Multiobjective Optimization of Superconducting Linear Motor Considering General Racetrack Coils

To improve the ride comfort of an electrodynamic suspension (EDS) train on the Yamanashi test line, an optimization of the air-cored superconducting linear synchronous motor (SLSM) is conducted to reduce the thrust ripple, considering the geometry of general racetrack coils. First, an analytical model based on general racetrack coils is given to calculate the thrust of the SLSM, which takes the elliptic effect edges into consideration. Second, combining the analytical model with the response surface method, a surrogate model is yielded to express the thrust with six variables. Third, the multiobjective optimization of the SLSM is carried out, taking the surrogate model as the fitness function of the genetic optimization algorithm. Fourth, the thrust ripple of the optimized SLSM is evaluated by finite-element models and compared with that of the original, considering the variable postures of the secondary resulting from the multi-degree-of-freedom motions of the EDS train. Finally, the optimization is verified by the measured thrust. Consequently, the thrust ripple of the SLSM is reduced by 49% with the invariant thrust and material consumption. In this work, an optimization of the SLSM is provided to enhance the comfort of the Yamanashi test line and the future EDS system.