A New Magnetless Flux-Reversal HTS Machine for Direct-Drive Application

The concepts of axial-flux (AF) structure and the high-temperature superconductor (HTS) excitation are newly applied into the flux-reversal (FR) machine in this paper. With such application, a new magnetless AF-FRHTS machine is formed. The proposed machine inherently provides a bipolar flux-linkage to enhance the performance, so that its torque density can be comparable to the permanent-magnet (PM) counterparts. In addition, the proposed machine makes an improvement on the torque density and the flux-regulating capability for the wide-speed range operation through the external HTS excitation. Based upon all these characteristics, the AF-FRHTS machine becomes more favorable for hybrid electric vehicle (HEV) applications. To be specific, the proposed machine is designed and evaluated based on the standards suggested for typical passenger HEVs. The corresponding performances of the AF-FRHTS machine are analyzed by using the 3D finite element method (3D-FEM).