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

The winding current response speed and the adequate commutation significantly affect 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, the sensorless inverter-fed BDCM drive with a proposed current command generation scheme is established. An intelligent commutation instant tuning technique is developed to pursue better motor torque generating characteristics. For achieving this goal, the motor drawn line current minimization is employed as the performance index in making the commutation tuning. After generating the current command with adequate commutation, a robust current-mode controller is further developed and applied to greatly 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. In Addition, 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.