the phase current estimated value of the other one phase is peak-held in a period of one electrical cycle or more.

  Based on the maximum current values Iu_max, Iv_max, Iw_max and the minimum current values Iu_min, Iv_min, Iw_min of each phase, the short circuit phase number determination unit 45 is a single-phase short circuit or a multiphase short circuit. “Short-circuited phase number determination processing” is performed to identify the above. Details of the “short circuit phase number determination process” will be described later.

  The rotational speed calculation unit 46 calculates the MG rotational speed N [rpm] by time differentiation of the electrical angle θ and multiplying by the conversion coefficient. As indicated by the broken line, in the third embodiment, the short circuit phase number determination unit 45 selects whether or not to execute the short circuit phase number determination process according to the MG rotation speed N.

  Next, the current path and current behavior when the inverter 60 is short-circuited will be described with reference to FIGS. FIG. 2 shows a current path at the time of one-phase short-circuit when the switching element 61 of the U-phase upper arm is short-circuited. If the current flowing in the neutral point of the MG 80 is positive and the current flowing out of the neutral point is negative, the U-phase current Iu having a relatively large amplitude flows in the positive direction. A small V-phase current Iv and a W-phase current Iw flow in the negative direction.

  FIG. 3 shows current behavior during short-circuit of (a) one upper arm phase (for example, U phase), (b) two upper arm phases (for example, U phase, V phase), and (c) three upper arm phases. 3A, when the U-phase upper arm 1-phase is short-circuited, the lower limit of the U-phase current amplitude range (that is, the current minimum value Iu_min) is the upper limit of the V-phase and W-phase current amplitude ranges (that is, the maximum current value Iv_max, Iw_max). Here, the difference between the lower limit of the U-phase current amplitude range and the upper limit of the V-phase and W-phase current amplitude ranges is referred to as a peak interval Δ. Note that “0” on the vertical axis is not used as a reference value.

  FIG. 4 shows current behavior during short-circuiting of (a) one lower arm phase (eg, U phase), (b) two lower arm phases (eg, U phase, V phase), and (c) three lower arm phases. 4A, when the U-phase lower arm 1-phase is short-circuited, the upper limit of the U-phase current amplitude range (ie, the maximum current value Iu_max) is the lower limit of the current amplitude range of the V-phase and the W-phase (ie, the minimum current value Iv_min). Iw_min). Here, the difference between the upper limit of the U-phase current amplitude range and the lower limit of the V-phase and W-phase current amplitude ranges is referred to as a peak interval Δ. Note that “0” on the vertical axis is not used as a reference value.

  Thus, in the present embodiment, attention is paid to the fact that the short-circuited current amplitude range of one phase and the normal current amplitude range of the other two phases are separated from each other without overlapping each other. Then, the short-circuit phase number determination unit 45 compares the current maximum values Iu_max, Iv_max, Iw_max and the current minimum values Iu_min, Iv_min, Iw_min of each phase to identify one-phase short-circuit and multi-phase short-circuit. Next, details of the process performed by the MG control device 40 when a short circuit occurs in the inverter 60 will be described for each embodiment.

(First embodiment)
The short-circuit occurrence process according to the first embodiment will be described with reference to the flowchart of FIG. 5 and the time chart of FIG. In the description of the flowchart below, the symbol “S” means a step. Note that a step number may be missing for the sake of sharing the step number with flowcharts of other embodiments. Moreover, the part enclosed with the broken line is equivalent to the short circuit phase number determination process.

In the initial S1, the inverter operation unit 41 operates the inverter 60 by normal control, that is, MG control following the torque command Trq ^* . In S2, it is determined whether or not a short circuit occurrence of the inverter 60 is detected by the short circuit occurrence detection unit 43. If YES, the process proceeds to S5. Further, the abnormality flag 1 in FIG. 6 is turned ON. In S5, the phase current peak value acquisition unit 44 acquires the current maximum values Iu_max, Iv_max, Iw_max and the current minimum values Iu_min, Iv_min, Iw_min of each phase.

  In S <b> 6, the short circuit phase number determination unit 45 determines whether or not the “one-phase short circuit condition” is satisfied. The “one-phase short-circuit condition” is satisfied when at least one of the “upper arm one-phase short-circuit condition” or the “lower arm one-phase short-circuit condition” is satisfied. The “upper arm one-phase short-circuit condition” is satisfied when any of the expressions (1.1), (1.2), and (1.3) is satisfied. The “lower arm one-phase short-circuit condition” is satisfied when any of the expressions (2.1), (2.2), and (2.3) is satisfied.

[Upper arm 1-phase short-circuit condition]
Iu_min> Iv_max and Iu_min> Iw_max (1.1)
Iv_min> Iw_max and Iv_min> Iu_max (1.2)
Iw_min> Iu_max and Iw_min> Iv_max (1.3)

[Lower arm 1-phase short-circuit condition]
Iu_max <Iv_min and Iu_max <Iw_min (2.1)
Iv_max <Iw_min and Iv_max <Iu_min (2.2)
Iw_max <Iu_min and Iw_max <Iv_min (2.3)

  The phase in which the current minimum is evaluated in equations (1.1), (1.2), and (1.3), and the current in equations (2.1), (2.2), and (2.3) The phase for which the maximum value is evaluated is referred to as a “specific phase”. In formulas (1.1), (1.2), and (1.3), when the specific phase is the U phase, the V phase, and the W phase, one-phase short circuit of the upper arm of the specific phase occurs, respectively. Means that. In the formulas (2.1), (2.2), and (2.3), when the specific phase is the U phase, the V phase, and the W phase, the one-phase short circuit of the lower arm of the specific phase occurs, respectively. Means that.

  If YES in S6, a one-phase short circuit is detected in S7. Further, the abnormality flag 2 in FIG. 6 is turned ON. Thereafter, in S8, the inverter operation unit 41 switches the control mode of the inverter 60 from MG control to three-phase ON control. In the three-phase ON control, the three-phase upper arm is turned on and the three-phase lower arm is turned off, or the three-phase upper arm is turned off and the three-phase lower arm is turned on. The drive is substantially stopped.

  In the case of NO in S6, that is, in the case other than the single-phase short circuit, a multi-phase short circuit is detected in S9. Since it is considered that it is a serious abnormality that the switching elements of the two or three phases at once fail, the MG control device 40 immediately shuts down the inverter 60 in S10.

  In this way, the short-circuit phase number determination unit 45 determines whether the current minimum value of a specific phase, which is an arbitrary one of the three phases, is greater than the current maximum value of the other two phases, or the current maximum value of the specific phase is When the current is smaller than the other two-phase current minimum values, it is determined that the one-phase short circuit of the specific phase. In that case, YES is determined in S6, and a one-phase short circuit is detected in S7. Moreover, the short circuit phase number determination part 45 determines with it being a multi-phase short circuit, other than 1 phase short circuit. In that case, it determines with NO by S6, and a multiphase short circuit is detected by S9.

  The effect of 1st Embodiment is demonstrated compared with the prior art of patent document 1 (patent 5003589 gazette) and patent document 2 (Unexamined-Japanese-Patent No. 2006-123141). In the prior arts of Patent Documents 1 and 2 that involve the calculation of the absolute value and the zero-cross determination, there is a possibility that the number of short-circuit phases may be erroneously identified due to the offset deviation of the zero reference value and the influence of noise. On the other hand, in the first embodiment, by comparing the magnitude relationship between the current values of the respective phases without using the comparison with the reference value, the one-phase is not affected by the offset deviation or the noise due to the variation of the current sensor. A short circuit and a multiphase short circuit can be appropriately identified.

  In the first embodiment, when the one-phase short circuit is detected, the driving of the MG 80 is stopped by setting the inverter 60 to the three-phase ON control. For example, in a hybrid vehicle, the fail-safe property can be improved by switching to running with only the engine. Furthermore, the short-circuit phase number determination unit 45 executes the short-circuit phase number determination process only when the short-circuit occurrence detection unit 43 detects the short-circuit occurrence of the inverter 60, and does not execute the normal-phase other than the occurrence of the short-circuit. Therefore, it is possible to reduce the processing impossibility during normal operation.

(Second Embodiment)
A second embodiment will be described with reference to FIG. In the short-circuit phase number determination process of the second embodiment with respect to the first embodiment, whether the upper arm is short-circuited or the lower arm is short-circuited in S6 for determining the establishment of the one-phase short-circuit condition and S7 for detecting the one-phase short-circuit. Is added. After S5, first, the short circuit phase number determination unit 45 determines whether or not the upper arm one-phase short circuit condition is satisfied in S6U. If YES in S6U, an upper arm one-phase short-circuit is detected in S7U.

  In the case of NO in S6, the short circuit phase number determination unit 45 next determines whether or not the lower arm one-phase short circuit condition is satisfied in S6L. If YES in S6L, a lower arm 1-phase short circuit is detected in S7L. If an upper arm one-phase short circuit or a lower arm one-phase short circuit is detected in S7U or S7L, the control is switched to three-phase ON control in S8. If NO in S6L, a multiphase short circuit is detected in S9, and the inverter 60 is immediately shut off in S10.

  Note that the execution order of S6U and S6L may be switched. In the second embodiment, information indicating which of the upper and lower arms is the switching element having the short-circuit failure is obtained, which is useful for repairing the inverter 60 and analyzing the cause of the failure.

(Third embodiment)
A third embodiment will be described with reference to FIGS. In the process of the third embodiment shown in FIG. 8, S3 and S4 are added to the process of the first embodiment of FIG. Note that S3 and S4 are independent steps, and only one of them may be added to the processing of the first embodiment. Further, instead of the process of the first embodiment, a form in which S3 and S4 are added to the process of the second embodiment of FIG. 7 is also included in the third embodiment.

  When the occurrence of a short circuit in the inverter 60 is detected in S2, the short circuit phase number determination unit 45 instructs the relay operation unit 42 to turn off the power relay 20 in S3. That is, the short-circuit phase number determination unit 45 performs the short-circuit phase number determination process after turning off the power supply relay 20, thereby preventing the influence of power supply fluctuation during the determination.

  In S4, the short circuit phase number determination unit 45 determines whether or not the MG rotation speed N is equal to or greater than a predetermined determination limit value N_Jlim. When the MG rotation speed N is equal to or greater than the determination limit value N_Jlim, it is determined YES in S4, the process proceeds to S5, and the short-circuit phase number determination process is executed. When the MG rotation speed N is less than the determination limit value N_Jlim, it is determined NO in S4, the process proceeds to S10, and the inverter 60 is immediately shut off.

  FIG. 9 shows an example of the relationship between the MG rotation speed N and the one-phase short-circuit peak interval Δ. As a result of evaluation with MG80 having a certain operating characteristic, in any one-phase short circuit of the upper arm and the lower arm, the peak interval Δ is almost zero in the low rotation region of 200 rpm or less, and the significant peak interval Δ in the region of 300 rpm or more. Appeared. Further, when the MG rotation speed N increased to several thousand rpm or more, the peak interval Δ tended to converge. Therefore, in this example, a value near 300 rpm is set to the determination limit value N_Jlim, and when the MG rotation speed N is less than the determination limit value N_Jlim, it is determined that the success / failure determination of the one-phase short-circuit condition is impossible, and the short-circuit phase number determination The processing is not executed.

  Thereby, the determination in the area | region which cannot distinguish a 1 phase short circuit and a multiphase short circuit can be excluded beforehand. However, in reality, even if the low rotation region of less than about 300 rpm is excluded, there is no problem from the viewpoint of fail-safe when a short circuit abnormality occurs during normal traveling.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIG. In 4th Embodiment, S5F which removes noise is added after S5 of phase current peak value acquisition in a short circuit phase number determination process. In S5F, the phase current peak value acquisition unit 44 processes the peak hold value of each phase current with a low-pass filter or uses a moving average of one or more cycles of electric current, so that the maximum current value and the minimum current value of each phase are obtained. The noise is removed from the output and output to the phase current peak value acquisition unit 44. In addition, in the process of FIG. 10, although S3 of power supply relay OFF by 3rd Embodiment and S4 of rotation speed determination are implemented similarly, one or both of these may be abbreviate | omitted. In the fourth embodiment, the influence of noise on the current detection value can be reduced.

(Other embodiments)
(A) In the third embodiment, the execution of the short-circuit phase number determination process is stopped in a low rotation region where the MG rotation number N is less than the determination limit value N_Jlim. In addition, for example, when another abnormality is detected and the inverter is immediately shut off regardless of the result of the short-circuit phase number determination, the execution of the short-circuit phase number determination process may be stopped.

  (B) The motor control device of the present invention is not limited to the MG that is a power source of a hybrid vehicle or an electric vehicle, and may be applied to any three-phase AC motor to which three-phase AC power is supplied from an inverter.

  As mentioned above, this invention is not limited to the said embodiment at all, In the range which does not deviate from the meaning, it can implement with a various form.

40 ... MG control device (motor control device),
43 ... Short-circuit occurrence detection unit,
44 ... Phase current peak value acquisition unit,
45... Short circuit phase number determination unit,
60: Inverter,
61-66... Switching element,
80: MG (motor).

Claims (5)

A motor control device that converts DC power from a DC power source into three-phase AC power and supplies it to the motor (80) by an inverter (60) in which a plurality of switching elements (61-66) of the three-phase upper and lower arms are bridge-connected. Because
In the inverter, a short-circuit occurrence detection unit (43) for detecting that a short circuit of the switching element of one phase or more has occurred,
A phase current peak value acquisition unit (44) for acquiring a current maximum value and a current minimum value of each phase based on a detected value or an estimated value of a phase current in a period of one or more cycles of the motor;
When the occurrence of a short circuit in the inverter is detected by the short circuit occurrence detection unit, the short circuit of the inverter is a one-phase short circuit, a two-phase or a three-phase compound based on the maximum current value and the minimum current value of each phase. A short-circuit phase number determination unit (45) for performing a short-circuit phase number determination process for identifying whether the phase is short-circuited,
With
In the short circuit phase number determination process, the short circuit phase number determination unit,
When the current minimum value of a specific phase that is any one of the three phases is larger than the current maximum value of the other two phases, or when the current maximum value of the specific phase is smaller than the current minimum value of the other two phases The motor control device that determines that the specific phase is a one-phase short circuit and determines that it is a multi-phase short circuit in a case other than the one-phase short circuit. In the short circuit phase number determination process, the short circuit phase number determination unit,
If the current minimum value of the specific phase is larger than the current maximum value of the other two phases, it is determined that the one-phase short circuit of the upper arm of the specific phase,
The motor control device according to claim 1, wherein when the maximum current value of the specific phase is smaller than the minimum current value of the other two phases, it is determined that the one-phase short circuit of the lower arm of the specific phase.   When the occurrence of a short circuit in the inverter is detected by the short circuit occurrence detection unit, the short circuit phase number determination unit turns off the power supply relay provided between the DC power source and the inverter, and then determines the short circuit phase number. The motor control apparatus according to claim 1 or 2, wherein the process is executed.   The motor control device according to any one of claims 1 to 3, wherein the phase current peak value acquisition unit removes noise from a current maximum value and a current minimum value of each phase and outputs the noise to the short-circuited phase number determination unit. .   The motor control device according to any one of claims 1 to 4, wherein the short-circuit phase number determination unit stops the execution of the short-circuit phase number determination process when the rotation speed of the motor is less than a predetermined determination limit value. .

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