Interleaved high step-up converter with built-in transformer and voltage doubler for PV grid-connected generation systems

In this paper, a zero voltage transition (ZVT) interleaved high step-up converter with built-in transformer and voltage doubler for photovoltaic (PV) grid-connected generation system is proposed. The built-in transformer and the voltage doubler are employed to extend the voltage gain, reduce the switch voltage stress, which makes the low on-resistance switch can be adopted to reduce the conduction losses. The active clamp circuit is employed to recycle the leakage inductance energy of the built-in transformer and to absorb the turn-off voltage spikes on the main switches. Furthermore, zero voltage switching (ZVS) performance is achieved for both the main switch and the clamp switch during the whole switching transition, which can reduce the switching losses. In addition, the reverse-recovery problem of the output diode and the double voltage diode is alleviated by the leakage inductance of the built-in transformer, which can reduce the reverse-recovery losses. Due to the factors mentioned above, the proposed converter is suitable for the high step-up and high power applications. Finally, a 1kW prototype of the PV grid-connected generation system is built to demonstrate the effectiveness of the proposed converter in high step-up and high power applications.