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A high-precision measurement thermocouple input module and

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CN103542954B
CN103542954B CN 201310470168 CN201310470168A CN103542954B CN 103542954 B CN103542954 B CN 103542954B CN 201310470168 CN201310470168 CN 201310470168 CN 201310470168 A CN201310470168 A CN 201310470168A CN 103542954 B CN103542954 B CN 103542954B
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CN 201310470168
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CN103542954A (en )
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章伟杰
朱武亭
张文
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上海发电设备成套设计研究院
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Abstract

本发明涉及一种高精度的热电偶输入模块,包括隔离器、放大器、模数转换单元、控制器、数模转换单元及电子开关,隔离器与热电偶相连,放大器的输出端模数转换单元,模数转换单元的输出端连接控制器,其特征在于:隔离器的接地端在接地的同时向外引出接地接口,隔离器的电压输出端同时向外引出两个接口,控制器根据由模数转换单元获得的信号向数模转换单元输出反馈信号,数模转换单元的输出端向外引出输出接口。 The present invention relates to a high-precision thermocouple input module, and connected to the separator, amplifiers, analog-digital conversion unit, a controller, a digital to analog conversion means and electronic switches, isolators and the thermocouple, the output of the analog-digital conversion unit amplifier , the output of analog to digital conversion unit connected to a controller, wherein: the grounding terminal isolator ground lead outwardly while the interface is grounded, the voltage output of the isolator two interfaces simultaneously drawn out, the controller according to the mold a signal conversion unit to obtain a feedback signal output to the digital to analog conversion means, the output of digital to analog converting an output interface lead outwardly. 本发明的另一技术方案是提供了一种高精度的热电偶输入测量方法,采用上述的热电偶输入模块。 Another aspect of the present invention is to provide an accurate input thermocouple measurement method using the above-mentioned thermocouple input module. 本发明的优点是:保证热电偶信号整体绝对精度在0.1~0.2℃,相对精度能达到0.005~0.01%,能够满足工业控制过程的真正需要。 Advantage of the present invention are: to ensure absolute accuracy of the overall thermocouple signal 0.1 ~ 0.2 ℃, the relative accuracy of 0.005 to 0.01% can be achieved, it is possible to meet the real needs of the industrial control process.

Description

一种高精度的热电偶输入模块及测量方法 A high-precision measurement thermocouple input module and

技术领域 FIELD

[0001] 本发明涉及一种高精度的热电偶输入模块及测量方法,用于提高热电偶或毫伏等小信号的测量精度,属于自动控制仪表技术领域。 [0001] The present invention relates to a thermocouple input module and a high-precision measurement method for improving measurement accuracy thermocouple or millivolt signal is small, belonging to the technical field of automatic control instrument.

背景技术 Background technique

[0002] 热电偶是由两种不同成份的金属线在其端部连接以形成闭合回路,直接用作测量介质温度的一端叫做工作端(也称为测量端),另一端叫做冷端(也称为补偿端),当工作端与冷端之间存在温度差时,回路中就会有电流通过,此时两端之间就存在热电动势(塞贝克效应),根据情况选择不同的金属材质便会得出大约与温度差成比例的电压输出。 [0002] The thermocouple is composed of two metal wires of different compositions are connected at their ends to form a closed loop, used directly as a measurement of one end, called the working end of the medium temperature (also referred to as measuring end), called the cold end and the other end (also compensation called terminal), when there is between the working end and the cold end temperature difference, there will be a current through the circuit, when there is a thermoelectromotive force (Seebeck effect) between the two ends, according to the case of selecting different metallic materials it will come to approximately the temperature difference is proportional to the output voltage. 但是这个电压都很非常小,例如比较最常见的镍铬-镍硅K分度热电偶-270 °C〜1372 °C对应的热电势为-6.458mV〜54.886mV,镍铬-铜镍合金E分度热电偶_270°C〜1000°C对应的热电势为-9.835mV 〜76.373mV。 However, this voltage is very small, the most common example, by comparing nickel-chromium - nickel silicon K thermocouple of -270 ° C~1372 ° C corresponding to the thermoelectric potential of -6.458mV~54.886mV, nickel-chromium - copper-nickel alloy E thermocouple of _270 ° C~1000 ° C corresponding to the thermoelectric potential of -9.835mV ~76.373mV.

[0003] 分散控制系统(DCS)或可编程控制系统(PLC)等控制系统的热电偶输入模块的信号处理方法是获得由热电偶产生的热电动势(毫伏电压信号),将其作为模拟电信号经过放大器放大到伏电压信号,再经由模数转换器(ADC)输入到控制芯片的数字数据中,由控制芯片或交由上位机根据分度号查表或采用温度估算模型公式处理来转换成实际温度。 [0003] The signal processing method of distributed control system thermocouple input module (DCS) or a programmable control system (PLC) control system and the like is to obtain a thermal electromotive force (mV voltage signal) generated by the thermocouple, it as analog signal through the amplifier to the voltage signal V, and then the digital data is input to the controller chip via analog to digital converter (the ADC), a control chip or to the host computer converts the look-up table according to the indexing number or model equation using a temperature estimation process into the actual temperature.

[0004] 早期由于半导体技术相对落后,为了克服控制芯片处理速度慢且存储器容量小的问题,采用各种各样的温度估算模型公式来处理。 [0004] As the semiconductor technology is relatively backward earlier, in order to overcome the control chip processing speed and memory capacity of a small problem, a variety of treatment temperature estimation model equation. 随着控制芯片处理速度和存储容量的技术指标大幅度的提升,采用最原始的查表来克服温度估算模型公式与实际温度的微小的误差。 With the greatly improved chip control processing speed and storage capacity specifications, the most primitive look-up table to overcome the slight temperature estimation error of the model equation and the actual temperature.

[0005] 从表面上来看,热电偶信号测量精度会集中到模数转换器(ADC)上,一般模数转换器采用12位,虽然模数转换器理论分辨率为1/4096 (即万分之二),但是由于放大器和模数转换器等元器件的参考电压和电阻等元器件的温飘等等原因,实际上整个热电偶信号的测量精度一般为0.1〜0.2%之间,即使有些厂家将模数转换器提高到13位或14位、甚至15位,但整体测量精度并不能提高多少。 [0005] On the surface, the thermocouple signals will concentrate on the measurement accuracy analog to digital converter (the ADC), generally 12-bit analog to digital converter, while analog to digital converter with a resolution of 1/4096 theory (i.e., very bis), but due to other components of the amplifier and an analog reference voltage and resistance components of the temperature drift and other reasons, virtually the entire measurement accuracy of the thermocouple signal is generally between 0.1 to 0.2%, even though some manufacturers to increase the analog to digital converter 13 or 14, or even 15, but the overall measurement accuracy does not improve much.

[0006] 在工业过程控制中,这种相对精度对于执行机构的阀位开度、压力、流量、液位、电压电流等等过程变量问题并不大,但是对于温度信号,由于它没有具体的量程范围,一般情况下热电偶输入模块为兼容各种分度号的热电偶信号,采用的热电势信号会有足够的上限裕度,折算成温度量程上限会达到200(TC,这时相对精度折算成绝对值会到2°C〜4°C。而实际上,低温度一般会发生在设备启动过程,当工业过程正常运行时,主要的温度过程参数会在一个较高的温度下进行小幅度的变化。例如600MW超超临界火力发电机组锅炉过热器出口温度在50%额定工况以上时温度基本在560±10°C之间运行,温度变化范围在20°C,而如果作为锅炉安全保护信号使用,跳炉值也仅为597°C,温度变化为+37°C这时2°C〜4°C的绝对误差就显得非常严重。 [0006] In industrial process control, such relative position accuracy of the opening degree of the valve actuator, pressure, flow, level, and so the process variable voltage current problem is not large, but the temperature signal since it has no specific scale range, generally thermocouple input module is compatible with various indexing number of thermocouple signals, thermoelectric power signal employed will be sufficient margin limit, converted into the upper limit will reach a temperature range of 200 (TC, this time relative accuracy to be converted into an absolute value of 2 ° C~4 ° C. in fact, the low temperature generally occurs startup of the device, when the industrial process during normal operation, the temperature of the main process parameters will be small at a high temperature the variation width. e.g. 600MW thermal ultra-supercritical unit boiler superheater outlet temperature between the temperature of substantially 560 ± 10 ° C at above 50% rated operating conditions, the temperature range at 20 ° C, and if a boiler safety use protection signal, the value of only hop furnace 597 ° C, the temperature change is + 37 ° C in this case the absolute error of 2 ° C~4 ° C is very serious.

发明内容 SUMMARY

[0007] 本发明要解决的技术问题是保证热电偶信号的精度。 [0007] The present invention is to solve the technical problem is to ensure the accuracy of the thermocouple signal.

[0008] 为了解决上述技术问题,本发明的一个技术方案是提供了一种高精度的热电偶输入模块,包括隔离器、放大器、模数转换单元、控制器、数模转换单元及电子开关,隔离器与热电偶相连,放大器的输出端模数转换单元,模数转换单元的输出端连接控制器,其特征在于:隔离器的接地端在接地的同时向外引出接地接口,隔离器的电压输出端同时向外引出两个接口,分别为第一电压输出接口及第二电压输出接口,控制器根据由模数转换单元获得的信号向数模转换单元输出反馈信号,数模转换单元的输出端向外引出输出接口,通过电子开关的动作使得放大器的同相输入端与第一电压输出接口连接,同时放大器的反相输入端与接地接口连接,或者使得放大器的同相输入端与输出接口连接,同时放大器的反相输入端与接地接口连接,或者使得放大器的同 [0008] In order to solve the above problems, an aspect of the present invention is to provide a highly accurate thermocouple input module, comprising a separator, amplifiers, analog-digital conversion unit, a controller, a digital to analog conversion means and electronic switches, a thermocouple connected to the isolator, the output of the analog-digital conversion unit amplifier, the output of analog-digital conversion unit connected to a controller, wherein: the grounding terminal isolator ground lead outwardly while the interface is grounded, a voltage isolator while the output terminal lead-out two interfaces, namely a first voltage and a second voltage output interface output port, a feedback control signal to the digital to analog conversion means in accordance with an output signal obtained by the conversion unit, the output of digital to analog conversion means end of the external lead-output interface, by the operation of the electronic switch so that the amplifier's noninverting input terminal of the output interface is connected to a first voltage, while the inverting input terminal of the amplifier to the ground interface, or such that the amplifier's noninverting input terminal connected to the output interface, while the inverting input terminal of the amplifier and a ground interface, or such that the amplifier with 输入端与输出接口连接,同时放大器的反相输入端与第二电压输出接口连接。 An input terminal connected to the output interface, while the inverting input terminal of the second voltage amplifier and the output interface.

[0009] 优选地,所述放大器为可编程运算放大器。 [0009] Preferably, the programmable amplifier is an operational amplifier.

[0010] 优选地,所述电子开关共有两个,均为单刀双掷电子开关。 [0010] Preferably, the electronic switch consists of two, are single pole double throw electronic switch.

[0011] 优选地,所述模数转换单元和所述数模转换单元选用12位精度的转换器。 [0011] Preferably, the conversion unit and the DAC unit selected 12 bit converter.

[0012] 本发明的另一技术方案是提供了一种高精度的热电偶输入测量方法,采用上述的热电偶输入模块,其基本思路是: [0012] Another aspect of the present invention is to provide an accurate input thermocouple measurement method using the above-mentioned thermocouple input module, the basic idea is:

[0013] 降低放大器的放大倍数,预测实际测量温度值后将温度的上下限量程基准点从超大量程范围切片分割成小量程范围。 [0013] The amplification of the amplifier is reduced, the predicted values ​​of the actual measured temperature of the upper and lower temperature limits after the reference point away from the large-scale range of the small-scale range is divided into sections. 控制器利用数模转换器作为反馈端与输入端形成一个闭环回路,调整放大器的参考基准值以克服输入端和反馈端的综合误差。 DAC controller uses a closed loop is formed, with reference to the reference value adjusting amplifier as the feedback terminal and the input terminal to overcome the synthetic error input terminal and the feedback terminal. 大幅度提高放大器的放大倍数,结合修正过的放大器的参考基准值,经过控制器的计算得出高精度的热电偶信号对应的温度值特征在于,具体步骤为: Substantial increase in amplification of the amplifier, the reference value in conjunction with corrected reference amplifier, derived through calculation controller accurate temperature thermocouple signal characteristic value corresponding to that specific steps:

[0014] 第一步、操作电子开关,使得放大器的同相输入端与第一电压输出接口连接,同时放大器的反相输入端与接地接口连接,将放大器的放大倍数设置为A,控制器获得由模数转换单元的输出电压Vp的初始值,根据输出电压Vp的初始值及其对应的温度Tp,将热电偶输入模块的上限量程值定义为Tp+A°C,下限量程值定义为Tp-AtC,根据分度号查表找到与Tp+A°C相对应的热电动势VO ; [0014] The first step, operating the electronic switches, such that with the amplifier inverting input terminal connected to the first voltage output interfaces, while the inverting input terminal of the amplifier and the ground interface, the amplification of the amplifier is set to A, obtained by the controller the initial value of the output voltage Vp of the analog to digital conversion means, according to the initial value of the output voltage Vp and the corresponding temperature Tp of, the thermocouple input module upper range value is defined as Tp + a ° C, the lower limit of the range is defined as Tp- AtC, according to the look-up table to find the number of indexing and Tp + VO thermoelectromotive force corresponding to the a ° C;

[0015] 第二步、操作电子开关,使得放大器的同相输入端与输出接口连接,同时放大器的反相输入端与接地接口连接,调整控制器的反馈电压Vf,使得输出接口上的参考电压Vref=VO+Δ 1,△ I为放大器及模数转换单元的输入综合误差; [0015] The second step, an operation of electronic switches, such that the amplifier's noninverting input terminal connected to the output interface, while the inverting input terminal of the amplifier and the ground interface, the controller to adjust the feedback voltage Vf, so that the reference voltage Vref the output interface = VO + Δ 1, △ I synthetic error converting an input unit and an amplifier module;

[0016] 第三步、操作电子开关,使得放大器的同相输入端与输出接口连接,同时放大器的反相输入端与第二电压输出接口连接,将放大器的放大倍数设置为B,B远大于Α,此时,放大器的同相输入端上的参考电压Vref = VO+Δ 1,放大器的反相输入端上的电压为隔离器的输出电压Vi,端差值为VO+Δ 1-Vi,减去放大器及模数转换单元的输入综合误差Δ I后,最终模数转换单元的输出电压Vp = VO+Δ 1-V1-Δ I = VO-Vi,该热电动势对应的温度Ti,则最终的温度值为Tp+A-Ti。 [0016] The third step of operating an electronic switch, such that the amplifier's noninverting input terminal connected to the output interface, while the inverting input terminal of the second voltage amplifier is connected to the output interface, the amplification of the amplifier is set to B, B is much larger than Α in this case, the inverting input of the amplifier on the end of the reference voltage Vref = VO + Δ 1, the voltage on the inverting input of the amplifier output voltage Vi of the isolator, the difference is the end VO + Δ 1-Vi, subtracts after entering the integrated error amplifier and an analog-digital conversion unit Δ I, the output voltage Vp final analog to digital conversion unit = VO + Δ 1-V1-Δ I = VO-Vi, the thermal electromotive force corresponding to a temperature Ti, the final temperature value Tp + A-Ti.

[0017] 本发明的优点是:保证热电偶信号整体绝对精度在0.1〜0.2°C,相对精度能达到0.005〜0.01%,能够满足工业控制过程的真正需要。 Advantages [0017] of the present invention is: to ensure absolute accuracy of the overall thermocouple signal 0.1~0.2 ° C, the relative precision can reach 0.005~0.01%, to meet the real needs of the industrial control process.

附图说明 BRIEF DESCRIPTION

[0018]图1为本发明提供的一种高精度的热电偶输入模块示意图。 [0018] FIG. 1 is a high-precision thermocouple input module of the present invention provides a schematic diagram.

具体实施方式 detailed description

[0019] 为使本发明更明显易懂,兹以优选实施例,并配合附图作详细说明如下。 [0019] To make the present invention more comprehensible, a preferred embodiment hereby embodiments accompanied with figures are described in detail as follows.

[0020] 如图1所示,本发明提供的一种高精度的热电偶输入模块,包括隔离器、放大器、模数转换单元ADC、控制器、数模转换单元DAC及电子开关,隔离器与热电偶相连,放大器的输出端模数转换单元ADC,模数转换单元ADC的输出端连接控制器,其特征在于:隔离器的接地端在接地的同时向外引出接地接口4,隔离器的电压输出端同时向外引出两个接口,分别为第一电压输出接口I及第二电压输出接口3,控制器根据由模数转换单元ADC获得的信号向数模转换单元DAC输出反馈信号,数模转换单元DAC的输出端向外引出输出接口2,通过电子开关的动作使得放大器的同相输入端SA与第一电压输出接口I连接,同时放大器的反相输入端SB与接地接口4连接,或者使得放大器的同相输入端SA与输出接口2连接,同时放大器的反相输入端SB与接地接口4连接,或者使得放大器的同相输 [0020] As shown, a high-precision thermocouple input module of the present invention is provided, including an isolator, an amplifier, the ADC conversion unit, a controller, a digital to analog converter DAC and an electronic switch means, and the isolator 1 thermocouple connected to the output of analog-digital conversion unit ADC amplifier, the output of the ADC conversion unit connected to the controller, wherein: the ground lead terminal isolator ground terminal 4, while the spacer outwardly ground voltage while the output terminal lead-out two interfaces, namely a first voltage and a second voltage output interface I output interface 3, a controller feedback digital to analog conversion means based on a signal from the DAC output to the analog-digital conversion unit ADC signal obtained, a digital to analog output of the converter unit drawn outwardly DAC output interface 2, through the operation of the electronic switch so that the amplifier's noninverting input terminal of the first voltage and the SA connected to an output interface I, while the inverting input of the amplifier SB interface 4 is connected to the ground, or so that the noninverting input of the amplifier inverting input terminal of the interface 2 is connected to the output SA, SB while the inverting input terminal of the amplifier 4 is connected to the ground of the interface, or such that the amplifier 入端SA与输出接口2连接,同时放大器的反相输入端SB与第二电压输出接口3连接。 The end connector 2 is connected with the output SA, SB while the inverting input terminal of the second voltage amplifier 3 is connected to the output interface.

[0021 ] 放大器为可编程运算放大器。 [0021] The operational amplifier is a programmable amplifier.

[0022] 电子开关共有两个,均为单刀双掷电子开关。 [0022] There are two electronic switches, are single pole double throw electronic switch.

[0023] 模数转换单元ADC和所述数模转换单元DAC选用12位精度的转换器,本领域技术人员也可以根据需要选用其他精度的转换器。 [0023] conversion unit ADC and the DAC unit selected 12 bit DAC converter, those skilled in the art may also need to use other precision converter.

[0024] 利用上述模块的热电偶输入测量方法,其步骤为: [0024] With the above-described measuring method thermocouple input module, comprising the steps of:

[0025] 第一步、操作电子开关,使得放大器的同相输入端SA与第一电压输出接口I连接,同时放大器的反相输入端SB与接地接口4连接,将放大器的放大倍数设置为A,控制器获得由模数转换单元ADC的输出电压Vp的初始值,根据输出电压Vp的初始值及其对应的温度Tp,将热电偶输入模块的上限量程值定义为Tp+A°C,下限量程值定义为Tp-AtC,根据分度号查表找到与Tp+A°C相对应的热电动势VO ; [0025] The first step, operating the electronic switches, such that with the amplifier inverting input terminal SA and the first voltage output connected to interface I, while the inverting input terminal of the amplifier SB and the interface 4 is connected to ground, the amplification of the amplifier is set to A, the controller obtains based on the initial value of the output voltage Vp corresponding to the temperature Tp and the initial value conversion unit ADC output voltage Vp, the upper range value is defined as the thermocouple input module Tp + a ° C, the lower limit of measuring range value is defined as Tp-AtC, according to the look-up table to find the number of indexing and Tp + VO thermoelectromotive force corresponding to the a ° C;

[0026] 第二步、操作电子开关,使得放大器的同相输入端SA与输出接口2连接,同时放大器的反相输入端SB与接地接口4连接,调整控制器的反馈电压Vf,使得输出接口2上的参考电压Vref = VO+Δ 1,Al为放大器及模数转换单元ADC的输入综合误差; [0026] The second step, an operation of electronic switches, such that the inverting input terminal of the amplifier SA is connected to the output interface 2, while the inverting input of the amplifier SB interface 4 is connected to the ground, adjusting the feedback voltage Vf controller, so that the output interface 2 the reference voltage Vref = VO + Δ 1, Al is the input of the amplifier and the analog-digital conversion unit ADC integrated error;

[0027] 上述第二步的推导过程为: [0027] The derivation of the above-described second step is:

[0028] 若调整控制器的反馈电压Vf为热电动势V0,则Vref参考电压=VO-A 2,Δ 2为反馈综合误差,则输出电压Vp = Vref- Δ I = VO- Δ 2- Δ I。 [0028] If the feedback voltage Vf thermoelectromotive force adjustment controller is V0, the reference voltage Vref = VO-A 2, Δ 2 is the integrated feedback error, the output voltage Vp = Vref- Δ I = VO- Δ 2- Δ I . 若要使得输出电压Vp = V0,则通过反向计算,需要将控制器的输出反馈电压Vf调整为VO+Δ 2+Δ 1,此时,Vref = Vf-A 2=νθ+Δ2+Δ 1-Δ2 = VO+Δ 10 To the output voltage Vp = V0, the reverse calculation is necessary to output a feedback voltage Vf of the controller is adjusted to VO + Δ 2 + Δ 1, this time, Vref = Vf-A 2 = νθ + Δ2 + Δ 1 -Δ2 = VO + Δ 10

[0029] 第三步、操作电子开关,使得放大器的同相输入端SA与输出接口2连接,同时放大器的反相输入端SB与第二电压输出接口3连接,将放大器的放大倍数设置为B,B远大于Α,此时,放大器的同相输入端SA上的参考电压Vref = VO+Δ 1,放大器的反相输入端SB上的电压为隔离器的输出电压Vi,端差值为VO+ Δ 1-Vi,减去放大器及模数转换单元ADC的输入综合误差AI后,最终模数转换单元ADC的输出电压Vp = VO+ Δ 1-V1-Δ I = VO-Vi,该热电动势对应的温度Ti,则最终的温度值为Tp+A-Ti。 [0029] The third step of operating an electronic switch, such that the amplifier's noninverting input terminal of the interface 2 is connected to the output SA, SB while the inverting input terminal of the second voltage amplifier 3 is connected to the output interface, the amplification of the amplifier is set as B, B is much greater than [alpha], this time, with the amplifier inverting input terminal of the reference voltage Vref SA = VO + Δ 1, the voltage on the SB input terminal of the inverting amplifier output voltage Vi of the isolator, the difference is the end VO + Δ 1 -vi, after subtraction of the input amplifier and the integrated error AI conversion unit ADC, the final conversion unit ADC output voltage Vp = VO + Δ 1-V1-Δ I = VO-Vi, the thermoelectromotive force corresponding to the temperature Ti , the final temperature value Tp + a-Ti.

[0030] 以下结合数据来进一步说明本发明。 [0030] The following binding data to further illustrate the invention.

[0031] 利用高精度的信号发生器对热电偶输入模块的第一通道输出27.025mV(此热电动势在K分度号对应650°C ),热电偶输入模块的工作过程如下(为便于理解,计算测量值时放大倍数被忽略): [0031] The use of high-precision signal generator to the first output channel thermocouple input module 27.025mV (this corresponds to the thermoelectromotive force at 650 ° C K dividing), a thermocouple input module operates as follows (for ease of understanding, magnification is ignored when calculating the measured value):

[0032] 第一步、操作电子开关,使得放大器的同相输入端SA与第一电压输出接口I连接,同时放大器的反相输入端SB与接地接口4连接,设置放大器的放大倍数为50,得到Vp的初始值26.856mV,根据Vp的初始值26.878mV及对应的温度Tp (646.53°C ),将它的上限量程值定义为28.984mV(696.53 °C ),下限量程值定义为24.758mV(596.53°C )。 [0032] The first step, operating the electronic switches, such that with the amplifier inverting input terminal SA and the first voltage output connected to interface I, while the inverting input of the amplifier SB interface 4 is connected to the ground, provided for amplification of the amplifier 50, to give 26.856mV Vp of the initial value, the initial value Vp of 26.878mV and the corresponding temperature Tp (646.53 ° C), it is defined as the upper range 28.984mV (696.53 ° C), the lower limit value is defined as the range 24.758mV (596.53 ° C).

[0033] 第二步、操作电子开关,使得放大器的同相输入端SA与输出接口2连接,同时放大器的反相输入端SB与接地接口4连接,控制器的反馈电压Vf为28.984mV,通过输入端得到的Vp为28.704mV,通过反向计算,若要使得Vp为28.984mV,则将控制器的反馈电压Vf设定为29.264mV。 [0033] The second step, an operation of electronic switches, such that the inverting input terminal of the amplifier SA is connected to the output interface 2, while the inverting input of the amplifier SB and the interface 4 is connected to ground, the feedback voltage Vf controller is 28.984mV, by entering end Vp is obtained 28.704mV, by reverse calculation, so that Vp is to 28.984mV, then the feedback voltage Vf is set to the controller 29.264mV.

[0034] 第三步、操作电子开关,使得放大器的同相输入端SA与输出接口2连接,同时放大器的反相输入端SB与第二电压输出接口3连接,设置放大器的放大倍数为500,此时,Vref为29.131mV,Vi为信号发生器的实际输入27.025mV,端差值为2.106,最终得到Vp为1.959mV,折算最终被测量信号的热电动势为27.025,对应的温度为650°C,测量误差为 [0034] The third step of operating an electronic switch, such that the amplifier's noninverting input terminal of the interface 2 is connected to the output SA, SB while the inverting input terminal of the second voltage amplifier 3 is connected to the output interface is provided for the amplification of the amplifier 500, this when, Vref is 29.131mV, Vi 27.025mV actual input signal generator, the difference is 2.106 end, Vp is finally obtained 1.959mV, thermoelectromotive force is eventually converted to 27.025 measurement signals, corresponding to a temperature of 650 ° C, measurement error

Claims (3)

1.一种高精度的热电偶输入模块,包括隔离器、放大器、模数转换单元(ADC)、控制器、数模转换单元(DAC)及电子开关,隔离器与热电偶相连,放大器的输出端连接模数转换单元(ADC),模数转换单元(ADC)的输出端连接控制器,其特征在于:隔离器的接地端在接地的同时向外引出接地接口(4),隔离器的电压输出端同时向外引出两个接口,分别为第一电压输出接口( I)及第二电压输出接口( 3 ),控制器根据由模数转换单元(ADC)获得的信号向数模转换单元(DAC)输出反馈信号,数模转换单元(DAC)的输出端向外引出输出接口( 2 ),通过电子开关的动作使得放大器的同相输入端(SA)与第一电压输出接口(I)连接,同时放大器的反相输入端(SB)与接地接口(4)连接,或者使得放大器的同相输入端(SA)与输出接口(2)连接,同时放大器的反相输入端(SB)与接地接口(4)连接,或者使得放大器 A high precision thermocouple input module, comprising a separator, amplifiers, analog-digital conversion unit (the ADC), a controller, a digital to analog conversion means (DAC) and an electronic switch connected to the thermocouple isolator, the output of the amplifier voltage of the ground terminal isolator ground lead outwardly while grounding the interface (4), isolator: end connected digital conversion unit (ADC), analog-digital conversion unit (ADC) connected to the output controller, wherein while the output terminal lead-out two interfaces, namely a first voltage output interface (I) and a second voltage output interface (3), the controller according to the signal from the analog-digital conversion unit (ADC) obtained in the digital-analog conversion unit ( DAC) outputs a feedback signal, the output of digital to analog conversion means (DAC) of the external lead-output interface (2), by the operation of the electronic switch so that the non-inverting input terminal of the amplifier (SA) a first voltage output interface (I) is connected, while the inverting input of the amplifier (SB) and the ground connector (4) is connected, or so that the noninverting input terminal of the amplifier (SA) and an output interface (2) is connected, while the inverting input of the amplifier (SB) and the ground connector ( 4) connection, or such that the amplifier 同相输入端(SA)与输出接口( 2 )连接,同时放大器的反相输入端(SB )与第二电压输出接口( 3 )连接; 所述放大器为可编程运算放大器; 所述电子开关共有两个,均为单刀双掷电子开关。 Inverting input terminal (SA) and an output interface (2) is connected, while the inverting input of the amplifier (SB) and a second voltage output interface (3); said programmable amplifier is an operational amplifier; a total of two of the electronic switch a, are single pole double throw electronic switch.
2.如权利要求1所述的一种高精度的热电偶输入模块,其特征在于:所述模数转换单元(ADC)和所述数模转换单元(DAC)选用12位精度的转换器。 2. a high-precision thermocouple input module according to claim 1, wherein: said analog-digital conversion unit (ADC) and the digital to analog conversion means (DAC) of the selected 12 bit converter.
3.一种高精度的热电偶输入测量方法,采用如权利要求1所述的热电偶输入模块,其特征在于,步骤为: 第一步、操作电子开关,使得放大器的同相输入端(SA)与第一电压输出接口(I)连接,同时放大器的反相输入端(SB)与接地接口(4)连接,将放大器的放大倍数设置为A,控制器获得模数转换单元(ADC)的输出电压Vp的初始值,根据输出电压Vp的初始值及其对应的温度Tp,将热电偶输入模块的上限量程值定义为Tp+A°C,下限量程值定义为Tp-AtC,根据分度号查表找到与Tp+A°C相对应的热电动势VO ; 第二步、操作电子开关,使得放大器的同相输入端(SA)与输出接口(2)连接,同时放大器的反相输入端(SB )与接地接口( 4 )连接,调整控制器的反馈电压Vf,使得输出接口( 2 )上的参考电压Vref= VO+Δ 1,Δ I为放大器及模数转换单元(ADC)的输入综合误差; 第三步、操作电子开关,使得放 3. A method of measuring the thermocouple input high precision, using the thermocouple input module as claimed in claim 1, wherein the steps of: a first step of operating an electronic switch, such that the non-inverting input terminal of the amplifier (SA) an output interface connected to the first voltage (the I), while the inverting input of the amplifier (SB) and the ground connector (4) is connected to the amplification of the amplifier is set to a, the controller obtains the output conversion unit (ADC) of the initial value of the voltage Vp, the output voltage Vp in accordance with the initial value and the corresponding temperature Tp of, the upper range value is defined as the thermocouple input module Tp + a ° C, the lower limit of the range value is defined as Tp-AtC, in accordance with indexing number lookup to find the Tp + a ° C corresponding to the thermoelectromotive force VO; a second step of operating an electronic switch, such that the inverting input terminal of the amplifier (SA) and an output interface (2) is connected, while the inverting input of the amplifier (SB ) and the ground connector (4) is connected to the controller to adjust the feedback voltage Vf, so that the output interfaces (on the reference voltage Vref 2) = VO + Δ 1, Δ I of amplifier and analog-digital conversion unit (ADC) input of integrated error ; a third step of operating an electronic switch, such that the discharge 大器的同相输入端(SA)与输出接口(2)连接,同时放大器的反相输入端(SB)与第二电压输出接口(3)连接,将放大器的放大倍数设置为B,B远大于Α,此时,放大器的同相输入端(SA)上的参考电压Vref= VO+Δ 1,放大器的反相输入端(SB)上的电压为隔离器的输出电压Vi,端差值为V0+Al-Vi,减去放大器及模数转换单元(ADC)的输入综合误差Δ I后,最终模数转换单元(ADC)的输出电压Vp=VO+Δ 1-V1-Δ 1=VO-Vi,该热电动势对应的温度Ti,则最终的温度值为Tp+A-Ti。 With the inverting input terminal of the amplifier (SA) and an output interface (2) is connected, while the inverting input of the amplifier (SB) and a second voltage output interface (3) connected to the amplification of the amplifier is set to B, B is much greater than with [alpha], at this time, the amplifier inverting input terminal of the reference voltage Vref (SA) = VO + Δ 1, the voltage on the inverting input of the amplifier (SB) is the output voltage Vi isolator ends difference is V0 + al-Vi, subtracting amplifier and analog-digital conversion unit (ADC) input of integrated error Δ I, the final output voltage conversion unit (ADC) of Vp = VO + Δ 1-V1-Δ 1 = VO-Vi, the thermoelectromotive force corresponding to the temperature Ti, the final temperature value Tp + a-Ti.
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CN202018345U (en) * 2011-03-07 2011-10-26 济南大学 Novel thermocouple temperature measurement module
CN102426066A (en) * 2011-09-26 2012-04-25 天津成科自动化工程技术有限公司 Switching detection circuit using multi-channel PT100 thermistors as temperature sensor
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