无刷直流电机PWM_ON_PWM调制方式转矩特性研究

转矩脉动是影响无刷直流电机性能的重要因素。对PWM_ON_PWM调制方式换相区间与非换相区间转矩脉动进行计算与分析,并与其它经常使用的四种调制方式进行对比,以寻求低转矩脉动的最佳PWM调制策略。在换相区间,推导了转矩脉动的解析表达式,绘制了转矩脉动随占空比D的变化曲线,提出根据不同转速采用不同调制方式的控制方法。在非换相区间,分析了关断相续流和非导通相续流产生的条件,总结了不同PWM调制方式非换相转矩脉动的规律,论述了采用PWM_ON_PWM调制方式对非换相转矩脉动的影响。最后对一台10k W无刷直流电机转矩脉动进行测试,验证了所提结论的正确性。

Torque characteristic of brushless DC motors by PWM_ON_PWM modulation

Torque ripple is an important factor affecting the performance of brushless DC motors ( BLD-CM) .The commutation and non-commutation torque ripple were calculated and analyzed caused by PWM-ON-PWM modulation.And compared with other often used four PWM modes,modulation strategy of the least torque ripple was found.In the commutation interval, the analytical expressions of torque rip-ple were induced, the curve was drawn with different modulation modes and duty cycle,and the control strategy was proposed using different modulation methods according to the different speed.In the non-commutation interval, the conditions were analyzed caused by diode freewheeling of the floating phase and inactive phase, the rules were summarized torque ripple changed with different control strategy,and the effects of using PWM-ON-PWM modulation were discussed on non-commutation torque ripple.Last, a rig for the 10kW motor was built for test,and the experimental results were provided to demonstrate the valid-ity of the proposed conclusion.