Dynamic Modeling of the Resonant Series-Bridge DCX Converter

A DC transformer (DCX) is a dc-dc converter that operates at a fixed voltage conversion ratio, enabling optimized design and the potential for higher performance. The resonant Series-Bridge DCX (SB-DCX) topology has recently been adopted for DCX applications due to its inherent, open-loop DCX operation. However, a scalable and analytically tractable time-invariant dynamic model for this topology has remained a challenge. This paper examines the challenges associated with developing a time-invariant dynamic model and proposes the use of half-cycle averaging, resulting in a linear time-invariant (LTI) model with a convenient circuit-based representation. The model predicts both the steady-state and large-signal dynamic characteristics of the topology under certain assumptions. Simulation results are presented, demonstrating strong agreement between the observed dynamic behavior and the model’s predictions. Further, a hardware prototype is used to experimentally validate the dynamic behavior at 170 W peak output power and 30 V input, with results shown for a 50% load transient response. The developed model accurately predicts both the average output voltage and the tank current envelope.