A Modified Dual-Output Interleaved PFC Converter Using Single Negative Rail Current Sense for Server Power Systems

The interleaved PFC topologies have been widely used since they allow for smaller components, improved thermal performance, better transients, and reduced current ripple. In this letter, conventional two-phase interleaved universal input PFC topology is modified to obtain dual independent outputs for server applications, which minimizes the transient effects of interleaving legs on each other through two split dc buses. A new digital control method using only one current sensor located on the negative dc rail is proposed to control the dual-output interleaved PFC converter. Double-loop digital control of two interleaving stages is implemented using a single low-cost microcontroller (TMS320F28027-PiccoloA). In the proposed control technique, the control circuitry, input voltage, and current sensing circuits are shared between two PFC power stages, which minimize the size and the cost of the design significantly.