Synchronous Rectification and Braking Control for Brushless DC Motor With Single Current Sensor

With single current sensor between the DC power supply and bus capacitance, the miniaturization, low cost and high reliability can be achieved for brushless DC motor controller featured by low voltage and high current.However, it is a challenge that the phase current can't be detected directly. In view of efficient recovery of braking energy and precise torque control, the synchronous rectification and braking control for the controller was proposed. The commutation characteristic with synchronous rectification and braking control was analyzed. Then the DC-link bus current based phase current reconstruction method in different conduction intervals was presented.Based on the reconstruction value, the phase current closed-loop control was accomplished. Simulation and experiment results show that the phase current reconstruction with single current sensor is feasible, and the synchronous rectification and braking control is suitable for brushless DC motor.