Induction motor iron losses measurement with a static converter supply using a slotless rotor test bench

The increase in core losses in an induction motor supplied by a switching power supply is analyzed in the paper. Tests have been performed on a motor structure implemented with a slotless rotor without active conductors. Such a structure allows the performance of more significant measurements in order to evaluate the dependence of core losses on the supply voltage waveform. Core losses with the rotor at synchronous speed and with a locked rotor have been measured using sinusoidal, square wave, and a pulse-width modulation (PWM) inverter supply. The two rotor conditions mentioned allow a better understanding of the significance of the stator and the rotor core losses compared to the core losses of the entire machine. In particular the rotor core losses, which are usually considered negligible during the motor short circuit test, have been measured and compared with stator losses for different supply conditions