DC ready devices - Is redimensioning of the rectification components necessary?

DC has several advantages over ac. In relation with the changes needed in todays ac power system to deal with dominating amounts of fluctuating renewable energy, it seems wise to consider dc as an alternative. One of the problems with introducing dc grids is the lack of availability of dc devices. DC ready devices that work on both - ac and dc - would simplify a smooth introduction of dc there, where it has its biggest advantage. This is especially interesting for newly built infrastructure, e.g. in developing countries with bad ac infrastructure, but also for upgrading the power of existing ac cables when needed. As most ac devices today already have dc/dc converters inside, the changes are not as big as one might assume. In this paper the rectification stage and power factor correction is looked at in detail and it is shown that in most cases there is no need for re-dimensioning of components to make devices dc ready. Other important points are subject of ongoing research as are dc microgrids in general.