Investigation of Iron Losses in Mixed Frequency Flux Density Waveforms

A multi-harmonic magnetic flux density waveform controller for the Epstein frame is developed. The controller has the ability to produce high quality, single frequency, flux waveforms with low harmonic content and non-sinusoidal waveforms consisting of a superposition of many harmonics. The controller employs proportional control on the real and imaginary parts of the secondary voltage harmonics, where the real axis is determined by the fundamental harmonic, and can be used to either add or cancel higher order harmonics. Specific loss measurements are reported for 29 gauges M19 from AK Steel. Single frequency data are used to determine the coefficients of the frequency-domain Bertotti equation; the coefficients are then applied to the time-domain Bertotti loss equation. Magnetic loss testing is performed on non-sinusoidal flux-density waveforms, and the ability of both the frequency and time-domain Bertotti equations to predict the loss is discussed and compared with the measured loss.