JP2005117756A - Failure diagnosis device of dc voltage detecting circuit and motor control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a failure diagnosis device of a DC voltage detecting circuit for diagnosing the failure of a circuit for detecting a DC voltage, and to provide a motor control system having the failure diagnosis device. <P>SOLUTION: Reference value of a DC voltage VB is determined and the DC voltage VB is compared with the reference value. In PWM control, the difference of current difference ΔΔi in one period of carrier is detected, and then the reference value of the difference of current difference ΔΔi is calculated from a superposed voltage Vp and a d-axis current id and compared with the difference of current difference ΔΔi. At the time of rectangular wave control, a variation ΔVB before and after switching is determined from the DC voltage VB and the information of a switching phase, and then the reference value of variation ΔVB is calculated from the current isw of the switching phase and compared with the variation ΔVB. When the difference from the reference value exceeds a specified value, a decision is made that a voltage detecting section 7 has failed and a switch 12 is turned to the PWM control section 9 side and the DC voltage VB being outputted from the voltage detecting section 7 is fixed to a minimum guarantee voltage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor control system that detects a DC voltage for driving a motor and controls the motor based on the detected DC voltage value.

  There is known a motor drive device that detects a DC voltage supplied from a battery to an inverter by a voltage sensor and controls a current supplied to the motor based on the DC voltage value (Patent Document 1).

JP 2002-191198 A

  In this motor drive device, if the voltage sensor fails, the correct voltage cannot be detected and the motor cannot be controlled properly.

A failure diagnosis apparatus for a DC voltage detection circuit according to the present invention includes a DC voltage detection means for detecting a DC voltage for driving a motor, and a control for controlling the motor based on the value of the DC voltage detected by the DC voltage detection means. The frequency of the fluctuation component generated in the DC voltage is detected, the reference value of the DC voltage is obtained from the frequency, and the comparison result between the reference value and the DC voltage value is obtained. An abnormality of the DC voltage detecting means is detected.
The DC voltage detection circuit failure diagnosis apparatus according to the present invention includes a DC voltage detection means for detecting a DC voltage for driving a motor, a current detection means for detecting a motor current, and a voltage further applied to the voltage applied to the motor. And a voltage superimposing unit that superimposes the motor, and is mounted on a motor control system that PWM-controls the motor based on the value of the DC voltage detected by the DC voltage detecting unit and the value of the current detected by the current detecting unit. The difference of the current generated by the voltage superimposed by the voltage superimposing means is calculated based on the value of the current detected by the current detecting means, and the reference value of the difference is calculated based on the calculated difference and the superimposed voltage. The abnormality of the DC voltage detecting means is detected based on the comparison result between the calculated reference value and the difference.
Further, the failure diagnosis apparatus for a DC voltage detection circuit according to the present invention includes a DC voltage detection means for detecting a DC voltage for driving a motor, a current detection means for detecting a current of the motor, and a voltage waveform applied to the motor. And switching means mounted on a motor control system that controls the rectangular wave of the motor based on the value of the DC voltage detected by the DC voltage detection means and the value of the current detected by the current detection means. The change amount of the DC voltage when the applied voltage waveform is changed by the means is calculated, the reference value of the change amount is calculated based on the value of the current detected by the current detection means, and the calculated reference value and the change amount are calculated. Based on the comparison result, the abnormality of the DC voltage detecting means is detected.
A motor control system according to the present invention includes a DC voltage detection unit that detects a DC voltage for driving a motor, a current detection unit that detects a current of the motor, and a voltage superimposition unit that further superimposes a voltage on the voltage applied to the motor. And a switching means for changing a voltage waveform applied to the motor, a DC voltage value detected by the DC voltage detection means and a current value detected by the current detection means based on the PWM control or the rectangular wave. Control means for controlling, selection means for selecting either PWM control or rectangular wave control as a motor control method by the control means, and voltage superimposed by voltage superimposing means when PWM control is selected by the selection means Is calculated based on the value of the current detected by the current detection means and superimposed on the calculated difference. When calculating the reference value of the difference based on the pressure, detecting the abnormality of the DC voltage detection means based on the comparison result between the calculated reference value and the difference, when the rectangular wave control is selected by the selection means, The amount of change in the DC voltage when the applied voltage waveform is changed by the switching means is calculated, the reference value of the change amount is calculated based on the value of the current detected by the current detecting means, and the calculated reference value and change A failure detection device that detects an abnormality of the DC voltage detection means based on the comparison result with the amount, and when the failure detection device detects an abnormality of the DC voltage detection means, the control method selected by the selection means is PWM control. The fixed value is output from the DC voltage detecting means.

According to the present invention, the DC voltage for driving the motor is detected by the DC voltage detecting means, the frequency of the fluctuation component generated in the detected DC voltage is detected, the reference value of the DC voltage is obtained from the frequency, and the reference Since the abnormality of the DC voltage detecting means is detected based on the comparison result between the value and the value of the DC voltage, the abnormality of the DC voltage detecting means can be detected.
Further, according to the present invention, the difference between the currents generated by the voltage further superimposed on the applied voltage to the motor is calculated based on the detected current value, which is mounted on the motor control system that performs PWM control of the motor, and the calculation The reference value of the current difference is calculated based on the current difference and the superimposed voltage, and the abnormality of the DC voltage detecting means is detected based on the comparison result between the calculated reference value and the current difference. Therefore, the abnormality of the DC voltage detection means can be detected.
Further, according to the present invention, it is mounted on a motor control system that controls a motor with a rectangular wave, and the amount of change in DC voltage when the applied voltage waveform to the motor is changed is calculated, and based on the detected current value. Since the reference value of the change amount of the DC voltage is calculated and the abnormality of the DC voltage detection means is detected based on the comparison result between the calculated reference value and the change amount of the DC voltage, the abnormality of the DC voltage detection means is detected. Can be detected.
According to the motor control system of the present invention, when either the PWM control or the rectangular wave control is selected to control the motor and the abnormality of the DC voltage detecting means is detected, the motor control method is fixed to the PWM control, Since a fixed value is output from the DC voltage detection means, the motor can be operated even when the DC voltage detection means fails.

  FIG. 1 shows an embodiment of a motor control system provided with a DC voltage detection circuit failure diagnosis apparatus according to the present invention. In this motor control system, the synchronous motor 1 is driven by the DC energy of the battery 2. DC power supplied from the battery 2 is input to the inverter 3 via the relay 6, converted into three-phase AC power by the inverter 3, and supplied to the synchronous motor 1. At this time, in the inverter 3, based on the switching signals Pu, Pv, and Pw from the motor controller 4, the DC power from the battery 2 is switched by a power conversion element such as an IGBT to convert it into uvw three-phase AC power.

  The switching control unit 8 of the motor controller 4 outputs a switching signal to the switch 12 based on the torque command value τr from the outside, the motor speed ωm, and the inverter input voltage VB, and switches the switch 12. By switching the switch 12, the output destination of the torque command value τr from the switching control unit 8 is switched to either the PWM control unit 9 or the rectangular wave control unit 10. The motor speed ωm is calculated in the PWM control unit 9 or the rectangular wave control unit 10 that outputs the torque command value τr. A method for calculating the motor speed ωm will be described later. The inverter input voltage VB is detected by the voltage detector 7.

  The PWM control unit 9 performs PWM control based on the torque command value τr, determines switching signals Pu, Pv, and Pw based on PWM pulses as described later, and outputs them to the inverter 3. The rectangular wave control unit 10 performs rectangular wave control based on the torque command value τr, determines switching signals Pu, Pv, and Pw using rectangular waves as described later, and outputs them to the inverter 3.

  A switching method of the switch 12 in the switching control unit 8 will be described with reference to FIG. FIG. 2A is a diagram illustrating an example of a relationship between the torque command value τr and the motor speed ωm and the switching destination of the switch 12 when the inverter input voltage VB is VB1. When the intersection of the torque command value τr and the motor speed ωm is in the PWM control region indicated by reference numeral 102, the switch 12 is switched to the PWM control unit 9 side. At this time, the synchronous motor 1 is controlled by PWM control. When the intersection of the torque command value τr and the motor speed ωm is in the rectangular wave control region indicated by reference numeral 103, the switch 12 is switched to the rectangular wave control unit 10 side. At this time, the synchronous motor 1 is controlled by rectangular wave control.

  FIG. 2B is a diagram showing an example of the relationship between the torque command value τr and the motor speed ωm and the control method when the inverter input voltage VB is VB2. Similarly to the case of FIG. 2A, when the intersection of the torque command value τr and the motor speed ωm is in the PWM control range indicated by reference numeral 104, the switch 12 is switched to the PWM control unit 9 side. When the intersection of the torque command value τr and the motor speed ωm is in the rectangular wave control region indicated by reference numeral 105, the switch 12 is switched to the rectangular wave control unit 10 side. Here, VB1 <VB2, and as shown in FIGS. 2A and 2B, the rectangular wave control region becomes narrower as the inverter input voltage VB becomes higher.

  Thus, whether the control method is PWM control or rectangular wave control is determined by the torque command value τr and the motor speed ωm, and the relationship varies depending on the inverter input voltage VB. Based on the torque command value τr, the motor speed ωm, and the inverter input voltage VB, the switching control unit 8 determines the switching destination of the switch 12 in this way and outputs a switching signal. Further, when an abnormal signal is input from the failure diagnosis unit 11 described later, the switch 12 is always switched to the PWM control unit 9 side regardless of the torque command value τr and the motor speed ωm.

  The voltage detection unit 7 detects the inverter input voltage VB and outputs it to the switching control unit 8, the PWM control unit 9, the rectangular wave control unit 10, and the failure diagnosis unit 11. Further, when an abnormal signal is input from the failure diagnosis unit 11 described later, a predetermined value set in advance is output as the inverter input voltage VB. The predetermined value is set to the lowest value (minimum guaranteed voltage) among the possible values of the inverter input voltage VB.

  When the voltage detector 7 fails, the inverter input voltage VB cannot be detected correctly. If rectangular wave control is performed at this time, a switching signal as described later cannot be output correctly, and the synchronous motor 1 cannot be controlled. Therefore, when the voltage detection unit 7 becomes abnormal, the switch control unit 8 always switches the switch 12 to the PWM control unit 9 side and fixes the inverter input voltage VB to a predetermined value as described above. Abnormality of the voltage detection unit 7 is detected by the failure diagnosis unit 11 as described below.

  The failure diagnosis unit 11 diagnoses the voltage detection unit 7 and detects an abnormality thereof. This is done by the following three methods. The first is performed when power is not supplied to the inverter 3, that is, when the relay 6 is open, which is called diagnosis when the relay is open. The second is performed during PWM control, which is called diagnosis during PWM control. The third is performed during rectangular wave control, which is called diagnosis during rectangular wave control. When an abnormality of the voltage detection unit 7 is detected by any method, the failure diagnosis unit 11 outputs an abnormality signal to the switching control unit 8 and the voltage detection unit 7. Of the above three methods, the first diagnosis when the relay is opened will be described below. The diagnosis during the second PWM control and the diagnosis during the third rectangular wave control will be described later.

-Failure diagnosis when relay is open-
The diagnosis when the relay is opened is performed based on the value of the inverter input voltage VB detected by the voltage detector 7 and the ripple frequency fω. An example of the inverter input voltage VB detected by the voltage detector 7 when the relay 6 is open is shown in FIG. At this time, in the inverter input voltage VB, a full-wave rectified portion of the induced voltage by the synchronous motor 1 as shown by reference numeral 100 appears. The induced voltage by the synchronous motor 1 changes in proportion to the motor speed ωm. The ripple frequency fω represented by the reciprocal of the time width indicated by reference numeral 101 appears at a frequency that is six times the motor speed ωm. Therefore, the reference value VB * of the voltage to be detected by the voltage detection unit 7 when the relay 6 is open can be expressed by the following equation (1). Here, φ represents the magnetic flux generated by the magnetic poles of the synchronous motor 1.
VB * = 1.35 · 2π · (fω / 6) · φ (1)

In the diagnosis when the relay is opened, the voltage reference value VB * obtained by the equation (1) and the inverter input voltage VB detected by the voltage detector 7 are compared by the following equation (2) to detect the voltage. It is determined whether the unit 7 has failed. If the expression (2) is satisfied, it is determined that the voltage detector 7 has failed. If not, it is determined that it has not failed. Here, k is a threshold value for determination, and is set in advance. In this way, the failure diagnosis unit 11 performs a diagnosis when the voltage detection unit 7 opens the relay and detects an abnormality.
| VB * -VB |> k (2)

  Next, the PWM control unit 9 will be described. The PWM controller 9 has the configuration shown in FIG. 4 and outputs switching signals Pu, Pv, Pw based on PWM pulses to the synchronous motor 1 based on the torque command value τr. Each configuration of FIG. 3 will be described below.

  The current command value generation unit 13 determines a d-axis current command value idr and a q-axis current command value iqr with respect to the torque command value τr input from the switching control unit 8 of FIG. To the unit 14. Here, the d-axis indicates the direction of the magnetic pole position (magnetic flux) of the synchronous motor 1, and the q-axis indicates the direction that is electrically orthogonal to the d-axis. Composed. Note that idr and iqr can be set at various ratios with respect to the torque command value τr. The motor loss differs depending on the ratio, and the ratio between idr and iqr that minimizes the motor loss is determined by the motor speed and the inverter input. Varies with voltage. Therefore, in the current command value generation unit 13, the motor loss with respect to the torque command value τr is determined based on the motor speed ωm obtained by the speed detection unit 21 and the inverter input voltage VB detected by the voltage detection unit 7 in FIG. The optimum idr and iqr are output with the smallest number.

  When the rotor having a magnet rotates in the synchronous motor 1, the dq axis coordinate system also rotates. The rotational displacement amount of this dq axis coordinate system, that is, the phase of the magnetic pole is represented by θ, and hereinafter this will be referred to as the magnetic pole position θ. The speed detector 21 detects the magnetic pole position θ at regular intervals, and obtains the motor speed ωm from the amount of change. The magnetic pole position θ is determined by the magnetic pole position detector 20 from the output current of the synchronous motor 1 by a method described later.

  The current sensors 5u, 5v, and 5w provided outside the PWM controller 9 detect the three-phase (u-phase, v-phase, and w-phase) currents of the synchronous motor 1, respectively. These detected motor currents are output to the current detector 19.

  The current detector 19 samples the motor current detected by the current sensors 5u, 5v, and 5w. FIG. 5 shows the sampling timing. The current detection unit 19 samples the detected motor current in accordance with the timing of each vertex (each point indicated by reference numeral 107) in the carrier wave indicated by reference numeral 106 in FIG. This timing is determined by a timing signal Pd output from a PWM signal generator 16 described later. In addition, although the carrier wave 106 has shown the example at the frequency of 10 kHz, it is good also as another frequency. Sampling values iu, iv and iw with respect to the motor current of each phase of uvw thus sampled are output to the coordinate converter 18 and the magnetic pole position detector 20 shown in FIG.

  The coordinate conversion unit 18 performs coordinate conversion on the motor current sampling values iu, iv and iw input from the current detection unit 19 based on the magnetic pole position θ output from the magnetic pole position detection unit 20, and d−q The d-axis current id and the q-axis current iq in the axis coordinate system are calculated. The calculated d-axis current id and q-axis current iq are output to the current control unit 14. The d-axis current id is also output to the failure diagnosis unit 11 in FIG.

  The current control unit 14 obtains a d-axis current deviation based on a difference between the d-axis current command value idr input from the current command value generation unit 13 and the d-axis current id input from the coordinate conversion unit 18. Further, a well-known proportional / integral control calculation is performed on the d-axis current deviation to obtain a d-axis voltage command value Vds. To this d-axis voltage command value Vds, a superimposed voltage Vp output from a superimposed voltage generation unit 17 described later is added, and the d-axis voltage command value Vds1 is output to the coordinate conversion unit 15. Similarly, the q-axis voltage command value Vqs obtained for the q-axis current command value iqr and the q-axis current iq is also output to the coordinate conversion unit 15. At this time, the superimposed voltage Vp is not added to the q-axis voltage command value Vqs.

  The coordinate conversion unit 15 performs coordinate conversion on the input d-axis voltage command value Vds1 and q-axis voltage command value Vqs on the basis of the magnetic pole position θ output from the magnetic pole position detection unit 20, and 3 in the stationary coordinate system. Phase voltage command values Vus, Vvs and Vws are calculated. The calculated three-phase voltage command values Vus, Vvs and Vws are output to the PWM signal generator 16.

  The PWM signal generation unit 16 normalizes the three-phase voltage command values Vus, Vvs, and Vws input from the coordinate conversion unit 15 with respect to the inverter input voltage VB, and compares each with the carrier wave to calculate the pulse width, thereby calculating the three-phase PWM pulses Pu, Pv and Pw are output to the inverter 3. Thereby, the voltage applied to the synchronous motor 1 is determined. Further, the PWM signal generation unit 16 extracts a signal Pd indicating the sampling timing from the carrier wave, and outputs it to the current detection unit 19 and the superimposed voltage generation unit 17.

  The superimposed voltage generator 17 outputs a superimposed voltage Vp indicated by reference numeral 108 in FIG. The polarity of the superimposed voltage Vp indicated by reference numeral 108 can be switched every half cycle of the carrier 106, that is, at each point timing indicated by reference numeral 107. The switching timing is determined by the timing signal Pd output from the PWM signal generator 16 shown in FIG. By superimposing the superimposed voltage Vp whose polarity has been switched in this way on the d-axis voltage command value Vds output from the current control unit 14, a current change corresponding to the magnetic pole position θ is generated in the three-phase current of the synchronous motor 1. . The generated current change is detected by the current sensors 5u, 5v, and 5w, and the magnetic pole position detector 20 determines the magnetic pole position θ by a method described later. The superimposed voltage Vp is also output to the failure diagnosis unit 11 in FIG.

The magnetic pole position detection unit 20 obtains the magnetic pole position θ by obtaining a current difference generated by the superimposed voltage Vp from the motor current sampling values iu, iv and iw during one period of the carrier wave. This method will be described below. First, with respect to the sampling values iu and iv of the motor current, the differences Δiu and Δiv in the first half cycle of the carrier wave are obtained by the following equation (3). Here, the first sampling time in one cycle to be calculated, for example, time t0 in FIG. 5 is represented as time t (2n), and the next sampling time, for example, time t1 is represented as time t (2n + 1).
Δiu (t (2n)) = iu (t (2n + 1)) − iu (t (2n))
Δiv (t (2n)) = iv (t (2n + 1)) − iv (t (2n)) (3)

  Next, the obtained differences Δiu and Δiv are converted into differences Δiα and Δiβ in a two-phase alternating current (α-β) coordinate system. This converted difference is expressed as Δiα (t (2n)) and Δiβ (t (2n)).

For the contents described above, instead of the difference Δiu or Δiv, the difference Δiw of the sampling value iw is obtained by the following equation (4), and either the difference Δiw and the difference Δiu or Δiv, or the differences Δiu, Δiv and Δiw From all, Δiα (t (2n)) and Δiβ (t (2n)) may be obtained.
Δiw (t (2n)) = iw (t (2n + 1)) − iw (t (2n)) (4)

Next, the same calculation is performed during the latter half cycle, that is, from time t (2n + 1) to time t (2n + 2), and the difference Δiα (t of the two-phase alternating current (α−β) coordinate system at this time (2n + 1)) and Δiβ (t (2n + 1)) are obtained. Thereafter, ΔΔiα and ΔΔiβ, which are the differences between Δiα and Δiβ during one period of the carrier wave, are obtained by the following equation (5).
ΔΔiα = Δiα (t (2n + 1)) − Δiα (t (2n))
ΔΔiβ = Δiβ (t (2n + 1)) − Δiβ (t (2n)) (5)

  ΔΔiα and ΔΔiβ calculated in this way are each expressed as a vector in a two-phase alternating current (α-β) coordinate system, and the phase angle of the combined vector is θab. In FIG. 6, when the vector indicated by reference numeral 109 is ΔΔiα and the vector indicated by reference numeral 110 is ΔΔiβ, the phase angle 112 of the vector indicated by reference numeral 111 obtained by combining the vectors 109 and 110 represents θab. This θab is the magnetic pole position θ.

Further, when the vector 111 is expressed as a current difference difference ΔΔi, this ΔΔi can be expressed as the following equation (6) by using ΔΔiα and ΔΔiβ in the equation (5). The current difference difference ΔΔi is output from the magnetic pole position detection unit 20 to the failure diagnosis unit 11 of FIG.
ΔΔi = √ (ΔΔiα ² + ΔΔiβ ² ) (6)

  As described above, the magnetic pole position θ is obtained. Based on the magnetic pole position θ, the voltage applied to the synchronous motor 1 is determined by the method described above.

-Fault diagnosis during PWM control-
Here, the diagnosis at the time of the 2nd PWM control among the diagnosis of the voltage detection part 7 performed by the failure diagnosis part 11 of FIG. 1 is demonstrated. Diagnosis at the time of PWM control is performed by comparing ΔΔi expressed by the above equation (6) with a reference value ΔΔi * of the current difference difference expressed by the following equation (7). In addition, Ld in Formula (7) is the inductance in the d-axis of the synchronous motor 1, and decreases as the absolute value of the d-axis current id increases. Therefore, the reference value ΔΔi * values for id and Vp are tabulated in advance, and the reference value ΔΔi * is determined by the id value output from the coordinate conversion unit 18 and the Vp value output from the superimposed voltage generation unit 17. Determine the value of.
ΔΔi * = 2Vp / Ld (7)

When the voltage detector 7 fails, the detected inverter input voltage VB is different from the original value. As described above, the current command value generation unit 13 generates PWM pulses that realize the three-phase voltage command values Vus, Vvs, and Vws based on the value of the inverter input voltage VB. Therefore, when the voltage detection unit 7 fails, a deviation occurs with respect to the superimposed voltage Vp that should be output, and accordingly, a deviation also occurs in the superimposed voltage applied from the inverter 3 to the synchronous motor 1. There is also a deviation in the difference of ΔΔi. From this, by comparing ΔΔi and ΔΔi * by the following formula (8), it is determined whether or not the voltage detection unit 7 is out of order. If the expression (8) is satisfied, it is determined that the voltage detection unit 7 has failed, and if not, it is determined that it has not failed. Here, α is a threshold value for determination, and is set in advance. In this way, the failure detection unit 11 performs diagnosis during PWM control of the voltage detection unit 7 and detects an abnormality thereof.
| ΔΔi * −ΔΔi |> α (8)

  Next, the rectangular wave control unit 10 of FIG. 1 will be described. The rectangular wave control unit 10 has the configuration shown in FIG. 7, and similarly to the PWM control unit 9 described above, the rectangular motor switching signals Pu, Pv, and Pw are sent to the synchronous motor 1 based on the torque command value τr. Output to. Each configuration of FIG. 7 will be described below.

  The voltage phase calculation unit 23 determines the voltage phase γ for the torque command value τr input from the switching control unit 8 in FIG. 1 via the switch 12 and outputs the voltage phase γ to the switch selection unit 24. This voltage phase γ is calculated as follows after determining the d-axis current command value idr and the q-axis current command value iqr, which are two-phase DC current command values. The d-axis current command value idr and the q-axis current command value iqr are determined by a current table stored in advance based on the torque command value τr, the motor speed ωm, and the inverter DC input voltage VB.

The voltage to be applied in the d-axis direction is Vd, and the voltage to be applied in the q-axis direction is Vq. At this time, assuming that the inductance in the d-axis direction is Ld and the inductance in the q-axis direction is Lq, Vd and Vq are 90 ° phase with respect to the d-axis current command value idr and the q-axis current command value iqr, respectively. Advances. Therefore, Vd and Vq are expressed as the following formula (9). The term ωm · φ included in the expression of Vq represents a voltage that compensates for the counter electromotive force generated in the q-axis direction. This counter electromotive force is generated in the q-axis direction electrically orthogonal to the d-axis which is the direction of the magnetic pole position θ as the motor 1 rotates.
Vd = −ωm · Lq · iqr
Vq = ωm · φ + ωm · Ld · idr (9)

  FIG. 8 shows a vector diagram of the d-axis applied voltage Vd and the q-axis applied voltage Vq represented by the above equation (9). The dq axis coordinate system is inclined by the magnetic pole position θ indicated by reference numeral 61 with respect to the two-phase alternating current (α-β) coordinate system and the uvw phase coordinate system which are stationary coordinate systems. A vector denoted by reference numeral 64 represents a d-axis current command value idr, and a vector denoted by reference numeral 65 represents a q-axis current command value iqr. At this time, it is assumed that the vector 64 by idr is oriented in the negative direction of the d-axis, and the vector 65 by iqr is oriented in the positive direction of the q-axis.

  The d-axis applied voltage Vd is represented by a vector denoted by reference numeral 66 by the vector 68 according to the term of -ωm · Lq · iqr in the equation (9). Further, the q-axis applied voltage Vq is represented by a vector indicated by reference numeral 67 by the vector 69 by the term of ωm · φ and the vector 70 by the term of ωm · Ld · idr in the equation (9). When a vector indicated by reference numeral 70 obtained by combining the vector 66 and the vector 67 is a voltage command vector Vr, a phase indicated by reference numeral 62 when the voltage command vector Vr is viewed from the d-axis is a voltage phase γ. Note that the vector indicated by reference numeral 71 obtained by combining the vector 64 and the vector 65 represents a current command vector i that is a combination of the d-axis current command value idr and the q-axis current command value iqr.

  Note that the phase of the voltage command vector Vr when viewed from the stationary coordinate system with the α axis as a reference, that is, the phase indicated by reference numeral 63 is expressed as a voltage phase θv. This voltage phase θv is used in selection of a switching pattern described later. Note that θv = θ + γ.

  As described above, the voltage phase γ is determined in the voltage phase calculation unit 23 of the rectangular wave control unit 10. Next, the switch selection unit 24 will be described. The switch selection unit 24 selects a switching pattern based on the total value of the voltage phase γ and the magnetic pole position θ, that is, the voltage phase θv described above, and outputs switching signals Pu, Pv and Pw using rectangular waves. When these switching signals are input to the inverter 3, a voltage corresponding to the switching signal is applied to the synchronous motor 1. The voltage applied to the synchronous motor 1 by the switching signal is a positive voltage or a negative voltage having a predetermined voltage value, and the switching signal indicates either the positive voltage or the negative voltage.

  The switch selection unit 24 divides the α-β coordinate system (uvw coordinate system) into six sections for every electrical angle of 60 ° in order to perform 180 ° energization rectangular wave control, and which section has the voltage phase θv value. A different switching pattern is selected depending on whether it corresponds to. FIG. 9A shows a state where the α-β coordinate system is divided into six sections. The sections indicated by reference numerals 73 to 78 are referred to as sections I to VI, respectively. For example, the section indicated by reference numeral 73, that is, the section where the voltage command vector Vr indicated by reference numeral 71 is located when the voltage phase θv is −30 ° to 30 °. , Section I. Similarly, when θv is 30 ° to 90 °, Section II, when it is 90 ° to 150 °, Section III, when it is 150 ° to 210 °, Section IV, when it is 210 ° to 270 °, Section V, 270 The interval VI to 330 ° is defined as section VI.

  FIG. 9B shows switching patterns to be selected in each of the sections I to VI in FIG. For example, in the section I, the switching signals Pu, Pv, and Pw are output so that the u phase is a positive voltage and the v phase and the w phase are negative voltages. Further, when the voltage phase θv is an angle indicated by reference numeral 63 in FIG. 9A, the voltage command vector Vr indicated by reference numeral 71 is located in the section III. Therefore, the u phase and the w phase are negative according to FIG. 9B. A switching signal is output so that the voltage and the v-phase are positive.

  The switch selection unit 24 outputs switching signals Pu, Pv, and Pw that change the waveform of the voltage applied to the synchronous motor 1 by selecting the switching pattern in this way. Information on the selected switching pattern is output to the magnetic pole position detector 26. In addition, information on the phase to be switched, that is, the uvw phase that changes the voltage from positive to negative or from negative to positive is output to the current detection unit 27 and the failure diagnosis unit 11 of FIG.

  The current detection unit 27 samples the motor current detected by the current sensors 5u, 5v, and 5w. The sampling timing at this time is different from the current detection unit 19 of FIG. 4 and a predetermined timing is used. The sampled values iu, iv and iw for the sampled motor currents of each phase of uvw are output to the magnetic pole position detector 26. Further, information on the phase to be switched is input from the switch selection unit 24, and the current of the phase is set as isw and output to the failure diagnosis unit 11 in FIG. That is, isw = iu if the switching phase is u phase, isw = iv if v phase, and isw = iw if w phase.

  The magnetic pole position detection unit 26 obtains the AC voltage applied to the synchronous motor 1 based on the switching pattern information output from the switching selection unit 24. The induced voltage of the motor is detected from this AC voltage and the motor current sampling values iu, iv and iw output from the current detector 27, and the magnetic pole position θ is obtained from the phase of the induced voltage. The obtained magnetic pole position θ is output to the switch selector 24 and the speed detector 25.

  Similar to the speed detection unit 21 in FIG. 4, the speed detection unit 25 detects the magnetic pole position θ output from the magnetic pole position detection unit 26 at regular intervals, and obtains the motor speed ωm from the amount of change. The obtained motor speed ωm is output to the voltage phase calculator 23.

-Failure diagnosis during rectangular wave control-
Here, the diagnosis at the time of the 3rd rectangular wave control among the diagnosis of the voltage detection part 7 performed by the failure diagnosis part 11 of FIG. 1 is demonstrated. FIG. 10 shows an example of the relationship among the motor current value, switching pattern, inverter input current, and inverter input voltage during rectangular wave control. When switching signals Pu, Pv and Pw having a switching pattern indicated by reference numeral 81 are output to the inverter 3, an AC voltage corresponding to the switching signals Pu, Pv and Pw is applied to the synchronous motor 1. Change. At this time, the inverter input current input to the inverter 3 changes as indicated by reference numeral 82, and the inverter input voltage also changes as indicated by reference numeral 83. In the diagnosis during the rectangular wave control, the amount of change in the inverter input voltage is detected.

  As described above, the inverter input voltage VB is detected by the voltage detector 7 of FIG. The difference between the voltage value VBa before the switching and the voltage value VBb after the switching based on the detected inverter input voltage VB and the information on the phase to be switched output from the switch selection unit 24 in the diagnosis during the rectangular wave control. And the absolute value of the difference is defined as a change amount ΔVB = | VBa−VBb |. ΔVB is a change amount of a portion indicated by reference numeral 84 in FIG. Further, the reference value ΔVB * of the voltage change amount is obtained from the phase current isw output from the current detection unit 27 for switching. The reference value ΔVB * of the voltage change amount is measured in advance with respect to the current isw at the time of switching, and is tabulated as ΔVB * with respect to the value of the current isw in the switching phase.

Further, by comparing ΔVB and ΔVB * thus obtained by the following equation (10), it is determined whether or not the voltage detection unit 7 has failed. If the expression (10) is satisfied, it is determined that the voltage detector 7 has failed, and if not, it is determined that it has not failed. Here, β is a threshold value for determination, and is set in advance. In this way, the failure detection unit 11 performs a diagnosis during the rectangular wave control of the voltage detection unit 7 and detects the abnormality.
| ΔVB * −ΔVB |> β (10)

  FIG. 11 is a flowchart showing the flow of the failure diagnosis process for the voltage detection unit 7 described above. This flowchart is based on a program executed by the motor controller 4 and is always executed during the operation of the motor controller 4.

  In step S1, it is determined whether the relay 6 is off (open) or on (connected). This determination is performed by a signal (not shown) output from the relay 6 to the motor controller 4. If the relay 6 is off, the process proceeds to step S2, and if it is on, the process proceeds to step S8.

  In step S <b> 2, the failure diagnosis unit 11 detects the ripple frequency fω from the inverter input voltage VB output from the voltage detection unit 7. As described above, the ripple frequency fω is detected by detecting the time width shown in FIG. 3 based on the VB waveform and calculating the reciprocal of the time width. Further, a voltage reference value VB * is calculated from the above-described equation (1) based on the detected ripple frequency fω.

  In step S3, the failure diagnosis unit 11 compares the inverter input voltage VB output from the voltage detection unit 7 with the voltage reference value VB * calculated in step S2 by the above-described equation (2), and opens the relay. Diagnose the time. If the expression (2) is satisfied, it is determined that the voltage detection unit 7 has failed, and the process proceeds to step S4. If the expression (2) is not satisfied, it is determined that the voltage detection unit 7 has not failed, and the process proceeds to step S7.

  In step S <b> 4, assuming that the voltage detection unit 7 has failed, the failure diagnosis unit 11 outputs an abnormality signal to the switching control unit 8 and the voltage detection unit 7.

  In step S5, when an abnormality signal is output from the failure diagnosis unit 11, the voltage detection unit 7 outputs the inverter input voltage VB fixed to a predetermined value set in advance. This predetermined value is the lowest value of the above-mentioned minimum guaranteed voltage, that is, the value that the inverter input voltage VB can take.

  In step S6, when an abnormality signal is output from the failure diagnosis unit 11, the switching control unit 8 outputs a switching signal for fixing the switch 12 to the PWM control unit 9 side to the switch 12. By doing so, the rectangular wave control is not performed. After executing Step S6, the process returns to Step S1.

  In step S7, it is assumed that the voltage detector 7 has not failed. At this time, no abnormality signal is output from the failure diagnosis unit 11. After executing Step S7, the process returns to Step S1.

  In step S8, the switching control unit 8 determines whether the current motor operation is PWM control or rectangular wave control. This determination is made according to the state of the switching signal output from the switching control unit 8 to the switch 12. If it is determined that the PWM control is selected, the process proceeds to step S9. If it is determined that the rectangular wave control is selected, the process proceeds to step S11.

  In step S9, the failure diagnosis unit 11 detects the current difference difference ΔΔi output from the magnetic pole position detection unit 20 shown in FIG. The current difference difference ΔΔi is calculated by a process of detecting a magnetic pole position (not shown) that is executed in the magnetic pole position detection unit 20 in parallel with the failure diagnosis process according to the flowchart of FIG. Further, the reference value ΔΔi * of the current difference difference expressed by the above-described equation (7) is determined based on the id value output from the coordinate conversion unit 18 in FIG. 4 and the Vp value output from the superimposed voltage generation unit 17. Is calculated.

  In step S10, the failure diagnosis unit 11 compares the current difference difference ΔΔi detected in step S9 with the reference value ΔΔi * of the current difference difference calculated in step S9 by the above-described equation (8). Diagnose during PWM control. If the expression (8) is satisfied, it is determined that the voltage detection unit 7 has failed, and the process proceeds to step S4. If the expression (8) is not satisfied, it is determined that the voltage detection unit 7 is not broken, and the process proceeds to step S7.

  In step S11, the failure diagnosis unit 11 uses the inverter input voltage VB output from the voltage detection unit 7 and the switching information output from the switch selection unit 24 in FIG. The amount ΔVB is detected. Further, the reference value ΔVB * of the above-described voltage change amount is calculated from the phase current isw output from the current detection unit 27 of FIG.

  In step S12, the change amount ΔVB detected in step S11 is compared with the reference value ΔVB * of the voltage change amount similarly calculated in step S11 by the above-described equation (10), and diagnosis during rectangular wave control is performed. Do. If the expression (10) is satisfied, it is determined that the voltage detection unit 7 has failed, and the process proceeds to step S4. If the expression (10) is not satisfied, it is determined that the voltage detection unit 7 has not failed, and the process proceeds to step S7.

According to the DC voltage detection circuit failure diagnosis apparatus described above, the frequency of the fluctuation component generated in the DC voltage detected by the voltage detector 7 is detected, the reference value of the DC voltage is obtained from the frequency, and the reference value and the DC voltage are detected. Since the abnormality of the voltage detection unit 7 is detected based on the comparison result with the value of, the abnormality of the voltage detection unit 7 can be detected immediately.
The DC voltage detection circuit failure diagnosis apparatus described above is mounted in a motor control system in which the PWM control unit 9 performs PWM control of the synchronous motor 1. According to this failure diagnosis apparatus, the difference between the currents generated by the voltage superimposed by the superimposed voltage generation unit 17 is calculated based on the current values detected by the current sensors 5u, 5v, and 5w. A reference value of the current difference is calculated based on the calculated current difference and the superimposed voltage, and an abnormality of the voltage detection unit 7 is detected based on a comparison result between the calculated reference value and the current difference. To do. Since it did in this way, abnormality of the voltage detection part 7 can be detected immediately.
Further, the above-described fault diagnosis device for the DC voltage detection circuit is mounted on a motor control system in which the rectangular motor control unit 10 controls the synchronous motor 1 in a rectangular manner. According to this failure diagnosis apparatus, the change amount of the DC voltage detected by the voltage detection unit 7 when the applied voltage waveform to the synchronous motor 1 is changed by the switch selection unit 24 is calculated. Based on the value of the current detected by the current sensors 5u, 5v and 5w, a reference value for the amount of change in the DC voltage is calculated, and based on a comparison result between the calculated reference value and the amount of change in the DC voltage, An abnormality of the voltage detection unit 7 is detected. Since it did in this way, abnormality of the voltage detection part 7 can be detected immediately.
In the motor control system according to the present invention, the switching control unit 8 selects either the PWM control unit 9 or the rectangular wave control unit 10 to perform PWM control or rectangular wave control of the synchronous motor 1. According to this motor control system, when an abnormality is detected in the voltage detection unit 7, the switching control unit 8 is switched to the PWM control unit 9 side to fix the control method of the synchronous motor 1 to PWM control. The minimum guaranteed voltage of the inverter input voltage VB, which is a fixed value, is output. Since it did in this way, the operation | movement of the synchronous motor 1 can be continued even when the voltage detection part 7 fails.

  In the above-described embodiment, the example in which the failure diagnosis unit 11 is a part of the function of the motor controller 4 has been described. However, the function of the failure diagnosis unit 11 is separated and a DC voltage detection circuit separate from the motor controller 4 is provided. A failure diagnosis apparatus may be used. Or it is good also as a failure diagnosis apparatus of the DC voltage detection circuit which isolate | separates from the motor controller 4 combining other functions, and implement | achieves this function.

  In the above-described embodiment, the DC voltage detection means is the voltage detection section 7, the current detection means is the current sensors 5u, 5v and 5w, the voltage superposition means is the superposition voltage generation section 17, the switching means is the switch selection section 24, and the selection means is The switching controller 8 and the switch 12 respectively realize the control means, and the motor controller 4 as the control means and the failure diagnosis unit 11 as the failure detection device. However, these are merely examples, and each component is not limited to the above-described embodiment as long as the characteristics of the present invention are not impaired.

  In the above-described embodiment, the example in which the synchronous motor 1 is controlled by the inverter 3 has been described. However, as long as the functions corresponding to the voltage detection unit 7 and the failure diagnosis unit 11 are provided, not only the synchronous motor but also an induction motor The present invention can also be applied to control a DC motor or other type of motor.

It is a figure which shows one Embodiment of the motor control system provided with the failure diagnosis apparatus of the DC voltage detection circuit by this invention. It is a figure which shows the example of the relationship between torque command value (tau) r and motor speed (omega) m, and the switching destination of switch 12, (a) is an example when inverter input voltage VB is VB1, (b) is inverter input voltage VB is VB2. Each example is shown below. It is a figure which shows the example of the waveform of the inverter input voltage VB detected when the relay 6 is open | released. 3 is a diagram illustrating a configuration of a PWM control unit 9. FIG. It is a figure which shows the timing of the sampling of the motor current in the electric current detection part. FIG. 6 is a vector diagram showing a relationship between current value differences ΔΔiαf and ΔΔiβf and a current difference difference ΔΔi and a phase angle θab representing a magnetic pole position θ during one period of a carrier wave. 2 is a diagram illustrating a configuration of a rectangular wave control unit 10. FIG. It is a vector diagram which shows the relationship between an electric current command value and a voltage phase. It is a figure which shows the relationship between a mode area and a switching pattern, (a) shows the relationship between a stationary coordinate system and a mode area, (b) shows the relationship between a mode area and a switching pattern, respectively. It is a figure which shows the relationship between a motor phase current, a switching pattern, and inverter input DC voltage fluctuation | variation. It is a figure which shows the flowchart of a failure detection process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Synchronous motor 2 Battery 3 Inverter 4 Motor controller 5u, 5v, 5w Current sensor 6 Relay 7 Voltage detection part 8 Switching control part 9 PWM control part 10 Rectangular wave control part 11 Fault diagnosis part 12 Switch

Claims (4)

DC voltage detecting means for detecting a DC voltage for driving the motor;
Mounted in a motor control system comprising control means for controlling the motor based on the value of the DC voltage detected by the DC voltage detection means,
The frequency of the fluctuation component generated in the DC voltage is detected, the reference value of the DC voltage is obtained from the frequency, and the abnormality of the DC voltage detecting means is detected based on the comparison result between the reference value and the value of the DC voltage. A fault diagnosis apparatus for a DC voltage detection circuit. DC voltage detecting means for detecting a DC voltage for driving the motor;
Current detecting means for detecting the current of the motor;
Voltage superimposing means for further superimposing a voltage on the voltage applied to the motor,
Mounted in a motor control system that PWM-controls the motor based on the value of the DC voltage detected by the DC voltage detection means and the value of the current detected by the current detection means,
The difference between the currents generated by the voltage superimposed by the voltage superimposing means is calculated based on the value of the current detected by the current detecting means, and the reference value of the difference based on the calculated difference and the superimposed voltage And detecting an abnormality of the DC voltage detecting means based on a comparison result between the calculated reference value and the difference. DC voltage detecting means for detecting a DC voltage for driving the motor;
Current detecting means for detecting the current of the motor;
And at least switching means for changing a voltage waveform applied to the motor,
Mounted in a motor control system that performs rectangular wave control of the motor based on the value of the DC voltage detected by the DC voltage detection means and the value of the current detected by the current detection means,
The amount of change in the DC voltage when the applied voltage waveform is changed by the switching means is calculated, the reference value of the amount of change is calculated based on the value of the current detected by the current detection means, and the calculation is performed. An apparatus for diagnosing a failure in a DC voltage detection circuit, wherein an abnormality of the DC voltage detection means is detected based on a comparison result between a reference value and the amount of change. DC voltage detecting means for detecting a DC voltage for driving the motor;
Current detecting means for detecting the current of the motor;
Voltage superimposing means for further superimposing a voltage on the applied voltage to the motor;
Switching means for changing a voltage waveform applied to the motor;
Control means for PWM control or rectangular wave control of the motor based on the value of the DC voltage detected by the DC voltage detection means and the value of the current detected by the current detection means,
Selection means for selecting either the PWM control or the rectangular wave control as a method for controlling the motor by the control means;
When PWM control is selected by the selection unit, a difference in current generated by the voltage superimposed by the voltage superimposing unit is calculated based on the value of the current detected by the current detection unit, and the calculated difference Calculating a reference value of the difference based on the superimposed voltage, detecting an abnormality of the DC voltage detection means based on a comparison result between the calculated reference value and the difference,
When the rectangular wave control is selected by the selection means, the change amount of the DC voltage when the applied voltage waveform is changed by the switching means is calculated, and based on the value of the current detected by the current detection means A failure detection device that calculates a reference value of the change amount and detects an abnormality of the DC voltage detection means based on a comparison result between the calculated reference value and the change amount,
A motor characterized by fixing the control method selected by the selection means to PWM control and outputting a fixed value from the DC voltage detection means when an abnormality of the DC voltage detection means is detected by the failure detection device. Control system.

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