Winding Structure Impact On High Speed Permanent Magnet Motor Efficiency

This work deals with the analysis of winding structure impact on the efficiency of high speed permanent magnet motors driven by pulse-width modulated (PWM) inverters. The magnetic field evaluation is performed by employing a 2D transient finite element model which is coupled with external circuit equations. The developed model enables the determination of stator winding copper losses (both skin and proximity effects are considered), stator and rotor core losses and permanent magnet losses due to the eddy currents. Furthermore, motor’s torque ripple characteristics are calculated and the impact of the inverter’s switching frequency is studied. The derived results are compared to the corresponding ones obtained when a pure sinusoidal source is used to drive the PMSM considered. The impact of the conductor’s strands number and wire diameter on the stator winding copper losses due to proximity and skin effects is also presented and discussed in detail.