Multilayer Windings Effect on Interior PM Machines for EV Applications

This paper mainly studies the effect of the winding layer number on the performance of interior permanent-magnet (IPM) synchronous machines equipped with fractional-slot concentrated windings (FSCWs) for electric vehicle applications. In order to quantitatively evaluate FSCW-IPM machines with different numbers of winding layers, three models with single-, double-, and four-layer winding configurations have been built to compare back electromagnetic force, average torque, torque ripple, core losses, copper losses, flux-weakening capability, overload capability, etc. Both theoretical and finite-element analysis results illustrate that multilayer windings yield lower d-axis inductance and weaker flux-weakening capability but better overload capability. It is also shown that torque ripple and core losses are significantly reduced in machines with multilayer windings.