Abstract
This paper presents a method of increasing the load capacity of magnetic suspension systems. The limits of coil current and suspension gap determine the load capacity. In PID-controlled systems, the displacement is kept zero and the coil current increases when load is added to the floator. In contrast, the current is kept zero and the gap decreases in zero-power controlled systems. As a result, the load capacity is determined by the current limit in the former and the gap limit in the latter. It can be increased by switching them each other. The switching stiffness control is applied for this purpose. Experimental results demonstrate the operating range is extended almost twice.
