Novel high-gain hybrid current-driven DC-DC converter topology

A novel high gain current-driven DC-DC converter topology is proposed in this paper. This circuit is aimed for applications which require wide input and output voltage ranges, such as PV micro-inverters, electric vehicle battery chargers etc. As compared to the resonant converters, the size of inductor can be reduced by an order of magnitude and resonant capacitors eliminated, by the use of current-driven topology. These advantages result in increased power density and higher power conversion efficiency of the converter. A major limitation of the current-driven topology is that it can provide a maximum gain of just over unity. Further, this value of maximum gain also depends on the parasitic capacitances of the converter components. These issues make the converter operation more susceptible to component parasitics (such as the transformer inter-turn capacitance), resulting in degraded converter performance. The high-gain current-driven topology, presented in this paper overcomes the disadvantages of the conventional current-driven converter topology, by the introduction of a parallel capacitor at the high voltage side of the transformer winding. Introduction of parallel capacitor provides a two-fold advantage to the conventional current-driven topology. First it makes the effect of parasitic capacitor small so that the control system is not much sensitive to it, and it provides a high gain due to pre-charging of the network inductances at the beginning of each switching cycle. Simulation and experimental results validate the viability of proposed converter topology for applications requiring wide range of input and output voltages.