| With the development of laptop computer, more and more electrical equipments on the adapter for laptop computer. According to IEC61000-3-2 standard for harmonic current, The power adapter higher than 75W must be have the technology of Power Factor Correction. Therefore, high efficiency notebook power with power factor correction functions to become a research focus. On the basis of extensive investigation and in-depth study. This paper proposed a program of laptop computer with high efficiency and hight Fower Factor, designed a model machine of 90W laptop power adapter.This paper reviews the development of the adaptors, and points out some design issues. In order to meet the requirement of the next generation of adaptor, this paper proposed a two-stage approach, which consists a power factor correction (PFC) stage and a dc/dc stage. The PFC stage is a Boost converter operating in discontinuous current mode (DCM) boundary to achieve high power factor and avoid reverse recovery of the Boost diode. The dc/dc stage using flyback converters. In order to increase the efficiency of the PFC stage at low line, its output voltage is modulated by the mains input voltage. Boost converter operating in double-boost mode. In order to provide high efficiency at all power levels, proposed a multi-mode control scheme. Its applies to quasi-resonant operation at high power levels, quasi-resonant operation with valley skipping, as well as to reduced frequency operation at lower power levels. At low power levels, the PFC switches off to maintain high efficiency.Adopting the proposed two-stage approach, a 90W adaptor with universal input and 19.5V/4.6A output is designed. Its electrical specification is tailored on a typical hi-end portable computer power adapter. The peculiarities of this design are the higher power factor, the higher power density, the lower standby loss and the higher overall efficiency. The experimental results verify the effectiveness of the proposed approach. |
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