Range winding for wide input range front end DC/DC converter

Hold up time requirement is a special requirement for a front end (FE) converter. The converter needs to provide output voltage within regulation for 20 ms after the AC input is lost. When designing the FE DC/DC converter, we want it to operate over a wide input range so that we can use less high voltage bus capacitor to meet the requirement. The converter efficiency is reduced at normal operating conditions, in order to cover wide input range. This paper demonstrates a new method to cover wide input range while also optimizing the normal condition operation with range winding.