High Power Factor Correction of a Single Stage Bidirectional Wireless Battery Charger for EV

This paper analyzes a novel floating active filter circuit connected in series to the primary-side high-frequency (HF) AC link of an induction power transfer (IPT) system, suitable for compact bidirectional wireless battery chargers for electric vehicles. The proposed circuit has the advantages of other single-stage topologies, such as avoiding main heavy passive elements like DC-link capacitor and grid side inductor, increasing the power density and achieving a low-profile power converter design. However, this novel circuit also solves the main disadvantages of single-stage conversion systems in IPT converters, the transferred fluctuating power or the power factor in the off-board system. A prototype with Gallium Nitride (GaN) High Electron Mobility Transistors (HEMT) has been developed to validate the circuit concept and to analyze the Power-Factor-Correction (PFC) performance of the wireless battery charger.