Motor control device, and method and device for estimating magnetic flux of electric motor

Abstract

The invention provides a motor control device, and a method and a device for estimating magnetic flux of an electric motor, and the device and the method can detect magnetic flux of a stator in high precision. The motor control device is provided with a magnetic flux estimator for estimating a vector of stator magnetic flux of the electric motor based on a difference between the output voltage and a voltage drop caused by a coil resistance of the electric motor, and a phase estimator for estimating a phase of the stator magnetic flux based on the vector of the stator magnetic flux estimated by the magnetic flux estimator. The magnetic flux estimator includes a variable low-pass filter for applying a low-pass filter to the difference at a cut-off frequency according to a frequency of the output voltage, and a phase adjuster for retarding at least one of an output phase of the variable low-pass filter and a phase of the difference before inputted into the variable low-pass filter.

Description

technical field [0001] The disclosed embodiments relate to a motor control device, a magnetic flux estimating device for a motor, and a magnetic flux estimating method. Background technique [0002] There is known a control device that drives a motor such as a synchronous machine or an induction machine without using a position sensor. For example, there is known a technique of estimating the stator magnetic flux of the motor from the current and voltage of the motor, and controlling the motor based on the estimated stator magnetic flux (for example, refer to Patent Document 1). [0003] Patent Document 1: Japanese Patent Laid-Open No. 2012-228083 [0004] However, when an integrator is used to estimate the stator magnetic flux, if there is an offset error in a current detector that detects the current of the motor, an offset may occur in the estimated value of the stator magnetic flux. Therefore, vibrations corresponding to the drive frequency of the motor may be included...

AI Technical Summary

Problems solved by technology

[0004] However, in the case of stator flux estimation using an integrator, when there is an offset error in the current detector that detects the current of the motor, an offset may occur in the estimated value of the stator flux

Therefore, vibration corresponding to the driving frequency of the motor may be included in the speed or phase obtained from the estimated value of the stator magnetic flux, and the motor may not be controlled with high precision.

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