M-Phase N-Segment Flux-Reversal-Free Stator Switched Reluctance Machines

This paper describes a class of switched reluctance machines (SRM) whose stators have no flux reversals. Previously published work describes a two-phase flux-reversal-free-stator SRM and this paper extends the concept to an SRM with any number of phases. For the first time in literature, SRMs with flux reversal free stators and flux reversal free rotor back irons are developed in concept and presented in their realizable forms. Reversal of magnetic flux in the iron core results in increased core-loss when compared to iron cores which do not experience flux-reversals. The novel SRMs in this paper have balanced radial forces. In addition, the stators can be constructed in a segmental fashion. The stators of the segmental SRM are magnetically isolated from one another. Segmental stators are advantageous in high power applications and applications where the stator diameter is limited by the maximum size of the stamping die. This paper also contains a generalized design method which describes how to accomplish an n-segment stator from an m-phase SRM. Furthermore, a sub-class of SRMs is also presented which, in addition to be above stated advantages has no flux-reversals in the rotor back-iron. Three novel three- phase SRMs are compared to a conventional SRM through finite element (FE) simulations. Static and dynamic finite element simulations presented show core-loss, efficiency, output power, torque ripple and radial forces for all four machines. The flux- reversal-free-stator concept is verified by FE simulations.