Realization of zero-power control in a two-degree-of-freedom double parallel magnetic suspension system

A basic single-degree-of-freedom magnetic suspension system consists of one floator, one electromagnet and one amplifier. For multi-degree-of-freedom control, multiple electromagnets and multiple amplifiers are necessary, which increases the cost of total system. As a means of overcoming this problem, parallel magnetic suspension has been proposed which controls multiple floators or multi-degree-of-freedom motions with a single power amplifier. This paper focuses on the zero-power control in a two-degree-of-freedom double parallel magnetic suspension system. The steady-state characteristics of this system are clarified by theoretical analysis. When the disturbance acts on one of the suspended points, a steady displacement appears only in the corresponding suspended point. The direction of the steady displacement is opposite to the direction of the disturbance. In addition, the direction of the transient response depends on the point that the disturbance acts on. In experimental apparatus, step response and frequency response are measured to verify the predictions.