Flux-weakening control method for variable frequency controller of permanent magnet synchronous motor

Abstract

The invention relates to the technology of a motor, solves problems that rotating speed of the motor cannot be effectively increased due to the limit of output voltage of an inverter and the fact that a control voltage space vector of the motor surpasses a voltage limit circle or an operation current space vector of the motor surpasses a current limit circle when an existing permanent magnet synchronous motor works at a higher frequency, and provides a flux-weakening control method for a variable frequency controller of the permanent magnet synchronous motor. The technical scheme can be summarized as the follows: a system samples DC bus voltage Vedc, and control voltage (img file='DDA0000579050440000011.TIF' wi='168' he='64') and (img file='DDA0000579050440000012.TIF' wi='94' he='72') are respectively obtained via calculation, wherein (img file='DDA0000579050440000013.TIF' wi='64' he='72') is a d-axis voltage instruction value, (img file='DDA0000579050440000014.TIF' wi='56' he='77') is a q-axis voltage instruction value, and (img file='DDA0000579050440000015.TIF' wi='64' he='72') is working voltage of the motor. Then modulation degree (img file='DDA0000579050440000016.TIF' wi='96' he='64') is calculated, and a preset flux-weakening control depth coefficient (img file='DDA0000579050440000017.TIF' wi='88' he='64') is systematically acquired. Besides, the d-axis current instruction value and the q-axis current instruction value are adjusted in real time according to comparison of (img file='DDA0000579050440000018.TIF' wi='74' he='64') and (img file='DDA0000579050440000019.TIF' wi='64' he='64'). The beneficial effects of the flux-weakening control method are that control is stable and thus the method is suitable for the permanent magnet synchronous motor.

Description

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AI Technical Summary

Benefits of technology

This technology improves how fast an AC machine's power supply changes its operating frequencies by gradually reducing it until reaching certain limits where there will no damage or malfunctioning components inside them. By doing this, the efficiency of the electric drive increases while maintaining optimal performance for different types of loads such as pumps, fans, motors, etc.).

Problems solved by technology

This patented technical problem addressed in this patents relates to improving the performance and efficiency of electric motors used for various applications such as industrial machines. Current methods have limitations in achieving these goals because they require complicated computations involving multiple variables which result in slowing down and decreased controller responsiveness during certain phases of machine rotation. Additionally, existing techniques involve adjustments based upon predetermined values without considering changes over longer periods of time.

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