The Design Of Control Algorithm For MHz Level Single-switched Resonant Converter With Wide Voltage Input

The single-switched resonant converter has the advantages of simple structure,small volume and simple control mode.Meanwhile,soft switching technology is used to improve the switching frequency and working efficiency of the converter circuit.It has a broad application prospect in medium and small power adapters.However,stress of vonerter is large,resulting in low input voltage,narrow input voltage range and other problems,which affect the practicality of this kind of power supply topology.In view of the above problems,a digital multi-mode control algorithm for MHz level single transistor resonant converter with wide input voltage range is designed.Firstly,the working principle of single-switched resonant converter is analyzed,and the relationship between voltage stress and input voltage,output voltage and turn ratio is found.Secondly,the steady-state loss models of continuous conduction mode and discontinuous conduction mode are established to find the optimal conduction point and improve the converter efficiency in a wide input voltage range.Thirdly,a multi-mode control algorithm is designed to solve the problems of circuit efficiency and voltage stress to adapt different input voltage and load.On this basis,the designed control algorithm is written into register transfer level code and verified by co-simulation of Modelsim and MATLAB.Finally,a experiment prototype based on FPGA is built to verify the effectiveness of the multi-mode control algorithm.The results of software simulation and physical prototype expriment show that the input voltage range is expanded from less than 100 V to 100 V ～ 200 V,the ratio between voltage peak and input voltage is reduced from 3 ～ 3.5 to 2 ～ 2.5,the full load average efficiency is86.5%,the peak efficiency is 88%,and the full load switching frequency is 1.25 MHz.The multi-mode control algorithm effectively broadens the input voltage range and ensures high efficiency.