Bidirectional converters are used to transfer power between two sources. Most of these converters are developed using unidirectional converters and adding a switch in reverse parallel position with each diode and adding a anti-parallel diode with the main switch. These converters are employed in systems that require power transfer in two directions with energy storage capability such as hybrid electric vehicles, photovoltaic systems, fuel cell systems, and uninterruptible power supplies. The bidirectional DC-DC converters are categorized under isolated and non-isolated types. Isolated bidirectional converters are applied in applications which need high voltage gain and isolation. Non-isolated bidirectional converters have recieved the most attention due to their simplicity. In all DC-DC converters, the goal is increasing the switching frequency to reduce volume and size of passive components. However, in hard switching converter, increasing the switching frequency would increase the switching losses and noise.. In order to solve these problems, soft-switching condition should be provided for semiconductor devices. The main challenge is to provide soft-switching condition by employing minimum number of extra passive and active elements. In this thesis, two bidirectional convertrs based on zero voltage transition (ZVT) and active clamped methods are introduced. In ZVT methods, the auxiliary circuit is activated in a short period of time resulting in low circulating current. In addition, the voltage stress of the main switches is low. The main contribution of the proposed converter is reducing the number of auxiliary elements. Also, the first proposed converter provides soft-switching condition for main switches by employing only two auxiliary switches, a diode, an inductor, and a capacitor for both directions. The theoretical analysis and design guideline are presented in details. The presented simulation and experimental results are compared and a through discusion is provided. The second proposed converter is an active clamped-type which is obtained by omitting a switch and replacing it with a diode in the first proposed converter. As a result, simpler converter control is achieved. In contrast to other active clamped converters, the second proposed converter can operate under soft-switching condition even at light loads and high output voltages. Operation principles and design consideration are presented. Also, simulation and experimental results of the proposed converter verify the validity of theoretical analysis. Key words: Bidirectional Converter, Soft Switching, Zero Voltage Transition, Active Clam