13.56 MHz 1.3 kW resonant converter with GaN FET for wireless power transfer

Abstract

This paper presents a 1.3 kW resonant power amplifier using a Gallium Nitride (GaN) device at 13.56 MHz for wireless power transfer (WPT). The power amplifier driving the power transmitting coils is based on a Class Φ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> inverter, a single switch topology with low switch voltage stress and fast transient response. This implementation utilizes a recently available GaN device in a low inductance package that is compatible with operation in the 10's of MHz switching frequency. These power GaN switching devices have low gate resistance RG and low capacitance C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</inf> which greatly reduces the power requirements of the gate drive circuitry. This paper shows experimental measurements of the inverter in a WPT application and characterization of the system performance over various distances and operating conditions.