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 switch ing power supply is analyzed in the paper. The tests have been perform ed on a motor structure implemented with a slotless rotor without acti ve conductors. Such a structure allows to perform more significant mea surements in order to evaluate the dependence of core losses on the su pply voltage waveform. Core losses with the rotor at synchronous speed and with a locked rotor have been measured using sinusoidal, square w ave, 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 o f the entire machine. In particular the rotor core losses, which are u sually considered negligible during the motor short circuit test, have been measured and compared with stator losses for different supply co nditions.