Observer-Based Order-Reduction Speed Control for Converter-Fed BLDC Motors with Current-Loop Adaptation

This research considers the speed control problem for brushless DC motors (BLDCMs) fed by a buck converter subject to the BLDCM parameter and load uncertainty. This study makes three important contributions that distinguish it from previous results: (a) the plant model-free observer estimates the first-and second-order time derivatives for BLDCM speed by incorporating the disturbance-observing mechanism as the subsystem, (b) the proposed control law leads to the first-order closed-loop transfer function from the converter current reference to the DCM speed using observer-based active damping injection, and (c) the analytic variable feedback gain implements converter current-loop adaptation based on the size of the current error. Experimental analysis demonstrates the actual advantages of the proposed technique using a 420 W BLDCM fed by a DC/DC buck converter.