对减小无刷直流电机换相转矩脉动方法的最小换相时间研究

Simulation study on the minimum commutation time of a modulation method used to decrease commutation torque ripple of brushless DC motors

针对无刷直流电机存在较严重的换相转矩脉动问题,提出在换相期间,利用三相绕组共同调制方法,使关断相与导通相电流变化速度在每个PWM周期内保持一致,从而减小换相转矩脉动。在此基础上,进一步研究了换相转矩脉动与换相时间之间的关系,通过建立数学模型,利用线性规划分析方法,提出了在最短换相时间内减小换相转矩脉动的三相调制占空比边界条件,即最小换相时间法则,并通过设定占空比阈值使三相绕组共同调制方法适用于全速段。仿真实验结果表明,采用最小换相时间法则的三相绕组共同调制可以较好地抑制换相转矩脉动,验证了文中理论分析的正确性与有效性。

On the issues that brushless DC motors(BLDCM)have the problem of high torque ripples,a three-phase cooperative modulation was proposed in this paper to keep the current slope of off-going phase and on-going phase equal in each PWM period during commutation,and the commutation torque ripple was eliminated.On this basis,the relation between commutation torque ripple and commutation time was further studied.By establishing mathematics model,the boundary condition of three-phase modulation duty cycle with the linear programming method the was proposed,called the minimum commutation time rule,which was used to decrease commutation torque ripple in the minimum commutation time.After setting a threshold value of duty cycle,the three-phase cooperative modulation was applicable to a larger range of speed.The simulation results showed that three-phase cooperative modulation could eliminate commutation torque ripple well under the minimum commutation time rule.The validity and correctness of the theoretical analysis were verified.