The Analysis of Iron Losses in a 12-Slot 10-Pole Fractional-Slot Permanent Magnet Synchronous Motor with Various Stator Winding Methods

A fractional-slot permanent magnet synchronous motor under 180 degree sinusoidal current can be adopted for the electric power steering system of hybrid and electric vehicles. This motor has various stator winding methods such as double-layer and single-layer for its purpose. In this paper, we investigate the iron losses characteristic of the permanent magnet synchronous motor according to the various winding methods. To get the accurate hysteresis and eddy-current losses, we consider the time harmonics of the instantaneous flux density using finite element method. From the analysis results, we know that the most of the iron losses are generated in the stator and the stator teeth shoe part has the highest iron losses density because of its rotating magnetic flux. Under the light and the rated load, the single-layer has less iron losses compared to the double-layer. However, as the load increases, the iron losses in the single-layer rapidly become larger. This is because the magnetic circuits are saturated.