摘要：传统的无刷直流电机双闭环系统发生换相时，开通相和关断相的电流变化率不一致，会导致非换相电流脉动，从而引起电磁转矩波动。为改善换相期间出现的电流脉动现象，提出了采用重叠换相法结合换相区非换相相恒导通，开通相和关断相分别进行PWM调制的三相电流控制策略。通过数学模型推导出了换相区各占空比和换相时间的计算方法，并通过实验验证了所提方法的正确性和有效性。
关键词：无刷直流电机；换相电流脉动；重叠换相法
Abstract: When a commutation occurs in a conventional double closed loop system of brushless DC motors, the current slope of the offgoing phase and the ongoing phase is not equal, thus resulting in the current ripple of noncommutation phase and making the torque unstable. To improve the current ripple during commutation, a threephase corporative modulation based on that the noncommutation phase is always on while the offgoing phase and the ongoing phase are under modulation was adopted. The process to calculate the duty cycle of the offgoing phase and the ongoing phase and the commutation time was presented by establishing mathematical model. The experimental results show the correctness and effectiveness of the method.
Key words: brushless DC motors (BLDCM); commutation current ripple; overlap commutation