Current Sharing for a Multiphase Inverter Based on Coupled External Parallel Resonant Branches for Wireless Power Transfer System

A novel passive current sharing method for a multiphase wireless power transfer (WPT) system is proposed in this letter. For an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>-phase inverter, there would be <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> compensating inductors in the inductor–capacitor–capacitor series (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i>-S) compensated WPT system. The proposed scheme introduces <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> external parallel resonant branches coupled with these <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> compensating inductors. In this way, an extremely large impedance is introduced in each loop of the circulating currents so as to balance the phase currents. No additional passive components with the rated power level are added to the power transfer channel. The proposed method employs two coupled inductors, which is easy to realize. Two new integrated structures for coupled inductors are introduced. The mathematical model and the current sharing principle of the proposed method are analyzed in detail. A 1.6-kW <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i>-S compensated WPT experimental prototype with a four-phase inverter and the experimental results verify the effectiveness of the proposed current sharing method.