PM brushless dc motor drive with a new power-converter topology

With the growing potential for widespread use of permanent magnet brushless dc motor (PMBDC) drives in many low-cost applications, such as HVAC, refrigerators, and freezers in houses and small-velocity servos in process industries, it has become important to minimize the cost. One obvious place for cost reduction is in the cost of the inverter and its associated controller. With that perspective, a novel application of the converter topology for the PMBDC known as "C dump" in switched reluctance motor drives is proposed in this paper. The advantages and disadvantages of this topology vis-à-vis the conventional three-phase H-bridge converter, are highlighted from the points of view of economy in switches, volt-ampere rating, associated controller cost, and packaging. Design considerations for the PMBDC are derived for use with the proposed converter topology. The operational and design characteristics of this converter-driven PMBDC drive are derived for four-quadrant performance. Guidelines for the design of the proposed topology are derived and presented in the paper. Experimental results from a laboratory prototype are presented to validate the feasibility of the proposed PMBDC drive system.