Analysis of Traction Characteristics in Single-Sided Linear Induction Motors with Composite Secondary Considering Magnetic Saturation and Hysteresis

Since the linear induction motor for urban transit usually works with a magnetically saturated secondary back-iron, this paper presents an analytical method to consider the nonlinear phenomena, e.g. ferromagnetic saturation and hysteresis, which are mathematically modeled and analyzed by an experimental method. By solving the differential equations to the qusi-3D field distribution in linear induction motors, analytical expressions in each part are obtained, which takes the ferromagnetic saturation and hysteresis in the secondary back-iron, skin effects, transversal and longitudinal end effects into account. Traction characteristics in the linear motor for motoring operation under constant-current excitation are calculated and validated with experimental results, and it shows a good agreement. The analysis is correct over a wide range of operating conditions, and its calculation accuracy is distinctly better than those without considering the nonlinearity.