On The BLDCM's Control Via Fuzzy Controller

This thesis introduces a brief account of BLDCM and the development of fuzzy intelligent control first, then based on the analysis of the structure, the running principle, and the mathematical model of BLDCM, the simulation model of its timing system is established, and the transfer function is derived. A new intelligent control strategy is described according the programme of analysis and control, in which, the velocity is controlled by multiple control mode combining PI control with fuzzy control in the BLDCM double-closed-loop control system. Parameters of PI controller are setted by normal tuning methods. When the system parameters vary by state disturbance and structural disturbance at the moment of sudden change in setting value, the system automatically switches into the fuzzy control mode. After trapping system response at every sampling time, stabilizing control can be realized by increasing or reducing control quantity according to parameters tolerance and variance tendency of the time on the basis of motor system control experience and fuzzy mathematical theory. The simulation result shows that this new type of intelligent control is rapid in response and small in overshoot, and has better dynamic and static characterislics than traditional PI control.Furthermore, the reason which the torque ripple is produced is analyzed in detail, especially it is pointed out that the torque ripple, which caused by the phase conversion of the rotator winding, is restrained by the fuzzy current hysteresis controller. During the phase conversion, if the rise velocity of one phase current is not equal to the fall velocity of another one, the fuzzy current hysteretic controller will run to keep the total current amplitude unchanged in the circuit, which can restrain the torque ripples. The simulation shows that the proposed method has high precision and robustness.