JP3302854B2 - Induction motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an induction motor, particularly for improving the accuracy of torque control.

[0002]

2. Description of the Related Art FIG. 2 shows a configuration of a main part of an example of the prior art, which will be described with reference to FIG. In FIG. 2, reference numeral 1 denotes an inverter that drives a three-phase induction motor (hereinafter simply referred to as an electric motor) 2; 3, a voltage detector; 4, a current detector; 5, a magnetic flux calculator; 6, a torque calculator; It is a controller.

In the magnetic flux calculator 5, the primary interlinkage magnetic flux vector ψ 1 is obtained by the equation (1) from the primary voltage vector V 1 detected by the voltage detector 3 and the primary current vector I 1 detected by the current detector 4. It is calculated. Here, R1 is the primary resistance of the motor. The torque T is calculated by a torque calculation 6
Is calculated by equation (2). Where ψ1d, ψ1q
Is a component of the primary interlinkage magnetic flux vector ψ1, and I1d and I1q are also components of the primary current vector I1.

Ψ1 = ∫ (V1−R1 · I1) dt (1) T = ψ1d · I1q−ψ1q · I1d .... (2)

[0005] The torque controller 71 outputs a control signal of the inverter 1 such that the torque T output from the torque calculator 6 follows the torque command T *. The inverter 1 operates based on the input control signal and supplies electric power to the electric motor 2.

[0006]

As is well known, stray load loss is present in motors, and many motors have stray load loss of several percent or more at rated output. However, this loss is not reflected in the torque control of the prior art, and the output torque is reduced by an amount corresponding to the loss, so that the output torque according to the torque command cannot be obtained, and therefore, the torque control accuracy deteriorates.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made based on a technical idea of compensating a torque command or the like to compensate for a stray load loss of an electric motor. Things. Specifically, a command operation signal generator for calculating the square of the torque command or the current command for the torque command, a multiplier for multiplying the output of the command operation signal generator by a constant proportional to the stray load loss, and And an adder for adding the command to the command so that the output of the adder is obtained as a corrected torque command.

[0008]

[Operation] Due to the stray load loss, the output torque becomes lower than the torque command during power running, and the output torque increases in the regenerative torque direction from the torque command during regeneration. In other words, the output torque is shifted in the direction of stopping the rotation with respect to the torque command. Output torque can be obtained according to the torque command before the start.

By the way, if it is assumed that the stray load loss is caused by the gap harmonic magnetic flux, the stray load loss is proportional to the square of the primary load current and to the 1.5th power of the frequency.
In August, "Technical Report of the Institute of Electrical Engineers of Japan", No. 58, article "Load Loss of Induction Machine", it is described in the formulas (6) and (7). Thus, if the primary load current is a torque component current and the magnetic flux current is constant, it is proportional to the torque command,
The stray load loss is proportional to the square of the torque command. Therefore, the correction value corresponding to the stray load loss can be obtained by multiplying the square of the torque command by a constant. Further, the present invention is based on the drawings,
Details will be described.

[0010]

FIG. 1 shows the essential parts of an embodiment of the present invention shown in FIG. 2, wherein 72 is a torque controller, 8 is a command operation signal generator, 9 is a multiplier, 10 is a multiplier. Is an adder. That is, the command calculation signal generator 8 calculates the square value of the torque command T * and generates a signal to the multiplier 9. In the multiplier 9,
The output of the command operation signal generator 8 is multiplied by a constant corresponding to a stray load loss, and is output to the adder 10. In the adder 10, the multiplier 9
The output and the torque command T * are added to obtain a corrected torque command T * '.

The torque controller 52 gives the inverter 1 a control signal such that the torque T, which is the output of the torque calculator 6, follows the torque command T * ′. It is a matter of course that the inverter 1 operates based on the output of the torque controller 72 and can supply electric power to the electric motor 2.

[0012]

As described above, according to the present invention, the torque command can be corrected in accordance with the stray load loss of the electric motor, so that even if the stray load loss is large, the torque can be controlled with high accuracy. Equipment can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a main part of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 inverter 2 three-phase induction motor (motor) 3 voltage detector 4 current detector 5 magnetic flux calculator 6 torque calculator 71 torque controller 72 torque controller 8 command calculation signal generator 9 multiplier 10 adder T torque T * Torque command T * 'Torque command

Claims (1)

(57) [Claims] 1. An induction motor control device for controlling a three-phase induction motor output torque according to a torque command or a torque component current command, wherein a stray load loss of the three-phase induction motor is reduced.
Obtain the torque command or torque current command to compensate
Command operation signal for generating an output proportional to the square of the command
Comprising a No. generator, wherein an output of the finger-old computing signal generator
A control device for an induction motor, wherein the torque command or the torque component current command is compensated using a result of calculating a value corresponding to a stray load loss .