Integrated, Eddy-Current-Based Sensing of Rotor Position for Magnetic Levitation

Magnetically-levitated drives are compelling in applications where long-lifetime operation or process chamber encapsulation is a requirement. To exploit these advantages, contactless position sensors are needed for position information of the rotor. Off-the-market sensor technologies render high-performance magnetic levitation possible; yet their system integration may be challenging.In this work, a position sensing system based on Eddy-current generation is proposed. A single integrated circuit excites an array of four opposing miniature coils, allowing for differential measurement. Coupled to a micro-controller, it can estimate position of an electrically-conductive target —in this case the rotor of a magnetically-levitated drive— at high sampling rates.