Iron losses in magnetic materials with six-step and PWM inverter supply [induction motors]

The energetic behavior of two samples of soft magnetic materials fed by inverters has been studied. The authors dealt with the increase of the iron losses due to a nonconventional voltage supply. Six-step and PWM (pulse width modulated) inverter output voltages have been selected as the excitation waveforms for the samples under test. Extensive experimental results of high-quality grain-oriented silicon steel and amorphous-alloy-wound core samples are presented. A detailed description of the testing procedure is shown. The results are quite informative and quantify the iron-loss increase with nonsinusoidal supply in comparison with the results obtained by the standard tests (sinusoidal supply and Epstein method). The comparison can give useful indications to electromagnetic-device designers about the derating factors for the different magnetic materials that have to be used in designing devices fed by static power sources