考虑逆变器死区的轮毂永磁同步电机电流谐波解析建模与分析

Analytical Modeling and Analysis of Current Harmonics in hub Permanent Magnet Synchronous Motor Considering Dead-Time

逆变器死区时间的设置使得轮毂永磁同步电机供电电流产生谐波畸变,将导致电机转矩波动进而引起电动轮系统的纵向振动问题。文章首先搭建了考虑死区的轮毂电机矢量控制系统Simulink模型,通过仿真揭示了相电流畸变规律及谐波特征;其次推导了死区误差电压,对轮毂电机电流闭环控制系统进行等效建模,确定死区的影响为误差电压作用于闭环系统引起的动态响应,解释了死区影响机理,定量预测了电流谐波大小及其随电机转速变化规律;最后基于解析预测模型,分析了电流环PI参数、死区时间、开关频率等电机控制参数对死区电流谐波的影响。通过对死区电流谐波的解析建模,能够确定死区影响较为显著的转速区间及死区效应随各设计参数的变化规律,为死区影响的规避补偿提供了参考。

The setting of inverter dead-time causes the current distortion of hub permanent magnet synchronous motor,which results in torque ripples of motor as well as longitudinal vibration of electric wheel system.In this paper,the Simulink model of vector control system of hub motor is firstly built,revealing the distortion and harmonic characteristics of phase current through simulation.Secondly,the error voltages are analytically derived.Equivalent modeling is applied to the current closed-loop control system of hub motor and error voltages cause dynamic responses of the system,explaining the influence mechanism of dead-time.The magnitude of current harmonics and its variation with motor speed is quantitatively predicted.Finally,the influences of motor control parameters such as PI parameters,dead-time period and switching frequency on current harmonics are revealed based on the analytical model.Through analytical modeling of current harmonics,the speed range mostly influenced by dead-time and the effects with different design parameters are determined,providing reference for the evasion and compensation of dead-time effects.