Small-signal model analysis and control design of a double-ended forward converter in discontinuous-capacitor-voltage mode

A double-ended forward converter with an input inductor-capacitor filter has inherent power factor correction (PFC) properties and continuous input current when operating in discontinuous-capacitor-voltage mode (DCVM). In this study, the minimum separable switching configuration modelling is applied to the proposed converter operating in DCVM to obtain a small-signal model of the converter. The impact of the circuit parameters on the small-signal characteristic are discussed in details. The difference between the small-signal behaviour of the converter when operating as a DC/DC converter and a PFC converter is investigated. The modelling methodology is intended for the design of controllers in closed-loop operation. A 100 W prototype is implemented to demonstrate the feature of the small-signal behaviour.