Composite DC-DC Converter with Bipolar/bidirectional Current-Fed Push-pull Voltage Regulator

This paper presents a power converter to interface an extra low voltage bus, ELV (48 V) and a low voltage bus, LV (380 V) in a residential dc-dc nanogrid of 1.2 kW. The proposed converter makes use of a composite structure where a DC transformer (DCX converter) handles the major amount of the processed power between the DC buses. DCX is design to operate at a fixed duty-cycle where the transformer turns-ratio is optimized to ensure the lowest conduction losses. To provide voltage regulation to ELV bus, a parallel voltage regulator (DCR) is employed. The power handled by the DCR is proportional to its input voltage across capacitor $C$ 1.1 Results from a 1.2 kW laboratory prototype confirm the feasibility of the proposed composite converter and reveals that it is a strong candidate for DC-DC applictations with a narrow volage regulation range.