摘要：为解决传统反电势法滤波电路所带来的相移补偿问题，对传统的反电势法进行了改进研究，使得对反电势零点信号延时30°电角度即为换相信号。对换相期间所产生的虚假过零点的成因进行了理论分析，并采取相应的措施来减少对反电势零点信号的误判断。采用对称计数模式的PWM在导通期间检测反电势零点信号，通过不断比较分压后的端电压和重构虚拟中性电压，准确提取出反电势过零点信号，最终保证了直流无刷电机换相的准确程度。实验结果验证了该反电势零点检测方案的可行性。

关键词：直流无刷电机；反电势法；过零点检测；虚假过零点
Abstract: In order to solve the compensation problem of the phase delay in the conventional back EMF filter circuit, an improvement was made in the conventional back EMF method and commutation signal was acquired after the back EMF zerocrossing signal which delayed electrical angle 30° in this improved method. The cause of the false back EMF zerocrossing were theoretically analyzed, and appropriate measures were taken to reduce the misjudgement of the back EMF zerocrossing signal. During the symmetric PWM (pulse width modulation) on state, the back EMF zerocrossing detection was achieved. The back EMF zerocrossing signal was obtained by constantly comparing the divided terminal voltage and the voltage of reconstructed virtual neutral point. Finally ensured the accuracy of the brushless DC motor commutation. The results of the experiment verified the feasibility of the back EMF zerocrossing detection program.

Key words: brushless DC Motor；back EMF；Zerocrossing detection；false Zerocrossing