Effects of pulse-width-modulated supply voltage on eddy currents in the form-wound stator winding of a cage induction motor

The eddy currents of a form-wound multi-conductor stator winding because of the non-sinusoidal supply voltage in a cage induction motor are studied. The time and space dependence of the field, circuit variables and the motion of the rotor are modelled with the time-discretised finite-element analysis. A pulse-width-modulated voltage is used to supply the motor. The eddy-current loss distribution of the stator bars and the total eddy-current losses are studied. The radial distance of the stator bars from the air gap is re-emphasised as a design parameter because of its effect on the losses and the hot spots. The means for minimising the losses and avoiding the local hot spots are studied.