數(shù)控直流電流源的設(shè)計(jì)



技術(shù)指標(biāo)：
（1）恒流源輸出電流范圍：200～2000mA.
（2）要求輸出電流與給定值偏差的絕對(duì)值≤給定值的1%+10mA。
（3）具有“+”、“-”步進(jìn)調(diào)整功能，步進(jìn)≤10mA。
（4）改變負(fù)載電阻，輸出電壓在10V以內(nèi)變化時(shí)，要求輸出電流變化的絕對(duì)值≤輸出電流值的1%+10mA。
（5）紋波電流≤2mA。
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摘要
隨著電子技術(shù)的不斷進(jìn)步，對(duì)電子儀器的要求也不斷提高。電源作為電路的動(dòng)力源泉更是扮演著越來(lái)越重要的角色，隨著單片機(jī)技術(shù)的不斷發(fā)展和D/A，A/D技術(shù)的不斷成熟使得數(shù)控電源成為可能，數(shù)控電流源不論是在控制精度還是在可操作性上都有傳統(tǒng)電源無(wú)法比擬的優(yōu)勢(shì)。
本系統(tǒng)由單片機(jī)程控設(shè)定數(shù)字信號(hào)，經(jīng)過(guò)D/A轉(zhuǎn)換器AD5320輸出模擬量，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(guò)電流/電壓轉(zhuǎn)換后，通過(guò)A/D轉(zhuǎn)換芯片MAX1241，實(shí)時(shí)把模擬量轉(zhuǎn)化為數(shù)字量，再經(jīng)單片機(jī)分析處理，通過(guò)數(shù)字量形式的反饋環(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 ； AT89C52； 數(shù)控電源；  軟件修正;

Design of Numerically Controlled Constant-current Source
Abstract
Progress unremittingly the request to the electronics instrument technically to also raise continuously along with the electronics, the power supply is the motive source of the electric circuit to play a more and more important role more.Along with single slice machine technical of develop continuously with the D/A, the A/D is technical continuously the maturity make the number control power supply to make possible, count to control the electric current source and is control accuracy in spite of still on the maneuverability all there is traditional power supply can't compare to of advantage.
In the system, the digitally programmable signal from SCM is converted to analog value by DAC AD5320, 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 MAX1241, 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.
Key Words：voltage-controlled constant current source；AT89C52；Numerical controlled source；Software fixed ；

目錄
緒      論 1
第一章  概述 2
1.1 設(shè)計(jì)要求 2
1.2 理論分析 3
1.3 系統(tǒng)介紹 4
第二章  硬件設(shè)計(jì) 1
2.1 電源模塊 1
2.1.1  電源設(shè)計(jì) 1
2.2 恒流源模塊 3
2.2.1壓控電流源的設(shè)計(jì) 4
2.2.2電流采樣電路設(shè)計(jì) 5
2.3 單片機(jī)模塊 6
2.3.1  AT89S52芯片介紹 6
2.3.2  AT89S52 硬件電路設(shè)計(jì) 10
2.4 鍵盤模塊 13
2.4.1  MM74C922 13
2.4.2  鍵盤電路 13
2.5 顯示模塊 14
2.5.1  1602LCD顯示 14
2.5.2  LCD顯示硬件電路 16
2.6  A/D模塊 16
2.6.1  芯片MAX1241 17
2.6.2  A/D模塊電路 18
2.7  D/A模塊 19
2.8 存儲(chǔ)模塊 19
2.8.1  I2C總線 19
2.8.2  芯片24C02C 21
2.8.3  存儲(chǔ)模塊電路 22
第三章  軟件設(shè)計(jì) 24
3.1 編程語(yǔ)言描述 24
3.2 系統(tǒng)軟件的功能模塊 25
3.2.1  主程序設(shè)計(jì) 25
3.2.2  中斷程序設(shè)計(jì) 26
3.2.3中斷控制的相關(guān)寄存器 27
第四章  軟件仿真及數(shù)據(jù)分析 31
4.1  Proteus 31
4.2軟件仿真 31
4.3數(shù)據(jù)測(cè)試 33
4.3.1輸出誤差的測(cè)試 34
4.3.2負(fù)載變化的數(shù)據(jù)測(cè)試 35
第五章 設(shè)計(jì)總結(jié) 36
致  謝 37
參考文獻(xiàn) 38
附錄： 40