Motor short-circuit detection device and motor control system equipped therewith

Abstract

To specify short-circuited condition and a short-circuited part of a motor which is not in a steady state.SOLUTION: Amplitude and phase of secondary harmonics of d-axis current and q-axis current of a motor are calculated from secondary harmonics of the d-axis current and the q-axis current, pseudo q-axis current obtained by advancing secondary harmonics of the d-axis current by 90 deg or delaying the same by 270 deg, secondary harmonics of d-axis current and q-axis current, and secondary harmonics of pseudo d-axis current obtained by delaying the secondary harmonics of the q-axis current by 90 deg. After the amplitude and the phase of the secondary harmonics of the d-axis current and the amplitude and the phase of the secondary harmonics of the q-axis current are averaged, a low-pass filter ia applied to determine the amplitude of the secondary harmonics and the phase of the secondary harmonics and the presence / absence and site of an inter-phase short circuit or an inter-turn short circuit of the motor are specified using the amplitude of the secondary harmonics and the phase of the secondary harmonics.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a motor short-circuit detection device and a motor control system equipped therewith. [Background technology]

[0002] Electric vehicles and hybrid vehicles are widely used. Electric vehicles are equipped with a motor and are propelled by the power of the motor. Hybrid vehicles are equipped with an engine in addition to a motor and are propelled by appropriately combining the power of the motor and the engine. Generally, motor generators, in which power generation performance is considered as a design consideration, are used as motors. In addition to propelling electric vehicles, motor generators also brake electric vehicles through regenerative braking and charge the battery that drives the motor generator with the power generated by regenerative braking. In this specification, the term "motor" includes the concept of a motor generator.

[0003] As a technology related to the present invention, a method for diagnosing the degree of deterioration of an induction motor based on the harmonic components of the phase current flowing through the induction motor while the induction motor is in operation has been disclosed (Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2003-75516 [Overview of the project] [Problems that the invention aims to solve]

[0005] The conventional technology described above targets steady-state operation using induction motors, and calculates the harmonic content of the phase current using a fast Fourier transform (FFT). However, errors occur in the FFT calculation outside of steady-state operation, making it unsuitable for use in the main motors of electric vehicles and hybrid vehicles that operate in variable-speed states that are not steady-state. [Means for solving the problem]

[0006] One aspect of the present invention includes an extraction unit that measures the d-axis current and q-axis current of a motor and extracts the second harmonics of the d-axis current and the q-axis current; a first all-pass filter that changes the phase of the second harmonic of the d-axis current to calculate the second harmonic of a pseudo-q-axis current; a second all-pass filter that changes the phase of the second harmonic of the q-axis current to calculate the second harmonic of a pseudo-d-axis current; a first amplitude / phase calculation unit that calculates the amplitude and phase of the second harmonic of the d-axis current from the second harmonic of the d-axis current and the second harmonic of the pseudo-q-axis current; and a unit that calculates the amplitude and phase of the second harmonic of the q-axis current from the second harmonic of the q-axis current and the second harmonic of the pseudo-d-axis current. A motor short-circuit detection device comprising: a second amplitude / phase calculation unit; an averaging processing unit that averages the amplitude and phase of the second harmonic of the d-axis current and the amplitude and phase of the second harmonic of the q-axis current to calculate an averaged second harmonic amplitude and an averaged second harmonic phase; and a low-pass filter that is applied to the averaged second harmonic amplitude and the averaged second harmonic phase to output a second harmonic amplitude and a second harmonic phase, wherein the device performs at least one of the following: a process to detect a phase-to-phase short circuit or a turn-to-turn short circuit of the motor using the second harmonic amplitude, or a process to identify the location of a phase-to-phase short circuit or a turn-to-turn short circuit of the motor using the second harmonic phase.

[0007] Here, it is preferable that the first all-pass filter calculates the second harmonic of the pseudo-q-axis current by advancing the phase of the second harmonic of the d-axis current by 90 degrees or delaying it by 270 degrees, and the second all-pass filter calculates the second harmonic of the pseudo-d-axis current by delaying the phase of the second harmonic of the q-axis current by 90 degrees.

[0008] Furthermore, the process of identifying the location of a phase-to-phase short circuit or turn-to-turn short circuit in the motor using the second harmonic phase is preferably performed by identifying the location of the short circuit according to the phase range of the second harmonic phase.

[0009] Furthermore, the process of detecting a phase-to-phase short circuit or turn-to-turn short circuit of the motor using the second harmonic amplitude preferably involves using the second harmonic amplitude to determine the degree of the short circuit.

[0010] Another aspect of the present invention is a motor control system that controls the motor according to the determination result of a phase-to-phase short circuit or turn-to-turn short circuit of the motor by the motor short-circuit determination device.

[0011] Here, it is preferable to perform one of the following: continuous operation control, which continues the operation of the motor based on the value of the second harmonic amplitude; output torque limiting operation control, which limits the output torque of the motor during operation; or motor stop control, which stops the operation of the motor.

[0012] Furthermore, in the output torque limiting operation control, it is preferable to use currents obtained by applying a bandstop filter to remove second harmonics to the d-axis current and the q-axis current, instead of the d-axis current and the q-axis current. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a motor short-circuit determination device that identifies the short-circuit state and the location of the short circuit in a motor that is not in a steady state, and a motor control system equipped therewith. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows the configuration of a motor control system in an embodiment of the present invention. [Figure 2] This figure shows the configuration of the controller in an embodiment of the present invention. [Figure 3] This is a simulation result of what happens when an inter-turn short circuit occurs in the U-phase winding in an embodiment of the present invention. [Figure 4] This figure shows the change in the second harmonic of the dq-axis current when a VW phase short circuit occurs. [Figure 5] This figure shows the changes in the second harmonic of the three-phase current and dq-axis current when a short circuit occurs between the U-phase turns while the output torque is 0. [Figure 6] This figure shows the changes in the second harmonic of the three-phase current and dq-axis current when a UV phase short circuit occurs while the output torque is 0. [Figure 7] This figure shows the changes in the second harmonic of the three-phase current and dq-axis current when a short circuit occurs between the U-phase turns while the output torque is not zero. [Figure 8] This figure shows the changes in the second harmonic of the three-phase current and dq-axis current when a UV phase short circuit occurs while the output torque is not zero. [Figure 9] This figure shows the phase of the second harmonic of the dq-axis current when an inter-turn short circuit occurs in a state where the output torque is not zero. [Figure 10] This figure shows the phase of the second harmonic of the dq-axis current when a phase-to-phase short circuit occurs in a state where the output torque is not zero. [Figure 11] This figure shows the criteria for determining the phase of the second harmonic of the dq-axis current. [Figure 12] This is a flowchart showing the motor short-circuit detection process in this embodiment. [Figure 13] This is a flowchart showing the motor operation control process in this embodiment. [Modes for carrying out the invention]

[0015] As shown in the configuration diagram of Figure 1, the motor control system 100 in an embodiment of the present invention comprises a battery 10, an inverter 12, a motor 16, a current sensor 18, a resolver 20, a voltage sensor 22, and a controller 24. The following describes an example in which the motor control system 100 is mounted on an electric vehicle and the motor 16 drives the electric vehicle.

[0016] In the motor control system 100, the inverter 12, current sensor 18, resolver 20, and controller 24 constitute a motor control device for controlling the motor 16. The inverter 12 includes a U-phase switching arm 14u, a V-phase switching arm 14v, and a W-phase switching arm 14w. Each switching arm includes an upper switching element SP and a lower switching element SL connected in series. Each switching element may be an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). When an IGBT is used as the switching element, the two switching elements are connected in series, meaning that the collector electrode of one is connected to the emitter electrode of the other. When a MOSFET is used as the switching element, the two switching elements are connected in series, meaning that the drain electrode of the other is connected to the source electrode of the other.

[0017] When IGBTs are used as switching elements, each switching element comprises a diode in which the anode electrode is connected to the emitter electrode of the IGBT and the cathode electrode is connected to the collector electrode. When MOSFETs are used as switching elements, each switching element comprises a diode in which the anode electrode is connected to the source electrode of the MOSFET and the cathode electrode is connected to the drain electrode.

[0018] The U-phase switching arm 14u, V-phase switching arm 14v, and W-phase switching arm 14w are connected in parallel. That is, one end of the U-phase switching arm 14u, V-phase switching arm 14v, and W-phase switching arm 14w is connected in common, and the other ends of the U-phase switching arm 14u, V-phase switching arm 14v, and W-phase switching arm 14w are also connected in common. One end of each switching arm is connected to the positive terminal of the battery 10, and the other end of each switching arm is connected to the negative terminal of the battery 10.

[0019] The U-phase terminal 26u of the motor 16 is connected to the series connection point of the upper switching element SP and the lower switching element SL in the U-phase switching arm 14u. The V-phase terminal 26v of the motor 16 is connected to the series connection point of the upper switching element SP and the lower switching element SL in the V-phase switching arm 14v. The W-phase terminal 26w of the motor 16 is connected to the series connection point of the upper switching element SP and the lower switching element SL in the W-phase switching arm 14w.

[0020] The motor 16 includes a U-phase winding 16u, a V-phase winding 16v, and a W-phase winding 16w. In the example shown in Figure 1, the U-phase winding 16u, V-phase winding 16v, and W-phase winding 16w are connected in a Y-connection, with one end of each connected at a neutral point. The other ends of the U-phase winding 16u, V-phase winding 16v, and W-phase winding 16w are provided with U-phase terminals 26u, V-phase terminals 26v, and W-phase terminals 26w, respectively.

[0021] The current sensor 18 detects the current flowing through the U-phase terminal 26u, the V-phase terminal 26v, and the W-phase terminal 26w, and outputs the detected U-phase current value Iu, the detected V-phase current value Iv, and the detected W-phase current value Iw to the controller 24. The resolver 20 detects the mechanical angle θm of the motor 16 and outputs the mechanical angle θm to the controller 24. The mechanical angle θm is a value that indicates the actual rotation angle of the rotor of the motor 16. The controller 24 converts the mechanical angle θm into an electrical angle θ. The electrical angle θ is the angle obtained by converting one period of the electromagnetic field phenomenon around the rotor to 360°. The resolver 20 may also output the electrical angle θ to the controller 24. The voltage sensor 22 detects the terminal voltage of the capacitor C connected in parallel to both output terminals of the battery 10, detects the power supply voltage V, and outputs it to the controller 24.

[0022] The controller 24 controls the motor 16 based on torque command values ​​corresponding to the driving conditions and driving operations. Specifically, the controller 24 determines the d-axis current command value and the q-axis current command value based on the torque command value, and also determines the d-axis current measurement value and the q-axis current measurement value based on the U-phase current detection value Iu, the V-phase current detection value Iv, and the W-phase current detection value Iw. The controller 24 controls the inverter 12 based on the difference between the d-axis current measurement value and the d-axis current command value, the difference between the q-axis current measurement value and the q-axis current command value, and the electrical angle θ, and the inverter 12 switches the voltage applied to the motor 16.

[0023] Figure 2 shows the configuration of the controller 24. The controller 24 includes a motor control unit 40 and a short-circuit detection unit 42. The motor control unit 40 includes a three-phase / dq-axis converter 52, a current command generator 54, a d-axis subtractor 56d, a q-axis subtractor 56q, a d-axis PI calculator 58d, a q-axis PI calculator 58q, a dq-axis / three-phase converter 60, and a PWM controller 62. The controller 24 may be configured by a processor that executes a program. In this case, the processor executes a control program to realize the processing in the three-phase / dq-axis converter 52, the current command generator 54, the d-axis subtractor 56d, the q-axis subtractor 56q, the d-axis PI calculator 58d, the q-axis PI calculator 58q, the dq-axis / three-phase converter 60, and the PWM controller 62.

[0024] The three-phase / dq-axis converter 52 uses equations (1) and (2) to determine the d-axis current measurement value Iu, the U-phase current detection value Iv, and the W-phase current detection value Iw. d and q-axis current measurement I q Convert to.

[0025]

number

number

[0026] The current command generator 54 generates a torque command value T according to the driving conditions and driving operations. * Based on this, the d-axis current command value Id * and the q-axis current command value I q * are obtained. The d-axis subtractor 56d obtains the d-axis error by subtracting the d-axis current measurement value I d * from the d-axis current command value I d The q-axis subtractor 56q obtains the q-axis error by subtracting the q-axis current measurement value I q * from the q-axis current command value I q Here, the d-axis error indicates the difference between the d-axis current measurement value I d and the d-axis current command value I d * Also, the q-axis error indicates the difference between the q-axis current measurement value I q and the q-axis current command value I q * The d-axis PI calculator 58d applies proportional-integral processing to the d-axis error to obtain the d-axis control value v d The q-axis PI calculator 58q applies proportional-integral processing to the q-axis error to obtain the q-axis control value v q is obtained.

[0027] The dq-axis / three-phase converter 60 converts the d-axis control value v d and the q-axis control value v q into the U-phase voltage command value Vu, the V-phase voltage command value Vv, and the W-phase voltage command value Vw, and outputs them to the PWM controller 62. Here, the U-phase voltage command value Vu, the V-phase voltage command value Vv, and the W-phase voltage command value Vw are command values for PWM (Pulse Width Modulation) control of the U-phase switching arm 14u, the V-phase switching arm 14v, and the W-phase switching arm 14w, respectively.

[0028] The PWM controller 62 generates control signals UP and UL for the upper switching element SP and lower switching element SL of the U-phase switching arm 14u based on the U-phase voltage command value Vu. The control signal UP may be a square wave signal whose pulse width increases as the U-phase voltage command value Vu increases. The control signal UL may be a signal obtained by inverting the high / low of the control signal UP. When the control signal UP is high, the upper switching element SP of the U-phase switching arm 14u is turned on, and when the control signal UP is low, the upper switching element SP of the U-phase switching arm 14u is turned off. Similarly, when the control signal UL is high, the lower switching element SL of the U-phase switching arm 14u is turned on, and when the control signal UL is low, the lower switching element SL of the U-phase switching arm 14u is turned off.

[0029] Through a similar process, the PWM controller 62 generates control signals VP and VL for the upper switching element SP and lower switching element SL of the V-phase switching arm 14v based on the V-phase voltage command value Vv. The PWM controller 62 also generates control signals WP and WL for the upper switching element SP and lower switching element SL of the W-phase switching arm 14w based on the W-phase voltage command value Vw. Each switching element turns on when the control signal is high and turns off when the control signal is low.

[0030] For example, the control signals VP and VL are signals that are 120° behind the control signals UP and UL, respectively, and the control signals WP and WL are signals that are 120° behind the control signals VP and VL, respectively.

[0031] Through this control by the motor control unit 40, the torque command value T is applied to the U-phase winding 16u, V-phase winding 16v, and W-phase winding 16w of the motor 16. * The U-phase current iu, V-phase current iv, and W-phase current iw flow according to the corresponding values, and the motor 16 is set to the torque command value T * It generates torque corresponding to the value.

[0032] Next, the short-circuit detection unit 42 will be described. The short-circuit detection unit 42 detects a rare short (also called a layer short) as an abnormality in one of the U-phase winding 16u, V-phase winding 16v, or W-phase winding 16w. In the motor 16, the conductors that make up one phase of the windings among the multiple phase windings are adjacent to the conductors that make up the windings of other phases. Normally, adjacent conductors are insulated from each other. However, mechanical or thermal stress on the motor 16 can reduce the insulation resistance and cause a rare short. That is, a rare short can be a short circuit between windings of different phases, or an inter-phase short where the insulation resistance between windings of different phases becomes low.

[0033] Furthermore, in the motor 16, one phase winding is formed by overlapping and winding wires covered with an insulating coating. Normally, the wires are electrically insulated by the insulating coating, but mechanical or thermal stress can reduce the insulation resistance, causing a rare short circuit. Specifically, a rare short circuit can occur when different points in the wires constituting one phase winding short-circuit, or when the insulation resistance between different points in the wires constituting one phase winding becomes low, resulting in an inter-turn short circuit.

[0034] When such a rare short circuit occurs, it becomes difficult for the motor 16 to perform adequately. The short-circuit detection unit 42 detects the rare short circuit by the configuration and process described below. Figure 3 shows the configuration of the short-circuit detection unit 42 in this embodiment.

[0035] The short-circuit detection unit 42 includes a bandpass filter 64, an all-pass filter 66, a coordinate converter 68, an amplitude / phase calculator 70, an all-pass filter 72, a coordinate converter 74, an amplitude / phase calculator 76, an averaging processing unit 78, a low-pass filter 80, a short-circuit detection processing unit 82, and an operation control unit 84. The short-circuit detection unit 42 includes a d-axis current measurement value I d and q-axis current measurement I q The following is input: d-axis current measurement value I d and q-axis current measurement I qFor example, this can be input from the three-phase / dq axis converter 52 of the motor control unit 40.

[0036] The bandpass filter 64 measures the d-axis current I d and q-axis current measurement I q This is the second harmonic extraction section. The bandpass filter 64 measures the d-axis current I d Upon receiving the input, the d-axis current measurement I d Extracting the second harmonic of the d-axis current, the second harmonic I dbpf It outputs the q-axis current measurement I. q Upon receiving the input, the q-axis current measurement I q Extracting the second harmonic of the q-axis current, the second harmonic I qbpf The output is as follows. The bandpass filter 64 should be a bandpass filter with a center frequency of twice the electrical rotation frequency (dθ / dt / 2π).

[0037] The all-pass filter 66 is a d-axis current second harmonic I dbpf The phase is changed to generate the second harmonic of the pseudo-q-axis current. The all-pass filter 66 generates the second harmonic of the d-axis current I dbpf In response, the d-axis current second harmonic I dbpf The second harmonic of the pseudo-q-axis current is generated by advancing its phase by 90 degrees (or delaying it by 270 degrees) to create the pseudo-q-axis current second harmonic I. q_apf The coordinate converter 68 outputs the d-axis current second harmonic I from the bandpass filter 64. dbpf And from the all-pass filter 66, the pseudo-q-axis current second harmonic I q_apf In response, these are converted from the dq axis to the rotational second dq axis to generate the rotational second d axis current I d2h_d and rotational secondary q-axis current I q2h_d The amplitude / phase calculator 70 outputs the rotational secondary d-axis current I from the coordinate converter 68. d2h_d and rotational secondary q-axis current I q2h_d In response, the d-axis current second harmonic I dbpf and pseudo-q-axis current second harmonic I q_apf d-axis current measurement I calculated from d The d-axis current second harmonic phase I shows the phase of the second harmonic. 2hphi_d and d-axis current measurement Id The d-axis current second harmonic amplitude I shows the amplitude of the second harmonic. 2hamp_d Calculate and output the result.

[0038] The all-pass filter 72 is a q-axis current second harmonic I qbpf The phase is changed to generate the second harmonic of the pseudod-axis current. The all-pass filter 72 generates the second harmonic of the q-axis current I qbpf In response, the q-axis current second harmonic I qbpf The second harmonic of the pseudod-axis current is generated by delaying its phase by 90 degrees, resulting in the pseudod-axis current second harmonic I. d_apf The coordinate converter 74 outputs the q-axis current second harmonic I from the bandpass filter 64. qbpf And from the all-pass filter 72, the pseudo-d-axis current second harmonic I d_apf In response, these are converted from the dq axis to the rotational second dq axis to generate the rotational second d axis current I d2h_q and rotational secondary q-axis current I q2h_q The amplitude / phase calculator 76 outputs the rotational secondary d-axis current I from the coordinate converter 74. d2h_q and rotational secondary q-axis current I q2h_q In response, the q-axis current second harmonic I qbpf and pseudo-d-axis current second harmonic I d_apf q-axis current measurement I calculated from q Q-axis current second harmonic phase I, which indicates the phase of the second harmonic. 2hphi_q and q-axis current measurement I q Q-axis current second harmonic amplitude I, which shows the amplitude of the second harmonic. 2hamp_q Calculate and output the result.

[0039] The averaging processing unit 78 calculates the d-axis current second harmonic phase I from the amplitude / phase calculator 70. 2hphi_d and d-axis current second harmonic amplitude I 2hamp_d Furthermore, the amplitude / phase calculator 76 provides the q-axis current second harmonic phase I 2hphi_q and q-axis current second harmonic amplitude I 2hamp_q In response, these amplitudes and phases are averaged to obtain the averaged second harmonic phase I 2hphi and averaged second harmonic amplitude I 2hamp The low-pass filter 80 outputs the averaged second harmonic phase I from the averaging processing unit 78. 2hphi and averaged second harmonic amplitude I2hamp In response, the averaged second harmonic phase I 2hphi and averaged second harmonic amplitude I 2hamp Remove the high-frequency components and reduce the second harmonic phase I 2hphif and second harmonic amplitude I 2hampf The output is the low-pass filter 80's transmission frequency band is averaged to the extent that the short-circuit detection processing unit 82 (described later) can determine a rare short-circuit state, and the second harmonic phase I 2hphi and averaged second harmonic amplitude I 2hamp The settings should be adjusted appropriately to remove the high-frequency components. For example, the transmission frequency band of the low-pass filter 80 should be less than or equal to the transmission frequency band of the band-pass filter 64.

[0040] The short-circuit detection processing unit 82 outputs the second harmonic phase I from the low-pass filter 80. 2hphif and second harmonic amplitude I 2hampf In response, the second harmonic phase I 2hphif and second harmonic amplitude I 2hampf Based on this, the short-circuit determination processing unit 82 determines whether the motor 16 is in a rare short-circuit state. Furthermore, if the motor 16 is in a rare short-circuit state, the short-circuit determination processing unit 82 can determine whether it is a phase-to-phase short circuit or a turn-to-turn short circuit. In addition, if the motor 16 is in a phase-to-phase short circuit, the short-circuit determination processing unit 82 can determine whether it is a V-phase to W-phase short circuit (VW phase-to-phase short circuit), a W-phase to U-phase short circuit (WU phase-to-phase short circuit), or a U-phase to V-phase short circuit (UV phase-to-phase short circuit), and the degree of the short circuit. Furthermore, if the motor 16 is in a turn-to-turn short circuit, the short-circuit determination processing unit 82 can determine whether it is a U-phase turn-to-turn short circuit (U phase turn-to-turn short circuit), a V-phase turn-to-turn short circuit (V phase turn-to-turn short circuit), or a W-phase turn-to-turn short circuit (W phase turn-to-turn short circuit), and the degree of the short circuit. The determination process in the short-circuit determination processing unit 82 will be described later.

[0041] The operation control unit 84 performs operation control processing to set the operating conditions of the motor 16 according to the result of the determination of a rare short circuit state in the short-circuit determination processing unit 82. The operation control processing of the motor 16 by the operation control unit 84 will be described later.

[0042] [Short-circuit detection process] The following describes the short-circuit detection process for rare shorts in the short-circuit detection processing unit 82.

[0043] Figure 4 shows the time variation of the second harmonic of the dq-axis current (and the time variation after all-pass filtering) when the motor 16 experiences a VW phase short circuit, as well as the second harmonic amplitude and second harmonic phase of the dq-axis current output from the low-pass filter 80. As shown in Figure 4, when the motor 16 experiences a VW phase short circuit, the second harmonic phase of the dq-axis current output from the low-pass filter 80 remains stable within a phase range of 0 degrees to less than 120 degrees without significant time fluctuations. Similarly, the second harmonic amplitude of the dq-axis current output from the low-pass filter 80 also does not fluctuate significantly over time, exhibiting values ​​corresponding to the degree of the short circuit. The value corresponding to the degree of the short circuit is smaller for smaller short-circuit currents and larger for larger short-circuit currents.

[0044] Furthermore, even if motor 16 experiences a WU phase short circuit, the second harmonic amplitude and phase do not fluctuate significantly over time. When motor 16 experiences a WU phase short circuit, the second harmonic phase of the dq axis current stabilizes within a phase range of 120 degrees to less than 240 degrees. Similarly, even if motor 16 experiences a UV phase short circuit, the second harmonic amplitude and phase do not fluctuate significantly over time. When motor 16 experiences a UV phase short circuit, the second harmonic phase of the dq axis current stabilizes within a phase range of 240 degrees to less than 360 degrees.

[0045] Figure 5 shows the time variation of the second harmonic of the three-phase current and dq-axis current, as well as the second harmonic amplitude and second harmonic phase of the dq-axis current output from the low-pass filter 80, when a short circuit occurs between the U-phase turns of the motor 16 during operation with zero output torque. As shown in Figure 5, when the motor 16 experiences a short circuit between the U-phase turns, the second harmonic phase of the dq-axis current output from the low-pass filter 80 remains stable within a phase range of 90 degrees to less than 150 degrees without significant time fluctuations. Furthermore, the second harmonic amplitude of the dq-axis current output from the low-pass filter 80 is almost zero and does not fluctuate significantly over time.

[0046] Furthermore, even if the motor 16 experiences a V-phase turn-to-turn short circuit while operating with zero output torque, the second harmonic amplitude and second harmonic phase do not fluctuate significantly over time. When the motor 16 experiences a V-phase short circuit, the second harmonic phase of the dq-axis current stabilizes within a phase range of 210 degrees to less than 270 degrees, and the second harmonic amplitude of the dq-axis current stabilizes at approximately 0. Similarly, even if the motor 16 experiences a W-phase turn-to-turn short circuit while operating with zero output torque, the second harmonic amplitude and second harmonic phase do not fluctuate significantly over time. When the motor 16 experiences a W-phase short circuit, the second harmonic phase of the dq-axis current stabilizes within a phase range of 330 degrees to 360 degrees or 0 degrees to less than 30 degrees, and the second harmonic amplitude of the dq-axis current stabilizes at approximately 0.

[0047] Furthermore, if an inter-turn short circuit occurs in each of the two phases, the second harmonic phase will be in the midpoint of the phase range of the respective inter-turn short circuits. That is, if an inter-turn short circuit occurs in both the W and U phases, the second harmonic phase of the dq-axis current will stabilize in a phase range of 30 degrees to less than 90 degrees. If an inter-turn short circuit occurs in both the U and V phases, the second harmonic phase of the dq-axis current will stabilize in a phase range of 150 degrees to less than 210 degrees. If an inter-turn short circuit occurs in both the V and W phases, the second harmonic phase of the dq-axis current will stabilize in a phase range of 270 degrees to less than 330 degrees.

[0048] Figure 6 shows the three-phase current, the time variation of the second harmonic of the dq-axis current, and the second harmonic amplitude and phase of the dq-axis current output from the low-pass filter 80 when a UV-phase short circuit occurs in a motor 16 operating with zero output torque. When a UV-phase short circuit occurs in a motor 16 operating with zero output torque, the second harmonic phase of the dq-axis current stabilizes in a phase range of 240 degrees or more and less than 360 degrees. Also, the second harmonic amplitude of the dq-axis current is greater than 0 and shows a value corresponding to the degree of the short circuit.

[0049] Furthermore, if a WU phase short circuit occurs in the motor 16 while it is operating with zero output torque, the second harmonic phase of the dq axis current will stabilize in a phase range of 120 degrees or more and less than 240 degrees, and the second harmonic amplitude of the dq axis current will be greater than 0, showing a value corresponding to the degree of the short circuit. Also, if a VW phase short circuit occurs in the motor 16 while it is operating with zero output torque, the second harmonic phase of the dq axis current will stabilize in a phase range of 0 degrees or more and less than 120 degrees, and the second harmonic amplitude of the dq axis current will be greater than 0, showing a value corresponding to the degree of the short circuit.

[0050] Figure 7 shows the time variation of the second harmonic of the three-phase current and dq-axis current when a short circuit occurs between the U-phase turns of the motor 16 during operation with an output torque other than zero, as well as the second harmonic amplitude and second harmonic phase of the dq-axis current output from the low-pass filter 80. When a short circuit occurs between the U-phase turns of the motor 16 during operation with an output torque other than zero, the second harmonic phase of the dq-axis current stabilizes in a phase range of 90 degrees or more and less than 150 degrees. Also, the second harmonic amplitude of the dq-axis current is greater than zero and shows a value corresponding to the degree of the short circuit.

[0051] Furthermore, if a short circuit occurs between the V-phase turns of the motor 16 while it is operating with an output torque other than zero, the second harmonic phase of the dq-axis current will stabilize in a phase range of 210 degrees or more and less than 270 degrees, and the second harmonic amplitude of the dq-axis current will be greater than zero, showing a value corresponding to the degree of the short circuit. Also, if a short circuit occurs between the W-phase turns of the motor 16 while it is operating with an output torque other than zero, the second harmonic phase of the dq-axis current will stabilize in a phase range of 330 degrees or more and less than 360 degrees or 0 degrees or more and less than 30 degrees, and the second harmonic amplitude of the dq-axis current will be greater than zero, showing a value corresponding to the degree of the short circuit.

[0052] Furthermore, if an inter-turn short circuit occurs in each of the two phases of the motor 16 during operation when the output torque is not zero, the second harmonic phase will be in the intermediate range of the phase range for each inter-turn short circuit. That is, if an inter-turn short circuit occurs in both the W and U phases, the second harmonic phase of the dq-axis current will stabilize in a phase range of 30 degrees or more and less than 90 degrees. If an inter-turn short circuit occurs in both the U and V phases, the second harmonic phase of the dq-axis current will stabilize in a phase range of 150 degrees or more and less than 210 degrees. If an inter-turn short circuit occurs in both the V and W phases, the second harmonic phase of the dq-axis current will stabilize in a phase range of 270 degrees or more and less than 330 degrees. In all cases, the second harmonic amplitude of the dq-axis current is greater than zero and shows a value corresponding to the degree of the short circuit.

[0053] Figure 8 shows the three-phase current, the time variation of the second harmonic of the dq-axis current, and the second harmonic amplitude and phase of the dq-axis current output from the low-pass filter 80 when a UV-phase short circuit occurs in a motor 16 operating with an output torque other than zero. When a UV-phase short circuit occurs in a motor 16 operating with an output torque other than zero, the second harmonic phase of the dq-axis current stabilizes in a phase range of 240 degrees or more and less than 360 degrees, similar to when a UV-phase short circuit occurs in a motor 16 operating with an output torque of zero. Also, the second harmonic amplitude of the dq-axis current is greater than zero and shows a value corresponding to the degree of the short circuit.

[0054] Furthermore, if a WU phase short circuit occurs in the motor 16 while it is operating with an output torque other than zero, the second harmonic phase of the dq axis current will stabilize in a phase range of 120 degrees or more and less than 240 degrees, and the second harmonic amplitude of the dq axis current will be greater than zero, showing a value corresponding to the degree of the short circuit. Also, if a VW phase short circuit occurs in the motor 16 while it is operating with an output torque other than zero, the second harmonic phase of the dq axis current will stabilize in a phase range of 0 degrees or more and less than 120 degrees, and the second harmonic amplitude of the dq axis current will be greater than zero, showing a value corresponding to the degree of the short circuit.

[0055] Figure 9 is a diagram summarizing the phase of the second harmonic of the dq-axis current when a turn-to-turn short circuit occurs in each phase of a motor 16 in operation with an output torque other than zero. Figure 10 is a diagram summarizing the phase of the second harmonic of the dq-axis current when a phase-to-phase short circuit occurs between multiple phases of a motor 16 in operation with an output torque other than zero. Figure 11 is a diagram summarizing the determination conditions for the phase of the second harmonic of the dq-axis current.

[0056] Furthermore, the second harmonic phase conditions used to determine a rare short circuit are relative and will still hold even if the phase offset value is changed by any arbitrary amount.

[0057] Figure 12 is a flowchart showing the process by which the short-circuit detection processing unit 82 determines a rare short circuit. The process by which the short-circuit detection processing unit 82 determines a rare short circuit will be explained below with reference to Figure 12.

[0058] In step S10, it is determined whether the current rotational speed of the motor 16 is equal to or greater than a predetermined reference rotational speed. If the current rotational speed of the motor 16 is equal to or greater than the reference rotational speed, the process proceeds to step S12. If it is less than the reference rotational speed, the process is terminated, as it is determined that a rare short circuit cannot be detected. In this embodiment, the reference rotational speed is set to 1000 rpm as an example. However, the reference rotational speed is not limited to this, and should be set to a value that allows for appropriate detection of a rare short circuit according to the basic characteristics of the motor 16.

[0059] In step S12, based on the processing of the short-circuit determination unit 42 described above, the amplitude and phase of the second harmonic of the dq axis current (second harmonic amplitude I) 2hampf and second harmonic phase I 2hphifCalculate (). In step S14, it is determined whether the torque command value of the output torque for the motor 16 is 0. If the torque command value is 0 or approximately 0, the process proceeds to step S16. If the torque command value is other than 0, the process proceeds to step S24. Note that the reference value of the torque command for determining whether the torque command value is 0 or approximately 0 and whether it is other than 0 may be set to a value that can appropriately detect a rare short circuit according to the basic characteristics of the motor 16.

[0060] In step S16, when the torque command value to the motor 16 is 0 or approximately 0, that is, when the motor 16 is operating with an output torque of 0, a determination of a rare short circuit is made. Here, it is determined whether the amplitude of the second harmonic of the dq-axis current (second harmonic amplitude I 2hampf ) output from the low-pass filter 80 is greater than or equal to a predetermined reference amplitude value. If the amplitude of the second harmonic of the dq-axis current is greater than or equal to the reference amplitude value, the process proceeds to step S18. If it is less than the reference amplitude value, the process proceeds to step S22.

[0061] Here, the reference amplitude value may be set to a value that can appropriately detect a rare short circuit according to the basic characteristics of the motor 16. In a state where no inter-turn short circuit or short circuit has occurred, the amplitude of the second harmonic of the dq-axis current becomes approximately 0. Therefore, the reference amplitude value may be, for example, a value that can detect that the amplitude of the second harmonic of the dq-axis current is near 0.

[0062] In step S18, it is determined that an inter-phase short circuit has occurred. That is, the short circuit determination processing unit 82 determines that an inter-phase short circuit has occurred when the amplitude of the second harmonic of the dq-axis current is greater than or equal to the reference amplitude value when the motor 16 is operating with an output torque of (or approximately) 0. In step S20, the location of the inter-phase short circuit is determined. The short circuit determination processing unit 82 determines the phase of the second harmonic (second harmonic phase I 2hphifThe phases that fall within the phase range of the determination conditions () are considered to be short-circuit locations. Specifically, the determination conditions for the phase of the second harmonic of the dq-axis current shown in Figure 11 are created in a database, and this database is stored in memory so that it can be referenced by the short-circuit determination processing unit 82. By referring to this database, the short-circuit locations can be determined from the phase range of the second harmonic. However, the specific processing method is not limited to this, and the determination process based on the determination conditions for the phase of the second harmonic of the dq-axis current may be made into logic, and a program or logic circuit that performs the determination process based on this logic may be used.

[0063] In step S22, it is determined whether an inter-turn short circuit has occurred or not. Specifically, the short-circuit determination processing unit 82 determines whether an inter-turn short circuit has occurred or not when the motor 16 is operating with an output torque of 0 (or nearly 0) and the amplitude of the second harmonic of the dq axis current is less than the reference amplitude value.

[0064] If the torque command is not 0 in step S14, the process in step S24 is performed. In step S24, it is determined whether or not a phase-to-phase short circuit has occurred so far. If a phase-to-phase short circuit has occurred in the previous determination process, it is determined that a phase-to-phase short circuit has occurred and the determination process is terminated. If no phase-to-phase short circuit has occurred in the previous determination process, the process proceeds to step S26.

[0065] In step S26, a rare short circuit is determined when the motor 16 is operating with an output torque other than 0. Here, the amplitude of the second harmonic of the dq axis current output from the low-pass filter 80 (second harmonic amplitude I) is used. 2hampf It is determined whether the amplitude of the second harmonic of the dq axis current is greater than or equal to a predetermined reference amplitude value. If the amplitude of the second harmonic of the dq axis current is greater than or equal to the reference amplitude value, the process proceeds to step S28; otherwise, the process proceeds to step S32.

[0066] In step S28, it is determined that an inter-turn short circuit has occurred. That is, the short-circuit determination processing unit 82 determines that an inter-turn short circuit has occurred when the motor 16 is operating with an output torque other than 0 and the amplitude of the second harmonic of the dq axis current is greater than or equal to the reference amplitude value. In step S30, the location of the inter-turn short circuit is determined. Based on the determination condition for the phase of the second harmonic of the dq axis current, the short-circuit determination processing unit 82 determines the phase of the second harmonic (second harmonic phase I 2hphif It is assumed that an inter-turn short circuit occurs in a phase that falls within the phase range of the determination condition satisfied by ). Specifically, the determination conditions for the phase of the second harmonic of the dq axis current shown in Figure 11 are created in a database, and this database is stored in memory so that it can be referenced by the short-circuit determination processing unit 82. By referring to this database, the location of the short circuit can be determined from the phase range of the second harmonic. However, the specific processing method is not limited to this, and the determination process based on the determination conditions for the phase of the second harmonic of the dq axis current may be made into logic, and a program or logic circuit that performs the determination process based on this logic may be used.

[0067] In step S32, it is determined that no short circuit has occurred. That is, the short-circuit determination processing unit 82 determines that no short circuit has occurred when the motor 16 is operating with an output torque other than 0 and the amplitude of the second harmonic of the dq axis current is less than the reference amplitude value.

[0068] As described above, the motor control system 100 in this embodiment can detect rare short circuits in the motor 16 and pinpoint their location without calculating the harmonic content of the phase current's harmonic order using a Fast Fourier Transform (FFT). In particular, it can accurately detect rare short circuits in motors 16 mounted on electric vehicles and hybrid vehicles used in variable-speed conditions. Furthermore, it can suppress instability in the determination of short circuits and the location of short circuits due to offset errors in the three-phase current detector, gain imbalances, errors in the rotational position detector, and time changes in the amplitude and phase of the second harmonic of the dq-axis current.

[0069] [Operation control processing] Figure 13 is a flowchart showing an operation control process for controlling the operation of the motor 16 according to the determination result of a rare short circuit by the short circuit determination processing unit 82. Hereinafter, the operation control process of the motor 16 by the operation control unit 84 will be described while referring to Figure 13.

[0070] In step S40, it is determined whether the amplitude of the second harmonic of the dq-axis current (second harmonic amplitude I 2hampf ) output from the low-pass filter 80 is less than a predetermined first reference value. If the amplitude of the second harmonic of the dq-axis current (second harmonic amplitude I 2hampf ) is less than the first reference value, the process proceeds to step S42, and if it is greater than or equal to the first reference value, the process proceeds to step S44. The first reference value is set to the value of the amplitude of the second harmonic of the dq-axis current (second harmonic amplitude I 2hampf ) at which the operation of the motor 16 can be continued. For example, the first reference value is set to the maximum value of the amplitude of the second harmonic of the dq-axis current (second harmonic amplitude I 2hampf ) at which the operation of the motor 16 can be continued.

[0071] In step S42, the operation of the motor 16 is continued. The operation control unit 84 outputs a control signal to the PWM controller 62 of the motor control unit 40 to continue the operation of the motor 16 as usual. Thereby, the motor 16 continues to operate.

[0072] In step S44, it is determined whether the amplitude of the second harmonic of the dq-axis current (second harmonic amplitude I 2hampf ) output from the low-pass filter 80 is less than a predetermined second reference value. If the amplitude of the second harmonic of the dq-axis current (second harmonic amplitude I 2hampf ) is less than the second reference value, the process proceeds to step S46, and if it is greater than or equal to the first reference value, the process proceeds to step S52. The second reference value is set to the value of the amplitude of the second harmonic of the dq-axis current (second harmonic amplitude I 2hampf ) at which it is determined that the operation can be continued if a rare short circuit has occurred but the output torque from the motor 16 has been reduced. The second reference value is set to a value greater than the first reference value.

[0073] In step S46, a filter is inserted into the dq-axis current. For example, in addition to the bandpass filter 64 described above, a bandstop filter is applied to remove the frequency band of the second harmonic of the dq-axis current. By applying the bandstop filter to the dq-axis current to remove the second harmonic and generating a dq-axis current, the motor 16 can be operated without stopping by performing control based on this. In step S48, the first warning light is illuminated. The first warning light is provided, for example, on the console panel of a vehicle equipped with the motor 16, and by illuminating it, the driver can be notified that there is a problem with the motor 16. In step S50, the amplitude of the second harmonic of the dq-axis current (second harmonic amplitude I) is measured. 2hampf The torque of the motor 16 is controlled according to the magnitude of the ) (force). For example, the operation control unit 84 outputs a control signal to the PWM controller 62 of the motor control unit 40 to limit the output torque of the motor 16 more than during normal operation. As a result, the output torque of the motor 16 is controlled to output a lower torque than during normal operation.

[0074] In step S52, the motor 16 is put into stop mode. In step S54, the second warning light is illuminated. The second warning light is located, for example, on the console panel of the vehicle equipped with the motor 16, and illuminating it informs the driver that an abnormality has occurred that requires stopping the motor 16. In step S56, the motor 16 is controlled to gradually reduce its output torque to zero. For example, the driving control unit 84 outputs a control signal to the PWM controller 62 of the motor control unit 40 to gradually reduce the output torque of the motor 16 until it is zero. As a result, the output torque of the motor 16 is ultimately reduced to zero.

[0075] As described above, the short-circuit detection process and operation control process for the motor 16 in this embodiment make it possible to detect a short circuit in a motor being used in a variable-speed state without relying on calculations using FFT, and to appropriately control the motor's output torque according to the short-circuit state.

[0076] Although the embodiment shown involves mounting the motor control system 100 in an electric vehicle or a hybrid vehicle, it may also be mounted in other devices such as robots or industrial machinery.

[0077] Configuration 1: Measure the d-axis current and q-axis current of the motor. An extraction unit for extracting the second harmonic of the d-axis current and the q-axis current, A first all-pass filter that calculates the second harmonic of a pseudo-q-axis current by changing the phase of the second harmonic of the d-axis current, and a second all-pass filter that calculates the second harmonic of a pseudo-d-axis current by changing the phase of the second harmonic of the q-axis current, A first amplitude / phase calculation unit calculates the amplitude and phase of the second harmonic of the d-axis current from the second harmonic of the d-axis current and the second harmonic of the pseudo-q-axis current, and a second amplitude / phase calculation unit calculates the amplitude and phase of the second harmonic of the q-axis current from the second harmonic of the q-axis current and the second harmonic of the pseudo-d-axis current, An averaging processing unit calculates the averaged second harmonic amplitude and averaged second harmonic phase by averaging the amplitude and phase of the second harmonic of the d-axis current and the amplitude and phase of the second harmonic of the q-axis current. A low-pass filter applied to the averaged second harmonic amplitude and the averaged second harmonic phase, which outputs the second harmonic amplitude and the second harmonic phase, Equipped with, A motor short-circuit detection device characterized by performing at least one of the following: a process of detecting a phase-to-phase short circuit or a turn-to-turn short circuit of the motor using the second harmonic amplitude, or a process of identifying the location of a phase-to-phase short circuit or a turn-to-turn short circuit of the motor using the second harmonic phase. Configuration 2: A motor short-circuit detection device as described in Configuration 1, The first all-pass filter calculates the second harmonic of the pseudo-q-axis current by advancing the phase of the second harmonic of the d-axis current by 90 degrees or delaying it by 270 degrees. The motor short-circuit detection device is characterized in that the second all-pass filter calculates the second harmonic of the pseudo-d-axis current by delaying the phase of the second harmonic of the q-axis current by 90 degrees. Configuration 3: A motor short-circuit detection device according to configuration 1 or 2, A motor short-circuit detection device characterized in that the process of identifying the location of a phase-to-phase short circuit or turn-to-turn short circuit in the motor using the second harmonic phase identifies the location of the short circuit according to the phase range of the second harmonic phase. Configuration 4: A motor short-circuit detection device described in any one of configurations 1 to 3, A motor short-circuit detection device characterized in that the process of detecting a phase-to-phase short circuit or turn-to-turn short circuit of the motor using the second harmonic amplitude is used to determine the degree of the short circuit. Configuration 5: A motor control system that controls the motor according to the determination result of a phase-to-phase short circuit or turn-to-turn short circuit of the motor by a motor short-circuit detection device described in any one of configurations 1 to 4. Configuration 6: The motor control system described in configuration 5, A motor control system characterized by performing one of the following: continuous operation control, which continues the operation of the motor based on the value of the second harmonic amplitude; output torque limiting operation control, which limits the output torque of the motor during operation; and motor stop control, which stops the operation of the motor. Composition 7: The motor control system described in configuration 6, In the output torque limiting operation control, the motor control system is characterized in that a current obtained by applying a bandstop filter to remove second harmonics to the d-axis current and the q-axis current is used instead of the d-axis current and the q-axis current. [Explanation of Symbols]

[0078] 10 Battery, 12 Inverter, 14u U-phase switching arm, 14v V-phase switching arm, 14w W-phase switching arm, 16 Motor, 16u U-phase winding, 16v V-phase winding, 16w W-phase winding, 18 Current sensor, 20 Resolver, 22 Voltage sensor, 24 Controller, 26u U-phase terminal, 26v V-phase terminal, 26w W-phase terminal, 40 Motor control unit, 42 Short circuit detection unit, 42 Short circuit detection unit, 52 Three-phase / dq-axis converter, 54 Current command generator, 56d d-axis subtractor, 56q q-axis subtractor, 58d d-axis PI calculator, 58q q-axis PI calculator, 60 dq-axis / three-phase converter, 62 PWM controller, 64 Bandpass filter, 66 All-pass filter, 68 Coordinate converter, 70 Amplitude / phase calculator, 72 All-pass filter, 74 Coordinate converter, 76 Amplitude / phase calculator, 78 Averaging processing unit, 80 Low-pass filter, 82 Short-circuit detection processing unit, 84 Operation control unit.

Claims

1. Measure the d-axis current and q-axis current of the motor. An extraction unit for extracting the second harmonic of the d-axis current and the q-axis current, A first all-pass filter that calculates the second harmonic of a pseudo-q-axis current by changing the phase of the second harmonic of the d-axis current, and a second all-pass filter that calculates the second harmonic of a pseudo-d-axis current by changing the phase of the second harmonic of the q-axis current, A first amplitude / phase calculation unit calculates the amplitude and phase of the second harmonic of the d-axis current from the second harmonic of the d-axis current and the second harmonic of the pseudo-q-axis current, and a second amplitude / phase calculation unit calculates the amplitude and phase of the second harmonic of the q-axis current from the second harmonic of the q-axis current and the second harmonic of the pseudo-d-axis current, An averaging processing unit calculates the averaged second harmonic amplitude and averaged second harmonic phase by averaging the amplitude and phase of the second harmonic of the d-axis current and the amplitude and phase of the second harmonic of the q-axis current. A low-pass filter applied to the averaged second harmonic amplitude and the averaged second harmonic phase, which outputs the second harmonic amplitude and the second harmonic phase, Equipped with, A motor short-circuit detection device characterized by performing at least one of the following: a process of detecting a phase-to-phase short circuit or a turn-to-turn short circuit of the motor using the second harmonic amplitude, or a process of identifying the location of a phase-to-phase short circuit or a turn-to-turn short circuit of the motor using the second harmonic phase.

2. A motor short-circuit detection device according to claim 1, The first all-pass filter calculates the second harmonic of the pseudo-q-axis current by advancing the phase of the second harmonic of the d-axis current by 90 degrees or delaying it by 270 degrees. The motor short-circuit detection device is characterized in that the second all-pass filter calculates the second harmonic of the pseudo-d-axis current by delaying the phase of the second harmonic of the q-axis current by 90 degrees.

3. A motor short-circuit detection device according to claim 1, A motor short-circuit detection device characterized in that the process of identifying the location of a phase-to-phase short circuit or turn-to-turn short circuit in the motor using the second harmonic phase identifies the location of the short circuit according to the phase range of the second harmonic phase.

4. A motor short-circuit detection device according to claim 1, A motor short-circuit detection device characterized in that the process of detecting a phase-to-phase short circuit or turn-to-turn short circuit of the motor using the second harmonic amplitude is used to determine the degree of the short circuit.

5. A motor control system that controls the motor according to the determination result of a phase-to-phase short circuit or turn-to-turn short circuit of the motor by the motor short-circuit determination device according to any one of claims 1 to 4.

6. A motor control system according to claim 5, A motor control system characterized by performing one of the following: continuous operation control, which continues the operation of the motor based on the value of the second harmonic amplitude; output torque limiting operation control, which limits the output torque of the motor during operation; and motor stop control, which stops the operation of the motor.

7. A motor control system according to claim 6, In the output torque limiting operation control, the motor control system is characterized in that a current obtained by applying a bandstop filter to remove second harmonics to the d-axis current and the q-axis current is used instead of the d-axis current and the q-axis current.

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