Analysis and design of inductive wireless power transfer link for feedback-less power delivery to enclosed compartment

Abstract

The paper presents analytical investigation and hands-on design of inductive wireless power transfer link for a through-glass AC power delivery system into enclosed compartment such as industrial glove box or vehicle cabin. The system is fed from AC grid and creates a standard AC outlet within the enclosed compartment, capable of supplying loads of up to 1 kW. The system consists of three (namely, AC/DC, DC/DC and DC/AC) conversion stages, with the former and the latter realized by standard off-the-shelf units. The intermediate DC-DC power conversion stage, which is the paper focus, is realized by a from-scratch-built inductive wireless power transfer link, operating in load-independent voltage output regime without any feedback. It was recently shown that the output voltage of such a system, even when operating at load-independent frequency, remains influenced by the load due to practical issues. As a result, the output voltage resides within a certain range rather than remains constant, obtaining minimum/maximum values under rated load/no-load conditions, respectively. Since coils separating glass width typically possesses some finite uncertainty, values of both coupling coefficient and coils self-inductances may be different than nominal (design) ones and hence the output voltage would drift from its nominal range. Hence, due to the fact that upper and lower bounds of an inductive wireless power transfer link output voltage range are limited by DC link capacitor and DC/AC power stage constraints, tolerated glass width uncertainty is obtained in the paper. Moreover, compensating capacitors pair symmetrizing uncertainty tolerance of the inductive wireless power transfer link is also revealed. Simulations and experiments based on 400 V, 1 kW-rated inductive wireless power transfer link are presented to validate the analysis.