Oscillation Characteristics of HTS Maglev Under Strong Magnetic Field Fluctuations

The high Tc-superconducting maglev system relies on the diamagnetic and magnetic flux pinning characteristics of the superconductor in a magnetic field; its performance is closely related to the uniformity of the magnetic field along the magnetic track. How the amplitude of magnetic field fluctuations on the stability and dynamic behavior of magnetic levitation is still an open issue so far. In this paper, a large magnetic field fluctuation (∆Bz) with an adjustable fluctuation amplitude was generated by covering the silicon steel sheet on the magnetic track, which was superimposed on the original small fluctuating magnetic field (δBz) along the permanent magnetic track. Based on this platform, we have studied the combined influence of ∆Bz and ∆Bz on the dynamic characteristics of the magnetic levitation system. Very significant levitation oscillation behavior was found with its amplitude linearly varying with the magnetic fluctuation amplitude. However, the dynamical behavior of the levitation was governed by the cooperation of two driving forces of different characteristic frequencies, presenting a periodical motion to a period-doubling bifurcation, and finally evolving into a chaotic state under certain conditions.