A variable voltage converter topology for permanent-magnet brushless DC motor drives using buck-boost front-end power stage

A variant of a low cost, four-quadrant converter topology for permanent magnet brushless DC (PMBDC) motor drives is proposed in this paper. It has the advantage of variable DC input voltage to the machine through a buck-boost front-end power stage and hence low torque ripple at very low speeds, a desirable feature in high performance applications. It has a fixed commutation voltage, which is equal to the DC source voltage. Further, it is proved that the proposed power converter topology will enable the maximum extraction of power from PMBDC motor drives. In addition, the energization and commutation of machine phases can be achieved independently. Because of these features, the proposed topology provides high operational reliability for the motor drives