Modeling and Control of Magnetic Actuation Systems Based on Sensorless Displacement Information

This paper reveals the design and implementation of a magnetic actuation system (MAS) with noninvasive displacement measurement by current sensing only. A platform-independent MAS modeling methodology is utilized, describing the cross-coupled system behavior by the physical representation of mechanical and electromagnetic counterparts. An extended nonlinear inductor model is developed, demonstrating the challenging control task of displacement regulation. The inductor model facilitates the development of a combined current sensing methodology employing noninvasive displacement measurement. The combined sensor, based on adding a "shunt inductor" in series to the main actuator, performs both high-resolution displacement and dc current measurement with fast response and minimum losses. The MAS model and the combined sensor-based operation have been experimentally verified on a single-axis levitator prototype.