The ZVS voltage-mode class-D amplifier, an eGaN® FET-enabled topology for highly resonant wireless energy transfer

The popularity of highly resonant, loosely coupled, wireless energy transfer systems operating at 6.78 MHz has increased dramatically over the last few years. In this paper we present the zero voltage switching (ZVS) voltage mode class D amplifier topology and evaluate its performance as a suitable A4WP Class-3 compliant amplifier using eGaN FETs and compare the performance with MOSFETs. Experimental verification has revealed that the ZVS class D amplifier can inherently drive a reflected load impedance range from +20j Ω though −30j Ω and 1.7 Ω through 57 Ω while maintaining A4WP Class-3 compliance, which is a significantly wider range than any other topology explored as of this date. The eGaN FET based amplifier was found to have 30 % lower losses and operate as much as 17°C cooler when delivering 16 W into the load than a MOSFET version.

[1]  Tsai-Pi Hung.  High efficiency switching-mode amplifiers for wireless communication systems , 2008 .

[2]  J. Glaser,et al.  GaN Transistors for Efficient Power Conversion , 2019 .

[3]  W. Chen,et al.  A 25.6 W 13.56 MHz wireless power transfer system with a 94% efficiency GaN Class-E power amplifier , 2012, 2012 IEEE/MTT-S International Microwave Symposium Digest.

[4]  Johan Strydom,et al.  Design and evaluation of a 10 MHz gallium nitride based 42 V DC-DC converter , 2014, 2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014.

[5]  Johan Strydom,et al.  Evaluation of gallium nitride transistors in high frequency resonant and soft-switching DC-DC converters , 2014, 2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014.

[6]  Michael de Rooij.  eGaN FET based Wireless Energy Transfer Topology Performance Comparisons , 2014 .

[7]  Ryan Tseng,et al.  Introduction to the alliance for wireless power loosely-coupled wireless power transfer system specification version 1.0 , 2013, 2013 IEEE Wireless Power Transfer (WPT).

[8]  Johan Strydom,et al.  eGaN FETs in Low Power Wireless Energy Converters , 2013 .

[9]  S.-A. El-Hamamsy,et al.  Design of high-efficiency RF Class-D power amplifier , 1994 .

[10]  J. Strydom,et al.  Understanding the effect of PCB layout on circuit performance in a high frequency gallium nitride based point of load converter , 2013, 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC).