An interleaved single-stage LLC resonant converter used for multi-channel LED driving

In order to simplify circuit complexity, reduce cost and improve system efficiency, this paper proposes an interleaved single-stage LLC resonant converter to drive multi-channel light emitting diodes (LEDs) with high power-factor and current-sharing features. Two derivative buck-boost typed power-factor-correctors (PFCs) with interleaving 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, balanced switch currents, low dc-bus voltage, low input current harmonics, and high system reliability. With proper analysis and design, the power switches can turn on with zero-voltage-switching (ZVS), and the output rectifier diodes can turn off with zero-current-switching (ZCS), which results in low switching losses. Additionally, by connecting the primary windings of transformers in series, the current-sharing among all the LED channels can be achieved naturally. Operation principles and circuit analysis are addressed. Finally, a laboratory prototype with 220 V_rms utility-line voltage is implemented correspondingly to verify the validity of the theoretical predictions and the feasibility of the proposed circuit.