Loss Analysis of Magnet Eddy Current in a High-Power Density Machine Using a Field-Circuit Coupled Model

Magnetic eddy current losses is significant in permanent magnet motors, especially in high-power density permanent magnet motors. It significantly affects the magnet’s temperature and properties and may cause irreversible demagnetization. Several methods for reducing magnetic eddy current losses is proposed to address these problems. First, a field-circuit coupled mathematical model was established to calculate the magnetic eddy current losses. Experiments on the phase current and magnetic eddy current losses verify the accuracy of field-circuit coupled mathematical model. Then based on the model, the effect of the trigger angle, slot opening width, pole arc coefficient, pole arc center offset, and auxiliary slots on the magnetic eddy current losses were assessed. The results showed that the magnetic eddy current loss could be reduced by choosing a suitable leading trigger angle, pole arc coefficient, and pole arc center offset. A smaller slot opening width reduced the eddy current losses. A novel auxiliary slot with an optimized size is proposed to reduce eddy current losses. Finally, taking the trigger angle, slot opening width, pole arc coefficient, pole arc center offset and the auxiliary groove as the optimization factors and the magnetic eddy current loss as the optimization target, the optimal parameter scheme is obtained by Taguchi method. The simulation results show that the optimized magnetic eddy current losses is reduced by 8.57%.