Abstract: The large conversion ratio bi-directional DC-DC converter is widely applied in charge and discharge battery systems,automatic cars,uninterruptible power supplies（UPS）,generator systems,photovoltaic systems and aero power supplies,etc.The efficiency,size and cost are the key properties for these applications.A novel coupled-inductor bi-directional DC-DC converter is proposed and analyzed in this paper,which can overcome the shortage of non-isolated bi-directional DC-DC converters that its conversion ratio is restricted in a small range.This paper analyzes the principle and control model of the proposed converter.To accomplish the prominent dynamic performance of the large conversion ratio bi-directional DC-DC converters,the different operating modes are investigated and a improved control model is deduced from one-cycle control（OCC） technique based on effective duty ratio combined with optimum feedback compensation strategy.The novel converter combined with improved OCC control strategy is built.The computer simulation and experimental results verify the higher efficiency,good robust and fast response performance of the proposed circuit and its improved control strategy.