JPS6181196A - Controlling method of induction motor - Google Patents

Abstract

PURPOSE:To perform accurate positioning control by supplying a DC current between two terminals of a motor to stop braking and supplying a positive or negative current to the other terminal to control to correct the stopping position. CONSTITUTION:The operating arm transistors Tu, Tz of an inverter 12 are driven immediately before the stopping point to supply a brake current iR to an induction motor 14 to perform a control operation. Thus, the motor 14 stops at a time t=T1. At this time, if the stopping position of the motor 14 is overrun with respect to the target value, the transistor Tv of the inverter 12 is driven at a time t=T2 to supply a current is to the motor 14, thereby generating a torque. As a result, the stopping position of the motor 14 is controlled to be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling an induction motor for performing a positioning operation that can be applied to a variable speed drive system using an inverter.

[Conventional technology]

Conventionally, a drive device using vector control is known as a technique for performing this type of positioning operation. This drive device is essential in terms of performance.

However, it requires speed detection of the motor and a control circuit. It has the disadvantage of being expensive due to its complexity.

In addition, as a simple method, DC braking or mechanical braking is carried out by detecting a position signal, but the stopping accuracy varies depending on the Q load conditions (GD2 weight, etc.) There were drawbacks such as the inability to perform corrective control to perform a return operation when there is an overshoot.

[Problems to be Solved by the Invention] Therefore, in the present invention, the variation in stopping accuracy caused by the conventional control method described above is prevented, and return correction control for the target value is achieved by a relatively simple means, and the accuracy is improved. An object of the present invention is to provide a control method for an induction motor that can achieve high positioning control.

[Means for solving the problem] In the present invention, DC braking of the motor is performed by supplying DC current to two terminals of an induction motor via an inverter, and then the braking stop position of the motor is set to a target value. In order to do this, positive or negative current is supplied to other terminals of the electric motor via an inverter to generate positive or negative torque in the electric motor to perform position correction control.

That is, in the present invention, in a control method configured to perform a positioning operation by driving an induction motor with an inverter and controlling variable speed, a DC current is supplied between two terminals of the motor to brake the motor and stop the motor. The motor is characterized in that a positive or negative current is supplied to the terminal of the motor to correct the motor stop position.

In this case, it is preferable that the inverter is formed by bridge-connecting switching transistors, and when the motor stops braking, the transistors in a pair of arms connected to two terminals of the motor are driven in pulses to connect a DC power source between the two terminals. It is.

In addition, the correction control for the stop position of the motor is performed after the motor is braked and stopped by supplying a DC current between two terminals of the motor, and then one of the transistors of the pair of arms of the inverter connected to the other terminal is It is preferable to drive the transistor in pulses to generate a positive or forward torque in the motor.

[Operation] According to the present invention, first, a DC current is supplied between two terminals of the induction motor to perform a braking stop. In this case, if the stop position is over or under the target value, the other terminal of the induction motor is Proper position correction control is achieved by supplying negative or positive current to generate negative or positive torque on the motor to position the motor at the target value.

〔Example〕

Next, an embodiment of a method for controlling an induction motor according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a basic configuration diagram of an inverter that controls the speed of an induction motor that implements the control method of the present invention. That is, in FIG. 1, reference numeral 10 indicates a DC power source, and this DC power source 10 can be obtained, for example, by rectifying and smoothing a three-phase power source. Further, reference numeral 12 indicates an inverter, and this inverter 12 is a switching transistor T.
, T , T , T .

The VWX T and T are bridge-connected, the DC power supply 10 is connected to the DC power source 10, the induction motor Ia 14 is connected to the power ratio, and the induction motor 14 is operated with a variable frequency by switching each transistor.・It is configured to perform variable speed operation by supplying variable voltage AC voltage.

Next, the operation of the control method of the present invention will be explained.

Now, the induction motor 14 is connected to the circuit as shown in FIG.
The operation near the stop will be explained with reference to FIGS. 2 and 3. First, just before the stopping point, the operation arm transistors T 1 and T 2 of the inverter 12 are fixed, and the induction motor 14 is subjected to current limited operation using the braking current O 8 . As a result, the induction motor 14 receives DC braking and stops at time t=71 (see Figure 3). At t=72, the transistor TY of the inverter 12 is pulse-driven to supply a negative current to the induction motor 14. is supplied to generate reverse torque (see Figure 3). As a result, the stop position of the induction motor 14 can be corrected and controlled. On the other hand, if the stop position of the induction motor hoe 14 does not reach the target value, at time t=T2, the transistor TV of the inverter 12 is pulse-driven to supply a positive current to the induction motor 14 to generate forward torque. For example, the stop position of the induction motor 14 can be corrected and controlled in the same manner as described above.

[Effects of the Invention] As is clear from the embodiments described above, according to the present invention,
In a device that uses a transistor inverter to control the induction motor at variable speed, the inverter arm controls the inverter arm to supply direct current between arbitrary two-phase terminals to generate field magnetic flux, and to generate a positive or negative pulse to the other one-phase input terminal. Since the magnitude and direction of the output torque are controlled by passing a current, it is possible to easily achieve corrective control of the positioning operation of the induction motor to the target flow without configuring a complicated system. can.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a basic configuration circuit diagram of a control inverter showing an embodiment of the induction motor control method according to the present invention, and FIG. 2 is a circuit explanatory diagram showing the operation of the present invention control method based on FIG.
FIG. 3 is an operational waveform diagram of the induction motor illustrating the circuit operation shown in FIG. 2. 10... DC power supply 12... Inverter 14... Induction motor T u, TV, T,, T x, T Y,
Tz. ... Switching transistor B, ... Braking current and 8 ... Reverse current N ... Rotation speed FIG, 3

Claims (3)

[Claims] (1) In a control method in which an induction motor is driven by an inverter and variable speed controlled to perform positioning operation, a direct current is supplied between two terminals of the motor to brake and stop the electric port, and the other terminals are A method for controlling an induction motor, the method comprising: supplying a positive or negative current to correct a motor stop position. (2) In the method for controlling an induction motor according to claim 1, the inverter is formed by bridge-connecting switching transistors, and when the motor is stopped by braking, the transistors in the pair of arms connected to two terminals of the motor are connected to each other. A method of controlling an induction motor by pulse driving and connecting a DC power source between the two terminals. (3) In the method for controlling an induction motor according to claim 1, after the motor is braked and stopped by supplying a DC current between two terminals of the motor, an inverter connected to the other terminal is A method for controlling an induction motor, the method comprising performing correction control in which one of the transistors in a pair of arms is pulse-driven to generate positive or negative torque in the motor.