Analysis and design of axial inductive displacement sensor

An axial inductive displacement sensor, which can be fixed on radial direction to measure axial displacement of the suspended rotor, is proposed in this paper. Based on Schwarz-Christoffel transformation, 3D inductance of the proposed sensor is calculated. The novel approach for 3D inductance calculation is compared with 3D FEM results, showing the feasibility for practical applications. Static and dynamic characteristics are evaluated on a magnetic bearing platform. Sensitivity and linearity are 2.63 V/mm and 0.46%, respectively. Static noise result shows that the proposed sensor can reach a resolution of 5 μm. Dynamic characteristics tests, including vibrating and shocking experiments show that the displacement detection capability of the proposed sensor is similar to that of an eddy current sensor, showing the potential of the proposed sensor used in other fields where eddy current sensors have already be applied.