A three-level DC-DC converter using zero voltage and zero current switching is provided to reduce conduction loss of a main circuit element and loss of a transformer by decreasing a circulation current. A three-level DC-DC converter(300) using zero voltage and zero current switching includes a primary input terminal(10) and a secondary output terminal(30). The primary input terminal includes first and second switch sets, an input power supply, input capacitors, flying capacitors and auxiliary diodes, and coupling inductors. The primary input terminal and the secondary output terminal are magnetically coupled to each other through a transformer. The input power supply supplies electric energy to a primary coil of the transformer. One of terminals of the primary coil is connected to a contact point between the first and second switch sets, another terminal is connected to any one of the coupling inductors, and the other terminal is connected to a contact point between the auxiliary diodes.
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