Effect of Multilayer Windings on Rotor Losses of Interior Permanent Magnet Generator With Fractional-Slot Concentrated-Windings

Recently, the interior permanent magnet (IPM) machines have become a promising candidate for more and more applications, for their nice performances-wide speed range, considerable power density, and several other advantages. However, there are still some obstacles to overcome to improve the performances of the IPM machines with fractional-slot concentrated-winding (FSCW). Among which, the rotor losses, due to the large amounts of the magnetomotive force harmonics produced by FSCW, is a big threat to safe operation. In this paper, the effect of multilayer windings on rotor losses, especially the eddy-current losses in the permanent magnets of IPM machines with FSCW, is mainly investigated using the 2-D finite element analysis. Side effects on torque performances is also studied and compared with the double-layer windings.