Samith Sirimanna with advisor K. Haran

Magnet eddy currents are generated due to two main sources in permanent magnet synchronous machines: spatial and time harmonics. Discrete winding distribution in stator generates spatial harmonics that are asynchronous with the main rotor field while inverter switching create time harmonics in current waveform. Generally, resistance limited magnet loss models are accurate in predicting losses under relatively low fundamental frequencies. However, new thrust towards light-weight large pole-count machines with high fundamental frequencies may question the use of resistance limited models to capture slot harmonic magnet losses.

In this work, SPM quasi-3D reactance limited model is extended with inputs from planar resistive limited model to compute the slot harmonic magnet losses. Fig. 1 shows the flow chart for the magnet loss calculation algorithm taking inputs from both

resistance and reactance limited models. The results showed good agreement between loss prediction with FEA for wide range of fundamental frequencies.

Fig 1. Extended quasi-3D magnet loss model