Interleaved Boundary Conduction Mode (BCM) Buck Power Factor Correction (PFC) Converter

An interleaved boundary conduction mode power-factor-correction buck converter that maintains high efficiency across entire load and line range is proposed. The adaptive master-slave interleaving method maintains stable 180 degrees out-of-phase operation during any transient. By interleaving two parallel-connected buck converters, the input current ripple is halved while the ripple frequency is doubled, which leads to a smaller differential mode line filter. The line current harmonic distortion is analyzed to examine the allowable output voltage range while meeting harmonic regulations. The operation and performance of the proposed circuit is verified on a 300 W, universal line experimental prototype with 80 V output. The measured efficiencies remain above 96% down to 20% of full load across the entire universal line range. Even at 10% of full-load condition, the efficiency remains above 94%. The input current harmonics also meet the IEC61000-3-2 (class D) standard.