Loss calculation and thermal analysis of surface-mounted PM motor and interior PM motor

In this paper, the performances of a surface-mounted permanent magnet (SPM) motor and a hybrid magnetization interior permanent magnet (IPM) motor are compared, with particular reference to losses and temperature rise. The analysis reveals that the gross loss of the IPM motor is higher than that of the SPM motor. However, thermal analysis by the analytical lumped-circuit method shows that the rotor temperature rise of the SPM motor is higher than that of the IPM motor due to significant eddy-current loss and bad heat dissipation capability in the sleeve of the SPM motor. Predicted temperature rises are compared with measured results, and good agreement is achieved.