A Semi-Analytical Method for Obtaining the Flux-Linkage Characteristics of Mutually-Coupled Switched Reluctance Machine

In this paper, a semi-analytical model with a reduced dimension for mutually-coupled switched reluctance machine (MCSRM) is proposed, which does not need storage space in the microprocessor like the traditional look-up table. Moreover, it only needs to obtain a few sample data from finite element analysis (FEA) or experiments under 5 rotor positions, which can save abundant data acquisition time. Firstly, to reduce the dimension of the electromagnetic characteristics, the descriptive equations are transformed from three-phase static coordinate system to two-phase rotary coordinate system. Secondly, based on the analysis of harmonic components, the flux-linkage can be expressed by Fourier series with only DC, 6th and 12th spatial components, which contain only 5 Fourier coefficients. Accordingly, sample data at only 5 rotor positions need to be obtained to establish 5 simultaneous equations. The coefficients are calculated by solving the equations. Thirdly, based on the calculated coefficients, two nonlinear flux-linkage equations related to dq currents are established. Thereafter, dq currents can be calculated by solving the equations based on Newton-Raphson method. Finally, both simulation and experiment are conducted to verify the proposed method. The static and dynamic verifications under a set of conditions demonstrate the feasibility and accuracy of the proposed method.