JPH07111708A - Induction motor controller for motro vehicle - Google Patents

Abstract

PURPOSE:To allow continuous operation when an abnormality occurs in the compositional element of vector control. CONSTITUTION:A V/F control system for controlling only the speed without employing any sensor is provided in addition to a vector control system for controlling the torque and speed of an induction motor 8 based on the signal from a rotational speed sensor 9 and line current sensors 18, 19. The vector control system is normally operated and a switching is made to the V/F control system upon occurrence of abnormality in the compositional element of the vector control system thus sustaining the operational control of the motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction motor control device for an electric vehicle, which is capable of continuing operation while performing speed control by an accelerator even when an abnormality occurs in a control system of an induction motor for an electric vehicle. Regarding

[0002]

2. Description of the Related Art As a conventional failure countermeasure method for a control system for an induction motor, for example, there is a technique disclosed in Japanese Patent Laid-Open No. 2-266884. In the above publication,
Equipped with both a vector control system and a slip frequency control system as a control system for the induction motor.When the current detection is normal, the current is fed back to perform vector control, and when the current detection is abnormal, the current feedback is cut off to shift to the slip frequency control. It is disclosed.

[0003]

However, according to the failure countermeasure method for the conventional induction motor control system as described above, the vector control is switched to the slip frequency control as the failure countermeasure control method. Although it is possible to deal with a failure of the current sensor, it is impossible to deal with a failure of the rotation sensor, and there is a problem that it has to be stopped.

The present invention solves the above-mentioned conventional problems, and even when an abnormality occurs in a component of the vector control system, it is possible to return while controlling the speed by the accelerator without being forced to stop completely. An object of the present invention is to provide an induction motor control device for an electric vehicle.

[0005]

In order to solve the above-mentioned problems, in the present invention, an induction motor control device for an electric vehicle uses a signal of a sensor for detecting a rotation speed and a signal of a current sensor for detecting a line current. A general vector control system for controlling the torque and speed of the induction motor based on the above, and a V / F control system for controlling only speed without using the above-mentioned sensor are provided, and control is performed by the vector control system in a normal state. When an abnormality occurs in a component of the vector control system, the control is switched to the V / F control system so that the operation control of the electric motor can be continued. In practice, the speed during V / F control is controlled by the accelerator opening, the speed corresponding to the accelerator opening during V / F control is compared with the actual vehicle speed, and the vehicle speed is released. The V / F control is started when the speed drops to the speed corresponding to the degree. To switch from vector control to V / F control,
The rotation sensor abnormality detecting means and the current sensor abnormality detecting means are provided, and the vector control is switched to the V / F control according to the output signals of these abnormality detecting means. Further, when the vector control circuit and the V / F control circuit which are independent of each other are separately provided and the abnormality detecting means for detecting the abnormality of the vector control circuit constituent element detects the abnormality of the microcomputer, for example, , The control is switched from the vector control circuit to the V / F control circuit.

[0006]

In vector control, the driver controls the torque by the accelerator opening and adjusts the speed. However, depending on the state of charge of the battery, etc., the driver can adjust the torque in the motor both steadily and transiently. The rotation speed and the line current are constantly monitored so that the loss is as low as possible, and the optimum operating state in which the power consumption is the least is maintained. If an abnormality occurs in a component of the vector control system for monitoring these operating states, such as a rotation sensor or a current sensor, proper control cannot be performed. On the other hand, in the present invention, when the vector control system fails, the vehicle can be driven only by speed control, but the driver can manage to arrive at his / her home or the nearest service station. In other words, you can reach the house while dragging your foot (Limp Home limp h
ome), but this is practically
It is very effective. Note that switching from vector control to V / F control is performed when the actual traveling vehicle speed decreases from the vehicle speed during vector control to a relatively low speed determined by the accelerator opening during V / F control. Above all, it is easily executed.

[0007]

FIG. 1 is a diagram showing an embodiment of the present invention. The configuration will be described first with reference to FIG. The induction motor (IM) 8 is supplied with three-phase alternating current from the pulse width modulation (PWM) inverter 7. Further, the IM8 is connected with a rotation sensor 9 for outputting ON / OFF signals of two phases of A phase and B phase according to the rotation. The PWM inverter 7 has a switch C
The current controllers 3 and 4 and the output of the adder 21 that receives the outputs of the current controllers 3 and 4 are input via (SWC). Reference numeral 2 is a 2-phase / 3-phase coordinate converter that outputs a current signal of 2-phase out of 3-phase alternating current. The subtractors 22 and 23 output the difference between the output of the current sensors 18 and 19 and the output of the coordinate converter 2 and input them to the current controllers 3 and 4.
A magnetic flux command i * ds from the magnetic flux controller 1 is sent to the coordinate converter 2.
However, the torque command i is also sent via the switch A (SWA).
* Qs is input. The slip frequency power supply frequency calculator 5 is supplied with the magnetic flux command i * ds, the torque command i * qs, and the rotation frequency signal ω _r obtained from the output of the rotation sensor 9 via the signal processing circuit 10. The output of the slip frequency power supply frequency calculator 5 is input to the trigonometric function generator 6, and the trigonometric function generator 6 outputs the trigonometric function according to the rotation angle to the coordinate converter 2.

FIG. 2 is a detailed diagram of the rotation signal abnormality detection circuit 11 shown in FIG. 1, in which signals A phase and B of the rotation sensor 9 are shown.
The phases are input to the inverters 32 and 33, respectively, and their outputs are input to the OR circuit 31 and the J input of the JK flip-flop (FF) 30. On the other hand, the rotation sensor 9
Signals A and B are also input to the OR circuit 34, and the output thereof is used as the K input of the FF 30. The output of the FF 30 is the rotation signal abnormality detection signal F. In addition to the function described later, the rotation signal abnormality detection signal F turns on the alarm lamp 12 to warn the driver of the abnormal state and warn the driver.

FIG. 3 is a detailed diagram of the speed reduction detection circuit 16, in which the output of the speedometer 20 is input to the F / V converter 37 and used as a DC voltage signal S. This signal S is compared with the output of the buffer circuit 36 to which the accelerator signal is input by the comparator 35. If the signal S is lower than the output of the buffer circuit, the comparator 35 outputs the speed decrease signal S '.

FIG. 4 is a detailed view of the switch drive circuit 17, in which the rotation signal abnormality detection signal F is input to the inverter 40, and the switching drive control signals DSWA and DSWA and SWC.
It is output as SWC. The output speed decrease signal S ′ of the speed decrease detection circuit 16 is input to the AND circuit 41 together with the rotation signal abnormality detection signal F, and the output of the AND circuit 41 passes through the latch 42 and becomes the SWB switching drive control signal DSWB.

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described. FIG. 5 is a diagram sequentially showing, from top to bottom, operating current waveforms of respective parts of the induction motor control device for the electric vehicle according to the present invention. Normally, the control system operates by vector control when the rotation sensor is not defective. That is, a constant magnetic flux command i * ds is given, the generated torque is determined by the torque command i * qs based on the accelerator opening, and the three-phase AC is output to the PWM inverter 7. Specifically, the magnetic flux command i * ds from the magnetic flux controller 1 and the torque command i * qs
Is input to the slip frequency power supply frequency calculator 5, and the slip frequency ω _s

[0012]

[Equation 1]

[0013] However, r _2: 2 primary resistance L _2: 2 was calculated according to following leakage inductance + mutual inductance (number 1), the speed signal omega _r from the rotation sensor 9, from ω _s ω = ω _s + ω _r ……… Calculates the output frequency ω using (Equation 2). In the trigonometric function generator 6, θ = ∫ωdθ ... (Equation 3) determines the rotation angle θ, and sin θ and sin (θ-2π
/ 3) is calculated and output to the 2-phase / 3-phase coordinate converter 2. In the coordinate converter

[0014]

[Equation 4]

[0015]

[Equation 5]

As, the two-phase signal is converted into a three-phase signal.
i _w * is not calculated here, but a command value for the W phase is created as the sum of the error signals output from the current controllers 3 and 4. i
_u * and i _v *, respectively taking the difference between the output of the U-phase and V-phase output of the current sensor 18 and 19 outputs the PWM inverter 7, they are amplified by the current controller 3 and 4, through the SWC Is input to the PWM inverter 7,
Produces three-phase AC output with pulse width modulation. The IM8 rotates by this three-phase alternating current.

When the rotation sensor signal fails at the failure point K as shown in FIG. 5, the rotation signal abnormality detection circuit 11 immediately detects this and outputs a rotation signal abnormality detection signal F. As a result, the switch drive circuit 17 sets the DSWA and DSWC signals to "L", opens SWA and switches SWC, and the PWM inverter 7 stops the output. As a result, the power supply to the IM8 is cut off, and the rotation speed decreases. The speedometer 20 outputs a low frequency pulse as the vehicle speed decreases, and the output voltage of the F / V converter 37 of the speed decrease detection circuit 16 decreases accordingly. When the voltage falls below the voltage determined by the value of the accelerator command A, the speed reduction signal S'is output. When the signal S ′ is output, the rotation signal abnormality detection signal F has already been output, so that the AND circuit 41 of the switch drive circuit 17 outputs “H” and the latch 42 outputs “H”. Also hold. The output of the latch 42 becomes the DSWB signal and SWB
Is closed, and the accelerator signal is input to the slope signal generation circuit 13 that avoids a rapid rise, and the frequency signal f * that gradually rises is output to the three-phase AC generation circuit 15. Further, the frequency signal f * is input to the voltage pattern generation circuit 14 so as to perform the V / F control.
* Is output, and the signals f * and V * are the three-phase AC generation circuit 1
5, a three-phase alternating current is generated according to the signals f * and V *, and the PWM inverter 7 is driven via the SWC. When the abnormality of the rotation sensor 9 is detected in this way, the vector control is immediately stopped, the current supply to the IM 8 is continuously stopped until the speed decreases to the speed reduction limit speed determined by the accelerator opening, and the speed lower than the speed reduction limit is reached. If it drops to V /
Switch to F control and IM8 at a speed according to the accelerator opening.
To rotate. Also, if you switch to V / F control once,
By the holding action of the latch 42 of the switch drive circuit 17,
V / F control is continued even if the accelerator opening changes. In vector control, the accelerator opening serves as a torque command to drive the electric motor, but in V / F control, it becomes speed control.
The accelerator opening becomes the speed command. Therefore, it is desirable to limit the speed range in order to adjust the speed within the limited change range of the accelerator, and it is necessary to match the output frequency of the inverter determined by the accelerator with the speed of the vehicle at the time of control switching. There is.

FIG. 6 shows an abnormality detecting circuit for a current sensor, which detects an abnormal value output from the current sensor and generates an "H" output. Reference numerals 43 and 44 are comparators, which generate "H" output when the current sensor output outputs an abnormal value (whether positive or negative) which is not normal. This is ORed by the OR circuit 45 and used as the output of the abnormality detection circuit. By replacing the rotation signal abnormality detection circuit 11 shown in FIG. 1 with the circuit shown in FIG. 6, even if the current sensors 18, 19 become abnormal, the operation is switched to the V / F control to continue the operation. You can In addition, V / is provided separately from the microcomputer that constitutes the vector control circuit.
By providing the F control controller, the failure of the microcomputer can be detected by, for example, a well-known WDT (watchdog timer), and the operation can be continued even when the microcomputer fails.

[0019]

As described above, according to the present invention, a vector control system is additionally provided with a V / F control system, and the vector control is performed when an abnormality is detected in a component of the vector control system. And the vehicle speed changes to V
In the case of / F control, V / F control is started when the speed has dropped to near the command speed determined by the accelerator opening, and then V / F control is started.
By performing the / F control, the operation of the electric motor can be continued even when the sensor or the like fails, and a so-called limp home can be realized. When switching the control method, the vehicle speed that was usually relatively high during vector control is
Since the V / F control is started in a state where the vehicle speed has decreased to a predetermined speed, it is easy to execute even while traveling. As a countermeasure against the failure of the current sensor, the method of switching from the vector control to the slip frequency control is of course effective as it is, but when the rotation sensor fails, it cannot move at all, so it is very difficult to use in practice. According to the present invention, the operation can be continued anyway. Figure 1
In addition to the circuit configuration example shown in Fig. 2, as described above, it is also possible to adopt a configuration in which failure detection of a current sensor, a microcomputer, etc., which constitutes a vector controller, can be performed and operation can be continued in the event of a failure. Can be increased.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a detailed diagram of a rotation signal abnormality detection circuit shown in FIG.

FIG. 3 is a detailed diagram of a speed reduction detection circuit shown in FIG.

FIG. 4 is a detailed diagram of a switch drive circuit shown in FIG.

5 is a diagram sequentially showing, from top to bottom, operating current waveforms of respective portions of the induction motor controller for an electric vehicle according to the present invention shown in FIG.

FIG. 6 is a detailed diagram of an abnormality detection circuit of a current sensor.

[Explanation of symbols]

1 ... Magnetic flux controller 2 ... Two-phase / three-phase coordinate converter 3, 4 ... Current controller 5 ... Slip frequency power supply frequency calculator 6 ... Trigonometric function generator 7 ... Pulse width modulation type inverter 8 ... Induction motor 9 ... Rotation sensor 10 ... Rotation signal processing circuit 11 ... Rotation signal abnormality detection circuit 12 ... Warning lamp 13 ... Inclination signal generation circuit 14 ... Voltage pattern generation circuit 15 ... Three-phase AC generation circuit 16 ... Speed drop detection circuit 17 ... Switch drive circuit 18, 19 ... current sensor 20 ... speedometer 21, 22, 23 ... adder 30 ... JK flip-flop 31 ... OR circuit 32, 33 ... inverter 34 ... OR circuit 35 ... comparator 36 ... buffer circuit 37 ... F / V converter 40 ... inverter 41 ... AND circuit 42 ... Latch 43, 44 Comparator 45 ... OR circuit i * ds ... Magnetic flux command i * qs ... Click command SWA ... switch A SWB ... Switch B SWC ... switch C DSWA ... SW
A switching drive control signal DSWB ... SWB switching drive control signal DSWC ... SW
C switch drive control signal omega _r ... rotation frequency signal S '... speed reduction signal F ... rotation signal abnormality detection signal i _u * ... phase 3 obtained from the magnetic flux command signal i _v * ... 3 phase obtained from the torque command Signal A ... Accelerator command f * ... Frequency signal that gradually rises V * ... Voltage signal for V / F control

Claims (6)

[Claims] 1. A vector control system for controlling torque and speed of an induction motor based on a signal of a sensor for detecting a rotation speed and a signal of a current sensor for detecting a line current, and a speed without using the sensor. In an induction motor control device for an electric vehicle equipped with a V / F control system for controlling only the normal control, the control is performed by the vector control system during normal operation, and if an abnormality occurs in a component of the vector control system, the control is performed. V /
An induction motor control device for an electric vehicle, characterized in that the operation control of the electric motor can be continued by switching to an F control system. 2. The V / F control is started after the vector control is stopped because an abnormality has occurred in its constituent elements and then the traveling speed of the vehicle is reduced to a speed close to a predetermined low speed. The induction motor control device for an electric vehicle according to claim 1, wherein 3. A vehicle speed is configured so that the speed during V / F control is controlled by the accelerator opening, and the speed corresponding to the accelerator opening during V / F control is compared with the actual vehicle speed. When the speed decreases to the speed corresponding to the opening, V / F
The induction motor control device for an electric vehicle according to claim 2, wherein control is started. 4. An induction motor control for an electric vehicle according to claim 1, further comprising abnormality detecting means for the rotation sensor, wherein the control signal is switched from the vector control to the V / F control according to an output signal of the detecting means. apparatus. 5. An induction motor control for an electric vehicle according to claim 1, further comprising abnormality detecting means for the current sensor, wherein the vector control is switched to the V / F control by an output signal of the detecting means. apparatus. 6. A vector control circuit and V which are independent of each other.
/ F control circuit is provided separately, and when the abnormality detection means for detecting an abnormality in the vector control circuit component detects an abnormality, the control is switched from the vector control circuit to the V / F control circuit. The induction motor control device for an electric vehicle according to claim 1, characterized in that the control is performed.