Small-Signal Modeling of Asymmetrical Half Bridge Flyback Converter

A small-signal model for the asymmetrical half bridge flyback converter is presented. The effects of storage elements and peak current mode control on the transfer characteristics are investigated. The results show that the power stage of the studied converter is basically a fourth order system with two low-frequency poles and two high frequency poles. While the peak current mode control is applied, the transfer functions are reduced to three poles: one dominant pole dependent on the output capacitance and output load resistance, and two high-frequency poles determined by the resonant inductance and the DC blocking capacitance. The validity of the proposed models is verified by both PSPICE simulations and hardware experiments