Equivalent Circuit Analysis of Linear Phase-Shifting Transformer with End Effect

Abstract

The linear phase-shifting transformers (LPSTs) are a new type of transformers with a structure similar to a linear motor that can be used in multiplex technology. A reasonable equivalent circuit is the premise of control research. Based on one-dimensional electromagnetic field analysis of the LPST, we reference the theory of linear motor and propose an equivalent circuit model of the LPST. The LPSTs, which are a phase-shifting transformers based on linear motor structure, are affected by end effects. The end effects affect the mutual inductance and secondary resistance of the LPST, which is modified by four correction coefficients. This paper calculates the four correction coefficients, inductance, and resistance of the LPST and then proposes a single-phase T-type equivalent circuit model considering end effects. Using the analytical model, the output voltages under the three working conditions are calculated and analyzed, and the accuracy is verified by comparison with results obtained by the finite element method. Finally, the accuracy of the analytical method is further verified by experiments under two working conditions, which indicates that the equivalent model is credible and useful for control research of multi-inverter system based on the LPST.