Iron Losses Model for Induction Machines Considering the Influence of Rotational Iron Losses

Iron losses attract lots of attention because of the large proportion in the total losses of induction machines (IMs). However, the conventional iron losses estimation method is not precise enough, and an empirical coefficient is always needed in practical applications to further correct the iron losses. To decrease the error of two-termed alternate iron losses model (AILM), the variable coefficients alternate iron losses model (VCAILM) is proposed by fitting the different frequency and the amplitude of the magnetic flux density segmentally. Based on the VCAILM, an elliptical iron losses model (EILM) is proposed to evaluate the iron losses in IMs considering the rotational losses which are relevant to the magnetization direction and the axial ratio of the magnetic flux density vector. For the sake of validating the proposed model, the iron losses are evaluated and measured in two IMs with different poles. The iron losses obtained from the proposed EILM are compared with the results calculated by AILM, VCILM and experiments results according to IEEE 112B method. The comparisons clarify that the proposed EILM can account for the core losses in IMs with high accuracy.