Closed-Loop Control of Impedance Control Network Resonant DC-DC Converter

This paper introduces a closed-loop control architecture for an impedance control network (ICN) resonant dc-dc converter that regulates the converter's output voltage while achieving soft-switching across wide operating ranges. This architecture is based on enhanced phase-shift control of the ICN converter, in which the inverter and rectifier phase-shifts are simultaneously controlled to regulate the converter's output voltage, while operating the inverters with zero-voltage and near-zero current switching. A new small-signal dynamic model for the ICN converter is introduced to facilitate the design of the closed-loop controller. An additional state-feedback component is incorporated in the control architecture to guarantee stability and achieve good dynamic performance across wide variations in input voltage and output power. This closed-loop control architecture successfully regulates the output voltage of a prototype step-down ICN converter that operates over an input voltage range of 18 V to 75 V, an output voltage of 12 V, and a 10:1 output power range. The prototype closed-loop controlled ICN converter achieves a peak efficiency of 95.7%, and maintains efficiencies above 91.7% across its 4:1 input voltage range.