A Novel Adaptive Quasi-Constant On-Time Current-Mode Controlled Buck Converter

• Main Authors: Chin-Fu Nien, 粘儆夫
• Other Authors: 陳德玉
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/vdwkwg

博士 === 國立臺灣大學 === 電機工程學研究所 === 105 === In recent years, there have been a variety of constant on-time control (COT) schemes for DC power converter applications. This class of converters features high efficiency for both the heavy load and the light load conditions. However, its step-load transient response is, by-and-large, poor unless special circuitry is used to speed up the response. In this dissertation, an adaptive quasi-constant on time current mode (AQCOTCM) control scheme is described. Using this control scheme, a converter can achieve faster step-load response and operating frequency independence of load level while preserving the basic advantages of a conventional constant on-time current mode (COTCM) converter. In the dissertation, an explanation is given first about the basic characteristic of slow step-response of conventional COT schemes. Then modifications are described that lead to the AQCOTCM scheme. A small-signal control model is then developed that is essential for the proper design of the converter feedback control. Experimental results are shown for the verifications. Extension of the concept to multiphase buck converter application is also described