Circuital and mathematical modelling of flyback converters

A circuital and mathematical modelling of flyback converters is presented in this paper. It accounts for many parasitic elements of each flyback devices, among which transformer leakage inductances and junction capacitances of semiconductor devices. An equivalent circuital representation of the flyback converter is introduced at first, based on which a suitable mathematical model is determined. This requires the definition of appropriate switching signals in order to account for the different flyback operating modes properly. As a result, accurate voltage and current evolutions are achieved, especially regarding the transient phenomena occurring during both the TURN ON and the TURN OFF of the semiconductor devices. This is proved by a simulation study, which refers to the comparison between the proposed model and an accurate flyback circuital representation.