Magnetic equivalent circuit modelling of brushless doubly-fed induction generator

The brushless doubly-fed induction generator (BDFIG) has substantial benefits, which make it an attractive alternative as a wind turbine generator. The aim of this work is to present a nodal-based magnetic equivalent circuit (MEC) model of the BDFIG which provides performance characteristics and flux density distributions. The model takes into account stator winding distributions, special configuration of rotor bars, slotting effects, teeth saturation, flux fringing and current displacement effects. The real flux tubes are considered for creating an MEC network and calculating its non-linear elements. A method for simplifying the rotor magnetic network has been applied and Gauss elimination with partial pivoting approach is used to solve the equation system with sparse coefficient matrix. The model parameters are based solely on geometrical data and thus it is an appropriate tool for population-based design studies instead of computationally intense analysis of the finite element method. The steady-state results of the proposed model are verified experimentally. The comparisons demonstrate the effectiveness of the proposed model especially when the core is magnetically saturated.