Equivalent Circuit Derivation and Performance Analysis of a Single-Sided Linear Induction Motor Based on the Winding Function Theory

A linear metro that is propelled by a single-sided linear induction motor (SLIM) has recently attracted much attention. Compared with the rotating-induction-machine drive system, the SLIM drive has advantages such as direct thrust without needing friction between the wheel and the railway track, small cross-sectional area, lack of gear box, and flexible line choice on account of the greater climbing capability and smaller turning circle. However, due to its cut-open primary magnetic circuit, the SLIM has a longitudinal end effect and half-filled slots on the primary ends, which can reduce the air-gap average flux linkage and thrust. Based on the winding function method, the SLIM is supposed to have the following three groups of windings: 1) primary windings; 2) secondary fundamental windings; and 3) secondary end effect windings. The proposed method considers the actual winding distribution and structure dimensions. It can calculate the mutual, self, and leakage inductance to describe the influence of the longitudinal end effect and half-filled slots. Moreover, a new equivalent model is presented to analyze the different dynamic and steady-state performance. Comprehensive comparisons between simulation and experimental results that were obtained from both one arc induction machine and one linear metro indicate that the proposed model can be applied to predict the SLIM performance and control scheme evaluation.