Sensorless induction motor control device having function of correcting slip frequency of motor

Abstract

A sensorless induction motor control device with a function of correcting a slip frequency wherein a slip frequency estimation unit estimates the slip frequency from at least one kind of current flowing through the motor. A voltage command value calculation unit calculates a D-phase voltage command value and a Q-phase voltage command value which are used for controlling a voltage applied to the motor using a Q-phase current command value calculated based on a difference between a speed estimation value, which is calculated using an estimation value of the slip frequency, and an externally supplied speed command value. An ideal voltage command value determination unit determines an ideal voltage command value using the speed command value and the Q-phase current command value. An actual voltage command value calculation unit calculates an actual voltage command value using the D-phase voltage command value and the Q-phase voltage command value. and A slip frequency correction unit compares the ideal voltage command value with the actual voltage command value and changes the estimation value of the slip frequency to make it smaller if the actual voltage command value is smaller than the ideal voltage command value.

Description

technical field [0001] The present invention relates to a sensorless induction motor that is controlled by estimating the slip frequency from the current flowing in the coil of the motor instead of using a speed sensor to detect the speed of the motor, and estimating the speed of the motor using the slip frequency control device. Background technique [0002] Various methods are described in Japanese Patent No. 3067659 (JP3067659B), for example, regarding the control method of an induction motor without a speed sensor. However, in this control, the Slip rate is used to calculate the estimated speed and perform feedback control. When the speed feedback data is correct, the voltage command generated by this control becomes a desired command value. [0003] figure 1 It is a block diagram showing the configuration of a conventional sensorless induction motor control device that does not have a slip frequency correction function. figure 1 The control device is an independent ...

AI Technical Summary

Problems solved by technology

As a result, the estimated speed value ω r ^, excitation frequency command ω1 cmd Deviation from the true value causes the voltage command to be lower than the ideal value, and the motor cannot output the desired output

[0005] That is, when there is an error in the speed estimation value in the high-speed range, there is a problem that the current does not flow in the desired phase and the output drops.

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