Dynamic Modeling of a Hybrid Switched-Capacitor-Based Converter with Phase-Shift Control

This paper is focused on modeling of dynamic responses in a hybrid switched-capacitor based dc-dc converter with a nominal 2:1 conversion ratio. Operating the converter well above resonance minimizes current stresses, and allows zero voltage switching and simple phase-shift control. A discrete-time small-signal model is developed, which accurately captures high frequency dynamics including effects of L-r-C-r, resonance, and sampling associated with the phase-shift modulator. The model shows how the conversion ratio and the choice of the resonant frequency affect the location of high frequency zeros, which may be utilized to simplify control and compensation requirements, especially when operating well above resonance around the nominal 2:1 conversion ratio. The discrete time model facilitates direct Z-domain compensator design using digital phase-shift control. Simulation and experimental results are provided to validate the model.