Analysis and design of multiphase interleaved CRM Buck converter with wide load range

This paper presents a low-ripple wide-load-range LED driver with critical engineering value for industrial lighting systems. Based on a three-phase interleaved magnetically coupled Buck converter topology, the work systematically investigates the interaction between multi-phase coupled inductor current ripple and output current ripple. A normalized analytical model is developed to unveil the intrinsic characteristics of multi-phase magnetic coupling, with a focus on achieving zero-voltage switching (ZVS) over a wide range. The advantages of integrating negative coupling with critical conduction mode (CRM) are demonstrated, showing significant ZVS boundary expansion and circulating energy reduction. Magnetic circuit analysis guides key parameter optimization. The implemented prototype achieves constant-current output regulation across an ultra-wide range (3 33A, 1000% variation) under 480-600V input voltage, attaining a power density of 520W/in³. Experimental verification confirms that the system maintains output voltage self-adaptation across the entire load range, achieving full-load ripple suppression below 0.237% and a peak efficiency of 98.23%, fully compliant with stringent design specifications.