Magnetic Losses of Electrical Iron Sheets under AC Magnetization Superimposed with Higher Harmonics

The contribution of superimposed higher harmonics to magnetic losses in electrical iron sheets was examined at power frequencies. The results show that processes of magnetization by PWM voltage excitation are similar to those by ac magnetization with a carrier frequency superimposed, and are different from those due to square-wave voltage excitation with the same amplitude and the same time duration, with more lower-order harmonics. We propose a practical method for measuring the magnetic loss equivalent to that under PWM voltage excitation.