An isolated hybrid switched C-L DC-DC circuit with high step-up ratio and reduced switch voltage stress

This paper introduces a high step-up ratio isolated dc-dc circuit which can be used as an interface between 20 V-40 V PV panels and high voltage dc system, up to 1000 V. By combining the switched inductor (SL) and quasi switched capacitor (QSC) structures with the traditional isolated full bridge circuit, the 50 times boost ratio is realized with small turns ratio. In this case, the leakage inductance can be much smaller and the reactive current can be reduced. Also, the voltage stress on both primary and secondary side switches are lower than their counterparts in full bridge circuits, which enable the using of lower voltage rated switches. Therefore, both the switches´ losses and overall cost can be reduced. Complete circuit description and operation principles are presented in this paper. In order to verify proposed functions, a lab prototype has been assembled and the experimental results are included in this paper.