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

Abstract

This paper deals with the analytical prediction of static flux-linkage characteristics of switched reluctance (SR) machines, which have emerged as competitive candidates in various applications, including automotive, aerospace, machine tools, and renewable energy. 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 effective air-region permeance. The predictions by the proposed method are compared with the results of FEA and three existing analytical methods, considering seven different SRM designs and different sets of machine dimensions. The results of the proposed method are found to be accurate and comparable to those of FEA in all cases. Further, based on magnetic material characteristics and machine dimensions, the static flux-linkage characteristics at the aligned and unaligned rotor positions are predicted. The aligned and unaligned flux-linkage characteristics of a 10000-rpm, 5-kW SR machine, thus predicted, are verified through FEA and experiments. As an application of the proposed analytical method, electromagnetic design of a 40-kW, 80000-rpm, 600-V SRM is carried out and is validated through static FEA and simulations.