Small-signal analysis of open-loop PWM flyback dc-dc converter for CCM

A flyback dc-dc converter is obtained from the conventional buck-boost converter by replacing the inductor with an isolation transformer. A transformer in the flyback converter is used to achieve a dc isolation between the input and the output of the converter. This paper presents dc and small-signal circuit models for the flyback converter for continuous conduction mode (CCM). The parasitic components are included in these models. The dc model is used to derive the equations for the dc voltage transfer function and the efficiency. The small-signal model is used to derive the equations for the open-loop small-signal transfer functions, such as control-to-output transfer function, input-to-output transfer function, input impedance, and output impedance. Bode plots are also given for the small-signal transfer functions.