Brushless Direct-Current Motor Sensorless Control System Based on Periodic Load

According to the characteristics of periodic fluctuation of beam pumping unit load, a parameter based on fuzzy reasoning self-tuning PI controller is proposed and introduced into the speed loops, improving the defection of traditional PI control is unable to follow the real-time defect load change parameters, thereby inhibiting speed with load fluctuation. The position sensors of the brushless DC motor is replaced by the three harmonic method based on the back EMF, and the volume of the control system is reduced. The simulation model of speed and current double closed loop system based on sensorless control and fuzzy PI control is established by means of the mathematical model and mechanical equation of brushless motor for beam pumping unit, the ability of the proposed method to suppress the fluctuation of the speed with the load is verified. Finally, the correctness of the simulation model is verified by experiments.