A novel IDE control to improve light load efficiency for a full-bridge DC/DC converter

Server and telecom power systems have traditionally been using the Intermediate Bus Converter (IBC) or Adaptive Bus Converter (ABC). To improve power efficiency crossing load range is a hot topic in the recent years. Using digital control provides the possibility to have better efficiency than analog control. At light load, output inductor current can go negative through a synchronous rectifier (SR). The negative current can bring additional power losses. Well controlled synchronous rectifiers can emulate MOSFETs conduction like ideal diodes, and hence negative current is eliminated. This paper will propose a new control method for synchronous rectifiers to effectively eliminate output inductor negative current. A 360W 48V/12V DC/DC converter was built for the control validation. The power efficiency is increased by 7% at light load.