Research Of The Control Strategy For Interleaved LLC Resonant Converter

In the 21_thh century,the switching power supply and integrated chip get rapid development.The LLC resonant converter characterized by soft switching feature has taken the biggest part in the high frequency and higu power application.Two-phase interleaved LLC resonant converter has many new advantages over the tranditional LLC resonant converter,such as doubling the output power,reducing the output ripple,achieving load sharing and higher power density by magnetic integration etc,thus having significant research value.This paper focus on the boost inteleaved LLC resonant converter.Digital signal processor is selected as controller to realize the frequency modulation and closed-loop feedback.For the first step,the circuit topology and driving strategy is researched and the working mode under frequency modulation is analysed.For the second part,we establish the model of steady state and dynamic state in order to design the resonant parameter and controller patameter.Load sharing is taken into consideration,so a set of parameter full of robustness is got.And the method of dynamic modeling is extended description function method.Last but not least,simulation and experment have been done.The experimental prototype is 48V/400V/1000W.Results of simulation and experiment verified the rightness of this paper and the feasibility of scheme.When the converter worked in half load condition,the efficiency came to the climax of 92.48%.