戴维宁定理实验报告2.docx
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戴维宁定理实验报告2.docx
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戴维宁定理实验报告2
戴维宁定理实验报告-2
《电路原理》
实验报告
实验时间:
2012/4/26一、实验目的
1.验证戴维宁定理
2.测定线性有源一端口网络的外特性和戴维宁等效电路的外特性。
二、实验原理
戴维宁定理指出:
任何一个线性有源一端口网络,对于外电路而言,总可以用一个理想电压源和电阻的串联形式来代替,理想电压源的电压等于原一端口的开路电压,其电阻(又称等效内阻)等于网络中所有独立源置零时的入端等Uoc
R,见图2-1。
效电阻eq
caG被R1++测a线性有UocER2--电源二端Req路b网络db
R
图2-1图2-2
1.开路电压的测量方法
RR方法一:
直接测量法。
当有源二端网络的等效内阻与电压表的内阻相eqv比可以忽略不计时,可以直接用电压表测量开路电压。
ER方法二:
补偿法。
其测量电路如图2-2所示,为高精度的标准电压源,为
dGc标准分压电阻箱,为高灵敏度的检流计。
调节电阻箱的分压比,、两端的
GU,U电压随之改变,当时,流过检流计的电流为零,因此cdab
R2U,U,E,KEabcdR,R12
weldingproceduresofsteelpressurevesselNDT9JB/T4744-2000steelpressurevesselproductsmechanicalpropertiestestofweldedplateII,mechanicalequipmentinstallationengineering1GB150-982GB50128-2005verticalcylindricalsteelpressurevesselsteelweldedspecificationforconstructionandacceptanceofoiltank3JB/T4735-1997steelweldedatmosphericpressurevessel4GB50231-2009mechanicalequipmentinstallationengineeringconstructionandacceptancespecificationfor5GB50275-98compressor,fanandpumpinstallationengineeringconstructionandacceptancespecificationforlifting6HG20201-2000constructioninstallationengineeringconstructionstandard7,HG...Pressuregauges,usinganinstalledsparkarrestorforacetylenecylinders,illegalcarrying,usinggascylinders,eachoperatorfined20Yuan.Gasbottlewithoutthehotsunexposuremeasures,responsibilitiesofteamafineof50Yuan.(7)atheightandtheopeningandprovisionalprotectivemeasureshavebeentaken,theresponsibleunitfined200Yuan,constructionpersoninchargeafineof50Yuan.(8)nopermittoworkandthejobinaccordancewiththeprovisions,onthejobunitfined300yuan,theunitwillchargeafineof100Yuan.7.5.3accidentpenalties
(1)injuriesfatalitiesdirectlypunished1~2million.Directresponsibilityfortheaccidentandhavethecorrespondingresponsibilityofleadership,suchasconcerningadministrativesanctions,shouldbebroughttothecompanyortherelevantDepartment.
(2)personalinjuryaccidentoccurred,thedirectpunishment0.5-10,000yuan,responsibleforthedirectresponsibilityfortheaccidentandtheresponsibilityofleadership,suchasconcerningadministrativesanctionsshouldbedealtwithbythepersonnelDepartmentofthecompany.(3)personalinjury
R2式中为电阻箱的分压比。
根据标准电压和分压比就可求得EKK,R,R12
开路电压,因为电路平衡时,不消耗电能,所以此法测量精度较高。
UI,0abG
2.等效电阻的测量方法Req
对于已知的线性有源一端口网络,其入端等效电阻可以从原网络计算得Req
出,也可以通过实验测出,下面介绍几种测量方法:
abU方法一:
将有源二端网络中的独立源都去掉,在端外加一已知电压,
U测量一端口的总电流,则等效电阻。
IR,eq总I总
实际的电压源和电流源都具有一定的内阻,它并不能与电源本身分开,因此在去掉电源的同时,也把电源的内阻去掉了,无法将电源内阻保留下来,这将影响测量精度,因而这种方法只适用于电压源内阻较小和电流源内阻较大的情况。
ab方法二:
测量端的开路电压及短路电流则等效电阻UIocsc
UocR,eqIsc
abR这种方法适用于端等效电阻较大,而短路电流不超过额定值的情形,eq
否则有损坏电源的危险。
a
a+U被oc-R测LUVRL电Req路b
b
图2-3图2-4
方法三:
两次电压测量法
ababU测量电路如图2-3所示,第一次测量端的开路,第二次在端接一已oc
bUbaaR知电阻(负载电阻),测量此时、端的负载电压,则、端的等效电L
R阻为:
eq
weldingproceduresofsteelpressurevesselNDT9JB/T4744-2000steelpressurevesselproductsmechanicalpropertiestestofweldedplateII,mechanicalequipmentinstallationengineering1GB150-982GB50128-2005verticalcylindricalsteelpressurevesselsteelweldedspecificationforconstructionandacceptanceofoiltank3JB/T4735-1997steelweldedatmosphericpressurevessel4GB50231-2009mechanicalequipmentinstallationengineeringconstructionandacceptancespecificationfor5GB50275-98compressor,fanandpumpinstallationengineeringconstructionandacceptancespecificationforlifting6HG20201-2000constructioninstallationengineeringconstructionstandard7,HG...Pressuregauges,usinganinstalledsparkarrestorforacetylenecylinders,illegalcarrying,usinggascylinders,eachoperatorfined20Yuan.Gasbottlewithoutthehotsunexposuremeasures,responsibilitiesofteamafineof50Yuan.(7)atheightandtheopeningandprovisionalprotectivemeasureshavebeentaken,theresponsibleunitfined200Yuan,constructionpersoninchargeafineof50Yuan.(8)nopermittoworkandthejobinaccordancewiththeprovisions,onthejobunitfined300yuan,theunitwillchargeafineof100Yuan.7.5.3accidentpenalties
(1)injuriesfatalitiesdirectlypunished1~2million.Directresponsibilityfortheaccidentandhavethecorrespondingresponsibilityofleadership,suchasconcerningadministrativesanctions,shouldbebroughttothecompanyortherelevantDepartment.
(2)personalinjuryaccidentoccurred,thedirectpunishment0.5-10,000yuan,responsibleforthedirectresponsibilityfortheaccidentandtheresponsibilityofleadership,suchasconcerningadministrativesanctionsshouldbedealtwithbythepersonnelDepartmentofthecompany.(3)personalinjury
U,,ocR,,1R,,eqLU,,
第三种方法克服了第一和第二种方法的缺点和局限性,在实际测量中常被采用。
3.如果用电压等于开路电压的理想电压源与等效电阻相串联的电路RUeqoc
(称为戴维宁等效电路,参见图2-4)来代替原有源二端网络,则它的外特性
应与有源二端网络的外特性完全相同。
实验原理电路见图2-5b。
U,f(I)
ACmAmAQN
I3R5100Ω12RR3510ΩR3RΩ5101KΩ1KΩRcqVRLVRL1KΩR6++1KΩ1KREER1244Ω--10V6VQ'+ocUM-B
(a)(b)
图2-5
三、预习内容
在图2-5(a)中设=10V,=6V,=1K,,根据戴维宁定理将AB以EER,R1212
左的电路化简为戴维宁等效电路。
即计算图示虚线部分的开路电压U,等效内ocR阻I及A、B直接短路时的短路电流之值,填入自拟的表格中。
eqsc
UocReqIsc
8V500Ω16mA
四、仪器设备
1.电路分析实验箱一台
2.直流毫安表一只
3.数字万用表一台
五、实验内容与步骤
weldingproceduresofsteelpressurevesselNDT9JB/T4744-2000steelpressurevesselproductsmechanicalpropertiestestofweldedplateII,mechanicalequipmentinstallationengineering1GB150-982GB50128-2005verticalcylindricalsteelpressurevesselsteelweldedspecificationforconstructionandacceptanceofoiltank3JB/T4735-1997steelweldedatmosphericpressurevessel4GB50231-2009mechanicalequipmentinstallationengineeringconstructionandacceptancespecificationfor5GB50275-98compressor,fanandpumpinstallationengineeringconstructionandacceptancespecificationforlifting6HG20201-2000constructioninstallationengineeringconstructionstandard7,HG...Pressuregauges,usinganinstalledsparkarrestorforacetylenecylinders,illegalcarrying,usinggascylinders,eachoperatorfined20Yuan.Gasbottlewithoutthehotsunexposuremeasures,responsibilitiesofteamafineof50Yuan.(7)atheightandtheopeningandprovisionalprotectivemeasureshavebeentaken,theresponsibleunitfined200Yuan,constructionpersoninchargeafineof50Yuan.(8)nopermittoworkandthejobinaccordancewiththeprovisions,onthejobunitfined300yuan,theunitwillchargeafineof100Yuan.7.5.3accidentpenalties
(1)injuriesfatalitiesdirectlypunished1~2million.Directresponsibilityfortheaccidentandhavethecorrespondingresponsibilityofleadership,suchasconcerningadministrativesanctions,shouldbebroughttothecompanyortherelevantDepartment.
(2)personalinjuryaccidentoccurred,thedirectpunishment0.5-10,000yuan,responsibleforthedirectresponsibilityfortheaccidentandtheresponsibilityofleadership,suchasconcerningadministrativesanctionsshouldbedealtwithbythepersonnelDepartmentofthecompany.(3)personalinjury
1.用戴维宁定理求支路电流I3
测定有源二端网络的开路电压和等效电阻RUeqoc
按图2-5(a)接线,经检查无误后,采用直接测量法测定有源二端网络的开路电压。
电压表内阻应远大于二端网络的等效电阻。
RUeqoc
用两种方法测定有源二端网络的等效电阻Req
A.采用原理中介绍的方法二测量:
首先利用上面测得的开路电压和预习中计算出的估算网络的短路电RUeqoc
流大小,在之值不超过直流稳压电源电流的额定值和毫安表的最大量限的IIscsc
条件下,可直接测出短路电流,并将此短路电流数据记入表格2-1中。
Isc
B.采用原理中介绍的方法三测量:
接通负载电阻,调节电位器,使=1K,,使毫安表短接,测出此时RRRL4L
U,并记入表格2-1中。
的负载端电压
表2-1
U项目(V)R(,)(V)(mA)UIeqocsc
数值8.0175.36315.485506.4
R取A、B两次测量的平均值作为(I的计算在实验报告中完成)eq3
2.测定有源二端网络的外特性
调节电位器即改变负载电阻之值,在不同负载的情况下,测量相应的RR4L
负载端电压和流过负载的电流,共取五个点将数据记入自拟的表格中。
测量时注
U意,为了避免电表内阻的影响,测量电压时,应将接在AC间的毫安表短路,
I测量电流时,将电压表从A、B端拆除。
若采用万用表进行测量,要特别注意换档。
3.测定戴维宁等效电路的外特性。
U将另一路直流稳压电源的输出电压调节到等于实测的开路电压值,以此oc
R,R,RR作为理想电压源,调节电位器,使,并保持不变,以此作为等效56eq6
内阻,将两者串联起来组成戴维宁等效电路。
按图2-5(b)接线,经检查无误后,weldingproceduresofsteelpressurevesselNDT9JB/T4744-2000steelpressurevesselproductsmechanicalpropertiestestofweldedplateII,mechanicalequipmentinstallationengineering1GB150-982GB50128-2005verticalcylindricalsteelpressurevesselsteelweldedspecificationforconstructionandacceptanceofoiltank3JB/T4735-1997steelweldedatmosphericpressurevessel4GB50231-2009mechanicalequipmentinstallationengineeringconstructionandacceptancespecificationfor5GB50275-98compressor,fanandpumpinstallationengineeringconstructionandacceptancespecificationforlifting6HG20201-2000constructioninstallationengineeringconstructionstandard7,HG...Pressuregauges,usinganinstalledsparkarrestorforacetylenecylinders,illegalcarrying,usinggascylinders,eachoperatorfined20Yuan.Gasbottlewithoutthehotsunexposuremeasures,responsibilitiesofteamafineof50Yuan.(7)atheightandtheopeningandprovisionalprotectivemeasureshavebeentaken,theresponsibleunitfined200Yuan,constructionpersoninchargeafineof50Yuan.(8)nopermittoworkandthejobinaccordancewiththeprovisions,onthejobunitfined300yuan,theunitwillchargeafineof100Yuan.7.5.3accidentpenalties
(1)injuriesfatalitiesdirectlypunished1~2million.Directresponsibilityfortheaccidentandhavethecorrespondingresponsibilityofleadership,suchasconcerningadministrativesanctions,shouldbebroughttothecompanyortherelevantDepartment.
(2)personalinjuryaccidentoccurred,thedirectpunishment0.5-10,000yuan,responsibleforthedirectresponsibilityfortheaccidentandtheresponsibilityofleadership,suchasconcerningadministrativesanctionsshouldbedealtwithbythepersonnelDepartmentofthecompany.(3)personalinjury
重复上述步骤测出负载电压和负载电流,并将数据记入自拟的表格中。
六、实验结果与分析
1.应用戴维宁定理,根据实验数据计算支路的电流)),并与计算值进行比较。
R3
实验数据计算:
I3=UOC/(Req+RL)=5.32mA
理论计算值:
I3=U/(Req+RL)=5.33mA
2.在同一坐标纸上作出两种情况下的外特性曲线,并作适当分析。
判断戴维宁定理的正确性。
(1)
12345RL(,)1000900800700600
5.3715.1814.9484.7074.328U(V)
5.1995.6976.1086.6087.331I(mA)
(2)
12345RL(,)10
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