Thermal analysis and comparison of permanent magnet motor and generator

In this paper, both analytical lumped-circuit method and finite element analysis are employed to predict the temperature rises of two identical prototype surface-mounted permanent magnet machines when they are back-to-back connected mechanically and used as a motor and a generator, respectively. The predicted results are validated by the experiment. The analysis reveals that the eddy current losses in magnets and sleeve cause higher temperature rise than that in the stator winding in both machines. The analytical lumped-circuit method takes much less time and the accuracy is even higher than the 2D finite element analysis with due account for the duty cycle, cooling effect, and interface gaps between components, although more detailed temperature distribution inside components can be obtained using the finite element analysis.