Individual step-up converter with active recovery stage for high efficiency conversion of photovoltaic energy

摘要

The incessant involving of smart grids associated with renewable energies increases the demand in high efficiency converters. So it is important to consider all possible improvements involving reliability and simple structures. In this study we demonstrate the improvement potentiality of a DC/DC step-up converter, connected to a HVDC bus, based on a MCB-RS model (Magnetically Coupled Boost with Recovery Stage). We suggest a new possibility of improvement of the converter by mastering its active switch allowing an easier control of the internal voltage inherent to the recovery stage. The suggested solution permits a saving of the internal energy and prevents the over heating of certain components, like recovery diode. In the MCB-RS converter, the losses are for a main part dissipated in the recovery diode, representing a non-negligible amount of power. Thus, we propose to save this energy by the insertion in the recovery circuit of an additional parallel switch. This solution offers an additional advantage by making possible the flow back of a certain amount of energy by keeping in the on state the parallel switch. Finally we compare the simulated results with a real system and validate this new performing structure.