Design and Analysis of a new Flux-adjustable Permanent Magnet Motor Considering Efficiency Characteristic over Wide Speed Ranges

This paper presents a new wide speed range permanent magnet motor taking advantage of controllable main flux and leakage flux characteristic. The innovation lies in that the saturation level of the leakage flux path can be controlled by applying different q-axis load current, and thus the d-axis magnetic field can be controlled without any additional d-axis current. This phenomenon is explained by theoretical equations and finite-element analysis firstly. Then motor topology is proposed with special arc-shaped magnets and flux barriers, and the electromagnetic performances, such as torque-speed envelope and efficiency map, are evaluated. The results show that the proposed motor can maintain high efficiency within a relatively wide speed range.