Primary Side Hybrid Reconfigurable Compensation for Wireless EV Charging With Constant Current/Constant Voltage Control

Abstract

The recent advancements in wireless power transfer (WPT) technology have expanded its ap-plications, including electric vehicle (EV) charging. However, the requirement for precise control of lithium batteries necessitates operation in constant current (CC) and constant voltage (CV) modes. Traditional approaches to achieve CC/CV mode often rely on additional communication techniques or numerous passive elements. This paper introduces a simplified WPT system for EV charging that ensures CC and CV outputs without the need for communication or a back-end converter. Utilizing a reconfigurable LCC-S compensation topology, the system maintains high efficiency through the soft switching of inverters. The design employs fixed resonant frequencies to achieve CC and CV outputs under zero-phase angle conditions and incorporates tuning method for zero voltage switching to minimize switching losses. The system designed using a single relay to switch between SS (series-series) topology during CC mode and LCC-S(inductor-capacitor–capacitor-series) topology during CV mode, thereby eliminating frequency variation and reducing passive components. Primary-side measurements manage secondary-side voltage and mode control via parameter estimation method, ensuring voltage gain stability despite changes in magnetic coupling. Experimental validation on a 3.3 kW test prototype demonstrates a maximum power transfer efficiency of 92.5%, maintaining stable CC and CV outputs.

Keywords

• Wireless power transfer
• constant current mode
• constant voltage mode
• compensation technique
• electric vehicle