Model based investigation of reluctance force shunt damping—A numerical parameter study

Abstract

An electromagnetic energy converter for vibration damping is studied. The device consists of a coil linked with a magnetic circuit with permanent magnetization and a variable air gap between the fixed magnet and a moving yoke. The reluctance force in the air gap causes magnet and yoke to attract each other. Passive shunts of the coil lead to a hysteresis between reluctance force and motion of the yoke causing damping. A numerical model is set up which describes the magnetic circuit by lumped elements. The nonlinear dynamic state equation of the magnetic flux is solved for harmonic air gap oscillation using the Harmonic Balance Method. Equivalent linear stiffness and damping of the flux-depending reluctance force are computed in order to study the mechanical behaviour of the system. Besides consideration of resistively shunted reluctance force dampers, deployment of a resonant shunt is proposed in order to amplify the damping effect. The influence of shunt parameters on the frequency-depending mechanical behaviour is investigated. Based on the frequency-depending equivalent damping, a suitable application for shunted reluctance force dampers is examined.