A dual consequent pole variable flux Vernier machine for wide speed range

Abstract

This paper proposes a variable-flux Vernier machine with dual consequent pole configuration to realize wide speed-range operation. The rotor has a consequent pole structure with high coercive force (HCF) material composed permanent magnets (PMs), whereas the stator has PMs positioned between the flux modulation poles. Stator-mounted PMs are made of low coercive force (LCF) materials that can be easily demagnetized or magnetized for variable-flux machines. By changing the magnetization state of the LCF PMs, suppression of magnetic flux was increased to reach higher-speed operation. Demagnetization of the stator LCF PMs reduced the total magnetic flux to reach a higher speed range. In addition, reverse magnetization allowed the machine to achieve further speed-range enhancement. The proposed machine was improved with a parametric selection process. Machine performance of each magnetization state was analyzed by way of speed torque curves and efficiency maps.