基于电压反馈的PMSM电流采样误差消除方法

PMSM Current Sampling Error Elimination Method Based on Voltage Feedback

永磁同步电机的矢量控制中,电流采样的误差会引起转速和转矩的脉动,需予以消除。变频器通常采用相电阻采样,各相电流的幅值变化规律一致,故幅值间的不一致可以预先离线标定出来。但电流采样中的零漂随着供电而变化,需要在线消除。由于电流环的控制作用,尽管实际电流存在误差,用于反馈的采样电流很可能接近正弦,此时利用采样电流本身进行误差消除就十分困难。为此,推导了αβ轴电压与三相电流零漂的关系,通过电压中的直流分量来体现相电流中的零漂分量,进而设计了电压反馈模块,用以估计和消除相电流中的零漂。所提方法简单易行,实验结果表明该方法能消除电流采样中的误差,应用该方法的控制系统能有效减小转速波动。

In the vector control of permanent magnet synchronous motor(PMSM),current sampling error causes the pulsation of the speed and torque,which needs to be eliminated.The inverter usually dopts phase resistances for sampling,which makes the amplitude of each phase current change in the same law,thus the inconsistency among the amplitudes can be pre-calibrated offline.However,the zero drift in the current sampling varies with the power supply and needs to be eliminated online.Due to the control of the current loop,although the actual current has errors,the sampling current for feedback is likely to be close to sinusoidal.So it is very difficult to use the sampling current itself for error elimination.For this reason,the relationship between the αβ-axis voltage and the three-phase current zero drift is derived.The zero drift component of the phase current is represented by the direct current(DC)component of the voltage.A voltage feedback module is designed to estimate and eliminate the zero drift in phase current.The proposed method is easy to apply.The experimental results show that the method can eliminate current sampling error.The control system using this method can effectively reduce speed fluctuations.