Study and Design of a Variable Frequency Synchronous Rectified VRM with Phase Reduction Optimization

• Main Authors: Jui-Chien Wang, 王瑞乾
• Other Authors: 歐勝源
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/w456v9

碩士 === 國立臺北科技大學 === 電機工程系研究所 === 99 === This thesis proposes a novel control method that combines automatic phase reduction with switching frequency modulation and applies to the synchronous rectified buck converter on motherboards. The proposed novel control method decreases phases and increases switching frequency in light loads, on the contrary, increases phases and decreases switching frequency in heavy load. Due to the proposed novel control method, it can further improve output voltage ripple with phase reduction and increase the efficiency in light loads. To match the required output voltage specifications, a load current threshold is predetermined and the switching frequency is fixed as the load current is higher than the threshold. Finally, this paper implements an eight-phase synchronous rectified buck converter, compared to conventional constant frequency techniques, the efficiency can be increased up to 30% for eight-phase one under the proposed novel control method.