Yiqiu Tan, Hengda Li, Danfeng Zhou, Qiang Chen, Haochen Zhu, Zihao Wang, Aoqi Tang, Mingxin Liu, Peichang Yu, Jie Li
-Superconducting electrodynamic suspension (EDS) systems generate the required propulsion, levitation, and guidance forces for vehicle motion through electromagnetic interactions between ground coils and onboard superconducting coils. The propulsion coils (providing propulsion force) and the null-flux coils (providing levitation and guidance forces) are typically installed separately. In the 1980s, an integrated Propulsion-Levitation-Guidance (PLG) coil was proposed to reduce the number of ground coils and lower system costs, combining all three functional requirements into a single coil design. Visually resembling conventional null-flux coils in appearance, the PLG coils are distinguished by their active three-phase alternating current (AC) excitation. However, extensive research and experimental studies revealed that PLG coils exhibit significant propulsion force fluctuations, which not only increase control complexity in the propulsion system but also adversely affect the maintenance of the superconducting state of the superconducting coils. This paper presents an improved PLG system design featuring a double-layer coil configuration, which achieves significant reduction in propulsion force fluctuations without increasing material costs. A comprehensive theoretical model is developed for the fully coupled dynamic circuit, explicitly incorporating mutual inductance coupling between adjacent PLG coils. The model's validity is rigorously verified through comparison with experimental data obtained from the Miyazaki test line. Based on the structural parameters of the PLG coils in the Miyazaki test line, this paper presents the structural parameters of the double-layer PLG coils. Through comparative analysis of the theoretical electromagnetic force characteristics between the two kinds of coil structures, the superior performance of the double-layer PLG coils is confirmed.