Study on sensorless brushless DC motor fuzzy self-tuning-PID control system

Based on the analysis of position-sensorless brushless DC motor commutation and anti electromotive force during starting process, a commutation module is established based on anti electromotive force. In order to solve the start problem with anti electromotive force commutation, "three step" start technology is adopted during starting process, which are rotor pre-positioning, speed up outboard synchronization and speed up from outboard synchronization switching to self-synchronization, and a result the same as using position-sensor is achieved. Self-tuning fuzzy PID controller is used in brushless DC motor control. The double-loop speed control is used in the system; the current loop is controlled by hysteresis control, and fuzzy-tuning PID controller is used in the speed loop. Simulation results show that this position-sensorless brushless DC motor control system based on self-tuning fuzzy-PID controller is as good as the brushless DC motor control system with position sensor, features fast response and small over-tuning; and has better static and dynamic characteristics than conventional PID controller.