Optimal field excitation control of a claw pole motor for hybrid electric vehicle

Permanent magnet synchronous motors (PMSMs) with rare-earth permanent magnets (PMs) are most popular for automotive applications in which high torque density and high efficiency are required. Because the rare-earth materials have risks of lacking stable supply, rare-earth-free motors such as claw pole motors are widely studied. This paper presents the driving characteristics of a claw pole motor with no use of heavy rare-earth materials. In this motor the magnetic flux density in the air gap can be controlled arbitrarily by controlling field current. This paper shows that the variable field excitation can contribute to enlarge high efficiency range compared with fixed field excitation. Moreover, the electricity consumption driven in the Japan's fuel economy criteria (JC08 cycle) as EV and HEV applications are discussed.