Anti-fall-attract Control of a Permanent Magnetism Suspension System with Flux Path Control

Permanent magnetic levitation is a typical nonlinear system. With the air gap between magnetic conductors and suspensions object is changed, the control characteristics changes and affects the stability of the system. In order to prevent the external interference causing the suspended object falls or attract on it,as the system deviating from the equilibrium point. Anti-fall- Attract Control method based on air gap variation is proposed. According to the selection of multiple design points in the whole air gap, a gain regulation is designed at each design point. Finally, a complete anti-fall and antiattract control law is obtained by interpolating between these linear controllers,which improves the controllability,stability and robustness of the system. The simulation and experimental results show that the anti-fall and anti-attract control method can effectively compensate for the uneven variation of suspension force when the suspension is moving. External disturbance causes the air gap large, suspension force is increased rapidly, the suspension object can be prevented from falling;External disturbance causes the air gap smaller, suspension force is reduced quickly, the suspension object can be prevented attract to magnetic conductors.