Loss estimation and sensing property enhancement for eddy-current-type proximity sensor

Eddy-current-type proximity sensor is a noncontact-type sensing device to detect the approach of a conductor by an increase of coil resistance due to eddy current loss. This paper investigates electromagnetic (EM) characteristics of the actual proximity sensor by the finite-element method and provides knowledge to enhance sensing property. In particular, the influence of eddy current loss to sensing property is shown and quantitatively estimated. Furthermore, modified models of the actual sensor are proposed and calculated as numerical experiments. As a result, enhanced sensing properties of the proposed models are shown

I. Introduction

Eddy-Current-Type proximity sensor is a noncontact-type sensing device to detect the approach of a conductor by an increase of the equivalent ac resistance of excitation coil due to eddy current loss in the conductor [1]. Its advantages are robustness for environmental conditions, such as water/oil-resistance properties, simple structure, and so on.