A novel hybrid-excited flux bidirectional modulated machine for electric vehicle propulsion

Abstract

This paper presents a novel hybrid-excited flux-bidirectional-modulation (HE-FBM) machine. The key of the proposed machine is to utilize both dc field excitation and permanent magnets (PMs) in the stator/rotor to realize hybrid field excitations and effective flux regulation. In this proposed design, there are two sets of consequent-pole PMs, on the outer stator and on the rotor respectively. Dual magnetic gearing effect is artfully incorporated into the design to ensure an effective magnetic coupling among the magnetic fields excited by the armature windings, the dc field windings and the two sets of PMs. With this arrangement, the air-gap flux can be strengthened or weakened by the adjustment of the dc field current, thereby allowing the electromagnetic torque and output voltage to be effectively regulated over a wide range of speeds. This machine has good application potentials in direct-drive electric vehicle propulsion which needs a wide constant power operation range. The performance of this newly proposed HE-FBM machine is analyzed using finite element method.