Modeling and analysis of primary side regulated flyback converter with pulse frequency modulation

A small signal model of primary side regulated (PSR) flyback converter with pulse frequency modulation (PFM) is firstly proposed in this paper. Output cable voltage drop compensation related to switching frequency is considered in the novel model (PFM-PSR model), which has another advantage of fast calculating. Frequency performance of entire loop is discussed with proposed model. A prototype is built and tested, experimental result fits theoretical analysis. The proposed model is proved to be accurate to reflex frequency characteristics of flyback system, which means that this model is effective in loop designing.