Design and Optimization of a Self-Inductive Displacement Sensors Based on LC Resonant Circuit

This study, a differential self-inductive displacement sensor based on LC resonant circuit is proposed for high-precision rotor position detection in active magnetic levitation bearing systems. The relationship between the air gap variation and the inductive characteristics is analyzed by establishing an equivalent magnetic circuit model, and a differential structure is used to suppress the nonlinear error. The finite element simulation shows that the sensor has linear output characteristics in the measurement range of 0-0.9 mm with a sensitivity of 43.6 V/mm. The innovative introduction of the LC parallel resonant measurement circuit improves the sensitivity by 79.1% compared with the traditional bridge method, while maintaining excellent anti-interference and thermal stability. Experimental validation shows that the sensor exhibits a linear sensitivity of 1.45 mH/mm in the range of 0-0.4 mm, root-mean-square error of 0.0013 mH, with a maximum inductance change rate of 138%. The design provides a reliable solution for micron-level displacement detection in magnetic bearing systems, meeting the demand for precision control of high-speed rotors.