Analytical Calculation of Open-Circuit Magnetic Field in Linear Phase-Shifting Transformer Based on Exact Subdomain Model

Linear phase-shifting transformers (LPSTs) are a new type of transformer that can be used in multi-rectifier and multi-inverter systems. However, calculating a precise magnetic field distribution in LPSTs, which is the key premise for obtaining accurate transformer parameters and performance evaluations, remains a challenging task. The present work addresses this issue applying the exact subdomain method (ESM) to establish an analytical model of the magnetic field distribution in an LPST with an arbitrary number of slots in two-dimensional Cartesian coordinates using the magnetic vector potential as the solution variable. The Poisson equations are established in the slot subdomain of the primary side, and the Laplace equations are established in the slot subdomain of the secondary side and in the air gap subdomain. The harmonic coefficients are obtained using the Fourier series method in conjunction with the boundary conditions, and the distribution of the open-circuit magnetic flux density is then solved in each subdomain. The model effectively accounts for the cogging effect on the magnetic field distribution. The inductance of the primary side and the induced potential of the secondary side are obtained using the magnetic flux linkage method. The accuracy of the proposed analytical model is verified by comparison of the results obtained with those obtained by the finite element method (FEM). (c) 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.