WO2011072420A1 - 一种数字温度补偿的流量测量装置 - Google Patents

一种数字温度补偿的流量测量装置 Download PDF

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Publication number
WO2011072420A1
WO2011072420A1 PCT/CN2009/001469 CN2009001469W WO2011072420A1 WO 2011072420 A1 WO2011072420 A1 WO 2011072420A1 CN 2009001469 W CN2009001469 W CN 2009001469W WO 2011072420 A1 WO2011072420 A1 WO 2011072420A1
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Prior art keywords
fixed resistor
operational amplifier
inverting input
fixed
digital
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PCT/CN2009/001469
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English (en)
French (fr)
Inventor
牟昌华
赵迪
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北京七星华创电子股份有限公司
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Priority to PCT/CN2009/001469 priority Critical patent/WO2011072420A1/zh
Priority to JP2012543435A priority patent/JP5511978B2/ja
Priority to EP09852158.6A priority patent/EP2515087A4/en
Priority to US13/516,581 priority patent/US8733179B2/en
Publication of WO2011072420A1 publication Critical patent/WO2011072420A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/696—Circuits therefor, e.g. constant-current flow meters
    • G01F1/6965—Circuits therefor, e.g. constant-current flow meters comprising means to store calibration data for flow signal calculation or correction

Definitions

  • the present invention relates to a thermal flow measuring device, and more particularly to a digital temperature compensated flow measuring device. Background technique
  • a flow controller can be used to measure the flow of fluid through the device.
  • Thermal measurement is an important method of flow controller flow measurement. Its main principle is to detect the flow of fluid by measuring the amount of heat that the fluid flows through the sensor, that is, the temperature.
  • the sensor mainly uses the Wheatstone bridge. As shown in Figure 1/2, the upstream and downstream windings of the sensor are heat-generating devices. When a fluid passes, it will cause a temperature change, and a change in temperature will cause a change in resistance. The change in resistance will be reflected by the voltage change, so that the flow rate of the fluid can be measured by measuring the voltage value.
  • the upstream and downstream windings of the sensor often do not correspond very well due to their own tolerances and errors in production. This causes the asymmetry of the upstream and downstream windings. This asymmetry often causes the temperature of the sensor due to temperature changes. Drift phenomenon, the size of the sensor affected by temperature, determines the level of the sensor.
  • the original thermal sensor adopts a constant current driving mode, that is, the circuit provides a constant current, so that the sensor is more susceptible to temperature and environment, so the product has zero drift and low precision.
  • the present invention provides a digital temperature compensated flow measuring device for solving the problem of the existing flow measuring device, which replaces the constant current driving mode in a constant temperature manner, has high precision, good stability, and has automatic temperature according to temperature.
  • the function of adjustment can overcome the deficiencies of the prior art.
  • the present invention employs the following technical solutions.
  • the invention provides a digital temperature compensated flow measuring device, which is composed of an operational amplifier, a digital potentiometer, a sensor winding, and a plurality of fixed resistors, one end of the sensor winding
  • the operational amplifier is connected to the phase input terminal, and the other end is grounded; a fixed resistor is connected between the non-inverting input terminal and the output terminal of the operational amplifier, and the reverse input terminal is connected to one end of the fixed resistors R 2 and R 3 , the fixed
  • the other end of the resistor R 2 is connected to the output end, the other end of the fixed resistor R 3 is grounded, the end of the fixed resistor R 2 connected to the output end, and the inverting input end are also connected to the number
  • the high end of the potentiometer is connected, and one end of the fixed resistor R 3 is connected to the lower end of the digital potentiometer, and the inverting input end is also connected to the sliding end of the digital potentiometer.
  • a fixed resistor FU is connected between the output terminal of the operational amplifier and the high end, and between the fixed resistor R 2 and the high end.
  • a fixed resistor R 5 is connected between the fixed resistor and the low end.
  • the digital temperature-compensated flow measuring device of the invention replaces the constant current driving mode by means of constant temperature, and the sensor can work in a stable environment, therefore, the device has high precision and good stability;
  • the function of automatic temperature adjustment can compensate the sensor error caused by the manufacturing process according to the temperature, so the temperature coefficient of the sensor is more than doubled than the existing products.
  • Figure 1/2 is a schematic circuit diagram of a conventional flow measuring device
  • 2/2 is a schematic diagram showing the circuit configuration of a digital temperature compensated flow measuring device according to an embodiment of the present invention. detailed description
  • the digital temperature compensated flow measuring device comprises: an operational amplifier, a digital potentiometer, a sensor winding R ⁇ , and a plurality of fixed resistors.
  • the circuit is composed as follows: One end of the sensor winding RC is connected to the non-inverting input terminal of the operational amplifier, and the other end is grounded.
  • the non-inverting input terminal of the operational amplifier is connected with a fixed resistor.
  • the inverting input terminal is connected to the fixed resistor and one end of R 3 .
  • the other end is connected to the output terminal, the other end of the fixed resistor R 3 is grounded, the end of the fixed resistor connected to the output end, and the inverting input end are also connected to the high end of the digital potentiometer.
  • H is connected, the R 3 ground end of the fixed resistor is connected to the lower end L of the digital potentiometer, the inverting input terminal is also connected to the sliding end W of the digital potentiometer;
  • the output of the operational amplifier is between the high end H of the digital potentiometer and the fixed resistor
  • a fixed resistor R4 is connected between R 2 and the high-end H of the digital potentiometer;
  • a fixed resistor R 5 is connected between the fixed resistor R 3 and the lower end L of the digital potentiometer; the inverting input terminal of the operational amplifier and the sliding end of the digital potentiometer W
  • the digital potentiometer can be connected to the CPU that implements the control, and the resistance value is changed
  • the amplifier's in-phase and inverting inputs will reach the same potential.
  • the temperature of the sensor winding Ro increases with the passing current of the current
  • the op amp has the same potential at the inverting and inverting inputs. In this way, in any state, the sensor windings will maintain the same resistance value, that is, the temperature will not change, so that the sensor will not be affected by the environment and temperature, thus making the device zero drift and high accuracy of the device.
  • the CPU issues an instruction according to the temperature value, adjusts the digital potentiometer in real time, changes its resistance value, and adjusts the ratio of R 2 , thereby adjusting the resistance of the sensor winding, completing the digital temperature compensation, the sensor error caused by the manufacturing process, and improving the temperature of the sensor.
  • the coefficient makes the device stable at zero point and can be adapted to occasions where the temperature changes drastically.
  • the digital temperature-compensated flow measuring device of the invention can greatly improve the temperature index of the thermal mass measuring device, and the zero point is stable, and can be adapted to occasions where the temperature changes drastically, and further, the sensor error caused by the manufacturing process is compensated according to the temperature.
  • the temperature coefficient of the sensor can reach 0.02% FS/'C or more, more than double the existing products.
  • the device has very positive social benefits and extremely realistic economic benefits.

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Volume Flow (AREA)
  • Details Of Flowmeters (AREA)

Description

一种数字温度补偿的流量测量装置 技术领域
本发明涉及热式流量测量装置， 尤其涉及一种数字温度补偿的流量测量 装置。 背景技术
流量测量和控制是工业领域中非常重要的一部分。 流量控制器可用来测 量控制通过该设备的流体的流量。 热式测量是流量控制器流量测量的一种重 要的方法， 其主要原理是通过测量流体流过传感器时带走热量的多少， 也就 是温度的高低， 来检测流体的流量。 传感器主要釆用了惠斯通电桥的方式， 如图 1/2 所示， 传感器上游和下游绕组是发热器件， 当有流体经过时， 会引 起温度变化， 而温度的变化会导致电阻的变化， 电阻变化将由电压变化反映， 这样， 可通过测量电压值来测量流体的流量。 但是在很多情况下， 传感器上 下游绕组由于本身的公差和生产当中的误差， 往往不是很对应， 这造成了上 下游绕组的本身不对称， 这种不对称往往造成传感器由于温度变化而出现的 温度漂移现象， 传感器受温度影响的大小， 决定了传感器的水平。
在目前绝大多数产品中， 并没有对这种情况进行补偿的任何方法， 只是 依靠高精度的加工减少公差并提高生产精度， 这样造成了巨大的浪费， 效果 也并不明显。 同时原有的热式传感器采用了恒电流的驱动方式， 即电路提供 恒定的电流， 这样传感器较容易受到温度和环境的影响， 因此产品零漂大， 精度低。 发明内容
本发明为解决现有流量测量装置的问题， 提供了一种数字温度补偿的流 量测量装置， 该装置以恒温的方式取代了恒电流的驱动方式， 精度高、 稳定 性好， 且具有根据温度自动调节的功能， 可克服现有技术的不足。
为实现上述目的， 本发明釆用如下技术方案。
本发明提供的数字温度补偿的流量测量装置，该装置电路由运算放大器， 数字电位器， 传感器绕组， 以及若干固定电阻构成， 所述传感器绕组一端与 所述运算放大器同相输入端相连， 另一端接地； 所述运算放大器同相输入端 与输出端之间连接有固定电阻^，反向输入端与固定电阻 R2、R3的一端相连， 所述固定电阻 R2另一端与所述输出端相连， 所述固定电阻 R3另一端接地， 所述固定电阻 R2与所述输出端相连的一端、 以及所述反相输入端均还与所述 数字电位器的高端相连， 所述固定电阻的 R3接地一端与所述数字电位器的低 端相连， 所述反相输入端还与所述数字电位器的滑动端相连。
其中， 所述运算放大器输出端与所述高端之间、 所述固定电阻 R2与所述 高端之间连接有固定电阻 FU。
其中， 所述固定电阻 与所述低端之间连接有固定电阻 R5。
其中，所述运算放大器反相输入端与所述滑动端之间连接有固定电阻 。 本发明的数字温度补偿的流量测量装置， 釆用恒温度的方式取代了恒电 流的驱动方式， 传感器可工作在稳定的环境中， 因此， 该装置精度高、 稳定 性好； 此外， 加入了根据温度自动调节的功能， 可以根据温度补偿由于制造 工艺造成的传感器误差， 因此传感器温度系数比现有产品好 1倍以上。 附图说明
图 1/2为传统的流量测量装置电路示意图；
图 2/2为依照本发明一种实施方式的数字温度补偿的流量测量装置电路 构成示意图。 具体实施方式
本发明提出的数字温度补偿的流量测量装置， 结合附图和实施例说明如 下。
如图 2/2 所示， 本发明提供的数字温度补偿的流量测量装置包括： 运算 放大器， 数字电位器， 传感器绕组 R^, 以及若干固定电阻。 电路构成如下： 传感器绕组一端 RC 与运算放大器同相输入端相连， 另一端接地； 运算放大 器同相输入端与输出端之间连接有固定电阻 反向输入端与固定电阻 、 R3的一端相连， 固定电阻 另一端与输出端相连， 固定电阻 R3另一端接地， 固定电阻 与输出端相连的一端、 以及反相输入端均还与数字电位器的高端 H相连， 固定电阻的 R3接地一端与数字电位器的低端 L相连， 反相输入端还 与数字电位器的滑动端 W相连;运算放大器输出端与数字电位器高端 H之间 以及固定电阻 R2与数字电位器高端 H之间连接有固定电阻 R4; 固定电阻 R3 与数字电位器低端 L之间连接有固定电阻 R5; 运算放大器反相输入端与数字 电位器滑动端 W之间连接有固定电阻 。 数字电位器可与实施控制的 CPU 相连， 根据 CPU发来的指令改变电阻值。
根据运算放大器的特点， 当电路由电流通过时， 放大器同相、 反向输入 端将达到相同的电势。传感器绕组 Ro 随电流的通过温度升高，由
Figure imgf000005_0001
( 1+αΤ ) 可知， 随温度的升高， 传感器绕组阻值变大， 其中， Rc。n,T 为传感 器绕组 RC 在温度 T时的阻值， Rc。iM)为传感器绕组 RC 在 0° 时的阻值， 而 电阻 R,、 R2、 R3均为固定电阻， 因此， 直至绕组满足条件：
R、 R2
Rco \ R3 时，
运算放大器同相、 反向输入端电势相同。 这样， 在任何状态下， 传感器绕组 都会保持电阻值不变， 也就是温度不变， 从而使传感器不会受到环境和温度 的影响， 因此使得装置零漂小， 挺高了装置的精度。
CPU根据温度值发出指令， 实时调整数字电位器， 改变其电阻值， 从而 调整 R2、 的比率， 以此调节传感器绕组的阻值， 完成数字温度补偿由于制 造工艺造成的传感器误差， 提高传感器温度系数， 使得该装置零点稳定， 可 适应于温度剧烈变化的场合。 工业实用性
本发明的数字温度补偿的流量测量装置， 可以极大地提高热式涑量测量 装置的温度指标， 其零点稳定， 可适应于温度剧烈变化的场合， 此外， 根据 温度补偿由于制造工艺造成的传感器误差， 传感器温度系数可以达到 0.02%FS/'C以上， 比现有产品好 1倍以上， 该装置具有十分积极的社会效益和 极其现实的经济效益。

Claims

权 利 要 求
1、 一种数字温度补偿的流量测量装置， 该装置电路由运算放大器， 数字 电位器， 传感器绕组， 以及若干固定电阻构成， 所述传感器绕组一端与所述 运算放大器同相输入端相连， 另一端接地； 所述运算放大器同相输入端与输 出端之间连接有固定电阻 R 反向输入端与固定电阻 R2、 R3的一端相连， 所 述固定电阻 R2另一端与所述输出端相连， 所述固定电阻 R3另一端接地， 所 述固定电阻 R2与所述输出端相连的一端、 以及所述反相输入端均还与所述数 字电位器的高端相连， 所述固定电阻的 R3接地一端与所述数字电位器的低端 相连， 所述反相输入端还与所述数字电位器的滑动端相连。
2、 如权利要求 1所述的数字温度补偿的流量测量装置， 其特征在于， 所 述运算放大器输出端与所述高端之间、所述固定电阻 R2与所述高端之间连接 有固定电阻 。
4、 如权利要求 1所述的数字温度补偿的流量测量装置， 其特征在于， 所 述固定电阻 R3与所述低端之间连接有固定电阻 R5。
5、 如权利要求 1所述的数字温度补偿的流量测量装置， 其特征在于， 所 述运算放大器反相输入端与所述滑动端之间连接有固定电视 。
PCT/CN2009/001469 2009-12-16 2009-12-16 一种数字温度补偿的流量测量装置 WO2011072420A1 (zh)

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Application Number Priority Date Filing Date Title
PCT/CN2009/001469 WO2011072420A1 (zh) 2009-12-16 2009-12-16 一种数字温度补偿的流量测量装置
JP2012543435A JP5511978B2 (ja) 2009-12-16 2009-12-16 ディジタル温度補償機能付き流量測定装置
EP09852158.6A EP2515087A4 (en) 2009-12-16 2009-12-16 Flow meter with digital temperature compensation
US13/516,581 US8733179B2 (en) 2009-12-16 2009-12-16 Flow meter with digital temperature compensation

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CN103048530A (zh) * 2011-10-12 2013-04-17 鸿富锦精密工业（深圳）有限公司 数字电源电流校准装置

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US8733179B2 (en) 2014-05-27
JP5511978B2 (ja) 2014-06-04
JP2013514521A (ja) 2013-04-25
EP2515087A4 (en) 2017-06-14
US20120325012A1 (en) 2012-12-27

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