Modeling Bidirectional Contactless Grid Interfaces With a Soft DC-Link

Abstract

Inductively coupled, bidirectional grid interfaces are gaining popularity as an attractive solution for vehicle-to-grid (V2G) and grid-to-vehicle (G2V) systems. However, such systems conventionally employ a large, electrolytic dc-link capacitor as well as a large input inductor, leading to expensive, bulky, and less reliable systems. Although, matrix converter (MC) based bidirectional inductive power transfer (BD-IPT) grid interfaces have been proposed as an alternative, implementation of safe and reliable MCs in BD-IPT applications is still a challenge, owing to the absence of natural freewheeling paths and higher complexity. As a solution, this paper proposes a new, inductively coupled, bidirectional grid interface, without a dc-link capacitor and an input inductor, consisting of two back-to-back connected converters. In contrast to existing bidirectional grid converters, the proposed system employs a simpler switching strategy with a lower switching frequency. A mathematical model, which predicts the behavior of the introduced system, is also presented. The feasibility of the proposed technique and the accuracy of the mathematical model are demonstrated through both simulations and experimental results of a 1.1-kW prototype system.