Design Methodology for High-Performance Segmented Rotor Switched Reluctance Motors

Switched reluctance motors (SRM) are becoming attractive due to the increasing cost of permanent magnets. It was reported that segmented rotor construction improves the torque output and efficiency of SRM. This paper investigates the effect of stator slot/rotor segment combination and number of phases on the performance of segmented rotor SRM (SSRM). It is found that SSRMs having higher number of rotor segments than stator slots have high efficiency and torque output, but they also have limitations of narrow speed range and low overload capability. On the other hand, it is found that SSRMs with higher number of both stator slots and rotor poles have high overload capability. The effect of increasing number of phases of SSRM is also evaluated. It is found that a polyphase SSRM improves the torque output, but does not have the limitations of low overload capability and narrow speed range. Thus, the choice of stator slot/rotor segment combination and number of phases depends largely on application. Procedure to select stator slot/rotor pole combination and number of phases of SSRM is presented here. Experimental results supporting conclusions from analysis are also given.