【正文】 山東科技大學 2020 級畢業(yè)設計（論文） 1 基于 UC3842 的單端反激式開關穩(wěn)壓電源的設計 摘要 隨著電力電子技術的飛速發(fā)展，電力電子設備與人們的工作、生活的關系日益密切，而電子設備都離不開可靠的電源。開關電源是利用現(xiàn)代電力電子技術，控制開關晶體管開通和關斷的時間比率， 維持穩(wěn)定輸出電壓的一種電源，一般由 PWM（ 脈沖寬度調制） 控制 IC 和 MOSFET 構成。隨著電子技術的發(fā)展記憶對提高穩(wěn)壓電源的轉換效率、減小其體積和重量等方面的深入研究，一種基于脈寬調制器 UCC3842 的開關電源應運而生，并逐步取代傳統(tǒng)的串聯(lián)線性穩(wěn)壓電源。本文基 于控制 芯片 UC3842 設計制作一款新穎的單端反激式、 固定電壓輸出的開關穩(wěn)壓電源， 適用于需要較大電流的直流場合。 并分析了該電源的工作原理，包括主電路、控制電路、反饋電路等。 關鍵詞 反激式開關穩(wěn)壓電源 電流型 PWM 占空比 UC3842 Abstract With the rapid development of power electronic technology, the power electronic equipment and people39。s work and life is increasingly close relationship, and electronic equipment are inseparable from reliable power power supply is the use of modern power electronic technology, control switch transistor opened and shut off time ratio, maintain a stable output voltage power supply, generally by PWM (pulse width modulation) control IC and MOSFET the development of electronic technology to improve manostat memory the conversion efficiency, reduce its size and weight, a thorough study on the based on pulse width omdulatros UCC3842 switch 山東科技大學 2020 級畢業(yè)設計（論文） 2 power emerged, and gradually replace traditional series linear on the control chip UC3842 design a new oneport flyback type, fixed voltage output the switching voltage stabilizer, applicable to need bigger current dc analyzes the working principle of the power supply, including the main circuit and control circuit, feedback circuit, etc. 目 錄 緒論 .......................................................................................................................................... 3 開關電源的背景、現(xiàn)狀和發(fā)展趨勢 ..................................................................... 3 線性電源與開關電源 .................................................................................................... 7 ........................................................................................................................ 7 ........................................................................................................................ 7 開關電源的原理 .............................................................................................................. 8 ............................................................................................................................ 8 ........................................................................................................................ 8 ........................................................................................................... 9 開關電源的分類 ........................................................................................................... 13 DC/DC變換 ................................................................................................................. 13 AC／ DC變換 ............................................................................................................... 16 開關電源的選用 ............................................................................................................ 17 ......................................................................................................... 17 ............................................................................................................................... 17 保護電路 ..................................................................................................................... 17 UC3842 ............................................................................................................................... 18 簡介 .............................................................................................................................. 18 結構介紹 ..................................................................................................................... 20 ...................................................................................................................... 24 技術參數 ..................................................................................................................... 26 基于 UC3842 的單端反激式開關電源的設計 ....................................... 30 開關 電源的電路組成 .............................................................................................. 30 山東科技大學 2020 級畢業(yè)設計（論文） 3 輸入電路各單元的原理及應用電路 .................................................................... 30 ...................................................................................................................... 30 電磁干擾濾波器（ EMI） ......................................................................................... 34 整流濾波電路 ............................................................................................................ 39 、抑制開關電源產生的干擾 .................................................................................... 45 、功率變換電路 .......................................................................................................... 50 、隔離單端反激式變換器電路 ................................................................................ 53 、電壓反饋電路的選用 ............................................................................................. 56 UC3842的供電 —— 啟動電路 ................................................................................. 63 、檢測信號的正確采樣電路 .................................................................................... 64 50%時電路的斜坡補償 ..................................................................... 65 3 開關電源系統(tǒng)的設計 .................................................................................................. 68 啟動電路 ......................................................................................................................... 68 短路過流、過壓、欠壓保護電路 ......................................................................... 69 反饋電路 .......................................................