Transformerless DC-DC step-up topologies with symmetrical outputs for renewable energy applications

In this work two transformerless DC-DC step-up converter topologies with symmetrical outputs are proposed for renewable energy applications. Both of them are based on the interleaved operation of two single structures of the combined H-bridge with a voltage doubler rectifier, which was introduced in a previous work. Experimental results are presented to evaluate the control strategy for balancing the output mid-point voltage of the combined H-bridge with voltage doubler. PSCAD/EMTDCTM simulations of the proposed interleaved converters, while operating with balanced symmetrical outputs, are presented in order to show their effectiveness as a front-end of multilevel inverters, when multiple DC input sources, such as solar photovoltaic arrays, are used.