An Integrated Boost Active Bridge Based Secondary Inductive Power Transfer Converter

Abstract

Due to its inherent safety, robustness, and high efficiency, inductive power transfer (IPT) technology is highly suitable for the implementation of wireless electric vehicle (EV) chargers. In addition, IPT-based EV chargers can provide consistent vehicle-to-grid services, opportunistic charging, and in-motion/dynamic charging. However, designing such systems to adhere to applicable standards, while ensuring constant power transfer, and high efficiency, remains a challenge. For example, to meet the requirements outlined by SAE J2954, a wireless charger should tolerate a coupling change from 10% to 30% and a battery voltage variation from 280 to 420 V. A boost active bridge (BAB) converter presented in previous work was shown as a suitable solution; however, this system utilized two additional dc inductors. As such, this article presents a BAB converter, which integrates the current splitting functionality previously achieved using two dc inductors into a Double D magnetic coupler. This achieves a reduction in the magnetic volume of approximately 70%. Analysis of the proposed converter together with detailed design guidelines to maximize power transfer efficiency for a system designed to meet the SAEJ2954 specifications is also presented. Experimentally obtained efficiencies from a 7-kW prototype system showed minimal variation over the full range of loading conditions, ranging between 94.2% and 92%.