Eddy Current Loss Reduction in PM Traction Machines Using Two-Tooth Winding

Permanent magnet synchronous machines with tooth concentrated windings are widely used in today´s hybrid electric vehicles (HEV). This is due to several well-known advantages provided by concentrated windings. Nevertheless, excessive heat generation in the rotor, caused by magnet losses, continues to be a major challenge for vehicle manufacturers. Usually magnet segmentation is proposed to meet the overheating challenge. This paper presents a PMSM that hardly generates any magnet losses over the whole operating speed range. In contrast to conventional approaches, the reduction of eddy current losses is achieved using a simple two-tooth winding with reduced harmonic content. 3D-FEM analysis of magnet losses shows that the magnet segmentation is no longer required for this winding topology. To demonstrate the great potential of this alternative, the winding is used for a 60-teeth/20-poles PMSM and is compared to a commonly used 30-teeth/20-poles PMSM with concentrated windings.