CALCULUL CÂMPULUI ELECTRIC ASOCIAT UNUI CUPLOR INDUCTIV DESTINAT TRANSFERULUI DE PUTERE WIRELESS

Abstract

"Contactless or wireless power transmission has become a widespread disruptive technology. Although known for more than 100 years, it is the result of the unprecedented development of microelectronics and power electronics in recent decades. Numerous technical solutions for near-field energy transmission at different power and frequency levels are currently established: capacitive electric field transmission (CPT), inductive magnetic field transmission (IPT), multi-coil transmission and simultaneous transmission via electric field and magnetic field as a combination of the first two. The materialization of the contactless transmission is achieved in theory and practice through different types of contactless coupling circuits, generically called ""contactless couplers"". The inductive coupler can be considered as an electrical transformer in air or with open magnetic circuit in which the primary (Tx) and the secondary winding (Rx) can occupy different positions from each other depending on the application [1]. It is considered a representative element for WPT (Wireless Power Transfer) systems currently used from transferred powers of several watts to tens or hundreds of kilo-watts. To increase the transfer efficiency, the coupler works at high frequencies, of the order of kHz or MHz and in some cases has planar windings, of different shapes, made of litz wire and usually has magnetic flux concentrators [2]. Any inductive coupler is integrated into a complex transmission system, consisting of many other components [3]. In addition to the electromagnetic calculation widely presented in other works, open magnetic circuit construction produces electric and magnetic scattering fields that have a negative effect on both electrical and electronic equipment in the vicinity and on human health if the exposure exceeds certain thresholds. These thresholds are indicated by international standards and requirements [4-5] achieved by applying the precautionary principle [6] so that they can be reviewed periodically and are not mandatory unless they are taken over in national law. In this paper we analyze by the finite element method, in approximate 2D, the electric field produced by an inductive coupler in various simplified construction variants and calculate certain related quantities of practical importance such as: electric field distribution in the field of calculation, electric field strength in the vicinity of the inductive coupler, equipotential lines, reactive power, equivalent capacities."