Performance and stability of a magnetic suspension device using a tuned LCR circuit

This paper presents an analysis of a magnetic suspension device utiising a tuned LCR circuit. The leakage flux of the electromagnet is taken into account. The method of averaging is applied to nonlinear differential equations which describe the system under the assumption that the system is operating near an equilibrium state. Response characteristics, i.e. the gap distance in an equilibrium state and the equivalent spring constant, are theoretically obtained. The static and dynamic stability criteria are sought. It is demonstrated that a quasiperiodic oscillation occurs in a system which is dynamically unstable. in this case the suspended object oscillates periodically in the steady state. The analytical result is confirmed by experimental observation.