Design of a Bidirectional High Power Inductive Power Transfer System with Auxiliary Winding for Automotive Applications

This article presents a high-power, highly efficient, bidirectional inductive power transfer (IPT) system for automotive applications using an intermediate coil to boost the system efficiency. It outlines the benefits of a three-coil system, namely, high power transfer capability and high robustness to clearance and misalignment. An equivalent circuit model is derived to enhance system understanding and tuning methodology for the compensation circuit is proposed. The coils and compensation circuitry were optimized for a resonant dual active bridge (DAB) topology. A 30 kW prototype was developed and tested, transferring power between 3.7 and 37.4 kW across an air gap of up to 150 mm, achieving efficiencies higher than 90% in all conditions. System performance was evaluated in both grid-to-vehicle and vehicle-to-grid modes.