Modeling and analysis of core losses of an IPM machine for online estimation purposes

Online estimation of losses is important to improve control, operation and monitoring of electrical machines. This paper focuses on investigation of iron losses using a magnetic circuit model for its accuracy and adaptability to online estimation purposes. A customized magnetic circuit of an IPM machine is proposed that captures slotting, non linearity, cross saturation and localized effect of flux bridges. A technique is presented to compute the alternating stator and rotor flux from the static magnetic circuit. The required computations are reduced introducing pseudo mmf sources that avoid solving magnetic circuit at several rotational steps. The stator and rotor core losses are found corresponding to each harmonic component of alternating flux density. The results are validated with Finite Element analysis with good correlation.