Iron loss under PWM voltage supply on Epstein frame and in induction motor core

A systematic PWM iron loss study has been carried out. All the loss components can be given as functions of the sum of pulses width in half a period. PWM loss surplus when compared with the sinusoidal supply is more pronounced in the laminations with more important part of dynamic loss in the whole loss outcome. Along the constant flux trajectories in variable speed regimes of the induction machines the iron losses are also constant. The underlying analysis has been developed for an alternative magnetic field and tested on an Epstein frame. However, the iron loss invariability (per cycle) on the constant flux trajectories has been confirmed in motor measurements, where the actual field is far more complicated.