铂电阻测温电路的设计.doc

虚拟仪器设计技术大作业题目：铂电阻测温电路的设计专业：电子信息科学与技术 班级：电本（2）班 学号：1150720079 姓名：张顶红 同组人：柳建、黄腾辉、罗凯、 颜超、舒样超、陈雷 指导老师：秦新燕 日期：2014年5月22号 物理与机电工程学院 目录1. 课程设计的目的2. 课程设计的任务3. 铂电阻测温电路原理及设计 3.1传感器模型的建立 3.2测温电路组成与原理 3.2.1稳压电路 3.2.2基本放大电路 3.2.3校正电路   3.2.4电路输出范围的调节 3.3整体电路分析与设计 3.3.1稳压电路分析 3.3.2铂电阻温度特性分析 3.3.3 Rw1作用分析 3.3.4电路验证 3.4实验数据处理四Labview虚拟仪器设计 4.1数据显示子程序VI设计 4.2接口电路的设计与编译五.仿真测温六总结 一.课程设计目的  在Multisim 中，可根据铂电阻阻值与温度的关系建立铂电阻模型，设计一个测温范围为0至100的测温仪。通过本课程设计，了解铂电阻测温的原理，会根据铂电阻的阻值与温度的关系建立仿真模型；掌握铂电阻的测温电路；熟悉LabVIEW虚拟仪器Multisim 的导入方法;提出铂电阻测温仪的优化方案。二.课程设计的任务 在Multisim中，可根据铂电阻阻值与温度的关系建立铂电阻模型，设计一个测温度范围为0100的测温仪。通过本设计，应掌握以下内容：1） 了解铂电阻测温的原理，会根据铂电阻的阻值与温度的关系建立仿真模型。2） 掌握铂电阻的测温电路。3） 会用LabVIEW设计温度显示模板，把电路输出电压值转换成温度及参数的显示。4） 熟悉LabVIEW虚拟仪器向Multisim的导入方法。3. 铂电阻测温电路原理及设计3.1传感器模型的建立 金属铂电阻器性能十分稳定，在-260+630之间，铂电阻用做标准温度计;在0+630之间铂电阻与温度的关系如下：Rt=R0*(1+A*t+B*t*)  其中（0时电阻）R0=100，A=3.9684×10-3，B= -5.847×10-7。然后把参数带入得:图3.1铂电阻模型Rt=-0.00005847100*t*t+0.0039684*t+100有了温度与铂电阻的关系式，我们可以建立以下的模型，如图3.1所示。以V1代表温度T，压控多项式函数模块用来实现上述函数，其输出为电压值，由铂电阻的原理，模型模拟的应是电阻值，所以再加一个比例系数为1的压控电阻，因此输出电阻值按算式随温度值的变化而变化。3.2测温电路组成与原理 当温度变化时，热电阻的阻值随温度的变化而变化。对温度的测量转化为对电阻的测量，可将阻值的变化转化为电压或电流的变化输入测量仪表，通过测量电路的转换，即可得被测温度。测温电路由以下4部分组成。3.2.1稳压电路 稳压环节用于为后面的电路提供基准电压，如图1所示。稳压二极管稳压电路的输出端接电压跟随器来稳定输出电压。电压跟随器具有高输入阻抗、低输出阻抗的优点。 稳压二极管稳压电路是最简单的一种稳压电路，它由一个稳压二极管和一个限流电阻组成。从图14-3的稳压管稳压特性曲线可以看到，只要稳压管的电流，则稳压管就使输出稳定在附近，其中是在规定的稳压管反向工作电流下，所对应的反向工作电压。限流电阻的作用一是起限流作用，以保护稳压管；其次是当输入电压或负载电流变化时，通过该电阻上电压降的变化，取出误差信号以调节稳压管的工作电流，从而起到稳压作用。图3.2.1稳压电路设计稳压二极管稳压电路首先需要根据设计要求实际电路的情况来合适地选取电路元件，以下参数是设计前必须知道的：要求的输出电压U0、负载电流的最小值Imin和最大值Imax(或者，负载RL的最大值Rmax和最小值Rmin)、输入电压UI的波动范围。根据以上的情况选取相应的元件及参数。3.2.2基本放大电路 本设计没有采用电桥法测量铂电阻，是因为铂电阻测温采用单臂电桥，单臂电桥本身存在一定的非线性，为了避免电桥引入的非线性，所以采用放大电路测温。 图3.2.2基本放大电路相当于下面两个简单的放大电路：3.2.3校正电路 铂电阻的总体测温电路如图。虽然铂电阻模型中温度的二次项系数很小，但仍然存在一定的非线性度，电路中由运算放大器U3和电阻R8、R9、R15组成的反向比例放大器为电路引入负反馈，可使电路输出地线性度变好。图中还由电阻Rw1引入了电流并联负反馈。 图3.2.3为铂电阻测温的总体电路。 图3.2.3测量电路  3.2.4电路输出范围的调节 由于铂电阻的阻值小且变化范围小，为了使输出变化明显，总体电路上又加了反向比例放大电路，通过调节Rw3的值可以调节输出电压的范围如图3.2.4。 图3.2.4电压输出电路3.3整体电路分析与设计 铂电阻测温的整体测量电路如图3.2.3所示，它由上节所介绍的各部分电路所组成，其中RW1用于基本放大电路调零，RW2用于调线性，RW3用于调节电压放大倍数。D1为稳压值为10V的稳压二极管，其最大直流电流为143mA。下面我们来对电路进行分析，并确定电路的参数。3.3.1稳压电路分析 将图3.2.3所示的稳压环节的输出端接一个负载电阻，如图3.3.1所示。为了确定这一负载电阻的大致范围，将与稳压环节相连的放大电路的输入端改接一个10V的直流源，然后对电路进行传递函数分析，其设置如图3.3.2所示，将新加入的直流源作为输入源（图中的vv11），电路的总输出端作为输出节点，接地端作为参考节点。传递函数分析的结果如图3.3.3所示，输入阻抗约为1.8K。 图3.3.1稳压电路 图3.3.2.“传递函数分析设置”对话框图3.3.3传递函数分析结果将图3.3.1中的R2设为1.82，然后对R1进行参数扫描，确定其取值。参数扫描的设置如图3.3.4所示，将R1从10到1K之间取10个扫描点，然后选择扫描直流工作点，输出节点为22点，其扫描结果如图3.3.5所示，R1应在120到230之间取值，才能保证稳压二极管工作在稳压状态，最后取R1为200。图3.3.4.参数扫描分析设置对话框图3.3.5.参数扫描分析结果 下面我们来分析电压跟随器在电路中的作用。将图3.2.1中运放的正输入端接一个10V的直流电压源，然后对修改后的电路进行传递函数分析，结果如图3.3.6所示，可见电压跟随器具有很高的输入阻抗和很低的输出阻抗。 图3.3.6.传递函数分析结果对图3.3.1所示的电路进行参数扫描分析，观察负载电阻R2变化对输出电压的影响。使R2在1到10K之间均匀的取10个值，然后对输出节点22进行直流工作点扫描，结果如图3.3.7所示。将图3.3.1中的电压跟随器去掉，将负载电阻R2直接与稳压二极管稳压电路的输出端相连，然后仍按上面的设置对R2进行参数扫描分析，分析结果如图3.3.8所示。比较图3.3.7和图3.3.8可知，由于电压跟随器的输入电阻较大，则流过R1的电流基本全部流向稳压二极管，且电压跟随器隔离了负载电阻变化对二极管稳压电路的影响，所以加电压跟随器的稳压电路，在稳压范围内输出电压较稳定，且约等于10V。 图3.3.7.带电压跟随器的稳压电路扫描 图3.3.8.去掉电压跟随器的稳压电路扫描3.3.2铂电阻温度特性分析 在图3.2.3的总测量电路中，对铂电阻模块进行直流扫描分析，观察测量温度与铂电阻阻值的关系。直流扫描分析的设置如图3.3.9所示，扫描电源为模拟测量温度数值的电压源V1，扫描范围为0V500V（即模拟0500的变化），观察节点2和15间的电压差的变化（模拟铂电阻的变化）。直流扫描分析的结果如图3.3.10所示，其中实线为分析所得的数据，虚线为连接实线两端点所得的直线，可见铂电阻的阻值与温度的关系存在非线性。因此需要调节RW2来调节负反馈的程度，从而矫正输出电压与温度的非线性关系。  图3.3.9.直流扫描分析设置对话框 图3.3.10铂电阻与温度的关系3.3.3 Rw1作用分析 将滑动变阻器RW1用一个任意大小的电阻代替，然后对该电阻进行参数扫描分析，观察RW1变化时，输出电压在什么时候接近于零。RW1阻值的扫描范围为1K到100K，从图3.3.11的分析结果可知，RW1取大约90K左右时，输出端电压才接近于零，所以应取100K的滑动变阻器来进行调零。最后调节滑动变阻器RW1使其两端阻值约为93.1 K。图3.3.11.Rw1大小的确定在去掉Rw1的情况下对电路进行直流扫描分析，观察V1在0100V扫描后输出电压的变化情况，结果如图3.3.12所示。加入滑动变阻器，并调整好滑动变阻器的大小后，再进行参数扫描分析，结果如图3.3.13所示。比较图3.3.12图3.3.13可知，两条曲线基本平行，滑动变阻器调节后，当温度为0时输出电压为0V，即Rw1的作用使测量电路调零。 图3.3.12无Rw1情况下直流扫描分析图3.3.13.Rw1调零后直流扫描分析3.3.4电路验证 铂电阻在实际使用时都会有电流流过，电流流过会使电阻发热，使电阻阻值增大，为了避免这一因素引起的误差，一般流过热电阻的电流应小于6mA。在铂电阻的连接回路添加测量探针，双击探针，在打开的“测量探针属性”对话框的Parameters选项中选择要显示的参数，如图3.3.14，单击电路仿真按钮，探针中显示的铂电阻中流过的电流为4.77mA，符合要求.最后对电路进行仿真，记录仿真数据，可得电路的输出电压值与电阻阻值的变化关系，可以看到测量电路的输出线性度很好。 3.3.14测量探针属性对话框3.4实验数据处理 从0开始到100，电路每变化5读一次数据，得下图表3.4.2，把U和Rt在MATLAB中用最小二乘法进行多项式拟合得：U=0.067*Rt-6.7031所以Rt=6.7031+U/0.067图3.4.1设备参数扫描 图表3.4.2实验数据T/C051015202530R100101.9827103.9626105.9394107.9134109.8845111.8526U/V-39.836m174.869m309.704m444.339m578.776m713.014m847.052mT/C35404550556065R113.8178115.7800117.7394119.6958121.6493123.5999125.5476U/V980.891m1.114531.247971.381211.514261.647101.77975T/C707580859095100R127.4923129.4341131.3730133.3090135.2420137.1721139.0993U/V1.912192.044442.176482.308332.439982.571432.702684 Labview虚拟仪器设计4.1数据显示子程序VI设计4.1.1首先建立一个子VI；选择“开始”菜单中的National Instruments LabVIEW 8.2命令，在Getting Started 窗口左边的Files控件里，选择Blank VI,建立一个新程序。4.1.2框图程序的绘制 ； 图4.1.2程序框图4.1.3定义图标与连接器，完成了子VI的建立。 图4.1.3.1设计时域信号采集器 图4.1.3.2子VI图标与接口4.2接口电路的设计与编译 接口部分的设计是为了把以上设计的子程序嵌入到Multisim 中以进行温度及其他参数的显示。本设计中接口电路的设计与编译分为6步：（1） 把Multisim安装目录下的Sampling->LabVIEW Instruments->Input文件夹复制到另外一个地方。（2） 在labVIEW中打开步骤（1）中所复制的Starter Input Instrument.lvproj工程，如图4.2.1所示。接口电路的设计在Starter Input Instrument。vit中进行。 图4.2.1Starter Input Instrument.lvproj工程图（3） 打开Starter Input Instrument。vit的框图面板，完成接口框图的设计，如图4.2.2所示。 图4.2.2接口电路的设计（4）编译之前，要对虚拟仪器进行基本信息设置，如图4.2.3所示。 图4.2.3虚拟仪器设置（5）打开图4.2.1中的程序生成规范,右击Source Distribution,在弹出的快捷菜单中选择属性命令进行设置并命名，如图4.2.4所示。 （a）文件分布设置 （b）源文件设置 图4.2.4编译属性设置对话框（6）编译完成后，在Input文件夹下生成一个Build文件夹，打开后把里面的文件复制到Circuit Design Suite 10.0/lvinstruments文件夹中，这样就导入了虚拟仪器，再打开Multisim时，在LabVIEW仪器下拉菜单下就会显示模块Proj2.五.仿真测温 前面已将温度测量系统的设计完成，打开前面在Multisim10中设计的电路，在LabVIEW仪器下拉菜单下就会显示设计的模块。把设计好的电路和显示模块相连接，电路调整后，进行仿真，验证电路设计是否合理，结果如图5.1所示。.（a）30时的结果 (b) 40时的结果 (c )50时的结果 (d)60时的结果 图5.1实验结果六总结本课程设计的测温仪利用铂电阻作为测温传感器，铂电阻模型的建立于测温电路的仿真设计全部在Multisim 下完成。设计LabVIEW虚拟仪器使其完成温度值及其他信息的显示，然后将设计好的LabVIEW虚拟仪器导入到Multisim 中。将测温电路输出的电压信号输入到新导入的LabVIEW仪器中，完成从电压到温度值的转换。126（英文版 ） easily blame, to prevent the broken window effect. Supervise the leading cadres to play an exemplary role, take the lead in the strict implementation of the < code > and < rule >, lead to safeguard the solemnity and authority of the party discipline, ensure that the party discipline and the laws and regulations for implementation in place. Throughout the discipline in the daily supervision and management, strengthen supervision and inspection, from the thorough investigation of violations of discipline behavior. Strengthen to key areas, key departments and key projects as well as the masses reflect the concentration of the units and departments for supervision. - strengthening supervision, discipline inspection and supervision of cadres to set an example for compliance with the < code > and < rule > is a man must be hexyl, blacksmith needs its own hardware. Discipline inspection organs as the executor of the party discipline, and supervisor of the defenders, for its supervision must be more strictly, discipline inspection and supervision of cadres to firmly establish the awareness of Party Constitution, sense of discipline and rules consciousness, politics loyalty, sense obey. Action speak Ji Ordinance to set an example of the regulations of the rule of law, strengthen supervision and accept the supervision of the firmness and consciousness, do comply with < > and < >. To firmly establish the discipline must first be disciplined, the supervisor will be subject to the supervision of "concept, and consciously safeguard and implement party compasses party, take the lead in practicing" three strict real strict, so loyal, clean, play. To be good at learning, the Constitution and the < code > as morality, politics and brought to fruition; to implement < >, do not want to, dare not, not with disciplinary ruler to supervision; to discipline a ruler, often the control inspection, and consciously in the ideological red line to draw the row Ming Good accumulation is indeed the bottom line, so that the heart has fear, said to have quit, the line has ended. Attached: indifferent to heart, calmly to the table in our life, there are many unpredictable things will happen, some good, some bad things, we cannot control is powerless to stop, but with time, you will find in life sometimes turns out to be not good, some bad things finally turned out to be a good thing, but then we muddy however did not know, this is the life teach us things. 1, life can be complex, can also be simple. Want simple life of precipitation, to have enough time to reflect, to make Become more perfect. Life is the most important thing is not to win, but the struggle; not to have conquered, but to have fought well. 2, the plain is the background of life. Live a plain life, give up on themselves is not a coward, but the wise answers; not disillusioned after the heart, such as ashes, but experience the storm after the enlightenment; not unrewarding perfunctorily, but calm attitude of life of unrestrained self-confidence. Plain living, there is no noise noisy, no earthly troubles, more did not fill in the discontent of desire, some just a calm, a calm. 3, memory of heart will not good things to erase the, life is a When no movie, pain is a beginning, the struggle is a kind of process, death is a kind of ending. Give up this giving up is the helpless, do not give up the abandoned, do not give up this giving up is ignorance, do not give up should not give up is persistent. 4, a thing figured is heaven, think impassability is hell. Since the living, to live better. Sometimes we because of too narrow-minded, too care around the chores and penny wise and pound foolish, not worth the candle. Some things to attract trouble and worry, completely depends on how we look at and deal with it. Don't always take everything back to things, and don't get into a blind alley, don't want to face, don't be narrow-minded. Poke to care, is a kind of open-minded, a free and easy. 5, I am not afraid of others behind me a knife, I afraid to look back and see stab me, is my intention to treat people; I am not afraid of the truth to tell the best friend, I'm afraid he turned to it as a joke to tell don't 6, when we are in a positive frame of mind, you will find many good things; and when we are in a negative state of mind, you will find many depressed things; life happy and worry, all is you of life attitude, optimistic, good luck; loss of sink, Eritrea company. When you are in adversity, may wish to change a point of view to think everything over to the good Think, because good mentality decided the fate of the! 7, people are tired, rest; heart tired, calm. Grow up, mature, this society read. Tired and sad, squat down, to their a hug. Because the world no one can sympathize with you, have mercy on you. You cry, tears is your own; you pain, no one can understand. Then you only tears to smile. 8, each people have youth,Each youth are a story, the life of the world never gets easier, I want what, wish the world all know, as has been the same; now want anything, for fear that others know, or like to lose the same. 9, the heart move, everything in the world is followed by birth, Rangrang, important thing is often the most difficult to open one's mouth, because words will reduce its importance; to let strangers people care about your life in the good things, the original is not easy 10, do not blame, do not laugh at who, also don't envy who. Like a person is a kind of feeling, not like a person is true. The truth is easy to explain, I feel Is unspeakable. The best travel life is that you in a strange place found a long lost touched. 11, happy life not in the bustling in, and in the peace of mind; no matter how many grievances, how uncomfortable, and ultimately to heal themselves or their own, others may got you to comfort, but never know your heart is how wanjianchuanxin. 12, ma'am, like a movie, learn to appreciate, learn to be grateful, learn tolerance, and goodness, helping others. Instead of accusing the society, as into one; and an exception is better to give than to what 13, don't envy him A sum of, don't lose your life and the life, respectively is: the former is a we experienced cannot escape in a day finally will last minute, while the latter is our persistent, we want to cherish the memory of those people and things. 14, learn to smile, learn to strong, the world you know so many people, so many people and you are, you cannot change also can't let everyone like you, so also do not want to do. Life is too short to go crazy to love to go to waste, to chase the dream to regret. 15, when temper, a blessing to go. A wounding elegant people, the key is to control their own emotions. With the mouth is the most stupid behavior. A control negative emotions than a can take a city more powerful water flow slow, language is expensive. People spent two years of time to learn to speak, but to spend a few years time to shut up. That is a kind of ability, that is a kind of wisdom. 16, life is not perfect, sometimes, growth is not a cry, not an eyeful of tears, there is no trace of emotion, there is no gleam of hope, no desire, no action, no static, there is only one kind of downward sinking feeling, sink A murky? 6? 7? 6? 7 sink? 6? 7? 6? 7 toward the bottom of the sink. 17, in some way, do not go, you will not know the other side scenery is beautiful. To you is not good, you do not mind too much, no one has an obligation to you; you learn knowledge, is you have weapons, you can start from scratch, but not unarmed; how do you treat people, does not represent how others treat you, if cannot see through this point, only inviting worry. 18, time is like a sponge in the water, as long as you are willing to squeeze, the total water is still there. Every life, after the ups and downs The best test of live, to life, survival and continuation, do not stop the struggle in the joys and sorrows of life on the road, so that different soul to bear life beat, acceptance of suffering. 19, indifferent to heart, calmly in table, elegant and comfortable life, do not take what is so impor