Influence of nonlinear characteristics of electromagnet and normal force of a linear induction motor on a magnetically levitated vehicle

摘要

In the literature related to maglev vehicles, most studies have primarily discussed the trade-off between a levitation system and guideway smoothness, such as deflection and surface roughness, and the optimization of a levitation controller. A dynamic model integrated with a kinematic vehicle, electromagnetic suspension system, guideway profile, and levitation controller model has been widely used for this purpose. However, in addition to guideway smoothness and stiffness, the normal force of a Linear induction motor (LIM) that is installed in the same bogie frame and drives the maglev vehicle can be regarded as a disturbance element affecting a levitation system. In addition, a linear model of an electromagnetic force is usually used in linear approximations around the nominal equilibrium point, in spite of its nonlinear characteristics. In this study, to analyze the interaction between electromagnetic and normal forces of the LIM, a dynamic model coupled with the normal force calculated from finite element analysis was developed. In addition, to comparatively analyze levitation stability by considering the linear and nonlinear characteristics of electromagnets, the non-linear electromagnetic forces measured in the experiment are coupled to the dynamic model. From the simulation results, it was confirmed that although a slight increase in current was observed with the LIM model when compared to without the LIM model, it produced no adverse effect on levitation stability. In simulation, considering the non-linear characteristics of an electromagnet, it was confirmed that the nominal current of the linear model converged to a higher value than the designed nominal current when the vehicle was standing still, whereas the nominal current of the non-linear was similar to the designed one.