Analysis and design of a novel interleaved single-stage LLC resonant AC-DC converter

This paper proposes a novel interleaved single-stage LLC resonant ac-dc converter. Two derivative buck-boost typed power-factor-correctors (PFCs) with interleaved operation are integrated with an LLC resonant converter to form the presented circuit. The proposed single-stage converter has the features of simple circuit structure, balance switch currents, low dc-bus voltage, low input current harmonics, and high system reliability. Both the active switches can turn on with zero voltage switching (ZVS), and both the output rectifier diodes can turn off with zero current switching (ZCS), which results in lower switching losses. Circuit derivations, operation principles, and circuit analysis of the proposed converter are addressed. Finally, a laboratory prototype with an 110Vrms utility-line voltage is implemented correspondingly. The experimental results have verified the validity of the theoretical predictions and the feasibility of the proposed circuit.