Research on the error compensation method for differential installation of displacement sensor for magnetic bearing

Abstract

The differential measurement method has advantages of high sensitivity, low drift error of sensor temperature, low common mode signal interference and elimination of sensor bias coupling. Therefore, it is widely used in the displacement measurement of the rotor of the magnetic suspension bearing. When the magnetic bearing utilizes the differential method to measure the rotor displacement, it also introduces the dynamic differential error caused by the inconsistency of the displacement characteristics. In addition, the deviations between differential signal and actual rotor displacement are caused by the difference of sensor differential installation position. To solve these problems, a method of error compensation for differential installation of displacement sensor for magnetic bearing is proposed. The projection compensation method is utilized to compensate the inconsistency error of displacement characteristics in differential signals. The displacement equation of the rotor under differential measurement is derived, and the real-time displacement of the rotor of magnetic bearing is solved through the displacement equation. Simulation and experimental results show that the differential measurement error of rotor displacement is decreased from 2.5% to 0.16% by using the error compensation method of differential installation of displacement sensor. It is of great significance for improving the control precision and stability of magnetic bearing.