CN211696724U - Multi-channel temperature signal conversion device - Google Patents
Multi-channel temperature signal conversion device Download PDFInfo
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- CN211696724U CN211696724U CN201922337693.4U CN201922337693U CN211696724U CN 211696724 U CN211696724 U CN 211696724U CN 201922337693 U CN201922337693 U CN 201922337693U CN 211696724 U CN211696724 U CN 211696724U
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Abstract
The utility model provides a multichannel temperature signal conversion equipment can gather, amplify, take care of multichannel different material thermocouple temperature sensor output signal, can calculate optimal ratio to the circuit parameter according to the design demand, can make the collection precision improve greatly through cold junction compensation, zero adjustment, amplitude limiting filtering processing, has the advantage of precision height, reliability height and adaptation more complicated environment; the provided detailed circuit design parameter calculation method can provide a complete design idea for the same type of design; the multi-channel temperature signal conversion device is used for acquiring and converting signals of the multi-channel thermocouple temperature sensors made of different materials, so that test equipment can be provided for different temperature measurement requirements of specific parts of the aerospace craft in the flying process, installation space is saved, and a design approach is provided for diversified use of the temperature sensors.
Description
Technical Field
The utility model belongs to the technical field of the space flight sensor, concretely relates to multichannel temperature signal conversion equipment.
Background
A large number of temperature testing problems exist in aviation, aerospace, energy, chemical engineering, textile and other scientific research and production, and particularly the temperature sensor has higher requirements in the aerospace field.
With the need for technical development, the temperature measurement requirements for aircraft components are also increasing. High temperature resistance is an important indicator of the choice of materials for aircraft structural components. Only if the actual high temperature which needs to be endured by each part of the aircraft during the flight period is determined, the safe temperature of each part of the aircraft can be monitored in real time, and the appropriate material can be selected.
When the high temperature actually born by a specific position in the flight process of the aerospace craft is measured, a proper temperature sensor and a temperature conversion device are required to be selected for collecting the temperature value. Because the requirements of materials, space and temperature range of each part of the aircraft are different, the temperature sensor is required to have the characteristics of different temperature measuring ranges, temperature measuring precision, thermal reaction speed and the like, different temperature measuring environments need thermocouples made of different materials for measurement, the temperature sensor is limited by narrow installation space of the aircraft, and only one temperature conversion device can be used, so that the multi-path temperature signal conversion device has to be designed to meet the use of novel space flight equipment.
SUMMERY OF THE UTILITY MODEL
In view of this, the present invention provides a multi-channel temperature signal transforming device, which can collect and transform signals for multi-channel thermocouple temperature sensors made of different materials.
A multi-channel temperature signal conversion device comprises a thermocouple input signal amplification module (1), a multi-channel signal conditioning module (2) and an output amplitude limiting filter module (4);
the thermocouple input signal amplification module (1) comprises a plurality of amplification submodules, and each amplification submodule is used for amplifying a temperature signal acquired by a thermocouple sensor connected to the front end of the amplification submodule; wherein, the amplification gain of each path of amplification submodule on the temperature signal is determined according to the temperature measurement range and the output voltage range of the thermocouple wire of the thermocouple sensor, and the relationship is satisfied:
wherein G is the amplification gain, UO (full)For the upper limit, U, of the output of the converter deviceO (zero)For the lower limit, U, of the output of the converter devicein(max)And Uin(min)Dividing values corresponding to the highest temperature and the lowest temperature of the working temperature ranges of all the accessed thermocouple sensors respectively;
the signal conditioning module (2) is used for respectively carrying out error compensation on the amplified temperature signals output by each path of amplification sub-module;
and the amplitude limiting and filtering module (4) is used for adjusting the temperature signal after the error compensation to a set range and outputting the temperature signal.
Preferably, the thermocouple input signal amplification module (1) is realized by adopting an AD8221 amplifier.
Preferably, the error compensation includes temperature compensation and zero point compensation.
Preferably, the temperature compensation is realized by a cold end amplification compensation circuit: the temperature measuring device comprises a temperature measuring chip and a calculating unit, wherein the temperature measuring chip is placed at a cold end of a thermocouple input signal; the calculation unit calculates and outputs a temperature compensation value:
V'＝(273.15+T0+ΔT)×1μA/K×RL×Acold
Wherein, T0At the current cold end temperature, AColdThe constant 273.15 and the constant 1 muA/K are the inherent parameters of the temperature measuring chip for the gain of the cold end compensation amplifying circuit.
Preferably, the zero point compensation is realized by adopting a 3.3V voltage reference chip and a voltage follower circuit; the 3.3V voltage reference chip provides reference voltage, and the voltage follower circuit is in impedance matching with a post-stage circuit.
And the power supply filtering module (3) is used for filtering and stabilizing the power supply for supplying power to the thermocouple signal amplifying module (1) and the multi-path signal conditioning module (2).
The utility model discloses following beneficial effect has:
the utility model relates to a multichannel temperature signal conversion equipment can gather, enlarge, take care of the different material thermocouple temperature sensor output signal of multichannel, can calculate optimal ratio to circuit parameter according to the design demand, through cold junction compensation, zero adjustment, amplitude limiting filtering processing can make the collection precision improve greatly, has the advantage of the environment that the precision is high, the reliability is high and adapt to more complicacy. The provided detailed circuit design parameter calculation method can provide a complete design idea for the same type of design; the multi-channel temperature signal conversion device is used for acquiring and converting signals of the multi-channel thermocouple temperature sensors made of different materials, so that test equipment can be provided for different temperature measurement requirements of specific parts of the aerospace craft in the flying process, installation space is saved, and a design approach is provided for diversified use of the temperature sensors.
Drawings
Fig. 1 is a block diagram of the present invention;
FIG. 2 is a circuit diagram of a multi-channel thermocouple signal amplification module made of different materials;
FIG. 3 is a circuit diagram of a multi-path signal conditioning module;
FIG. 4 is a circuit diagram of a power filter module;
fig. 5 is a block diagram of output clipping filtering.
Wherein: the device comprises a 1-thermocouple signal amplification module, a 2-multipath signal conditioning module, a 3-power supply filtering module and a 4-output amplitude limiting filtering module.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings by way of examples.
Because the difference of thermocouple operating temperature, electromotive force, linearity etc. such as K type thermocouple, tungsten rhenium thermocouple, platinum rhodium thermocouple, needs temperature conversion equipment to each way of different materials, the thermocouple of different temperature measurement ranges disposes the parameter alone, and this just needs a method of calculating each way of circuit parameter specially, the utility model discloses not only given complete set design circuit also given concrete circuit parameter calculation method. The signal conversion device can be universally used by the multiple paths of thermocouple temperature sensors made of different materials, the parameter configuration is convenient, the calculation is simple, the design and development period is greatly shortened, and the device has guiding significance on the design and development of the temperature sensor temperature signal conversion device.
The utility model aims at the space craft needs the demand that a temperature signal conversion equipment gathered, changed the different material thermocouple temperature sensor signal of multichannel, derives the temperature signal conversion equipment of a kind of adaptation various types thermocouple and multichannel sharing of design to the computational process that the design was derived has been given. Through actual circuit verification, the method has the advantages that circuit parameters can be flexibly configured and the output range can be adjusted according to technical requirements, the defect of large thermocouple temperature measurement error is overcome by a multi-path shared absolute temperature measurement chip hardware compensation mode, the device cost is saved, cold ends of all paths of thermocouples are in the same temperature environment, and the measurement accuracy, the sensitivity and the linearity of the thermocouple sensor are improved.
The utility model provides a its technical problem take following technical scheme to realize:
a multi-channel temperature signal conversion device is characterized in that: the circuit comprises a plurality of paths of thermocouple input signal amplification modules 1 made of different materials, a plurality of paths of signal conditioning modules 2, a power supply filtering module 3 and an output amplitude limiting filtering module 4. The input of the conversion device comprises a plurality of paths of thermocouple sensor signals made of different materials and positive and negative power supply input signals, and the output is a plurality of paths of conditioned voltage signals. Structurally, a positive power supply and a negative power supply are connected to a power supply filtering module 3 for filtering, and then the filtered positive power supply and the filtered negative power supply respectively supply power for a plurality of paths of thermocouple signal amplifying modules 1 and a plurality of paths of signal conditioning modules 2 which are made of different materials; the signals of the multiple paths of thermocouples made of different materials are input into an amplification module 1 for signal amplification, then the amplified signals are input into a signal conditioning module 2 for cold end compensation zero adjustment signal accumulation, and finally the signals are output through an amplitude limiting filtering module 4.
The input signals are output signals of thermocouple temperature sensors made of various different materials, and circuit parameters such as gain resistors, compensation resistors and zero point adjusting resistors need to be set for each path of signals according to the characteristics of the thermocouple made of various materials and the signal output range.
The power supply filtering module has the function of power supply filtering, and carries out filtering and EMC protection on input positive and negative power supplies through a capacitor, an inductor and a TVS tube, so that the power supply voltage is stable, and the interference of power supply disturbance on signals is reduced.
The multi-channel thermocouple input signal amplification module 1 for different materials amplifies microvolt level signals input by a temperature sensor to a volt level for a rear-stage conditioning circuit, selects an instrument amplifier chip powered by a positive power supply and a negative power supply, and has high amplification factor.
The selection of the signal amplification gain of the multi-channel thermocouple signal amplification module made of different materials is determined by the temperature measurement range and the output voltage range of the thermocouple wire, and the relation is satisfied as follows:
wherein G is the amplification gain, UO (full)For the upper limit, U, of the output of the converter deviceO (zero)For the lower limit, U, of the output of the converter devicein(max)/Uin(min)The index values corresponding to the highest temperature and the lowest temperature in the working temperature range of the thermocouples made of different materials are obtained by checking a thermocouple index table.
The gain resistor with proper resistance value is selected to ensure that the amplification gain of the amplification module meets the design requirement and satisfies the relation:
where G is the amplification gain and R isGAs an amplifier-inherent parameter, R1、R2For gain resistance, R can be calculated by the above formula1、R2The resistance value.
The multi-channel signal conditioning module consists of a temperature compensation circuit, a zero point adjusting circuit and a signal accumulation circuit and is used for accumulating signals of the thermocouple input amplification voltage, the cold end compensation voltage and the zero point adjusting voltage.
The output relationship is as follows:
Voutn＝(Vn1+Vn2)-Vn3
wherein, VoutnRepresents the output voltage, V, of the temperature signal after the nth path of conditioningn1Represents the output voltage, V, of the nth input signal amplification block 1n2Indicating the output voltage, V, of the nth path of the cold-end compensation circuitn3And represents the output voltage of the nth zero point adjustment circuit.
The temperature measurement chip of cold junction compensating circuit places near thermocouple input signal cold junction, can convert temperature signal into voltage signal, through the amplification of specific multiplying power for cold junction compensating circuit output voltage equals with thermocouple cold junction temperature variation voltage, and this is according to the thermocouple signal design explanation of a kind, and concrete design does:
the thermoelectric potential of the thermocouple meets the formula by taking 0 ℃ as a reference point for convenient calculation
E(T,T0)＝E(T,0)-E(T0,0)
When the cold end temperature changes by delta T, the thermocouple electromotive force is
E(T,T0+ΔT)＝E(T,0)-E(T0+ΔT,0)
At this time, the electromotive force variation of the thermocouple is
ΔE＝E(T,T0)-E(T,T0+ΔT)＝E(T0+ΔT,0)-E(T0,0)
The voltage is amplified by the amplifying module and then output to the cold end of the thermocouple of the conditioning circuit, and the change voltage is G delta E.
Designing a temperature compensation circuit according to a temperature compensation chip AD590 manual, and deducing a relation between compensation voltage output and temperature as follows:
V＝(273.15+T0)×1μA/K×RL×Acold
Wherein V is the output voltage of the cold end compensation circuit, T0Current cold end temperature, RLIs temperatureChip output resistor, AColdIn order to compensate the gain of the amplifying circuit, the constants 273.15 and 1 muA/K are intrinsic parameters of the absolute temperature measuring chip.
Because the temperature chip is put together with the thermocouple cold junction, when cold junction temperature variation delta T, the compensating voltage output is:
V'＝(273.15+T0+ΔT)×1μA/K×RL×Acold
RLThe output variation voltage of the compensating circuit at the time is taken to be 1000 omega (unit mV)
ΔV＝V'-V＝ΔT×ACold
The compensation of the voltage change of the cold end of the thermocouple according to the compensation circuit comprises the following steps:
GΔE＝ΔV＝G[E(T0+ΔT,0)-E(T0,0)]＝ΔT×Acold
Derived from the above equation:
the above formula can be seen
The slope K of the temperature electromotive force curve of the thermocouple and the working temperature range of the temperature signal conversion device are
Taking 10-20 temperature points in the temperature range, searching thermocouple graduation table to obtain electromotive force value corresponding to temperature, obtaining K value by least square fitting, determining amplification gain G, and obtaining amplification gain A of compensation circuit by multiplicationCold。
Design compensation circuit amplification gain A in actual circuitColdComprises the following steps:
wherein R is8、R9、R10Gain ofAnd (3) resistance, and obtaining a proper gain resistance value through the formula.
The zero point adjusting circuit is composed of a 3.3V voltage reference chip and a voltage follower circuit, the 3.3V voltage reference chip provides high-precision reference voltage, the voltage follower circuit is used for performing impedance matching with a post-stage circuit, the loading capacity is improved, and the specific design idea and the adjusting resistance value are calculated as follows:
and setting the cold end as 0 ℃, and calculating the characteristic condition that the temperature measuring end of the thermocouple is a measuring range off line:
the output of the amplifying module is
Vn1(mV)＝G×Uin(min)，
The output of the cold end compensation circuit is
Vn2(mV)＝ACold×273.15，
The zero setting circuit output is
Vn3＝(Vn1+Vn2)-UO (zero)
By calculation, V can be obtainedn3Design of the actual circuit Vn3Determined by the zeroing resistance value:
the zero-setting resistance value meeting the design requirement can be selected through the formula.
The output amplitude limiting and filtering module has the function of limiting the output of the conversion device within a specified voltage range through the positive and negative amplitude limiting diodes, and the resistors and the capacitors complete output impedance matching and filtering.
Example (b):
the utility model discloses an in the concrete implementation, temperature sensor is first the way: the output voltage range of the W-Re 3-W-Re 25 thermocouple is 0-2000 ℃; and a second path: the output voltage range of the W-Re 3-W-Re 25 thermocouple is 0-2000 ℃; and a third path: the K-type thermocouple has an output voltage range of-30 ℃ to +1000 ℃; and a fourth path: the K-type thermocouple has an output voltage range of-30 to +600 ℃.
The utility model discloses an in the concrete implementation, adopt dual supply 15V power supply, input signal amplification module has specifically adopted 4 AD8221 amplifiers, and configurable magnification reaches 300 times, input common mode voltage 1.15V.
The utility model discloses an in the concrete implementation, 4 way input signal amplification module's magnification respectively is
The utility model discloses an in the concrete implementation, what absolute type temperature measurement chip adopted is the AD590 chip, and this chip measurable temperature range is-55 ~ 150 ℃, and the precision is 1 ℃.
The utility model discloses an in the concrete implementation, 4 way cold junction compensation module's the amplifier circuit part's amplification gain is 1.43, 4.37, 7.11 respectively, then cold junction compensation module's output voltage is respectively:
V02_1＝(273.15+T0)×1μA/K×1000×1.43＝(273.15+T0)×1.43mV/K
V02_2＝(273.15+T0)×1μA/K×1000×1.43＝(273.15+T0)×1.43mV/K
V02_3＝(273.15+T0)×1μA/K×1000×4.37＝(273.15+T0)×4.37mV/K
V02_4＝(273.15+T0)×1μA/K×1000×7.11＝(273.15+T0)×7.11mV/K
the utility model discloses an in the concrete implementation, owing to require 4 ways temperature sensor output voltage scope to be +0.2V 0.1- +4.8V 0.1. Therefore, the output voltage of the zero point adjustment module is calculated as follows:
Vo3_1＝190.84mV
Vo3_2＝190.84mV
Vo3_3＝868.21mV
Vo3_4＝1539.24mV
the utility model discloses an in the concrete implementation, the final output voltage signal of amplitude limiting filtering module is:
VOUT＝(VO1+VO2)-VO3。
in summary, the above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A multi-channel temperature signal conversion device is characterized by comprising a thermocouple input signal amplification module (1), a multi-channel signal conditioning module (2) and an output amplitude limiting filtering module (4);
the thermocouple input signal amplification module (1) comprises a plurality of amplification submodules, and each amplification submodule is used for amplifying a temperature signal acquired by a thermocouple sensor connected to the front end of the amplification submodule; wherein, the amplification gain of each path of amplification submodule on the temperature signal is determined according to the temperature measurement range and the output voltage range of the thermocouple wire of the thermocouple sensor, and the relationship is satisfied:
wherein G is the amplification gain, UO (full)For the upper limit, U, of the output of the converter deviceO (zero)For the lower limit, U, of the output of the converter devicein(max)And Uin(min)Dividing values corresponding to the highest temperature and the lowest temperature of the working temperature ranges of all the accessed thermocouple sensors respectively;
the signal conditioning module (2) is used for respectively carrying out error compensation on the amplified temperature signals output by each path of amplification sub-module;
and the amplitude limiting and filtering module (4) is used for adjusting the temperature signal after the error compensation to a set range and outputting the temperature signal.
2. The multi-channel temperature signal conversion device according to claim 1, wherein the thermocouple input signal amplification module (1) is implemented by using an AD8221 amplifier.
3. The multi-channel temperature signal conversion device of claim 1, wherein said error compensation includes temperature compensation and zero point compensation.
4. A multi-channel temperature signal conversion device as claimed in claim 3, wherein said temperature compensation is implemented using a cold end amplification compensation circuit: the temperature measuring device comprises a temperature measuring chip and a calculating unit, wherein the temperature measuring chip is placed at a cold end of a thermocouple input signal; the calculation unit calculates and outputs a temperature compensation value:
V'＝(273.15+T0+ΔT)×1μA/K×RL×Acold
Wherein, T0At the current cold end temperature, AColdThe constant 273.15 and the constant 1 muA/K are the inherent parameters of the temperature measuring chip for the gain of the cold end compensation amplifying circuit.
5. A multi-channel temperature signal conversion device as claimed in claim 3, wherein said zero point compensation is implemented using a 3.3V voltage reference chip and a voltage follower circuit; the 3.3V voltage reference chip provides reference voltage, and the voltage follower circuit is in impedance matching with a post-stage circuit.
6. A multiple temperature signal conversion device according to claim 3, further comprising a power supply filtering module (3) for filtering and stabilizing the power supply for supplying power to the thermocouple input signal amplifying module (1) and the multiple signal conditioning module (2).
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117168758A (en) * | 2023-11-01 | 2023-12-05 | 中国空气动力研究与发展中心空天技术研究所 | Application method of hypersonic flight test parameter test system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117168758A (en) * | 2023-11-01 | 2023-12-05 | 中国空气动力研究与发展中心空天技术研究所 | Application method of hypersonic flight test parameter test system |
| CN117168758B (en) * | 2023-11-01 | 2024-01-23 | 中国空气动力研究与发展中心空天技术研究所 | Application method of hypersonic flight test parameter test system |
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