Theoretical research on new maglev ultra-low frequency vibration sensor

Aiming at the disadvantages of the widely used magneto-electric ultra-low frequency (ULF) vibration sensor, a kind of new maglev ULF vibration sensor is designed in this paper, which uses the hybrid-levitation structure with electromagnets and permanent magnets as the supporting element instead of the conventional spring structure. It can adjust the equivalent bearing stiffness coefficient and the equivalent damping coefficient by the closed-loop control system, thus the natural frequency of system can be reduced effectively, meanwhile the low measurement limit can be extended. The paper describes the working principle of maglev ULF vibration sensor in detail from the sensing mechanism, theoretical modeling and simulation analysis. The simulation results show that the velocity sensitivity of maglev ULF vibration sensor is 50 mV· s/mm, the acceleration sensitivity is 300 mV· s /mm and the lower-cut-off frequency is about 0.05 Hz. Thus, the maglev ULF vibration sensor has the advantages of lower-cut-off frequency, high sensitivity, small size and low weight. And this paper provides a new method for the current inertia ultra-low frequency ULF measurement.