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攀枝花学院本科毕业设计(论文)基于单片机数控式直流恒流源设计学生姓名:廖小军学生学号:200710501020院(系):电气信息工程学院年级专业:2007级电子信息工程指导教师:刘衍平(助教/硕士)二〇一一年六月摘要I摘要本系统以直流电流源为核心,AT89S52单片机为主控制器,通过键盘来设置直流电源的输出电流,设置步进等级可达1mA,并可由LCD1602显示电流设定值和实际输出电流值。本系统由单片机程控设定数字信号,经过D/A转换器(TLC5615)输出模拟量,再经过运算放大器隔离放大,控制输出功率管的基极,随着功率管基极电压的变化而输出不同的电流。单片机系统还兼顾对恒流源进行实时监控,输出电流经过电流/电压转换后,通过A/D转换芯片(TLC2543),实时把模拟量转化为数据量,再经单片机分析处理,通过数字量形式的反馈环节,使电流更加稳定,这样构成稳定的压控电流源。实际测试结果表明,本系统能有效应用于需要高稳定度的小功率恒流源的领域。关键字数控直流恒流源,单片机,D/A转换器,A/D转换,电压/电流转换器攀枝花学院本科毕业设计(论文)IIABSTRACTInthissystemtheDCsourceiscenterand89S52versionsinglechipmicrocomputer(SCM)ismaincontroller,outputcurrentofDCpowercanbesetbyakeyboardwhichsteplevelreaches1mA,whiletherealoutputcurrentandthesetvaluecanbedisplayedbyLCD.Inthesystem,thedigitallyprogrammablesignalfromSCMisconvertedtoanalogvaluebyDAC(TLV5616),thentheanalogvaluewhichisisolatedandamplifiedbyoperationalamplifiers,issenttothebaseelectrodeofpowertransistor,soanadjustableoutputcurrentcanbeavailablewiththebaseelectrodevoltageofpowertransistor.Usingthekeyboardtosettheneededoutputcurrentvalue,TheSCMbasedonsomespecificalgorithmtodealthecertainsettingsforprocessing.CorrespondingvoltageoutputbytheADCoutputvoltage-controlledcurrentsourcecircuit.Ontheotherhand,TheconstantcurrentsourcecanbemonitoredbytheSCMsystemreal-timely,itsworkprocessisthatoutputcurrentisconvertedvoltage,thenitsanalogvalueisconvertedtodigitalvaluebyADC,finallythedigitalvalueasafeedbackloopisprocessedbySCMsothatoutputcurrentismorestable,soastablevoltage-controlledconstantcurrentpowerisdesigned.Thetestresultshaveshowedthatthissystem,comparedwiththetraditionalregulatedcurrentsource,haseasytooperateandfeatureshighoutputcurrentstability.Keywords:Numericalcontroldcconstant-currentsource,microcontroller,D/Aconverter,A/Dconversion目录I目录摘要...........................................................................................................................................IABSTRACT......................................................................................................................................II目录.............................................................................................................................................I1绪论.........................................................................................................................................12数控直流恒流源系统描述.......................................................................................................22.1系统简介.................................................................................................................................22.2系统总体设计..........................................................................................................................32.3方案论证.................................................................................................................................32.3.1主控器...........................................................................................................................32.3.2供电电源........................................................................................................................32.3.3恒流源...........................................................................................................................42.3.4DAC和ADC方案论证.......................................................................................................52.3.5键盘...............................................................................................................................62.3.6显示...............................................................................................................................63系统硬件设计...........................................................................................................................83.1主控电路设计..........................................................................................................................83.2供电电源设计.........................................................................................................................93.2.1主电源...........................................................................................................................93.2.2单片机电源(第二级电源)..........................................................................................103.2.3电源参数计算...............................................................................................................103.3恒流源电路设计.....................................................................................................................113.4D/A转换电路设计..................................................................................................................123.4.1D/A和A/D转换器介绍................................................................................................123.4.2理论分析与参数计算....................................................................................................163.4测电路设计........................................................................................................................
本文标题:单片机控制的恒流源
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