Single-controllable-switch-based switched reluctance motor drive for low-cost variable- speed applications

A new low-cost, brushless variable-speed drive requiring only a single controllable switch is presented. The proposed converter (referred to as new single-switch converter) overcomes the drawback of the original single-switch-based four-quadrant motor drive in terms of recovery energy circulation. The drive system is realized using an asymmetric two-phase switched reluctance motor (SRM) and the proposed converter. The new drive system retains the unique features of self-starting for all rotor position and four quadrant operation of the original single-switch-based switched reluctance motor drive system. The paper presents operation principle, modeling, simulation, and design considerations of the converter in conjunction with the motor. Simulation results are based on a nonlinear model of the motor drive system. A prototype drive has been built and tested to verify its practical viability. The experimental results correlate well with the simulation, and demonstrate a performance comparable to conventional asymmetric bridge converter based drive with two switches per phase. The market relevance of this new drive system is primarily due to its lowest cost structure, packaging compactness, self-starting feature, variable-speed operation and four-quadrant capability. Because of these features, the new drive system offers a viable alternative for conventional fixed speed brush-commutator motors and variable-speed permanent magnet brushless dc motor drives in many high volume applications in the low-cost, energy efficient, high-volume categories such as fans, blowers, hand tools and home appliances.