Identification of flux density harmonics and resulting iron losses in induction machines with nonsinusoidal supplies

Accurate prediction of iron losses in electrical machines requires detailed information of flux density waveforms in the iron. In the case of an induction machine operating at partial load, many supply cycles must be modeled to obtain accurate flux density waveforms on the rotor. This may be particularly troublesome when nonsinusoidal supplies are used and many small time steps are required. This paper presents an approach to predict rotor flux density harmonics with data from a finite-element model of a single supply cycle. Using this approach, the influence of particular harmonics on total iron loss can be extracted. Predicted rotor losses are compared with those obtained using direct calculation of losses from time-stepped data and with test measurement.