【正文】 統(tǒng)加入嵌入式電源智能系統(tǒng)和數(shù)字控制。 關(guān)鍵詞 壓控直流源 ， PWM 調(diào)制芯片 ， 閉環(huán)控制 沈陽工程學(xué)院畢業(yè)設(shè)計(jì)（論文） II Abstract With the rapid development of singlechip technology, based on the singlechip microDepartment39。其輸出電流的大小通過隔離型電流傳感器轉(zhuǎn)換成對(duì)應(yīng)的模擬 信號(hào)。本系統(tǒng)由單片機(jī)程控輸出數(shù)字信號(hào)，經(jīng)過 D/A轉(zhuǎn)換器（ ADS7841）輸出模擬量，再經(jīng)過運(yùn)算放大器隔離放大，控制輸出功率管的基極，隨著功率管基極電壓的變化而輸出不同的電流?；?AT89C51 的 數(shù)控直流電流源 設(shè)計(jì) I 摘 要 隨著 單片機(jī) 技術(shù)的快速發(fā)展，基于 單片機(jī)的 微處器的應(yīng)用越來越廣泛。 AT89S52 單片機(jī)為主控制器，通過鍵盤來設(shè)置直流電源的輸出電流，設(shè)置步進(jìn)等級(jí)可達(dá) 1mA，并可由數(shù)碼管顯示實(shí)際輸出電流值和電流設(shè)定值。控制部分選用單片機(jī)與專用的 PWM 調(diào)制芯片相結(jié)合的方式來控制 MOSFET 開關(guān)管的導(dǎo)通。實(shí)際測(cè)試結(jié)果表明，本系統(tǒng)實(shí)際應(yīng)用于需要高穩(wěn)定度小功率恒流源的領(lǐng)域。s application of more and more widely. AT89S52based singlechip controller, through the keyboard to set the DC power supply output current, set the level of stepping up to 1mA, and the digital display from the actual output current value and current settings. The system consists of singlechip programmable digital signal output through D / A converter (ADS7841) analog output, and then zoom through the isolation amplifier to control the output power of the base tube, with the base of power changes in voltage output different currents. Control of some selected singlechip PWM modulation and the exclusive use of a bination of chips to control the MOSFET turnon switch. The size of its output current through the isolationtype current sensor into a corresponding analog signal. The actual test results indicate that this system applies to the actual needs of lowpower high stability constant current source of the field. Key Words DC voltage source, PWM modulation chips, closedloop control 基于 AT89C51 的 數(shù)控直流電流源 設(shè)計(jì) III 目 錄 摘 要 ................................................................................................................................................ I Abstract ...........................................................................................................................................II 目 錄 ............................................................................................................................................. III 1 引 言 ........................................................................................................................................... 1 數(shù)控直流電流源的簡(jiǎn)介 ................................................................................................... 1 國(guó)內(nèi)外研究現(xiàn)狀 ................................................................................................. 1 AT89C51單片機(jī)簡(jiǎn)介 .......................................................................................... 1 本文研究的主要內(nèi)容、目標(biāo)與方法 .................................................................... 2 數(shù)控直流電流源設(shè)計(jì)方法 ............................................................................................... 2 數(shù)控 直流電流源設(shè)計(jì)流程 ............................................................................................... 3 本文的目的和意義 .......................................................................................................... 4 ２數(shù)控直流電流源設(shè)計(jì)構(gòu)思 ......................................................................................................... 5 數(shù)控直流電流源主要單元器件的選擇 ........................................................................... 5 開關(guān)管的選擇 ....................................................................................................... 5 PWM 芯片的選擇 .................................................................................................... 5 電流傳感器的選擇 ............................................................................................... 6 A/D 和 D/A 芯片的選擇 ......................................................................................... 8 控制器芯片的選擇 ............................................................................................... 8 人機(jī)界面 ................................................................................................................ 8 輔助電源選擇 ....................................................................................................... 9 3 數(shù)控直流電流源的子模塊設(shè)計(jì) ................................................................................................ 10 電源輸入 EMI 濾波和主電路前級(jí)整流濾波穩(wěn)壓電路設(shè)計(jì) ......................................... 10 PWM 調(diào)制波與 MOSFET 的驅(qū)動(dòng)電路設(shè)計(jì) ........................................................................11 斬波電路與濾波穩(wěn)流電路設(shè)計(jì) .....................................................................................11 電流檢測(cè)電路設(shè)計(jì) ......................................................................................................... 14 單片機(jī)最小系統(tǒng)設(shè)計(jì) .................................................................................................... 15 A/D、 D/A 的轉(zhuǎn)換電路設(shè)計(jì) .......................................................................................... 15 鍵盤和顯示電路及輔助電源電路設(shè)計(jì) ........................................................................ 17 系統(tǒng)誤差分析 ................................................................................................................ 17 系統(tǒng)的熱設(shè)計(jì)與電磁兼容設(shè)計(jì) .................................................................................... 18 提高系統(tǒng)精度的技術(shù)措施 .......................................................................................... 19 4 數(shù)控直流電流源源碼 ............................................................................................................... 20 A/D 采樣程序 ................................................................................................................. 20 結(jié) 論 ............................................................................................................................................. 29 致 謝 ............................................................................................................................................. 30 參考文獻(xiàn) .............................................