This paper proposed a new SEPIC Boost DC-DC converter that uses only one auxiliary switch to create soft switching condition for all semiconductor devices. The auxiliary circuit comprises of one power switch (Sa), one resonant inductor (Lr), one resonant capacitor (Cr) and one diode (Do2). The auxiliary switch (Sa) controls the resonance during switching instants. The converter has simple structure and its control circuit remains PWM. Besides, the proposed converter has high voltage gain without using any transformer or coupled inductors. In addition, the auxiliary switch is not located in the main power path. Moreover, using soft switching techniques is the best way for reducing the size, weight and volume of the converter. Furthermore, reduction of input inrush current and voltage stress for the main switch is obtained by using SEPIC Boost structure. A laboratory prototype converter is designed and implemented. The experimental results presented confirm the theoretical and features of the proposed converter.
