Study On Buck Converter With Active Floating Charge Landing

The DC-DC converter intently powering modern microprocessors is known as a Voltage Regulator Module (VRM), which has been attracting more attention and has become a focus and challenge in the field of Switch Power. With the integration of ultra-large-scale integrated circuits getting higher and higher, the requirements for the VRM are more and more critical, for the future VRM, the output voltage is lower and lower while the total power needed is higher and higher, thus a twofold output current increase is introduced. At the same time, a faster transient response with very tight output voltage tolerance and high power density is required. All these prompts unprecedented challenges for designers of power supply. Today,5~12 V input DC/DC converter has been far and wide used in VRM's design. In future applications, it will be impractical for Voltage Regulator Modules (VRM) to draw power from the 12 V-output of the silver box because the voltage bus will be too low to deliver more power. Therefore, Distributed Power System (DPS) with bus of 48 V will be more feasible solutions for future high-end PCs.The traditional Buck converter has a simple designed structure and the merits of interleaving technology, but its switches duty cycle is so small which will bring lots of side-effect when it has high input voltage but low output voltage. So in order to take full advantages of Buck converter and avoid its disadvantages, on the base of Active Floating Charge Landing theory, a novel voltage regulator module—Buck converter with Active Floating Charge Landing is proposed.In this paper, the main study includes: Firstly, presents a novel VRM topology—Buck converter with Active Floating Charge Landing, the detailed steady operation principle, small signal model and merits of this new topology are presented compared to traditional Buck converter; secondly, The effects of magnetic path's coupling effect on converter's steady and dynamic performance are researched when Coupled inductor used as the output filter inductor, the theoretic analysis of design of coupled inductor is also presented; Thirdly, based on the comparison of traditional VRM control strategies and the characteristics of the new topology, proposes a novel control method with simple structure and fast transient response and gives its operation principle. Small signal model of the whole system is presented too; last, deeply analyses the design of main circuit's parameters and control circuit. The steady and dynamic simulation results of actual model by Saber software verify the correctness of theoretical analysis.