Comparison of Three Buck Topologies for Wide Output Voltage Applications

This paper investigates the suitability of three step-down dc-dc converter topologies as the final conversion stage in a wide output voltage modular ac-dc power supply. Single-phase, two-phase and three-level buck converters are evaluated over a wide range of outputs using analytical models and physical measurements. The converters' performance is evaluated at all operating points using statistical analysis of the converter component losses produced to assess their suitability for wide output voltage applications. The dynamic performance of the converters is also evaluated to determine their stability for on-the-fly variations in output voltage and load. The analysis finds that the three-level converter is more efficient across the full output range, with lower component loss variability compared to the one-phase and two-phase buck converters. However, it suffers from poor dynamic performance with high output deviations and slow response times. The analysis was verified using three prototype converters designed for 200 W, 15 V to 28 V output.