Speed control of brushless DC motor with grey predictor

A speed control approach with grey control theory is proposed based on the state-space model of the star-connected three-phase brushless DC motor in line-voltage mode. The algorithm of the grey predictor is given. Double-loop PI controllers and the GM (1, 2) are used to compensate the disturbance from the load and internal parameters of the motor, while the uncertainty part is considered as a grey system. To assure the system responds to the newest behavior in time, the initial discrete state sequence in GM (1, 2) model is established by the equal dimension and new information method. The simulation results have shown that the GM (1, 2) predictor can reduce the disturbance in the speed and current loops, and proved the effectiveness and good anti-disturbance ability of the proposed control method.