New Radial Sensor For Active Magnetic Bearings

Inductive and eddy current type sensors are widely used in active magnetic bearing (AMB) systems for measuring the position of the levitated body. State-ofthe- art sensors provide a good robustness but, quite often, an unsatisfactory cost-efficiency. Cost-efficiency, however, is a key issue for industrial AMB systems, especially for volume applications. While it is evident that cost reduction programs must consider every component in an AMB system, this paper describes a patented1 approach which specially focuses on the sensor technology, where a substantial potential for cost reductions is expected. Differing from the known and ongoing approach to totally abandon the integration of sensors and to implement a so-called self-sensing AMB system [2] – most often at the expense of a loss of system robustness and an increase in controller complexity – a new type of radial sensors based on a printed circuit board (PCB) with printed coils as a sensing element is introduced. This design features minimum space requirement, high sensing quality and low production costs at the same time.