New zero-voltage switching DC-DC converter for renewable energy conversion systems

This study presents a novel DC-DC converter for renewable energy conversion systems with photovoltaic (PV) solar cell or fuel cell stack input. The proposed converter is based on a boost converter and a voltage-doubler configuration with a coupled inductor to achieve high step-up voltage conversion ratio. An active snubber is adopted to clamp the voltage stress of the active switch and to release the energy stored in leakage and magnetising inductances. Compared to a conventional boost converter, the adopted converter has a wide turn-off period such that a high output voltage can be achieved. Since an asymmetrical pulse-width modulation is adopted to control both active switches, the leakage inductance and output capacitance of the active switch are resonant in the transition interval. Therefore both active switches are turned on at zero-voltage switching to overcome the disadvantages of a conventional boost converter with low circuit efficiency and narrow turn-off period. Finally, experiments conducted on a laboratory prototype rated at 400-W are presented to verify the effectiveness of the adopted converter.