Permanent magnet-assisted variable reluctance machines: An analysis of the working mechanism and characteristics

Abstract

<p indent=0mm>Variable flux reluctance (VFR) machines are very reliable and have a wide field-regulation range, but their torque density is low due to the absence of a permanent magnet (PM). Therefore, in this paper, a PM-assisted VFR (PMa-VFR) machine is proposed, and, focusing on the operation mechanism of the PMa-VFR machine, the air-gap flux density values for field winding, PM winding, and armature winding are deduced. The matching rule of various harmonics under magnetic-field modulation is revealed, and the action mechanism behind field winding and PM excitations with respect to influencing torque are explored. Then, the contribution of each working harmonic to the torque is obtained by Maxwell’s stress tensor method. Finally, a prototype is developed, and the operation mechanism and theoretical analysis are verified by experiments.