A 6.78MHz GaN-based Class-E Resonant Wireless Power Transfer System with Automatic Matching Point Searching Control for Zero Voltage Switching and Zero Voltage Derivative Switching

• Main Authors: Yeh, Che-Hao, 葉哲豪
• Other Authors: Chen, Ke-Horng
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/vhn2qr

碩士 === 國立交通大學 === 電控工程研究所 === 106 === Wireless power transfer system (WPT) technology in recent years gradually improves. A large number of commercial electronic equipment have great demands for high power. Thus, high power and high efficiency become an important issue. WPT system includes transmitter (TX) and receiver (RX). During the transmission, the changes of load and the relative distance affect transmission power and efficiency. Generally speaking, the most common solution is the frequency modulation technique but it contradicts the switching frequency requirement in the A4WP specifications. That is, the modulated frequency is far from the desired switching frequency which is defined as 6.78MHz ± 15kHz. Another intuitive practice is to use a number of compensation capacitors to digitally modulate and achieve the matching requirements corresponding to the variations of WPT system. Unfortunately, in order to resist wide load variation in high power demands, this modulation method must be combined with multiple high voltage switches and compensation capacitors, thereby occupying a larger footprint area and reducing control efficiency. In this thesis, a main structure with a Class-E power amplifier and a Gallium Nitride (GaN) power transistor used at the TX terminal are proposed. The control circuit causes the GaN power transistor to reach zero voltage (ZVS) switching and zero voltage derivative (ZVDS) switching. The power transmission achieves high power and high efficiency simultaneously. Moreover, compared with the state-of-the-arts, due to the voltage controlled compensation capacitor in the analogy modulation method, the control is relatively simple and area efficient.