A voltage-controlled Brushless DC motor drive over extended speed range

This paper presents a voltage controlled scheme for brushless DC (BLDC) motor drives. The scheme combines both the low speed PWM control and the high speed phase advance commutation to obtain an extended speed range drive feature. In addition, the proposed scheme does not have a current control loop. Hence, no current sensor is needed in the drive. To satisfy the required over load protection demand, an indirect over current limitation method is used to limit the DC link current during any over load operation. The operational criterion is based on the minimum current amplitude control of a vector controlled permanent magnet synchronous motor (PMSM) drive. Hence, the developed scheme is expected to have a high efficiency merit over wide speed range. Finally, a digital signal processor (DSP) based prototype is built and some experimental results are provided to show the feasibility of the proposed scheme.