Cage Losses in Induction Motors Considering Harmonics: A New Finite Element Procedure and Comparison With The Time-Domain Approach

The cage losses in induction machines due to spatial or time harmonics in the air-gap field are a crucial parameter for a precise estimation of the machine efficiency. Using finite element, the common approach to consider the overall cage losses, by performing complete time-domain analyses. Alternatively, a rough estimation is achieved introducing equivalent parameters in the circuital model. In this paper, a methodology for cage losses computation due to air-gap spatial field harmonics is described. The proposed finite element procedure is faster than the time-domain analysis, since it is based on magneto-static and linear time-harmonic simulations to carefully consider the iron saturation and compute the induced currents in a specific working point. In the paper, a detailed procedure description and comparison with respect the time-domain approach is reported.