BLDC motor full speed range operation including the flux-weakening region

This paper presents a full speed range control scheme for surface mount brushless dc (BLDC) motor. A topology, which looks like field-oriented controls for sinusoidal PM motor including the fifth and seventh harmonics, is developed first. Then combining the six-step current control used during constant torque region with the developed topology used during the flux weakening region and regeneration region, a novel full-speed BLDC control algorithm is introduced. The proposed method results in the same torque capability during constant torque region as in the six-step current control technique. Also, the same level of controllability as in the case of sinusoidal PM motor over the flux weakening region and regeneration operation compared to the conventional six-step BLDC drive system have been achieved. Simulations and experiments have been done to verify the validity of the proposed method.