JPS62250895A - Controller for ac motor - Google Patents

Abstract

PURPOSE:To contrive pulsation not to be generated on an AC motor and prevent oscillation from being applied to the side of a load or the like, by controlling the increment or reduction of motor torque when the rotation and stop of the AC motor are repeated. CONSTITUTION:When a vehicle in a specified load state is run at a slight and constant speed and when the rotation and stop of an induction motor c are repeated, then motor torque is increased as well as or more than load torque to be controlled, and so the induction motor c is continuously rotated and driven, and so the pulsation of an induction motor 10 is suppressed, and accordingly, the oscillation of the vehicle is extremely attenuated. As a result, without generated oscillation, the vehicle can be driven at a slight speed suitable for the operation of an accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to an AC motor control device that controls the torque generated by an AC motor using an inverter in response to the operation of an accelerator operator.

(Background of the Invention) This type of device has been proposed in Japanese Patent Application No. 60-100426, and conventionally, PWM inverters and the like have been used to control AC motors.

However, in the past, even when a pseudo sine wave drive voltage was applied from a PWM inverter to an AC motor, the torque generated by the AC motor would pulsate, and the maximum period would be the same as the motor applied voltage, so the AC motor would remain constant. When the motor is operated at low speed under a load condition, the motor torque periodically falls below the load torque as shown in Figure 2, and as a result, the AC motor repeatedly starts and stops, and as a result, for example, when the AC motor When used as a driving source for a vehicle, there has been a problem in that unpleasant vibrations are generated due to tire twisting and the like.

(Object of the invention) The present invention has been made in view of the above-mentioned conventional problems, and
The purpose is to provide an AC motor control device that prevents repetition of starting and stopping the motor when the AC motor is operated at a slow speed with a predetermined load, thereby solving the problem of pulsation caused by the motor load, etc. .

(Configuration and Effects of the Invention) In order to achieve the above object, an apparatus according to the present invention is configured as shown in FIG.

In the figure, the operation amount of the accelerator operator a is detected by the accelerator operation amount detection means, and the torque generated by the AC motor C is controlled according to the detected operation amount by the motor torque control means d using an inverter. ing.

Rotation and stop of the AC motor C are determined by the motor rotation/stop determination means e, and when the rotation and stop of the AC motor C are repeated, the torque generated by the AC motor C increases or decreases by a predetermined amount. A command is given to the motor torque control means d by the torque increase/decrease command means f.

(Description of Embodiments) Hereinafter, preferred embodiments of the apparatus according to the present invention will be described based on the drawings.

The induction motor 10 shown in FIG. 3 is used as a driving source for an electric vehicle, and a pulse generator 12 generates pulses synchronized with its rotation.

The output pulses of the pulse generator 12 are converted to 1 to 1 in the force counter 14, and the 1 to 1 values are sent to the CPU 2 in the motor control circuit 16 via l1018.
It is given to 0.

Further, the amount of depression of the accelerator pedal 22 is detected by the potentiometer 24, and the detection signal is also l1018.
is given to the CPU 20 via.

The CPU 20 uses the 100 revolutions of the AC motor obtained by the pulse generator 12 and the counter 14 and the amount of depression of the accelerator pedal 22 obtained by the potentiometer 24 to read the RAM according to the memory contents stored in the ROM of the memory circuit 24. A predetermined control calculation is performed using the control calculation, and a control command obtained by the control calculation is given to the PWM oscillator 26 via l1018.

The inverter control signal obtained by the PWM oscillator 26 is supplied to the PWM inverter 28, and the PWM
A pseudo sine wave driving voltage is applied to the AC motor 10 from the inverter 28 .

In FIG. 4, the procedure of the control process performed by the CPtJ20 is shown by flowchart 1-, in which the depression ff1A of the accelerator pedal 22 detected by the potentiometer 24 is first read (step 100), and then the pulse The rotation speed N of the AC motor 10 detected by the generator 12 and the counter 14 is read (step 102).

Then, it is determined whether the accelerator pedal depression mA read in the current processing cycle has changed from that before the previous processing cycle (step 104), and if the change is confirmed, (judgment), vector control calculation is started.

In this calculation, the amplitude command V8 of the motor mark/JO voltage and the slip frequency command fs'' are obtained (step 106), and then the period of the slip frequency command fs'' is determined by the frequency added to the rotational frequency f8 of the induction motor 10. and the amplitude v
A sinusoidal control command v8 varying by 8 is obtained (step 108).

By outputting the control command V* to the PWM generator 26 (step 110), the induction motor 10 is driven by the PWM inverter 28, and the generated torque is controlled according to the depression of the accelerator pedal 22 ff1A.

Here, no change is recognized in the depression ♀A of the accelerator pedal 22 during the process shown in FIG. If the will is given,
As shown in FIG. 2, it is determined whether the induction motor 10 is repeatedly rotating and stopping by monitoring the motor rotation speed N (step 112).

When it is determined that the induction motor 10 has not repeatedly rotated and stopped (negative determination in step 112), the vector control calculation described above is performed (steps 106, 108>, I11 command V
* is output (step 11O), and the same control as described above is performed.

On the other hand, when the depression ff1A of the accelerator pedal 22 is constant (negative determination in step 104) and the induction motor 10 is repeatedly rotating and stopping (affirmative determination in step 112), then The actual accelerator pedal depression MA read in is increased by a predetermined amount, and the new accelerator pedal depression i(A+'l
) are used to calculate the motor applied voltage amplitude command V8 and the slip frequency command fs8 (step 114).

Thereafter, a control command V* is determined based on the motor applied voltage amplitude command V8 and the slip frequency command fs" determined in this way (step 108), and the control command V
* is output to the PWM oscillator 26 (step 110)
.

Therefore, when the AC motor 10 repeatedly rotates and stops when the electric vehicle is driven at a constant speed under a predetermined running load, the accelerator pedal depression MA is corrected to increase successively.

Therefore, the torque generated by the induction motor 10 is controlled to increase by a predetermined amount, and as a result, the torque generated by the induction motor 10 increases to the fifth level.
As shown in the figure, the load torque is greater than that.

As explained above, according to the present embodiment, when the induction motor 10 is repeatedly rotated and stopped when the vehicle is running at a constant speed in a predetermined load state, the motor torque changes under the load. Since the torque is controlled to increase over and above the torque, the induction motor 10 is continuously driven to rotate, thereby preventing pulsation of the induction motor 10, and thus greatly reducing vehicle imaging.

As a result, it becomes possible to drive the vehicle at a slow speed that is faithful to the accelerator operation without causing vibration.

In this embodiment, the motor torque is controlled to increase when the rotation and stop of the induction motor 10 are repeated, but on the contrary, by decreasing the motor torque to below the load torque and controlling the induction motor 10 to stop. , it is also possible to reduce vibrations of the induction motor 10 and thus of the vehicle.

(Effects of the Invention) As explained above, according to the present invention, when the AC motor repeats rotation and stop, the motor torque is controlled in the increasing/decreasing direction or in the decreasing direction, so that the AC motor continuously rotates or The AC motor continues to stop rotating, so that no pulsation occurs in the AC motor, and therefore it is possible to effectively prevent vibrations from being applied to the load side of the AC motor.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to claims, FIG. 2 is an explanatory diagram of the operation of the conventional device, FIG. 3 is a block diagram showing a preferred embodiment of the device according to the present invention, and FIG. 4 is a diagram showing the operation of the embodiment in FIG. The flowchart to be described and FIG. 5 are characteristic diagrams for explaining the control operation of the embodiment in FIG. 10... Induction motor 12... Pulse generator 14... Counter 16... Motor control circuit 22... Accelerator pedal 24... Potentiometer 28... PWM inverter

Claims (1)

[Claims] (1) Accelerator operation amount detection means for detecting the operation amount of the accelerator operation element; motor torque control means for controlling the generated torque of the AC motor by an inverter according to the detected operation amount of the accelerator operation element; and AC motor rotation and stopping. and motor torque increase/decrease command means for instructing the motor torque control means to increase or decrease the motor torque by a predetermined amount when rotation and stop of the AC motor are repeated. AC motor control device.