Oscillating Ferromagnetic Yoke in the Magnetic Field of a Permanent Magnet

This paper deals with axial oscillations of a ferromagnetic yoke above the center of a rotationally symmetric pot-like core, made of magnetically soft steel, with a cylindrical axially poled permanent magnet (PM) in the center. Due to the vibration of the yoke in the static magnetic field of the PM, eddy currents are generated in the yoke. These currents, in turn, generate a dynamic magnetic force counteracting the excitation force and so damping the vibrations. Moreover, static magnetic force is present, which on the one hand limits the oscillatory system performance and on the other changes the dynamics of the oscillations. Simulations are compared with experimental results on a test stand. Good agreement was reached, suggesting correctness of the presented approach to the description of this electromechanical phenomenon.