Frequency-Based Load Sharing in Current-Mode-Controlled Buck Converters

摘要

Modular DC Zonal Electrical Distribution (DC ZEDS) offers advantages in both cost and weight over traditional radial shipboard distribution. In order to equip the next class of surface combatant with DC ZEDS, preparative research includes the design of autonomous dc-to-dc power converter modules having robust load sharing capability. This thesis examines the combined utility of current-mode switch control and frequency-based load sharing to promote equal load sharing among parallel dc-to-dc converter modules. Current-mode control with frequency-based load sharing is analyzed primarily with digital simulation. To that end, a state-space representation for a system of two converters and an Advanced Continuous Simulation Language (ACSL) simulation for a system of three converters are developed. Various studies were conducted to evaluate the performance of a proposed system for load sharing performance between dissimilar converters, for step changes in load, and for bringing a converter off-line. Additionally, a sub-circuit of frequency-based control-the rms frequency estimation circuit-was built, and its static performance evaluated. Finally, recommendations are made for further simulations which will better test the dynamic performance of this rms estimation circuit and the system of parallel converters employing frequency-based load sharing as a whole.