Eddy current speed sensor with magnetic shielding

Abstract

This paper presents the design and analysis of a new eddy current speed sensor with ferromagnetic shielding. Aluminum and solid iron are considered for the moving part. One excitation coil and two antiserially connected pick up coils are shielded by a thin steel lamination. 3D time stepping finite element analysis is used to analyze the sensor performance with different magnetic materials and compare with experimental results. The compactness, simplicity and excellent linearity with different magnetic materials for the moving part show uniqueness of the proposed speed sensor. The shielding increases sensitivity and reduces the influence of close ferromagnetic objects and interferences on the sensor performance.