Comparison of analytical and Finite Element calculation of eddy-current losses in PM machines

Permanent Magnet machines have a high force density and high efficiency. These machines can be made cost effective by using fractional-pitch windings as the fabrication of such windings can be automated. However, one big challenge to design such machines is to analyze the eddy-current losses, specifically in solid back-iron of the rotor/translator and magnets. This paper compares analytical calculation of eddy current losses with Finite Element (FE) calculation. The model is applied to calculate the losses in the solid back-iron of the linear PM generator of the Archimedes Wave Swing (AWS) for different combinations of number of poles and teeth. It was concluded that Eddy current losses in analytical model are over estimated for lower order harmonics and under estimated for higher order harmonics. The total losses however for both analytical and FE methods were found to be similar. Thus, the analytical method can be used to compare eddy current losses in topologies with different slot-pole combinations.