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), the proposed converter, and DSP controller. 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 SRM drive system. This 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 to 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 small appliances.