Modeling of Open Square Bifilar Planar Spiral Coils

Denivaldo P Da Silva,Sérgio F Pichorim

doi:10.1590/2179-10742018v17i31254

Abstract

In this paper an electrical model for square bifilar planar spiral coils (BPSC) is presented. Its main aim is the study of BPSC electrical parameters and behavior involving the frequency range where the first resonances (valley and peak) occur for bifilar coils in open-circuit configuration. A new approach to determine mutual capacitances of BPSCs based on coplanar waveguide (CPW) lines is presented. This study can be applied for modeling of passive self-resonant (PSR) sensors and wireless power transfer (WPT) systems. In order to validate the proposed model, three BPSCs were manufactured, tested by means of an impedance analyzer and also submitted to electromagnetic (EM) simulations. The results obtained, presented by means of tables and graphs, show that the present study is feasible and promising for the modeling of open square BPSCs.

Highlights

INTRODUCTIONThe conception of bifilar winding dates back to the last decade of the nineteenth century and is related to studies of the Serbian engineer Nikola Tesla (1856-1943) in the development of electrical devices intended to transmit and distribute high frequency electrical energy [1]-[2]
The conception of bifilar winding dates back to the last decade of the nineteenth century and is related to studies of the Serbian engineer Nikola Tesla (1856-1943) in the development of electrical devices intended to transmit and distribute high frequency electrical energy [1]-[2]. (a) (b)As an example, Fig. 1 shows the difference between the winding method of a monofilar and bifilar coil for the helical shape
This paper presents an electric model for the open square bifilar planar spiral coils (BPSC) that covers the first valley and the first peak of resonance

Summary

INTRODUCTION

The conception of bifilar winding dates back to the last decade of the nineteenth century and is related to studies of the Serbian engineer Nikola Tesla (1856-1943) in the development of electrical devices intended to transmit and distribute high frequency electrical energy [1]-[2]. BPSC can be applied, for example, as a passive self-resonant (PSR) sensor in the monitoring of soil [9] and wood [10] moisture, as well as for monitoring pressure, force and displacement [11] This monitoring is done, indirectly, by successive measurements of parallel resonance frequencies, where the first impedance peak occurs. PSR sensor resonates at a certain self-resonant frequency without the aid of external capacitors due to the inductive and capacitive effect that occurs in their metal tracks and the influence of the medium that surrounds them They are small, in the order of a few tens of millimeters, manufactured in PCB and coated with solder mask to protect against corrosion and short circuits between copper tracks.

MODELING OF OPEN SQUARE BPSC

Dinm Dinb

Resonance Valley

Doutb Dinb

Model EM Simulation

CONCLUSIONS