Control Scheme of a Bidirectional Inductive Power Transfer System for Electric Vehicles Integrated into the Grid

Abstract

Inductive power transfer (IPT) systems have become a very effective technology when charging the batteries of electric vehicles (EVs), with numerous research works devoted to this field in recent years. In the battery charging process, the EV consumes energy from the grid, and this concept is called Grid-to-Vehicle (G2V). Nevertheless, the EV can also be used to inject part of the energy stored in the battery into the grid, according to the so-called Vehicle-to-Grid (V2G) scheme. This bidirectional feature can be applied to a better development of distributed generation systems, thus improving the integration of EVs into the grid (including IPT-powered EVs). Over the past few years, some works have begun to pay attention to bidirectional IPT systems applied to EVs, focusing on aspects such as the compensation topology, the design of the magnetic coupler or the power electronic configuration. Nevertheless, the design of the control system has not been extensively studied. This paper is focused on the design of a control system applied to a bidirectional IPT charger, which can operate in both the G2V and V2G modes. The procedure design of the control system is thoroughly explained and classical control techniques are applied to tailor the control scheme. One of the advantages of the proposed control scheme is the robustness when there is a mismatch between the coupling factor used in the model and the real value. Moreover, the control system can be used to limit the peak value of the primary side current when this value increases, thus protecting the IPT system. Simulation results obtained with PSCADTM/EMTDCTM show the good performance of the overall system when working in both G2V and V2G modes, while experimental results validate the control system behavior in the G2V mode.