A non-isolated high step-up converter with built-in transformer derived from its isolated counterpart

In this paper, a non-isolated high step-up interleaved DC/DC converter is proposed for the photovoltaic and fuel cell grid-connected power applications. By employing the built-in transformer, the voltage gain is extended greatly without the extreme duty cycle and the voltage stress of the switches is reduced. The output diode reverse-recovery problem is alleviated by the leakage inductance of the built-in transformer, which reduces the reverse-recovery losses and the EMI noise. The active clamp scheme can suppress the surge voltage of the power switches and recycle the leakage energy. ZVS soft switching performance is realized for all the switches to reduce the switching losses. Finally, a 1 kW prototype with 40 V input and 380 V output is implemented and tested to show the performance of the presented converter.