Design, modeling and experimental validation of a novel transformer-type angular displacement transducer for engineering diagnostics

This paper presents the design, mathematical modeling, and experimental validation of a novel transformer-type angular displacement transducer intended for engineering diagnostics and monitoring applications. The proposed transducer is based on two horseshoe-shaped movable magnetic cores and an E-shaped fixed magnetic core with excitation and sensing windings connected in a differential configuration. The operating principle is based on a controlled variation of the effective air-gap area during angular motion, which provides a differential output signal proportional to the measured angular displacement. A mathematical model of the magnetic circuit is developed using differential equations derived from Kirchhoff’s laws, and analytical expressions are obtained for the magnetic flux and induced electromotive force as functions of the angular coordinate. The model shows that the proposed geometry ensures an extended linear static characteristic over a wide diagnostics range. The analytical results are supported by laboratory tests of the transducer prototype. The comparison between theoretical and experimental results shows a discrepancy of only 3.5-5.5 %, which confirms the adequacy of the proposed model. The developed transducer demonstrates a diagnostics range of approximately ±175° and can be recommended for control, monitoring, and measurement systems requiring a simple structure, improved linearity, and stable performance. The novelty of the proposed transducer lies in the combination of three features that, to the best of the authors’ knowledge, have not been jointly achieved in previously reported inductive or resolver-type angular sensors: (i) a variable-active-area differential magnetic circuit that ensures linearity by geometry alone, without correction electronics; (ii) a closed-form analytical model derived directly from Kirchhoff’s laws; and (iii) an experimentally validated diagnostics range of ±175°.