Modeling and Control of Integrated Coupled-Inductor Boost-Flyback Converter

A boost DC-DC converter, with high efficiency and high voltage gain and integrated with coupled-inductor boost flyback converter, is proposed in this paper. The dependence on duty cycle to realize high set-up ratio, in the conventional boosted circuit, is eliminated in this paper so that the converter can fulfill higher voltage gain using relatively small cycle duty. In comparison to traditional methods, this will effectively decrease voltage ripple of capacitor and lower the reverse recovery loss of diode. Firstly, this paper has a brief analysis of the operating principle of this converter and a small-signal model is established by using state space averaging method in continuous conduction mode(CCM). Secondly, the transfer function of control parameters to output parameters is, according to the model, built and correspondingly the closed-loop control system is designed via this function. Finally, the stability of closed-loop system and the accuracy of way of constructing model are verified in the stimulation. In the meantime, a 30W prototype that is used to test the performance of this converter is designed. The accordance of the results from stimulation and analysis demonstrates the correctness and feasibility of theoretical analysis of the model of proposed converter.