Flux-Path Control Magnetic Suspension System Using Voice Coil Motors

A novel magnetic suspension system with three flux-path control modules was developed. The module consists of a ferromagnetic plate, a voice coil motor (VCM) for driving the plate and a displacement sensor for detecting the position of the plate; the sensor is comprised of a V-shape plate spring and four strain gauges pasted on it. The ferromagnetic plate is inserted into the gap between a permanent magnet and a suspended object (floator). The lateral position of the plate is controlled by using the VCM and the sensor. Since the flux from the permanent magnet to the floator varies according to the position, the amplitude and direction of the attractive force acting on the floator can be adjusted with multiple modules. Stable suspension was achieved by applying PD control. A fluctuation was observed in the position of the floator. It was reduced by feeding back the lateral motions of the floator. The two-dimensional and three-dimensional noncontact manipulation of the floator was also achieved in the developed magnetic suspension system.