Motor control method and circuit for stable operation of AC motor in full frequency range

Abstract

The invention provides a motor control method and circuit for stable operation of an AC motor in a full frequency band, the low-speed and high-speed control switching is smooth, the stable range is widened, the speed regulation range is wide, and the application is wide. The method includes the steps of performing deviation processing on a given current Idref generated according to a set frequencyand a feedback current Idfed generated by collecting a current of an AC motor; performing PID control on the obtained deviation to generate an initial given direct-axis voltage; performing amplitudelimiting on the initial given direct-axis voltage according to an operating direction of the AC motor to obtain a given direct-axis voltage Udref; obtaining the corresponding set rotational speed according to the set frequency and obtaining a given quadrature-axis voltage Uqref from the set rotational speed; and synthesizing the given direct-axis voltage Udref with the quadrature-axis voltage Uqref to output the value and angle of the control voltage of the AC motor.

Description

technical field [0001] The invention relates to full-frequency range control of an AC motor, in particular to a motor control method and circuit for stable operation of an AC motor across a full-frequency range. Background technique [0002] With the development of society and technological progress, inverters are widely used in the industrial field to control the operation of motors. VF control is also called constant voltage frequency ratio control. It is an open-loop system controlled according to the steady-state relationship of the motor. It is a scalar control A sort of. Since there is no torque current loop control and it is based on steady-state control, it has disadvantages such as poor dynamic performance, poor start-up performance, and slow magnetic field establishment. However, due to its simplicity, ease of use, and little influence by parameter changes, its performance is also It can meet the general speed regulation requirements, so it is the most widely used...

AI Technical Summary

Problems solved by technology

Since there is no torque current loop control and it is based on steady-state control, it has disadvantages such as poor dynamic performance, poor start-up performance, and slow magnetic field establishment. However, due to its simplicity, ease of use, and little influence by parameter changes, its performance is also It can meet the general speed regulation requirements, so it is the most widely used and is favored by the majority of users.

[0003] However, due to the influence of stator resistance and dead zone, the VF load capacity is poor at low speed, and the operation is unstable in severe cases.

In addition, encoderless vector control has strong low-speed load capacity, but it is greatly affected by parameters and unstable

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