Direct Field Control of AMBs using Flux Feedback based on Integrable Hall Sensors

Within the last years magnetic bearing technology has been pushed by a significant upturn in oil & gas industry as well as in machining applications. Nowadays, specific high speed spindles are equipped with industrially standardized active magnetic bearing systems (AMB) allowing for highly precise rotor positioning due to their contact-free and low-maintenance operation. However, compared to conventional ball bearings well-established AMB systems are limited by their relatively low stiffness. In order to improve dynamic performance flux based control algorithms are under investigation for the last decades already. The main challenge is how to integrate commercially available magnetic field sensors into typical AMB air gaps. Within this research ultra-thin and flexible Bismuth Hall sensors with a total thickness of less than 100 µm were developed and integrated into an actively controlled magnetic suspension system. For the first time an AMB control using the direct feedback of bendable Bismuth sensors was implemented and its operational capability for accurate rotor positioning was demonstrated successfully and investigated by frequency response analysis.