Analysis and Control of Synchronous Rectification for MHz Class-E Resonant Rectifier with Load Variation

A synchronous rectification increases efficiency and mitigates thermal issues by replacing the diodes with switching devices. For this reason, a number of studies carried out the implementation of synchronous rectification for resonant converters. However, a thorough investigation on optimized synchronous rectification of Class-E resonant rectifier for a wide range of load was not addressed in previous works. This paper proposes a design and control method of synchronous Class-E resonant rectifier with comprehensive analysis. The switch ON and OFF analysis is developed based on the operating characteristics and mathematical equation of the synchronous rectifier for a wide range of loads. The optimum duty ratio is analytically investigated, and the proposed tracking algorithm ensures the optimum operation of synchronous rectification. As a result, the proposed method minimizes the switching and the diode conduction loss of the rectifier. For verification, a prototype of a 40 W resonant converter is implemented. The experimental result confirms the validity of the analysis and the control method with a fast dynamic response for all ranges of load.