A ferrite permanent magnet axial gap motor with segmented rotor structure for the next generation hybrid vehicle

Permanent magnet synchronous motors (PMSMs) are a key part of the current hybrid electric vehicle (HEV) drive system, and the sophisticated performance such as small size, high power density, and high efficiency is required to the PMSMs in the HEV drive system. Therefore, rare earth permanent magnet is generally employed in the PMSMs in order to satisfy those demands. However, rare earth materials contained in the rare earth permanent magnet have several concerns caused by uneven distribution, because the rare earth materials such as neodymium and dysprosium depend on China for 90% or more of the world share. Accordingly, the rare earth materials have the undeniable possibility of sudden rise of price or reinforcement of export restriction. On the other hand, the HEVs tend to be promoted rapidly because of growing concern about environmental problems. Therefore, it is very important to develop rare-earth-free motors for the next generation HEV drive system. This paper proposes a ferrite permanent magnet axial gap motor without the rare earth materials for the HEVs. In addition, the proposed motor structure and the analytical results with the 3D-FEA are introduced.