High-frequency And High-efficiency Design For Forced Resonant Flyback Converter With Primary Side Regulation

Since the forced resonant flyback converter can reduce the turn-on loss of the switching device and can take into account the low-cost requirements of switching power supplies,it has become one of the hotspots of soft switching topology research in recent years.However,in the current research,the forced resonant converter not only still uses secondary side regulation,but the control algorithm of zero voltage switching is too simple,resulting in the inability to achieve zero voltage switching in the full input voltage and full load range,which prevents the forced resonant converter from further high-frequency and high-efficiency.In view of the above issues,a solution based on the forced resonant flyback topology,using primary-side regulation mode and digital loop control to achieve accurate control of zero voltage switching and constant-voltage output,is researched and designed.Firstly,the working principle and loss of the forced resonant flyback converter based on Ga N power device is analyzed.Secondly,a primary-side sampling method based on the forced resonant flyback topology is designed,which is used to sample zero voltage switching accurately.Then,the zero-voltage switching adaptive digital control algorithm and the constant voltage multi-mode control algorithm using primary-side regulation are designed.Then,the topology and algorithms are simulated and verified on the Simulink and Modelsim simulation platform.Based on these,the topology and algorithm are tested on the FPGA prototype verification platform and the proposed primary-side sampling method and digital loop control algorithm have been verified in the end.According to measured results,the max frequency of the converter system is up to300 k Hz,which is 2～3 times of the traditional flyback converter.The converter has a high overall efficiency in the range of the full voltage input and full load,and the peak efficiency is up to 91.62%.In addition,the zero-voltage switching adaptive algorithm improves the efficiency of the converter system especially when the input voltage is high.When the input is230 Vac,the efficiency is increased by 1.93% and 1.26% respectively at the 100% load point and the 50% load point.