【正文】 Abstract With the development of microprocessor and digital processor, lower output voltage and higher current is needed to provide. Therefore, research on lower output voltage and higher current forward converter is widely focused on. Firstly, the high frequency transformer magic reset technique of traditional forward converter is introduced in this paper. The advantage and disadvantage of various magic reset topologies is pared. An active clamp forward converter is chosen as the main topology of this design. The working process of active clamp forward converter and the typical parameters of the calculation and derivation are analyzed. Thirdly, based on analysis of the three driving modes, pin function of the active clamp forward converter drive chip NCP1562 is introduced and the peripheral circuit is constructed. Mainly includes the auxiliary power supply, overcurrent protection, overvoltage or under voltage protection, oscillation frequency, error feedback input and so on. Finally, the calculation of parameters of the device, the final selection device, and use MATLAB to simulate system is pleted. The output wavefor m of voltage and current is briefly analyzed. The correctness and feasibility of the theoretical analysis of the design scheme is proved. Keywords Forward converter Active clamp Transformer magic reset III 目 錄 摘要 ....................................................................................................................... I Abstract ................................................................................................................ II 第 1 章 緒論 ........................................................................................................ 1 課題背景 .............................................................................................. 1 開關(guān)電源的發(fā)展 .......................................................................... 1 選題目的及意義 .......................................................................... 2 開關(guān)電源 .............................................................................................. 2 開關(guān)電源定義 .............................................................................. 2 開關(guān)電源基本結(jié)構(gòu) ...................................................................... 3 開關(guān)電源特點(diǎn) .............................................................................. 4 研究的主要內(nèi)容 .................................................................................. 5 第 2 章 正激變換器 ............................................................................................ 6 傳統(tǒng)單端正激變換器 .......................................................................... 6 帶復(fù)位繞組的單端正激變換器 .................................................. 6 RCD 箝位單端正激變換器 ........................................................... 7 LCD 箝位單端正激變換器 ........................................................... 9 有源箝位單端正激變換器 ................................................................ 10 有源箝位單端正激變換器工作原理 ........................................ 10 有源箝位正激變換器典型參數(shù)分析 ........................................ 16 變壓器磁芯參數(shù)分析 ................................................................ 18 本章小結(jié) ............................................................................................ 22 第 3 章 控制電路 .............................................................................................. 23 驅(qū)動脈沖調(diào)制方式分析 .................................................................... 23 PWM 脈沖寬度調(diào)制 ................................................................. 23 PFM 脈沖頻率調(diào)制 ................................................................... 24 PWMPFM 脈寬脈頻綜合調(diào)制 ................................................ 24 開關(guān)電源控制方式分析 .................................................................... 26 電壓控制型 ................................................................................ 26 IV 電流控制型 .................................................................................26 V2控制型 ....................................................................................27 驅(qū)動芯片 NCP1562 ............................................................................29 芯片簡要概述 .............................................................................29 各個(gè)引腳功能 .............................................................................30 NCP1562 外圍電路 ......................................................................32 反饋回路 .............................................................................................38 本章小結(jié) .............................................................................................41 第 4 章 器件選型及系統(tǒng)仿真 ...........................................................................42 器件選型參數(shù)計(jì)算 .............................................................................42 估算直流輸入、輸出功率 .........................................................42 計(jì)算最小和最大直流輸入電壓 .................................................42 整流橋后輸入濾波電容 CIN 的計(jì)算 ..........................................42 變壓器參數(shù)計(jì)算 .........................................................................43 各半導(dǎo)體器件參數(shù)計(jì)算 .............................................................45 箝位電容 C 的參數(shù) ....................................................................47 輸出濾波參數(shù) .............................................................................48 系統(tǒng)仿真 .............................................................................................49 開環(huán)主電路的仿真 .....................................................................49 閉環(huán)系統(tǒng)的仿真 .........................................................................53 本章小結(jié) .............................................................................................57 結(jié)論 ...........................