Design and development of low-cost and high-efficiency variable-speed drive system, with switched reluctance motor

Low-cost switched-reluctance-motor (SRM) drive systems are actively sought for high-efficiency home appliances and power tools. Minimizing the number of switching devices has been in power converters that is the main method to reduce drive costs. Single-switch-per-phase converters have been cost effective due to the compactness of the converter package resulting in a possible reduction in their cost. However, some of the single-switch-per-phase converters have the drawbacks that include higher losses and low-system efficiency. In order to overcome these shortcomings, the choice narrows down to the split ac converter through the quantitative analysis in terms of device ratings, cost, switching losses, conduction losses, and converter efficiency. Simulations to verify the characteristics of the converter circuit and control feasibility are presented. The motor drive is realized with a novel two-phase flux-reversal-free-stator SRM and a split ac converter. The efficiency with various loads is numerically estimated and experimentally compared from the viewpoint of subsystem and system in details. The acoustic noise with no load and full load is also compared. The focus of this paper is to compare the considered split ac converter to the asymmetric converter through experiments and demonstrate that the split ac converter is the most advantageous with respect to cost, efficiency and acoustic noise.