Analytical Field Calculation of Doubly Fed Induction Generator with Core Saturation Considered

Abstract

In this paper, an analytical field calculation model is developed for Doubly Fed Induction Generator (DFIG). The field calculation region is divided into five solution subdomains, i.e. rotor slot, rotor slot opening, air-gap, stator slot opening and stator slot. The vector potential in each subdomain can be obtained by solving the governing function with the variable separation method and employing the boundary conditions between of adjacent interface. Furthermore, to improve the correctness of the analytical field calculation model in condition of saturation, a modification method using equivalent air-gap permeability is proposed. The equivalent air-gap permeability is calculated by the magnetic equivalent circuit (MEC) method. Based on the developed analytical field calculation model, the air-gap flux density can be obtained and flux linkage, back-electromotive force (EMF) can also be further calculated. The accuracy of analytical field calculation model results is validated by the finite element analysis (FEA) method.