Influences of Rolling Motion on Yawing Torque in High-Speed Null-Flux EDS System With Asymmetric Figure-Eight-Shaped Coils

In high-speed null-flux electrodynamic suspension (EDS) system integrated levitation and guidance, the couplement of rolling and yawing motion dramatically threatens stability operations of system. In this article, a 3-D analytical method with asymmetric figure-eight-shaped coils model to describe the electromagnetic characteristics in the null-flux EDS system under the rolling motion, which can analyze dynamic variations in forces, rolling torque, yawing torque and electromagnetic stiffnesses with different rolling angles. First, the mechanism of yawing torque induced by rolling motion is theoretically introduced. Second, a 3-D analysis model for asymmetric figure-eight-shaped coils is established to investigate the changes of flux linkage, mathematical expressions of which are as a function for displacement and angle parameters of rolling and yawing motions. Third, the electromagnetic characteristics, i.e., forces, torques, stiffnesses, in null-flux EDS system integrated levitation and guidance with different rotation angles under rolling and yawing motion are calculated and analyzed by using the virtual displacement method. Finally, the accuracy and effectiveness of the calculation results are verified by 3-D finite element method (FEM) simulation and experimental measurements.