Design and analysis of a stator-doubly-fed doubly-salient permanent-magnet machine for automotive engines

This paper presents a new outer-rotor stator-doubly-fed doubly-salient permanent-magnet (SDF-DSPM) machine, which can be used as the integrated starter-generator for modern automobiles and mild hybrid electric vehicles. The key of the proposed machine is to incorporate both dc field windings and PMs in the inner stator, hence, offering a compact arrangement of hybrid field excitations. While armature windings are located in salient poles of the outer stator, the outer rotor is simply composed of salient poles without windings or PMs. In addition, an air bridge is purposely created in shunt with each PM in the inner stator, hence, providing an amplification effect for flux regulation. With this idea, the air-gap flux can be strengthened or weakened with a small dc field current so that the electromagnetic torque and induced electromotive force (EMF) can be effectively regulated. The newly designed SDF-DSPM machine is analyzed by using both the magnetic circuit model and finite element method, and assessed by performance simulation.