为了抑制永磁无刷直流电动机控制系统在换相过程中因电流波动引起的转矩脉动，提高系统效率及稳定性，提出一种基于控制换相电流的新方法。与传统方法相比，该方法以换相电流为研究对象，通过使关断相电流的下降率等于开通相电流的上升率来维持电流在换相期间的稳定，从而减少转矩脉动，它摒弃了传统方法中的以转矩为研究对象。实验结果表明，该方法在地铁屏蔽门的应用中取得良好效果，使电流波动减少8%，转矩脉动减少10%。 Abstract: In order to suppress torque ripple caused by current fluctuations in the process of commutation in permanent magnet brushless DC motor control system，improve the efficiency and stability of the system，this paper presents a new method which is based on controlling current during the commutation. This method took commutation current as research object. Compared with traditional methods，this method took commutation current as research object，and it kept commutation current stable during the commutation by making the decline rate of tun off phase current equal to the rise rate of the open one，thereby reducing the torque ripple，it abandoned the tradition method which took the torque as research object. The experimental results show that this method in the application of the subway platform screen door has achieved good results，current fluctuation reduced by 8%，and torque ripple reduced by 10% or so.