High-Speed Performance Improvements of a Two-Phase Switched Reluctance Machine Utilizing Rotor Conducting Screens

The two-phase 4/2 switched reluctance machine is suitable for high-speed operation. It has a simple and robust construction and can be operated from power converters that have no shoot-through mode. In this paper, conducting screens are incorporated in the rotor of a prototype 400 W, 7500 rpm two-phase switched reluctance machine. The effect of the conducting screens on current response, output torque, output power, and efficiency of the machine are experimentally evaluated and explained. The conducting screens improve the torque at higher speeds, increase the output power, and improve drive efficiency. At low speeds, the conducting screens improve rate of change of inductance and, hence, torque. At high speeds, enhancements of performance are due to a lowered unaligned inductance that provides an improved initial current response. At rotor speeds greater than base speed and below a breakpoint speed, it is found that the conducting screens are detrimental to the performance of the machine. A reason for this phenomenon is given.