Core-Loss Analysis of High-Speed Doubly Salient Electromagnetic Machine for Aeronautic Starter/Generator Application

Core-loss calculation is an important issue in the design and analysis of electric machines, especially in high-speed applications. However, because of the severe uneven distribution and local supersaturation of the flux density, in combination with the evident dc magnetic bias and the skin effect of the eddy current at a high frequency, it is difficult to estimate the core loss in a high-speed doubly salient electromagnetic machine. In this paper, two improved core-loss calculation methods are proposed. Additionally, an approach is established to determine the core-loss coefficients, which considers the influence of the frequency and amplitude of the flux density by adopting the function-fitting method. The change pattern of the core-loss coefficients is also investigated, together with the influence of the dc magnetic bias on the eddy-current loss. Finally, rotor-lock experiments and high-speed rotating experiments are both conducted. Additionally, two improved methods are used and compared for core-loss calculation.