Modelling and Compensation Design of Class-E Rectifier for Near-Resistive Impedance in High-Frequency Power Conversion

This article presents the investigation of circuit modelling, design, and optimization of the class-E rectifier to achieve a near-resistive impedance during a large load-range. Based on circuit modelling and impedance depiction, a circuit design concept of impedance compensation to achieve near-resistive impedance is proposed, and we selected the series inductor as the compensation network for class-E rectifiers.

After an optimized design, a 6.78-MHz wireless power transfer prototype was built with applying the proposed concept and tested. The experimental results match well with the circuit modelling and validate the impedance shift can be optimized by the proposed circuit design concept. The experimental prototype achieves 87.2% dc-dc efficiency at the rated 220-W output and the phase angle shift is lower than 10 during the load decreasing from 220-W rated output to the 40-W light-load output.

We also discuss the circuit design considerations and the hardware implementation of the prototype for the proposed design concept.