A Low Cost Linear Position Measurement System for Magnetically Levitated Rotor in Axial Flow Pump

This paper presented a scheme to measure axial and radial displacement of a magnetically levitated rotor based on linear Hall-effect sensors. The measurement system consists of six single-axis Hall sensors attached on the stator, and a ring permanent magnet mounted on the rotor as the magnetic flux source. The system is configured such that the angles of the magnetic flux into the sensors are monitored. Consequently, the errors caused by non-uniform magnetization and temperature dependence are minimized. The experimental results demonstrated a satisfactory performance of the measurement system. Since single-axis Hall sensors are used, this scheme provides a low-cost and compact in size solution for three- dimensional displacement measurement for levitated rotors.