高穩(wěn)定性鹵鎢燈光源的研制

測(cè)控論文編號(hào):CK046   論文字?jǐn)?shù):10179,頁數(shù):34

目  錄
1  前 言 2
2  系統(tǒng)原理及理論分析 3
2.1單片機(jī)最小系統(tǒng)組成 3
2.2系統(tǒng)性能 3
2.3恒流原理 3
3 總體方案及模塊電路設(shè)計(jì) 6
3.1總體方案論證及比較 6
3.2 恒流源方案選擇 7
3.3反饋閉環(huán)方案選擇 8
3.4控制單元方案選擇 8
3.5電源方案選擇 10
4  軟件設(shè)計(jì) 11
4.1 AT89S52簡(jiǎn)介 11
4.1.1引腳結(jié)構(gòu)及功能 12
4.2主程序模塊MAIN 14
4.3閉環(huán)比較子程序模塊BIHUAN 14
4.4電流設(shè)置子程序模塊SETUP 16
4.5鍵盤中斷子程序模塊KEYSCAN 16
 4.6顯示中斷子程序模塊LED 18
5  系統(tǒng)的調(diào)試 21
5.1  數(shù)字電路部分的調(diào)試 21
5.2  數(shù)據(jù)測(cè)試及分析 21
5.2.1輸出電流測(cè)試 21
5.2.2步進(jìn)電流測(cè)試 22
5.2.3工作時(shí)間測(cè)試 22
5.2.4誤差分析 23
5.2.5紋波電流測(cè)試 23
6   總  結(jié) 24
7   致 謝 25

摘  要
 光譜儀在檢測(cè)過程中，只有光源保持較高穩(wěn)定性的前提下，才能保證測(cè)量得到的吸光度值準(zhǔn)確可靠。要使溴鎢燈其光輻通量穩(wěn)定在0.1%內(nèi),相應(yīng)的供電電壓波動(dòng)要在0.1%以下，所以必須配套專用的光源供電電源。鑒于設(shè)計(jì)要求故要求恒流源有穩(wěn)定的輸出電流，而且精度要求較高。
 本系統(tǒng)以直流電流源為核心，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)4mA，并可由數(shù)碼管顯示實(shí)際輸出電流值和電流設(shè)定值。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（AD7543）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。單片機(jī)系統(tǒng)還兼顧對(duì)恒流源進(jìn)行實(shí)時(shí)監(jiān)控，輸出電流經(jīng)過電流/電壓轉(zhuǎn)變后，通過A/D轉(zhuǎn)換芯片，實(shí)時(shí)把模擬量轉(zhuǎn)化為數(shù)據(jù)量，再經(jīng)單片機(jī)分析處理， 通過數(shù)據(jù)形式的反饋環(huán)節(jié)，使電流更加穩(wěn)定，這樣構(gòu)成穩(wěn)定的壓控電流源。
關(guān)鍵詞：壓控恒流源；智能化電源；閉環(huán)控制 

Abstract
Spectroscope in examination process, only then the photo source maintains under the high stable premise, can guarantee the survey obtains extinction value accurate reliable. Must make the bromine-tungsten lamp its light spoke flux to stabilize in 0.1%, the corresponding power line voltage fluctuation must below 0.1%, must therefore form a complete set the special-purpose photo source electric power supply. Therefore in view of the fact that the design requirements the request constant current has the stable output current, moreover the accuracy requirement is high.
 In this system the DC source is center and 89S52 version single chip microcomputer (SCM) is main controller, output current of DC power can be set by a keyboard which step level reaches 4mA, while the real output current and the set value can be displayed by LED. In the system, the digitally programmable signal from SCM is converted to analog value by DAC (AD7543), then the analog value which is isolated and amplified by operational amplifiers, is sent to the base electrode of power transistor, so an adjustable output current can be available with the base electrode voltage of power transistor. On the other hand, The constant current source can be monitored by the SCM system real-timely, its work process is that output current is converted voltage, then its analog value is converted to digital value by ADC, finally the digital value as a feedback loop is processed by SCM so that output current is more stable, so a stable voltage-controlled constant current power is designed.
Keywords: voltage-controlled constant current source；intelligent power；closed loop control