Energy-Based Averaged Switch Modeling Applied to a High-Step Down Quasi-Resonant Soft-Switched Converter

This paper presents an energy-based modeling approach applied to a fully soft-switched quasi-resonant flying capacitor buck converter (FSQRB). The converter enables soft switching in both Discontinuous Conduction Mode (DCM) and Continuous Conduction Mode (CCM) with constant energy source behavior. We utilize this behavior to develop an energy-transfer-based unified dynamic model that describes both DCM/CCM operations and facilitates controller design. We also extend the energy-based modeling approach to other single-flying capacitor (SFC) buck-based topologies and boost topologies. The efficacy of this approach is validated through PLECS multi-tone analysis ac simulations, confirmed by Bode plots for various SFC buck & boost topologies. Moreover, for the FSQRB converter, the underlying energy transfer principle gives rise to interesting transfer function characteristics such as a favorable low-quality factor
$(Q_{o})$
, having an upper limit of
$1/\sqrt{2}$
. Experimental results demonstrating the response of a voltage-mode controller designed around the proposed FSQRB converter, highlight the dynamic salient features of this converter.