JPS60144159A - Controlling method of induction motor - Google Patents

Abstract

PURPOSE:To maintain the response of control systems irrespective of the primary frequency by associating a compensating element relating to the primary frequency and current control system. CONSTITUTION:Components eq of phase difference of 90 deg. to and components ed of the same phase as an exciting current phase reference signal are respectively detected by voltage detectors 19, 20. A d-axis voltage signal ed is compensating for the gain corresponding to the primary frequency command by a gain compensator 8, thereby obtaining an equivalent signal to the magnetic flux phiq of the q-axis component. The primary frequency is controlled by this signal. On the other hand, the component eq is subtracted by an adder 5 from the q-axis voltage command. This deviation can detect a signal equivalent to the deviation between the command of the magnetic flux of the d-axis component and the detected value by compensating the gain corresponding to the primary frequency command by the gain compensator 6. The torque current it* is altered in response to the deviation to control the rotating speed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a method for controlling an induction motor in which the primary current of the induction motor is divided into a torque current and an excitation current and each is controlled independently without using a speed detector. Regarding.

[Background of the invention]

IPEC(((1terHatiO(Ial powe
r ElectroHicsCoHfere4ce)
Collection of papers (1983, Vot 1 pp720-731
), errors in the secondary resistance of the induction machine, etc.

A method of compensating for vector control such as detection errors of speed detectors is described. According to this principle, out of the primary current command of the induction machine, the component that commands the excitation current and the same phase component IA
By controlling the primary current and primary frequency according to d and the 90-degree phase component e, various calculation errors in vector control can be compensated, and by setting the calculation error compensation it to 100 yen, It has been shown that vector control is possible without the need for a speed detector. However, in order to perform vector control without a speed detector, it is necessary to control the primary current and primary frequency according to e, , e, but when the -order frequency changes, ed and eq change. , - next current and -
The response of the control system for the next frequency changes, making it impossible to control the speed of the induction machine with high precision.

[Purpose of the invention]

The object of the present invention is to provide high speed,
The object of the present invention is to provide a control method that can perform high-response speed control.

[Summary of the invention]

The feature of the present invention is that the vector control conditions are such that the secondary magnetic flux component φ2d in the same direction as the excitation current command is constant and 90°
Phase component φ2. is zero, and each magnetic flux component φ2
．． By focusing on the fact that the product of φ2d and the primary frequency is ea and e, and incorporating the compensation element related to the -order frequency into the control system of the primary frequency and -order current, the primary frequency (rotational speed of the induction motor) Regardless, the present invention provides a method for controlling the primary current and the -order frequency while keeping the response of each control system constant.

[Embodiments of the invention]

FIG. 1 shows a circuit configuration diagram of a PWM inverter device according to an embodiment of the present invention. 1 is GTO (Gate Turn-of
2 is an induction motor, 3 is a speed command circuit, 4 is a speed change rate limiter, 5 is an excitation current component (excitation current component) determined by the speed change rate limiter 4 and the control system. An adder 6 detects the deviation from the output of the fundamental wave voltage detector 19 which detects a phase difference component of 90 degrees with respect to the current phase reference signal), and 6 changes the output of the adder 5 according to the primary frequency command. A gain compensator 7 is an output ψ width amplifier of the gain compensator 6. Reference numeral 8 denotes a fundamental wave voltage detector 20 that detects a component in the same phase as the excitation current component (excitation current phase reference signal) determined by the control system.
9 is an amplifier that amplifies the output of the gain compensator 8 according to the primary frequency command. 10 is an amplifier that adds the output of the speed change rate limiter and the output of the amplifier 9, and calculates the −th order frequency. This is an adder that outputs a command. 11 is an oscillator that outputs a two-phase sine wave signal with a frequency proportional to the output of the adder 10, 12 is an excitation current command circuit that commands the excitation current of the motor 2, 13 is an excitation current command i, *, and an amplifier 7 A coordinate converter 14 multiplies the torque current command i- from the oscillator 10 by the output signal of the oscillator 10, and outputs two-phase current command pattern signals i* and iρ*. Current command pattern signal i, +
15 is a current detector that detects the instantaneous value of the output current of inverter 1; 16 is a current detector that compares the current command pattern signal i1.l* with the current detection signal; A comparator outputs a PWM signal for controlling the switching element on and off, 17 is a gate circuit for providing a gate signal to the switching element, and 18 is a voltage detector for detecting the terminal voltage of the motor. In addition, the current detector 15 and the comparator 16
, the gate circuit 17, the voltage detector 18, and the inverter 1 are as follows:
Only the U-phase component is shown, and illustration of the ■-phase and W-phase components is omitted.

Next, the operation will be explained.

The voltage detectors 19 and 20 detect biaxial components of the motor voltage, that is, a component eq with a 90 degree phase difference and a component ea with the same phase as the excitation current phase reference signal, according to the following equations.

Here, V, = V, e6: Output signal of the detector 20 e,: Output signal of the detector 19 V, ~vW: Voltage of each phase of the motor This calculation can be easily performed using, for example, a multiplier and an adder. can be realized.

Voltage detection signal e4. e is the magnetic flux component φd if the influence of leakage impedance drop of the motor 2 is ignored.

There is the following relationship with φ.

Therefore, by compensating the gain of the d-axis voltage signal e in accordance with the frequency command of the gain compensator 8, a signal equivalent to the magnetic flux φ of the q-axis component can be obtained, and this signal The next frequency is controlled accordingly.

On the other hand, the q-axis voltage component e, is the d-axis magnetic flux component φd and the angular frequency ω!, as shown in equation (2). is proportional to.

Therefore, the output of the adder 5 is the deviation between the voltage command on the q-axis and the detected voltage, but the gain is compensated by the gain compensator 6 in accordance with the p-th frequency command, A signal equivalent to the deviation between the component magnetic flux command and the detected value can be detected. By changing the torque current it* according to this deviation, the rotational speed can be controlled according to the command value.

Therefore, according to the present invention, a constant frequency control response and constant speed control response can be obtained regardless of the missing frequency, and speed control with high speed response can be performed.

FIG. 2 shows another embodiment of the invention. In FIG. 2, when the output of the speed change rate limiter 4 changes slowly, the -missing frequency command and the output of the speed change rate limiter 4 can be considered to be approximately equal, so the output of the gain compensator 8 Compensation is performed using the output of the speed change rate limiter 4.

In the above embodiments, an example of application to a PWM inverter was described, but the present invention can be applied to other types of inverters as long as their output frequency and output voltage (current) can be controlled. I can do it.

Of course, even if digital control is performed using a computer, microprocessor, etc., the invention can be adopted.

〔Effect of the invention〕

According to the present invention, a constant speed control response can be obtained regardless of the primary frequency, and vector control that independently controls the torque current and excitation current can be realized without using a speed detector.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of one embodiment of the invention, and FIG. 2 is a system diagram of another embodiment of the invention.

Claims (1)

[Claims] 1. A method for controlling an induction motor in which torque current and excitation current are independently controlled by controlling the magnitude and frequency of the primary current of the induction motor, which is determined by a control system that detects the voltage of the induction motor. A first method of detecting a component in phase with the excitation current component, and 90
A second method of detecting a degree phase difference component, and controlling the torque current command and the primary frequency command by changing the deviation between the detection signal and the speed command according to the primary frequency command.
A method of controlling an induction motor based on the characteristics.