Rsearch on new AC/DC converter for high efficiency and low cost server power system = 고효율 저가격 서버 파워 시스템을 위한 새로운 AC/DC 컨버터에 관한 연구

As the global warming has been focused on the world-wide problem, many projects for reducing CO2 emissions are in progress. For the server power system, climate savers computing initiative (CSCI) have regulated CO2 emissions from the operation of computers. In this case, the server power system with single output must be satisfied with the gold level efficiency by 2010, which is 88%-92%-88% at 20%-50%-100% load conditions, respectively. This high efficiency becomes a big obstacle to the server power system with the power factor correction (PFC) circuit, the DC/DC converter, the stand-by circuit, hold up time regulation, and hot-swap function. Furthermore, low cost is required as the cost to the server power system is rapidly increased. To meet these market needs, this dissertation suggests three approaches which can achieve high efficiency and low cost server power system. First, a new modified flying capacitor passive lossess snubber with wide snubber reset ranges is proposed for the PFC stage. The proposed snubber has a new branch that consists of one coupled inductor and one diode compared to the conventional flying-capacitor passive lossless snubber. When the main switch is turned on, the voltage across flying-capacitor is charged to $2V_{in}$/n using a new branch without the help of the reverse recovery current of output diode. Therefore, it can effectively reduce the reverse recovery current maintaining wide snubber reset ranges. Furthermore, the output diode can achieve low voltage stress since the clamping diode is turned off before the voltage across flying capacitor reaches its peak value. Secondly, a new transformer integrated with additional resonant inductor is proposed for the DC/DC stage. For the DC/DC stage of server power system, phase-shift full-bridge (PSFB) converter with additional resonant inductor and clamping diodes is widely used due to the wide zero voltage switching (ZVS) ranges and the low voltage stress of secondary rectifiers. ...
Advisors
Moon, Gun-Wooresearcher문건우researcher
Publisher
한국과학기술원
Issue Date
2010
Identifier
455433/325007  / 020037612
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 전기 및 전자공학과, 2010.08, [ v, 85 p. ]

Keywords

hold up time; DC/DC converter; power factor correction circuit; Server power system; magnetizing current; 자화전류; 홀드 업 타임; DC/DC 컨버터; 역률보상회로; 서버 파워 시스템

URI
http://hdl.handle.net/10203/35618
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=455433&flag=t
Appears in Collection
EE-Theses_Ph.D.(박사논문)
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