Small Signal Modeling of LLC Converter with LED Load and Quasi-Resonant Controller Based Active Ripple Rejection

This paper has analyzed the defects of traditional extended description function (EDF) based LLC small signal modeling method when driving light emitting diode (LED) load and proposed an accuracy improvement method. Detailed model methods have been deduced, different compared thoroughly. To suppress second-order harmonic ripple in direct current link-induced output ripple, a quasi-resonant controller (QRC) is adopted to realize active rejection (ARR). Considering frequency changes with grid voltage frequency, single-phase software phase lock loop (SPLL) extract harmonic. By dynamically regulating control parameter QRC according locked ability immune deviation obtained. Based on deduced accurate model, digital designed stability, steady state dynamics performance guaranteed. The SPLL QRC-based ARR verified at last.