JP2000102297A - Controller for ac motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct vector control of an inverter, even when one of phase- current detecting means is out of order. SOLUTION: This controller for an AC motor has a d-q axis conversion means 22 coordinate-transformed into a d-axis current component and a q-axis current component, by using either two-phase currents in each phase current detected by phase-current detecting means 16-18, an out of order detecting means 19 for detecting the trouble of the phase-current detecting means 16, 17 which supply the d-q-axis conversion means 22 with the phase currents, and a sound-phase selecting means 20 for stopping the output of the phase current from one phase-current detecting means 16, in which trouble is detected by the trouble detecting means 19, and supplying the d-q axis conversion means 22 with the phase current from the other sound phase-current detecting means 17 and the phase current of the phase-current detecting means 18 for detecting residual one-phase current in each phase current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC motor control device for controlling an AC motor such as an AC motor for driving an electric vehicle by a vector-controlled inverter.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a block diagram illustrating a configuration of a conventional control device for an AC motor described in Japanese Patent Application Laid-Open Publication No. H10-209,004. In FIG. 2, command generation means 1 includes a d-axis command voltage signal Vd * and a q-axis command voltage signal Vq *.
And generates a two-axis voltage command signal and a command frequency signal ω in rotational rectangular coordinates. The command frequency signal ω is processed by the integrator 2 to calculate a phase, and the phase is input to the phase voltage converter 3 and the dq axis converter 4. Each axis command voltage signal Vd *, Vq * is coordinate-transformed by the phase voltage conversion means 3, and each phase voltage command signal Vu *, Vv *, Vw * is generated and input to the inverter 5. Then, the inverter 5 generates the respective phase voltages Vu, Vv, Vw based on the respective voltage command signals Vu *, Vv *, Vw * and supplies them to the AC motor 5. On the other hand, the respective phase currents iu, iv, and iw detected by the phase current detection means 7 to 9 are converted by the dq axis conversion means 4 into d-axis current components id and q The coordinate is converted into a two-axis current component of the axis current component iq.

[0003]

(Equation 1)

[0004] Each axis current component id, iq is processed by the arithmetic means 10, and a d-axis feedback voltage signal 10d and a q-axis feedback voltage signal 10q are output. Then, each axis feedback voltage signal 10d, 10q is subtracted from each axis command voltage signal Vd *, Vq * by a subtracter 1.
By subtracting the signals at 1 and 12 and inputting them to the phase voltage conversion means 3, the vector control of the inverter 5 is performed.

[0005]

Since the conventional AC motor control device is constructed as described above, the phase currents iu, iv, i for the three phases detected by the phase current detecting means 7 to 9 are provided.
Since the two-axis current component is calculated by performing the coordinate conversion based on w, there is a problem that the operation of the vector-controlled inverter 5 is stopped when any one of the phase current detection means 7 to 9 fails. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a control device for an AC motor that can perform vector control of an inverter even if one phase current detecting unit fails. It is assumed that.

[0006]

A control device for an AC motor according to the present invention drives a three-phase AC motor with an output of a three-phase inverter vector-controlled by a d-axis command voltage signal and a q-axis command voltage signal. Then, the phase current of the inverter is detected by the phase current detecting means, coordinate-converted into a d-axis current component and a q-axis current component, and a d-axis feedback voltage signal and a q-axis feedback voltage signal corresponding to each phase current component are generated. In a control device for an AC motor configured to control a phase voltage of an inverter based on a difference between each axis command voltage signal and each axis feedback voltage signal, any one of phase currents detected by phase current detection means may be used. Dq-axis conversion means for performing coordinate conversion into a d-axis current component and a q-axis current component using two phases, and phase current detection means for supplying a phase current to the dq-axis conversion means. A failure detecting means for detecting a failure, and stopping the output of the phase current from one of the phase current detecting means in which the failure is detected by the failure detecting means, and connecting the phase current from the other sound phase current detecting means to each phase. And a healthy phase selecting means for supplying the remaining one phase current of the current to the dq axis converting means.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing a configuration of the first embodiment. In FIG. 1, 13
Is a command generation means for generating a d-axis command voltage signal Vd *, a q-axis command voltage signal Vq *, and a command frequency signal ω in the rotation rectangular coordinates. Reference numeral 14 denotes a three-phase inverter to which DC power is supplied from a DC power supply (not shown) such as a train line, and phase voltage command values Vu * and V
Each phase voltage Vu, Vv, Vw is output based on v *, Vw *. Reference numeral 15 denotes a three-phase AC motor driven by the output of the inverter 14. Reference numerals 16 to 18 denote phase current detection means, which are the phase currents iu, iv, iw of the inverter 14, respectively.
Is detected. 19 is a failure detecting means, which is a phase current detecting means 1
Detects failures 6 to 18 and outputs a detection signal 19a.
Since the sum of the respective phase currents is "0" as shown in the equation (2), the failure detecting means 19 performs, for example, the following failure detection. iu + iv + iw = 0 (2) That is, (a) when iu = 0 iv + iw = 0 (b) when iv = 0 iu + iw = 0 (c) when iw = 0, iu + iv = 0, In (a), when iv + iw = 0, if iu ≠ 0, it is determined that the phase current detecting means 16 outputting the phase current iu is faulty. For the phase current detecting means 17 and 18, a failure is similarly determined from the conditions (b) and (c). Reference numeral 20 denotes a sound phase selecting means for selecting and outputting, for example, the phase currents iu and iv of two phases of the phase currents iu, iv and iw. Detection signal 1
By 9a, the output of the phase current iu from the phase current detection means 16 is stopped. Further, the sound phase selecting means 20 outputs the phase current iv from the other sound phase current detecting means 17 and the phase current iw detected by the remaining phase current detecting means 18. 21 is an integrator to which the command frequency signal ω is input, and outputs a phase θ. Reference numeral 22 denotes dq-axis conversion means to which, for example, phase currents iu and iv, which are outputs of the phase θ and the healthy phase selection means 20, are input, and are coordinate-converted into d-axis current components id and q-axis current components iq of rotation orthogonal coordinates. I do. 23 is each axis current component id, iq
Are input, and output the d-axis feedback voltage signal 23d and the q-axis feedback voltage signal 23q as voltage signals by multiplying by the respective gains. 24, 25
Is a subtractor which subtracts each axis feedback voltage signal 23d, 23q from each axis command voltage signal Vd *, Vq * and outputs each axis control voltage signal 24d, 25q. 26 is the phase θ
The phase voltage converting means to which the axis control voltage signals 24d and 25q are input outputs phase voltage command signals Vu * and Vw * for controlling the phase voltage of the inverter 14.

Next, the operation will be described. In FIG. 1, each axis command voltage signal Vd *, Vq
* And the phase voltage converting means 2 based on the phase θ of the integrator 21.
6 to output the phase voltage command signals Vu *, Vv *, Vw *. The inverter 14 controls the phase voltage command signals Vu * and V
v *, Vw *, and the phase voltages Vu, Vv, V
By outputting w, the AC motor 15 is driven. The phase currents iu, iv and iw detected by the phase current detection means 16 to 18 are input to the healthy phase selection means 20 and the phase current i for three phases is obtained.
Outputs any two phases of u, iv and iw. For example, when the phase currents iu and iv are output from the healthy phase selecting means 20, the dq axis converting means 22 together with the phase from the integrator 21 outputs the d d of the rotating rectangular coordinates as shown in the equation (3).
The coordinates are converted into an axis current component id and a q-axis current component iq. Equation (3) can be derived as follows. That is, equation (4) for performing coordinate conversion into each axis current component using the phase currents iu, iv, and iw for three phases, and each phase current iu, i
This is modified from the equation (5) in which the sum of v and iw becomes 0.

[0009]

(Equation 2)

Each axis current component i thus obtained
d and iq are processed by the calculating means 23 to obtain each axis current component i.
d-axis feedback voltage signal 23d corresponding to d and iq
And a voltage signal of the q-axis feedback voltage signal 23q. Then, the respective axis feedback voltage signals 23d and 23q are subtracted from the respective axis command voltage signals Vd * and Vq * by the subtracters 24 and 25, and the respective axis control voltage signals 24d and 25q are output. This axis control voltage signal 2
The phase voltage conversion means 26 generates the respective phase voltage command signals Vu *, Vv *, Vw * by 4d, 25q, and the phase voltages Vu, Vv, Vw of the inverter 14 are controlled. As a result, an appropriate three-phase AC voltage is supplied to the AC motor 15.

Here, it is assumed that the failure detecting means 19 detects, for example, a failure of one phase current detecting means 16 and a detection signal 19a is inputted to the healthy phase selecting means 20. In this case, the sound phase selecting means 20 outputs the phase current i from the phase current detecting means 16.
Stop output of u. Further, the sound phase selecting means 20 continuously outputs the phase current iv from the other sound phase current detecting means 17, and outputs the phase current iw detected by the remaining phase current detecting means 18 which has not been output until now. Is output.
As a result, the phase currents iv, iw
Is input, and the coordinates are converted into the respective axis current components id and iq by equation (6). Subsequent operations are performed when the phase currents iu and iv are d-
This is performed in the same manner as when the input is made to the q-axis conversion means 22.

[0012]

(Equation 3)

As described above, the d-q axis conversion means 22 converts the coordinates into the d-axis current component id and the q-axis current component iq of the rotation orthogonal coordinates by the two phase currents, and detects one of the phase currents. When the failure of the means is detected, the coordinate current is converted into each axis current component id, iq by the phase current from the other sound phase current detection means and the phase current from the phase current detection means which has not been used until now. As a result, the vector control can be continued, so that the reliability can be improved.

[0014]

According to the present invention, the output of the phase current from one of the phase current detectors in which a failure has been detected by the failure detector is stopped, and the phase current from the other sound phase current detector is removed from each other. By supplying the remaining one phase current of the phase current to the dq axis conversion means, each axis current component id, iq
Since the vector control can be continued after the coordinate conversion, the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional control device for an AC motor.

[Explanation of symbols]

14 inverter, 15 AC motor, 16-18 phase current detecting means, 19 failure detecting means, 20 sound phase selecting means, 22 dq axis converting means.

Claims (1)

[Claims] 1. An output of a three-phase inverter vector-controlled by a d-axis command voltage signal and a q-axis command voltage signal
The phase AC motor is driven, the phase current of the inverter is detected by phase current detection means, coordinate-converted into a d-axis current component and a q-axis current component, and a d-axis feedback voltage signal corresponding to each phase current component and In a control device for an AC motor, a q-axis feedback voltage signal is generated, and a phase voltage of the inverter is controlled by a difference between the axis command voltage signal and the axis feedback voltage signal. Dq-axis conversion means for performing coordinate conversion into the d-axis current component and the q-axis current component using any two phases of the respective phase currents detected by
Failure detection means for detecting a failure of the phase current detection means that supplies the phase current to the axis conversion means; and detection of the phase current from one of the phase current detection means for which a failure has been detected by the failure detection means. Sound phase selection for stopping the output and supplying the phase current from the other sound phase current detection means and the phase current of the remaining one phase among the phase currents to the dq axis conversion means. And a control device for an AC motor.