A non-isolated bidirectional DC-DC converter is proposed in this paper, which realizes zero ripple of low voltage side current by optimizing the coupling inductor. The proposed converter also has the advantages of high voltage gain (G=(1+D)/(1-D) in boost mode), reduced switch (only three), lower voltage stress (about half of the high voltage side voltage), and zero-voltage-switching for all switches. In addition, it requires only one magnetic core, and the input and output sides share the common ground. The working principle, steady-state characteristics, conditions of low voltage side zero current ripple, soft switching conditions and parameter design methods of the proposed converter are depth analyzed, and then verified by a 250 W/100 kHz simulation prototype.