Comparative Analysis of Normal Force Characteristics and Dynamic Influence of Linear Flux-Switching Permanent Magnet Motor for Rail Transit

The linear flux-switching permanent magnet motor (LFSPM) has significant potential for practical applications in the field of rail transit due to its advantages of high thrust density and high efficiency. However, LFSPM not only generates the thrust that provides power to the vehicle but also generates high normal force perpendicular to the track, which will have an important impact on the vertical dynamics of the train. The current research lacks an in-depth analysis of LFSPM normal force and a systematic study of the influence of LFSPM normal force on trains. Addressing this issue, this paper compares LFSPM with existing linear induction motors used in wheel-track trains. The causes of the normal force characteristics of LFSPM are analyzed by finite element calculation and air-gap magnetic density analysis. The specific effects of the normal force characteristics on the train system are discussed by building a motor-vehicle-track coupling dynamic model. The main effects include reducing the air gap width, increasing the air-gap fluctuation, and increasing the rail vibration. It is of great practical significance to reveal the generating principle of LFSPM normal force characteristics and the potential problems in wheel-track train application.