考虑定子电阻的无刷电机换相转矩脉动抑制

Suppression of torque ripple due to phase commutation in brushless DC motor drives considering the stator resistance

针对汽车电动助力转向系统用无刷直流电机的换相转矩脉动问题进行了理论分析。鉴于系统供电电压低,工作电流大的特点,研究了相电阻对换相转矩脉动的影响,得到较传统方法更为精确的判断公式,用于确定换相时的补偿相。弥补了在临界点附近,传统控制策略误补偿的缺点。为提高转矩脉动抑制的精确度,考虑相电阻的同时采用分段线性化方法来估算换相电流的斜率,得到补偿相的占空比对其进行PWM控制,使开通和关断相电流的变化速率相等,从而抑制换相转矩脉动,仿真和实验结果都验证了该方法的有效性。

This paper presents a theoretical analysis on the torque ripple due to phase commutation in BLDCM（brushless DC motor） drives for EPS（electric power steering） applications.Given the characteristics of the system＇s low supply voltage and high operating current,the influences of phase resistances on commutation torque ripple was investigated.Then a more precise rule than conventional method is derived to determine which commutated phase needs the compensation indeed within the commutation intervals,which makes up for the lake of error compensation of conventional scheme near the critical point.In order to improve the precise of suppression of torque ripples,a piecewise linearization method considering phase resistance was proposed to evaluate the slopes of the incoming and outgoing phase current to obtain the duty of the correct phase.The commutated phase current is balanced by using the PWM control method to reducing the commutation torque ripple.Effectiveness of the proposed scheme is verified through simulations and experiments.