LLC Resonant Converter, Synchronous Rectification, Body Diode
Abstract
This article explores the application of synchronous rectification (SR) in a half-bridge LLC resonant converter. It proposes a scheme that utilizes source-to-drain voltage (Vds) detection of the synchronous rectifier’s body diode. An SR controller dynamically adjusts the turn-on and turn-off times of the synchronous rectifier tominimize conduction losses through the body diode. This approach ensures effective gatedrive signal control across the entire operating frequency range, including both above and below the resonant frequency. Furthermore, the article presents two flowcharts designed to eliminate and minimize body diode conduction, ultimately improving converter efficiency. To validate the effectiveness of these flowcharts, PLECS simulations were conducted using data provided by Onsemi. The simulations evaluated both conduction and switching losses within the circuit, achieving a maximum efficiency of 97.7% at full load.
