Analysis of flux distribution and core losses in interior permanent magnet motor

The interior permanent magnet (IPM) motor with its robust rotor construction, hybrid torque production nature and flux-weakening capability is suitable for electric vehicle applications when wide speed and torque range is required. At high-speed operations, core losses become an important issue because they affect efficiency and raise operating temperatures. This paper discusses the results of two-dimensional finite element analysis into the relationship between flux distribution and core losses in the IPM motor. The analysis is further supported by flux measurements using search coils installed in an experimental motor. Three methods of predicting the core losses in IPM motor are also investigated. These methods are the empirical formula method, finite element computed waveform method and the search coil induced voltage method.