CN102426066A - Switching detection circuit using multi-channel PT100 thermistors as temperature sensor - Google Patents
Switching detection circuit using multi-channel PT100 thermistors as temperature sensor Download PDFInfo
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- CN102426066A CN102426066A CN2011102880657A CN201110288065A CN102426066A CN 102426066 A CN102426066 A CN 102426066A CN 2011102880657 A CN2011102880657 A CN 2011102880657A CN 201110288065 A CN201110288065 A CN 201110288065A CN 102426066 A CN102426066 A CN 102426066A
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Abstract
The invention relates to a switching detection circuit using multi-channel PT100 thermistors as a temperature sensor. The circuit comprises: a low temperature-drift constant current source, two 8-channel electronic switches, a high precision reference voltage source and a rail to rail double-channel high-precision operational amplifier. In the circuit, the PT100 thermistors are used to be the temperature sensor to perform temperature measurement. A current output by the constant current source flows through the PT100 so that a voltage signal which can show a linear change with the temperature change is generated on two ends. The two electronic switches are used to switch access and detection of the eight PT100s in the circuit. The reference voltage source and the operational amplifier are used to adjust the output voltage signal. The simple electronic switches are used in the circuit to perform switching. The detection of the eight-channel PT100s can be realized. Compared to a traditional PT100 detection circuit, by using the switching detection circuit of the invention, a lot of electronic components can be saved and a circuit board area can be reduced. Power consumption is reduced. Operation is stable and reliable and an application effect is very substantial.
Description
Technical field
The present invention relates to a kind of temperature sensing circuit, particularly a kind of change detection circuit that adopts multichannel PT100 thermistor as temperature sensor.
Background technology
At present, at power plant, cement mill, steel mill, mine and coastal dock, equipment such as the motor of long-time running and bearing the over temperature and heat fault occurs through regular meeting, also possibly cause the damage of entire equipment when serious, even cause the generation of personal injury; So must detect the temperature of these equipment in real time, report to the police during high temperature and perhaps shut down, to prevent device damage.Traditional detection method is motor or bearing producer pre-buried a plurality of PT100 thermistors on the equipment of its application, uses PT100 as temperature sensor then, is connected on the special-purpose temperature monitor that other watch-dog manufacturer produces and reads the PT100 temperature.
The circuit theory of traditional detection PT100 instrument mainly is: the resistance of PT100 is linear change with temperature; The low temperature drift steady state value electric current that uses constant current source to produce flows through PT100; It is linear that its voltage also is, and behind amplifying circuit adjustment voltage signal, uses its magnitude of voltage of ADC conversion to be digital value; Re-use MCU and read this numerical value, draw its measuring point temperature value through after the computing.But there is a very big shortcoming in this testing circuit; A cover testing circuit can only detect a PT100 thermistor exactly; If the pre-buried a plurality of PT100 of motor are to detect the temperature of diverse location; The then corresponding with it detecting instrument that same quantity need to be installed, the perhaps testing circuit of built-in same quantity in the detecting instrument causes high investment, the poor efficiency of detector; And complicated operation, less reliable.
Therefore, provide a kind of simple in structure, reasonable in design, easy and simple to handle, dependable performance, practical function adopts the change detection circuit of multichannel PT100 thermistor as temperature sensor significantly, becomes one of these those skilled in the art problem anxious to be addressed.
Summary of the invention
The objective of the invention is to overcome above-mentioned weak point, a kind of simple in structure, reasonable in design, dependable performance, easy and simple to handle, the employing multichannel PT100 thermistor of effectively the increasing work efficiency change detection circuit as temperature sensor is provided.
In other words, technical matters to be solved by this invention is that a kind of utilization factor is high, input cost is low, the multichannel PT100 of stable and reliable operation detects sample circuit for the equipment that needs multiple spot PT100 temperature detection provides.
For realizing that the technical scheme that above-mentioned purpose the present invention is adopted is: a kind of change detection circuit that adopts multichannel PT100 thermistor as temperature sensor is characterized in that said circuit comprises that it is two magnitude voltage signals amplification adjustment discharge circuit that core is formed that a low temperature drift constant current source, two 8 channel electron change-over switches, a high-accuracy reference voltage source and the high-accuracy amplifier of track to track two-way low temperature drift reach with it;
And be provided with 8 PT100 thermistors and be connected with low temperature drift constant-current source circuit output terminal as the temperature sensor thermometric;
Said low temperature drift constant-current source circuit uses constant pressure source, triode and build-out resistor to build, and connects the common point of an electronic switch, corresponding 8 road PT100 thermistors that connect of 8 passages of this electronic switch; And the voltage sample point of 8 PT100 of the corresponding connection of 8 passages that use another electronic switch, its common port connects amplifier, the external analog/digital signal conversion device of output terminal; Said accurate reference voltage connects amplifier.
Said two 8 channel electron change-over switches, the common point of one of them electronic switch connects the output of constant current source, and its 8 passages connect 8 road PT100 thermistors as the steady current output terminal, another termination power cathode of thermistor; And using the voltage signal sampling point of 8 passages of another electronic switch as these 8 PT100 of input end connection, its common port output voltage signal connects discharge circuit.
Said electronic switch adopts 8 passages or expands by the multiple relation, and corresponding expansion is provided with the PT100 thermistor.
The invention has the beneficial effects as follows: the present invention can connect and measures nearly 8 the road or more PT100 thermistor, uses the DC5V can normal and stable work, and working current is less than 15mA, energy-conservation low-power consumption; Programming devices such as circuit of the present invention can external single-chip microcomputer, ARM switch the interface channel of 8 road PT100, and through the adjustment discharge circuit, read outside ADC numerical value, and draw the Temperature numerical that 8 points are surveyed after calculating.This circuit uses simple electronic switch to switch, realize 8 the road or more PT100 detect, compare traditional P T100 testing circuit, have the advantage that can practice thrift electronic devices and components in a large number and dwindle board area; It is simple in structure, and is reasonable in design, easy and simple to handle, and reduces power consumption, stable and reliable operation, obvious application effect.
Description of drawings
Fig. 1 is a circuit block diagram of the present invention;
Fig. 2 is circuit theory diagrams of the present invention;
Fig. 3 is a channel switching circuit part equivalent resistance circuit diagram of the present invention;
Among the figure:
U1, U2 are 8 channel electron change-over switches, and U3A is one-level discharge circuit, U3B secondary discharge circuit, and U4 voltage source and Q1 triode are formed constant current source, and U5 is a reference voltage source;
J1 is for power supply and control signal is imported, the voltage signal output interface;
P6, P7 are 8 road PT100 access interfaces;
R1, R2 are current source output current adjustment build-out resistor;
R3, R4 are that the voltage signal multiple of first order discharge circuit amplifies build-out resistor;
R5, R6, R7, R8 are the voltage signal zeroing output build-out resistor of second level discharge circuit;
R9 is the current-limiting resistance of discharge circuit voltage signal output;
C1, C2, C3, E1 are respectively the decoupling capacitance of U1, U2, U3, U5;
C4 is the filter capacitor of discharge circuit output voltage signal;
U1R, U2R are two electronic switch passage equivalent internal resistances.
Embodiment
Below in conjunction with accompanying drawing and preferred embodiment, to according to embodiment provided by the invention, structure,
Details are as follows for characteristic:
Like Fig. 1-shown in Figure 3; A kind of change detection circuit that adopts multichannel PT100 thermistor as temperature sensor; This circuit comprises a low temperature drift constant-current source circuit, two 8 channel electron change-over switch integrated circuit (hereinafter to be referred as electronic switch); High-accuracy (output error≤a 0.2%) reference voltage source integrated circuit, and track to track two-way low temperature drift (temperature coefficient≤0.5uV/ ℃) operational amplifier integrated circuit (hereinafter to be referred as amplifier) and amplify with its two magnitude voltage signals that be core is formed and to adjust discharge circuit.
And be provided with 8 PT100 thermistors and be connected with low temperature drift constant-current source circuit output terminal as the temperature sensor thermometric; The electric current of constant current source output flows through the PT100 thermistor; Make its two ends produce the voltage signal that can be linear change with temperature change; Said two 8 channel electron change-over switches are used for switching access and the detection of 8 PT100 thermistors at this circuit, and reference voltage source and discharge circuit are used for the adjustment output of voltage signal.
Said low temperature drift constant-current source circuit uses constant pressure source, triode and build-out resistor to build, and connects the common point of an electronic switch, corresponding 8 road PT100 thermistors that connect of 8 passages of this electronic switch; And the voltage sample point of 8 PT100 of the corresponding connection of 8 passages that use another electronic switch, its common port connects amplifier, the external free ADC of output terminal (analog/digital signal conversion device); Accurate reference voltage connects amplifier.
Said low temperature drift constant-current source circuit uses constant pressure source, triode and build-out resistor to build, and connects the common point of an electronic switch, for the PT100 thermistor of place in circuit provides thermometric to use steady current; Said circuit only uses a cover constant-current source circuit to detect, and can simplify testing circuit design element quantity and power consumption greatly.
Described two electronic switch, the common point of one of them electronic switch connects the output of constant current source, and its 8 passages connect 8 road PT100 thermistors as the steady current output terminal, another termination power cathode of thermistor; And using the voltage signal sampling point of 8 passages of another electronic switch as these 8 PT100 of input end connection, its common port output voltage signal connects discharge circuit; Programming devices such as circuit of the present invention can external single-chip microcomputer, ARM; The channel selecting input pin that connects two electronic switch; And input Transistor-Transistor Logic level control signal, can arbitrary PT100 thermistor be switched this circuit of access and detect, there is not the sequence limit of detection; Switch the interface channel of 8 road PT100, and through adjusting discharge circuit, reading outside ADC numerical value.
The common port output voltage signal of another electronic switch inserts described discharge circuit; The common port of electronic switch at first connects the input end of first order discharge circuit, and voltage signal is amplified, and the output of first order discharge circuit connects second level discharge circuit input, and voltage signal is returned to zero; The output terminal of accurate reference voltage connects the second level another input end of discharge circuit provides the zeroing voltage signal; Second level discharge circuit output terminal can external free ADC (analog/digital signal conversion device); Carry out voltage signal acquisition; Can adjust the output voltage signal enlargement factor through the build-out resistor of adjustment first order discharge circuit; The output voltage signal of accurate reference voltage that can be through adjustment second level discharge circuit is adjusted the zeroing benchmark of output voltage signal; Can be through two-way discharge circuit adjustment output voltage signal scope, to adapt to different temperature-measuring ranges and ADC reference voltage.
Said circuit can be expanded according to identical circuit theory, can have the more electronic switch of hyperchannel number (for example 16 channel electron change-over switches or more multiples) through replacing, realizes switching the PT100 thermistor that inserts and detect corresponding greater number.
Below in conjunction with circuit theory diagrams the present invention is done and to further describe:
(1) external circuits can use power supply and control signal input, voltage signal output interface J1 to be the power supply of this multichannel PT100 testing circuit; Supply voltage DC5V; Supply current>15mA; Outer contact ADC on said power supply and control signal input, the voltage signal output interface J1 finally exports through adjusted PT100 voltage signal, can connect the analog to digital converter sampling; Outer contact CODE0 ~ CODE2 is the external circuit control signal wire, can use the GPIO output mode of single-chip microcomputer or ARM to connect, and the multichannel PT100 access point of controlling this testing circuit switches, and selects logic as shown in table 1:
Table 1
| The CODE2 level | The CODE1 level | The CODE0 level | Insert the PT100 numbering |
| L | L | L | PT100-1 |
| L | L | H | PT100-2 |
| L | H | L | PT100-3 |
| L | H | H | PT100-4 |
| H | L | L | PT100-5 |
| H | L | H | PT100-6 |
| H | H | L | PT100-7 |
| H | H | H | PT100-8 |
Said 8 road PT100 access interface P6 and P7 are the access point of 8 road PT100.
(2) because the output of current source components and parts is generally influenced by environmental temperature; Can not satisfy the request for utilization of thermometric; So constant-current source circuit uses reference voltage source, triode and the build-out resistor of low temperature drift to build, and not only falls low temperature drift, and can reduce cost; This constant current source U4 selects the reference voltage source LM285-ADJ of band feedback for use; Triode Q1 uses the 2N3906 amplified current; Build-out resistor R1 and R2 are respectively 1.2 K Ω and 120K Ω, and the output current computing formula of this constant current source is IOUT=1.24V/R1, and actual output current is about 1.03mA.
(3) owing to have certain internal resistance between each inner passage of electronic switch chip and its common port; And Ou Buding more than hundred from tens Europe to; If directly measure common port voltage; Can count its internal resistance voltage, cause under the similarity condition magnitude of voltage discrete excessive, so can not directly use; This testing circuit adopts two-way 8 channel electron change-over switches to switch; (it is as shown in Figure 3 that its internal resistance and PT100 are connected equivalent electrical circuit directly to measure the PT100 voltage; U1R and U2R are respectively the internal resistance of two electronic switch passages; Iin is the current source input, and Vout is a voltage output signal), avoid the problems referred to above.Two electronic switch U1 and U2 select 74HC4051 for use, use same coding definition, and output is corresponding one by one with the input channel numbering, need only three selection wires of use like this and just can select identical passage, complete operation.
(4) after the sampled voltage signal of PT100 is exported by U2 common port X, get into two-way track to track amplifier adjustment circuit this signal is adjusted, to be suitable for the ADC conversion in the external circuit; Because this circuit is the DC5V power supply, covers full scale for making output voltage signal as far as possible, so select high-accuracy track to track two-way amplifier (U3) for use, model is TLV2252; First order amplifier U3A makees the multiplication amplifying circuit, and voltage signal is enlarged into 21 times of input end, and computing formula is VOUT=VIN* (R4/R3+1); Second level amplifier U3B makees subtraction circuit; Be used for the zeroing operation; Computing formula is VOUT=VIN+-VIN-, and the PT100 output voltage zeroing during for suitable 0 ℃ is the REF3020 reference voltage device (U5) of 2.048V and select reference voltage for use; The output voltage of this circuit is 1.03mA*100 Ω * 21-2.048V=0.115V in the time of 0 ℃ like this, to try one's best near 0V; Output voltage in the time of 300 ℃ is 1.03mA*212 Ω * 21-2.048V=2.54V, is applicable to that reference voltage is the ADC sampling of 2.56V; Survey lower temperature if desired and perhaps use the reference voltage of other ADC instead, then can the reference voltage device (U5) and the enlargement factor (being R3, R4) of this discharge circuit be adjusted accordingly;
As shown in Figure 2; In the said two stage amplifer circuit, R3 connects positive input terminal and the power cathode of first order amplifier U3A, and R4 connects negative input end and the output terminal of U3A; R5 connects the output terminal of first order amplifier U3A and the positive input terminal of second level amplifier U3B; R6 connects positive input terminal and the power cathode of U3B, and R7 connects the output terminal of reference voltage source U5 and the negative input end of U3B, and R8 connects negative input end and the output terminal of U3B; R9 connects output terminal and the external free ADC of U3B, and C4 connects external free ADC and power cathode.
(5) output voltage of this testing circuit can use the inside ADC Direct Sampling of independent ADC or Chip Microcomputer A RM to detect, through just obtaining the Temperature numerical of PT100 institute measuring point after calculating; Use the GIPO of single-chip microcomputer or ARM that selection wire is carried out direct control selection ALT-CH alternate channel, switch the PT100 thermistor of place in circuit; Measure the PT100 of greater number if desired, then as long as just can realize by the quantity of this principle through expansion electronic switch TLV2252.
Above-mentioned with reference to embodiment to this employing multichannel PT100 thermistor as the detailed description that the change detection circuit of temperature sensor carries out, be illustrative rather than determinate; Therefore in the variation and the modification that do not break away under the general plotting of the present invention, should belong within protection scope of the present invention.
Claims (3)
1. a change detection circuit that adopts multichannel PT100 thermistor as temperature sensor is characterized in that said circuit comprises that it is two magnitude voltage signals amplification adjustment discharge circuit that core is formed that a low temperature drift constant current source, two 8 channel electron change-over switches, a high-accuracy reference voltage source and the high-accuracy amplifier of track to track two-way low temperature drift reach with it;
And be provided with 8 PT100 thermistors and be connected with low temperature drift constant-current source circuit output terminal as the temperature sensor thermometric;
Said low temperature drift constant-current source circuit uses constant pressure source, triode and build-out resistor to build, and connects the common point of an electronic switch, corresponding 8 road PT100 thermistors that connect of 8 passages of this electronic switch; And the voltage sample point of 8 PT100 of the corresponding connection of 8 passages that use another electronic switch, its common port connects amplifier, the external analog/digital signal conversion device of output terminal; Said accurate reference voltage connects amplifier.
2. employing multichannel PT100 thermistor according to claim 1 is as the change detection circuit of temperature sensor; It is characterized in that said two 8 channel electron change-over switches; The common point of one of them electronic switch connects the output of constant current source; Its 8 passages connect 8 road PT100 thermistors as the steady current output terminal, another termination power cathode of thermistor; And using the voltage signal sampling point of 8 passages of another electronic switch as these 8 PT100 of input end connection, its common port output voltage signal connects discharge circuit.
3. employing multichannel PT100 thermistor according to claim 1 it is characterized in that said electronic switch adopts 8 passages or concerns expansion by multiple, and corresponding expansion is provided with the PT100 thermistor as the change detection circuit of temperature sensor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2011102880657A CN102426066A (en) | 2011-09-26 | 2011-09-26 | Switching detection circuit using multi-channel PT100 thermistors as temperature sensor |
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| CN2011102880657A CN102426066A (en) | 2011-09-26 | 2011-09-26 | Switching detection circuit using multi-channel PT100 thermistors as temperature sensor |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102749945A (en) * | 2012-06-12 | 2012-10-24 | 王博思 | Control terminal and system for indoor temperature |
| CN103542954A (en) * | 2013-10-10 | 2014-01-29 | 上海发电设备成套设计研究院 | High-precision thermocouple input module and measurement method |
| CN105548714A (en) * | 2016-02-02 | 2016-05-04 | 中国人民解放军63908部队 | Missile-borne resistor adaptive measurement device on barrel missile and method |
| CN107247188A (en) * | 2017-08-10 | 2017-10-13 | 江南工业集团有限公司 | A kind of portable electric parameter intelligent detector |
| CN109240255A (en) * | 2017-07-10 | 2019-01-18 | 联合汽车电子有限公司 | Signal detection interface circuit, system and signal detecting method |
| CN109991295A (en) * | 2019-04-29 | 2019-07-09 | 福建海纳欣生物科技有限公司 | A kind of intelligent pH combination electrode and its implementation with temperature drift self-regulation |
| CN110108380A (en) * | 2019-05-30 | 2019-08-09 | 无锡市百川科技股份有限公司 | A kind of precise temperature measurement system applied to biphenyl heater box in weaving elasticizer |
| CN110132444A (en) * | 2018-02-08 | 2019-08-16 | 展讯通信（上海）有限公司 | Temperature sensing circuit |
| CN110940435A (en) * | 2019-11-29 | 2020-03-31 | 苏州长风航空电子有限公司 | 0 ~ 5V output Pt100 temperature signal conditioning circuit |
| CN111141406A (en) * | 2019-12-31 | 2020-05-12 | 深圳市科陆电子科技股份有限公司 | PT100 temperature measurement system and temperature measurement method |
| CN111583589A (en) * | 2020-03-25 | 2020-08-25 | 国网辽宁省电力有限公司大连供电公司 | Progressive operation detection system for early warning and protection large machinery of power pipe gallery |
| CN112461391A (en) * | 2020-11-11 | 2021-03-09 | 杭州仰仪科技有限公司 | Multi-channel thermistor iterative temperature measurement system in lithium battery isothermal calorimeter |
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Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102749945A (en) * | 2012-06-12 | 2012-10-24 | 王博思 | Control terminal and system for indoor temperature |
| CN102749945B (en) * | 2012-06-12 | 2015-03-11 | 王博思 | Control terminal and system for indoor temperature |
| CN103542954A (en) * | 2013-10-10 | 2014-01-29 | 上海发电设备成套设计研究院 | High-precision thermocouple input module and measurement method |
| CN103542954B (en) * | 2013-10-10 | 2015-12-09 | 上海发电设备成套设计研究院 | A kind of high-precision thermocouple input module and measuring method |
| CN105548714A (en) * | 2016-02-02 | 2016-05-04 | 中国人民解放军63908部队 | Missile-borne resistor adaptive measurement device on barrel missile and method |
| CN109240255A (en) * | 2017-07-10 | 2019-01-18 | 联合汽车电子有限公司 | Signal detection interface circuit, system and signal detecting method |
| CN107247188A (en) * | 2017-08-10 | 2017-10-13 | 江南工业集团有限公司 | A kind of portable electric parameter intelligent detector |
| CN110132444A (en) * | 2018-02-08 | 2019-08-16 | 展讯通信（上海）有限公司 | Temperature sensing circuit |
| CN109991295A (en) * | 2019-04-29 | 2019-07-09 | 福建海纳欣生物科技有限公司 | A kind of intelligent pH combination electrode and its implementation with temperature drift self-regulation |
| CN109991295B (en) * | 2019-04-29 | 2023-12-08 | 福建海纳欣生物科技有限公司 | Intelligent pH composite electrode with temperature drift self-adjustment function and implementation method thereof |
| CN110108380A (en) * | 2019-05-30 | 2019-08-09 | 无锡市百川科技股份有限公司 | A kind of precise temperature measurement system applied to biphenyl heater box in weaving elasticizer |
| CN110940435A (en) * | 2019-11-29 | 2020-03-31 | 苏州长风航空电子有限公司 | 0 ~ 5V output Pt100 temperature signal conditioning circuit |
| CN111141406A (en) * | 2019-12-31 | 2020-05-12 | 深圳市科陆电子科技股份有限公司 | PT100 temperature measurement system and temperature measurement method |
| CN111583589A (en) * | 2020-03-25 | 2020-08-25 | 国网辽宁省电力有限公司大连供电公司 | Progressive operation detection system for early warning and protection large machinery of power pipe gallery |
| CN112461391A (en) * | 2020-11-11 | 2021-03-09 | 杭州仰仪科技有限公司 | Multi-channel thermistor iterative temperature measurement system in lithium battery isothermal calorimeter |
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Application publication date: 20120425 |