Current-mode control and intelligent commutation tuning for sensorless BDCM drive

The winding current response and the adequate commutation significantly affects the control performance of a sensorless brushless DC motor (BDCM) drive. In this paper, the studies about these two issues to enhance the performance of BDCM drive are made. First, an intelligent commutation instant tuning technique is developed to pursue better motor torque generating characteristics of BDCM. The motor drawn line current minimization is employed as the performance index in making the commutation tuning. Then, a robust current-mode controller is proposed to speed up the square wave current tracking response, and the response is rather insensitive to the machine parameter and back electromotive force (back-EMF) changes. A simple starting method and a speed estimation approach are also proposed. Some experimental results are provided to demonstrate the validity of the proposed control method.