A High Voltage-Gain DC-DC Converter With Low Switch Voltage Stress

In this article, a high voltage gain dc-dc converter is proposed for renewable power generation applications. The proposed converter includes a former step-up unit and z ( z >1) resonant step-up units. The former unit includes two stages of boost circuits with a coupled inductor primary winding in each stage and the inputs and outputs of the two-stage boost circuits are connected in series. Each resonant step-up unit is composed of two secondary windings of coupled inductors, two secondary leakage inductors, one resonant capacitor, and two diodes. The former step-up unit and the secondary windings contribute to high voltage gain. Meanwhile, all the switches and diodes can be considered as two devices connected in series. Therefore, the voltage stresses are lower than the output voltage, especially the switches. In addition, the resonant unit helps to achieve zero-current-switching of the diodes. To verify the feasibility of the proposed converter, a 180-W laboratory prototype with only one resonant step-up unit has been built.