A Load-Independent ZVS Class-E2 Wireless Power Transfer with Receiver-side Constant-Frequency PWM Power Control

A compact and low-profile high frequency (HF) power converter is essential for a magnetically resonant wireless power transfer (WPT) system suitable for a small-scale electric load such as IoT equipments and medical implantable devices. This paper presents a new prototype of a class E HF inverter/active rectifier-based WPT system, where the load power control achieves only in the receiver (Rx) side while maintaining zero voltage soft-switching (ZVS) on the transmitter (Tx) side with the fixed frequency and duty cycle. The modeling-based analysis and design of PWM-controlled Rx-side class-E rectifier are originally presented in accordance with load-independent ZVS in the Transmitter (Tx)-side class-E inverter. The effectiveness of the modeling and design of the class-E2 WPT system are verified by experiment of 1MHz-8W prototype, after whereby the load-independent ZVS performance of class-E inverter is demonstrated with the relevant steady-state characteristics.