Improved E&S Model for Core Loss Calculation of Brushless Doubly Fed Machine With Hybrid Rotor

Brushless doubly fed machine (BDFM), a new type of adjustable-speed machine with special structure, shows promising features for the field of variable frequency speed regulation and wind power generation due to its inherent characteristics. However, the traditional loss calculation method is no longer applicable due to the special structure and complex magnetic field distribution of BDFM, especially for the proposed novel hybrid rotor structure which has better coupling ability than the commonly used rotor structures such as cage rotor and reluctance rotor. In this paper, in order to calculate the core loss accurately, an improved E&S model is applied to BDFM with hybrid rotor, and the analysis and calculation procedure are presented. In addition, based on the time-stepping finite-element model and harmonic analysis method, three different core loss models are established and compared with the proposed improved E&S model. Furthermore, the experimental result from a BDFM with hybrid rotor prototype is compared with the calculation results obtained by the above models, and the accuracy and feasibility of the improved E&S model are verified.