Robust current control for brushless DC motors

The winding current exciting responses of brushless DC motors significantly affect their torque generating charactcristics and hence the whole drive control perforinane. To obtain a quick and accurate current command tracking response, the application of control strategies for compensating the effects of key parameter variations is necessary. Robust control for achieving improved current responsc is studied. First, the model parameters for perfotming the current control loop design are estitnaled. Then a novel current control scheme is proposed, which consists of a feedback controller, a conunand feedforward controller atid a robust disturbance cancellation feedforward controller. The foimer two controllers are designed to fulfil the desired current control cliaracteristics at nominal case, and the robust controller is employed to reduce the effects of back electromotive force and parameter variations. The theoretic basis and design of the proposed control scheme are prcsented in detail. Through applying the designed current controller, the winding current response is speeded up and thus the motor dr2tw11 line current is decreased owing to the improved torquc gencrating characteristics. The elreciivcness of the proposed robust current control approach is dernonstratcd by simulation and incasured results.