eGaN FET based Wireless Energy Transfer Topology Performance Comparisons

eGaN FETs have previously been demonstrated in a traditional voltage mode class D wireless energy transfer system [1, 2] that had a peak efficiency over 70% and provided a 4% higher in total efficiency than a comparable MOSFET version. In this article eGaN FETs are again employed and compared in highly resonant wireless energy transfer where various topologies, such as the current mode class D, single ended class E, and a novel high efficiency voltage mode class D will be compared. The comparisons will be based on efficiency and sensitivity to load and coil coupling variations. Each of the topologies will be experimentally tested based on using the same source and device coil set with the same device rectifier and load. The experimental units will operate with loosely coupled coils at 6.78 MHz (ISM band) and deliver between 15 W and 30 W (depending on topology). The design of the amplifiers will look at ways that the device parameters, such as COSS can be included into matching network.