Novel permanent-magnet-assisted switched reluctance motor (I): Concept, design, and analysis

A novel permanent-magnet-assisted switched reluctance motor (SRM) having small excitation poles, where phase coils are concentrically wound on the poles and thin permanent magnets are inserted inside the poles, is proposed in this paper. This magnetic structure is feasible due to no flux reversals in the stator by means of large stator poles (hereinafter referred to as common poles) that do not have copper windings or permanent magnets. The insertion of permanent magnets into the stator excitation poles has a significant influence on positive torque improvement leading to a boost in efficiency. Three key design parameters such as the thickness of permanent magnets, space between two adjacent permanent magnets, and the width of stator excitation poles are determined during a design procedure in terms of the enhancement of positive torque. Step-by-step design optimization has been analytically conducted by means of static torque comparison along with dynamic efficiency estimation. The first prototype from its stator and rotor laminations up to physical assembly has been built up.