Analytical Prediction of Static Flux-Linkage Characteristics of Switched Reluctance Machine

This paper deals with the analytical prediction of static flux-linkage characteristics of switched reluctance (SR) machines at the aligned and unaligned rotor positions, which determine the torque output. Specifically, this paper proposes a novel flux-tube based approach to derive closed-form analytical expressions for the effective air-region permeance at the aligned and unaligned rotor positions in terms of machine dimensions. The proposed method does not require preliminary finite element analysis (FEA), and includes the effect of rotor pole height on the flux-linkage characteristics. The predictions by the proposed method for three different machines are compared with the results of FEA and of three existing analytical methods. The results of the proposed method are found to be accurate and comparable to those of FEA in all cases. The aligned and unaligned flux-linkage characteristics of a 10000-rpm, 5-kW SR machine, thus predicted, are verified through FEA and experiments. Correlation between machine characteristics and dimensions, combined with good accuracy and low computation time, make the proposed method a useful tool for design optimization.