CN108008162A - A kind of separator of the adjustable two-wire system current sensor exported in proportion - Google Patents
A kind of separator of the adjustable two-wire system current sensor exported in proportion Download PDFInfo
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- CN108008162A CN108008162A CN201810031835.1A CN201810031835A CN108008162A CN 108008162 A CN108008162 A CN 108008162A CN 201810031835 A CN201810031835 A CN 201810031835A CN 108008162 A CN108008162 A CN 108008162A
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- 230000033228 biological regulation Effects 0.000 claims abstract description 33
- 238000005070 sampling Methods 0.000 claims abstract description 18
- 230000005611 electricity Effects 0.000 claims description 12
- 230000008859 change Effects 0.000 claims description 9
- 238000005259 measurement Methods 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 3
- 230000011664 signaling Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000007717 exclusion Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 208000025274 Lightning injury Diseases 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 235000013399 edible fruits Nutrition 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000009123 feedback regulation Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000005211 surface analysis Methods 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/20—Modifications of basic electric elements for use in electric measuring instruments; Structural combinations of such elements with such instruments
- G01R1/203—Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
- G01R19/2506—Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details concerning sampling, digitizing or waveform capturing
- G01R19/2509—Details concerning sampling, digitizing or waveform capturing
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
The present invention relates to a kind of separator of the adjustable two-wire system current sensor exported in proportion, wherein, precision resistance is connected between the first output terminal and input terminal；Current signal is switched to voltage signal by precision resistance, and the cathode of precision resistance both end voltage is connected with one end of first resistor, and anode is connected with the inverting input of operational amplifier；The other end of first resistor is connected by digital regulation resistance with the second output terminal, and the other end of first resistor is also connected with the normal phase input end of operational amplifier；The output terminal of operational amplifier is connected with one end of sampling resistor；The resistance value of precision resistance is much smaller than first resistor and the resistance value of digital appliances；Digital regulation resistance is also connected with the microcontroller equipped with key circuit.In the case of without modifying to measuring instrument one sensor can use the present invention for the measuring instrument of two different measurement ranges.
Description
Technical field
The present invention relates to current acquisition technical field, more particularly to a kind of adjustable two-wire system electric current exported in proportion
The separator of sensor.
Background technology
Two-wire system sensor is not easy to be influenced by parasitic thermocouple and along wire resistance pressure drop and temperature drift, can use very cheap
Thinner conducting wire, a large amount of cables and mounting cost can be saved.Due to the above-mentioned advantage of two-wire system sensor so that most of
Sensor develops to two-wire system.The both threads that the both threads that measuring instrument is drawn directly are drawn with two-wire system sensor are connected, and carry
For the voltage needed for working sensor.It is expensive due to sensor, for the cost-effective use for needing to reduce sensor
Quantity, also there is some special circumstances, and the instrument of the different measurement ranges of two collection current signals is needed at the same time using a biography
The electric current of sensor.Due to the difference of two measuring instrument functions, the current signal of collection is not all full needed for two measuring instruments
Foot 1:1 relation.Therefore, it is necessary to a kind of dress that a sensor can be made to be used for the measuring instrument of two different measurement ranges
Put.
The content of the invention
The technical problems to be solved by the invention are to provide a kind of adjustable two-wire system current sensor exported in proportion
Separator, survey of the sensor for two different measurement ranges is made in the case of without modifying to measuring instrument
Measuring appratus uses.
The technical solution adopted by the present invention to solve the technical problems is：A kind of adjustable two wires exported in proportion is provided
The separator of current sensor processed, including precision resistance, operational amplifier and digital regulation resistance, the precision resistance are connected on
Between first output terminal and input terminal；Current signal is switched to voltage signal by the precision resistance, precision resistance both end voltage
Cathode is connected with one end of first resistor, and anode is connected with the inverting input of operational amplifier；The first resistor it is another
End is connected by digital regulation resistance with the second output terminal, the normal phase input end phase of the other end of first resistor also with operational amplifier
Even；The output terminal of the operational amplifier is connected with one end of sampling resistor；The resistance value of the precision resistance is much smaller than described the
The resistance value of one resistance and digital appliances；The digital regulation resistance is also connected with microcontroller, and the microcontroller is equipped with key circuit, leads to
Cross the digital signal that key change microcontroller is sent to digital regulation resistance and then change the resistance value of the digital regulation resistance, so as to change
Become the current ratio of the first output terminal and the second output terminal.
The resistance value of the sampling resistor is equal with the resistance value of the precision resistance.
The digital regulation resistance passes through I by a microcontroller2C bus communications data control.
The output terminal of the operational amplifier is also associated with negative-feedback circuit；The negative-feedback circuit includes triode, institute
State the base stage of triode with the output terminal of operational amplifier to be connected, emitter is grounded by 3rd resistor, collector and power end
It is connected.
Current-limiting resistance and zener diode, the current limliting electricity are also in series between the output terminal and ground of the operational amplifier
The connecting pin of resistance and zener diode is also connected with the base stage of triode.
First output terminal and the second output terminal are equipped with a full-bridge rectifier and decoupling capacitance, the decoupling capacitance
Both ends be also parallel with TVS pipe.
Beneficial effect
As a result of above-mentioned technical solution, compared with prior art, the present invention having the following advantages that and actively imitating
Fruit：The output current of one sensor is divided into two-way at the same time for the uses of two measuring instruments by the present invention, and can by by
Key selects the export ratio of two-way output end current signal, a sensor is made for the measuring instrument of two different measurement ranges
With.This satisfies wanting for some electric currents gathered at the same time with two different measuring instruments in special circumstances in a sensor
Ask, reduce the usage quantity of two-wire system current sensor, save cost, easy for installation, use is easy to operate.
Brief description of the drawings
Fig. 1 is the circuit diagram of the present invention；
Fig. 2 is the connection diagram when present invention uses.
Embodiment
With reference to specific embodiment, the present invention is further explained.It is to be understood that these embodiments are merely to illustrate the present invention
Rather than limit the scope of the invention.In addition, it should also be understood that, after reading the content taught by the present invention, people in the art
Member can make various changes or modifications the present invention, and such equivalent forms equally fall within the application the appended claims and limited
Scope.
Embodiments of the present invention are related to a kind of current splitters of two-wire system sensor, as shown in Figure 1, including accurate electricity
Hinder RCWith operational amplifier and digital regulation resistance R2, the precision resistance is connected on first for the first measuring instrument 1 of connection
Between output terminal and input terminal for connecting two-wire system sensor, for the current signal of two-wire system sensor to be converted to electricity
Press signal；The precision resistance RCCathode in the voltage signal at both ends is connected with one end of first resistor R1, anode and computing
The inverting input of amplifier is connected；The other end of the first resistor R1 and the normal phase input end phase of the operational amplifier
Even, the other end of the first resistor R1 also passes through digital regulation resistance R2 and the second output for connecting the second measuring instrument 2
End is connected；The output terminal of the operational amplifier and sampling resistor RSOne end be connected；The sampling resistor RSThe other end and
Two output terminals are connected；The sampling resistor RSOne end be also directly grounded；The precision resistance RCResistance value be much smaller than described first
Resistance R1 and digital regulation resistance R2；The digital regulation resistance R2 also passes through I2C buses are connected with microcontroller U0；The microcontroller U0
It is circumscribed with seven button K1~K8.
It can be seen from the above that the precision resistance for 2 Ω that connect in connection circuit of the measuring instrument 1 with sensor, will sense
Electric current in device is changed into voltage.The positive polarity is connected on first resistor R1, anode ground connection.Pass through first resistor R1 and numeral
" empty short " of the larger resistance of two resistance values of potentiometer R2 and operational amplifier and " void is disconnected " characteristic by B points voltage pull-down to-
VB, the second output end current I2 so can be obtained according to Kirchhoff's law, and I2 is with current output sensor ICChange
And change.
The output terminal of the operational amplifier is also associated with negative-feedback circuit；The negative-feedback circuit includes triode Q1,
The base stage of the triode Q1 is connected with the output terminal of operational amplifier, and emitter is grounded by 3rd resistor Re, collector with
Power end is connected.Current-limiting resistance Rm and zener diode Z are also in series between the output terminal and ground of the operational amplifier1, institute
Base stage of the connecting pin of current-limiting resistance Rm and zener diode Z1 also with triode Q1 is stated to be connected.
Triode Q1 is added to prevent the voltage of operational amplifier normal phase input end to be raised and lowered suddenly, in circuit to carry out
Feedback regulation, it is ensured that A points magnitude of voltage is 0.Current-limiting resistance Rm and zener diode Z1It can also avoid the base stage electricity of triode Q1
Press through big.
First output terminal and the second output terminal are equipped with a full-bridge rectifier so that when measuring instrument is reversed still
Can normal work.First output terminal and the second output terminal are equipped with decoupling capacitance C1 and C2, and decoupling capacitance C1 and C2 can
Ensure that circuit does not shake under long-term inductive load.The both ends of the decoupling capacitance are also parallel with TVS pipe Z1And Z2, TVS pipe Z1And Z2
The energy of moment overvoltage can be absorbed, prevents the energy such as lightning stroke, static discharge, surge from damaging current splitters.
Fig. 2 is the connection diagram when present invention uses.Wherein, IN3, OU3 end of current splitters respectively with two-wire system
The positive and negative terminal of sensor is connected, and the IN1 ends of current splitters are connected with+24V and the GND end of measuring device 1 respectively with OUT1 ends,
The IN2 ends of current splitters are connected with+24V and the GND end of measuring device 2 respectively with OUT2 ends.
Next the course of work of the present invention is illustrated with reference to Fig. 1, in Fig. 1, first resistor R1, current-limiting resistance Rm, the 3rd electricity
Hinder R3, precision resistance RC, sampling resistor RSChromatic circle resistance is used, wherein, first resistor R1, digital regulation resistance R2, current-limiting resistance
Rm, the resistance precision of 3rd resistor R3 are 1%, precision resistance RC, sampling resistor RSUsing the high-accuracy metal film resistors of RJ24,
Precision is 0.1%.Digital regulation resistance R2 uses AD5241BRZ1M chips.Microcontroller U1 uses STC89C51 chips.Button K0~
K8 uses the microswitch of 6*6*5mm.Exclusion P3 is 9 foot 10K exclusions.Operational amplifier uses LM358 or LM324 amplifier cores
Piece.Zener diode Z0For 1N4735.Current-limiting resistance RmWith zener diode Z0, can be to avoid the base voltage mistake of triode Q1
Greatly.Decoupling capacitance C1 and C2 are 10nF, ensure that circuit does not shake under long-term inductive load.The input terminal of two measuring instruments is all
There is a full-bridge rectifier, remain to work normally even if measuring instrument is reversed.Measuring instrument both ends are subjected to the high-energy punching of moment
When hitting, TVS pipe Z1And Z2Impedance value between both ends can be changed into high speed by Low ESR from high impedance, to absorb a wink
Between high current, its both end voltage clamp down on it is certain numerically so that the circuit element of protective current separator is from wink
The impact of state high voltage spikes.
Measuring instrument 1 is connected with sensor first, and the electric current flowed through in sensor is I1, passes through precision resistance RCBy electric current
Signal is converted to voltage signal V0, then V0=I1*RCAnalysis voltage signal V below0It is changed into the process of electric current I2：
Precision resistance R firstCThe voltage collected is V0, flow through the electric current Ic=V of first resistor R10/ R1, due to computing
The input terminal of amplifier can not possibly absorb electric current, then electric current Ic all flows through digital regulation resistance R2, then B point voltages VB=-Ic*
R2=-V0*R2/R1。
There was only sampling resistor R between 2 negative terminal of measuring instrument and whole transmitter circuitSWith digital regulation resistance R2, therefore institute
Some electric currents all flow through sampling resistor RSWith numerical value potentiometer R2.Digital regulation resistance R2 upper ends are virtual earth (0V), sampling resistor RSOn
End is GND.Therefore digital regulation resistance R2 and sampling resistor RSBoth end voltage is just the same, is equal to voltage VB, equivalent to sampling electricity
Hinder RSIt is in parallel with digital regulation resistance R2 to be used as current sampling resistor.Therefore circuit total current I2=VB/(RS//R2), if taking R2>
>RS, then I2=VB/RS=(R2/R1) * V0/RS, take RS=RCWhen, I2=(R2/R1) * I1.If it cannot meet R2>>RSAlso do not close
System, sampling resistor RSValue with digital regulation resistance R2 parallel connections is a fixed value, electric current I2 and voltage V0It is still linear relationship, by mistake
Poor proportionality coefficient can be eliminated in calibration.According to I2=(R2/R1) * I1, it is known that I2 and I1 are in a linear relationship, and proportionality coefficient is
R2/R1.Since first resistor R1 is fixed resistance, digital regulation resistance R2 is variable resistor, then passes through and adjusts digital appliances R2
Resistance value the electric current of the second output terminal of current splitters can be made to be zoomed in or out in multiple, and do not change substantially sensor collection
The primary current i.e. electric current of the first output terminal.
In order to adjust the resistance value of digital regulation resistance, single-chip minimum system is added.In order to easy to operate, if with the addition of
Dry button, the second different output current ratios can be selected by button.Wherein, digital regulation resistance R2 is chip
AD5241BRZ1M is I2C interface, there is 256 tap positions, the resistance value R at AB both endsABFor 1M Ω, R2=RWB=D*RAB/256+
The value range of 60 Ω, wherein D are 0~255 i.e. 0x00~0xFF.Microcontroller STC89C51 is simulated by I/O mouthfuls of P2.0, P2.1
I2C communicates, and is connected respectively with SCL, SDA pin of digital regulation resistance AD5241BRZ1M.First resistor R1 resistance values are 100K, are pressed
Lower button K1, microcontroller STC89C51 pass through I2C interface controls digital current potential to digital regulation resistance transmission digital signaling zero x33
199266 Ω (R2=R of device R2 resistance valuesWB=D*RAB/ 256+60=51*1M/256+60=199266 Ω), then I2=
(R2/R1) * I1=1.99266*I1≈2*I1, i.e. the second output end current and the first output end current output are than being 2:1；Press
Button K2, microcontroller STC89C51 send digital signaling zero x0D control digital regulation resistance R2 resistance values to digital regulation resistance
50838 Ω (R2=13*1M/256+60=50838 Ω), then I2=(R2/R1) * I1=0.50838*I1 ≈ 0.5*I1, i.e.,
Second output end current and the output of the first output end current are than being 1:2；Push button K3, microcontroller STC89C51 is to digital current potential
Device sends 101616 Ω (R2=26*1M/256+60=101616 of digital signaling zero x1A control digital regulation resistance R2 resistance values
Ω), then I2=(R2/R1) * I1=1.01616*I1 ≈ 1*I1, i.e. the second output end current and the first output end current export
Than for 1:1；It is other ratios that remaining button, which can control current splitters output current ratio as needed,.
In order to ensure A point voltages remain 0V, negative-feedback circuit is added.Lower surface analysis negative feedback process：If A points because
Certain reason is higher than 0V, then the output rise of 1 point of operational amplifier, and the rise of 3rd resistor R3 both end voltages, passes through 3rd resistor
The electric current of R3 becomes larger.Pass through sampling resistor RSElectric current also become larger, B point voltages are lower (negative more).The result is that pass through digital electricity
Position device R2 pulls down A point voltages.Conversely, if A points also can raise back 0V because certain reason is less than 0V by negative-feedback circuit.Always
It, the result of negative-feedback circuit keeps empty short, the i.e. A points voltage=0V of operational amplifier.
In addition to circuit is correct, the circuit normal work also require operational amplifier can single supply work, that is, do not having
In the case of having negative supply, input terminal still is able to receive 0V inputs, and can work normally.LM358/324 is most common and price
Minimum single supply op, power consumption 400uA/ can receive substantially per amplifier.
Therefore, the present invention by the output current ratio of key change current splitters, can make the electricity of a sensor
Flow measuring instrument use of the signal for two different measurement ranges, the electric current of the second output terminal can be 1 times of the first output terminal,
2 times, 1/2 times etc..Gathered at the same time in a sensor with two different measuring instruments in special circumstances this satisfies some
Electric current requirement, reduce the usage quantity of two-wire system current sensor, save cost, it is easy for installation, use operation letter
It is single.
Claims (6)
1. a kind of separator of the adjustable two-wire system current sensor exported in proportion, it is characterised in that including accurate electricity
Resistance, operational amplifier and digital regulation resistance, the precision resistance are connected between the first output terminal and input terminal；The accurate electricity
Current signal is switched to voltage signal by resistance, and the cathode of precision resistance both end voltage is connected with one end of first resistor, anode and fortune
The inverting input for calculating amplifier is connected；The other end of the first resistor is connected by digital regulation resistance with the second output terminal,
The other end of first resistor is also connected with the normal phase input end of operational amplifier；The output terminal of the operational amplifier and sampling electricity
One end of resistance is connected；The resistance value of the precision resistance is much smaller than the first resistor and the resistance value of digital appliances；The numeral electricity
Position device is also connected with microcontroller, and the microcontroller is equipped with key circuit, is sent by key change microcontroller to digital regulation resistance
Digital signal so that change the resistance value of the digital regulation resistance, so as to change the electric current ratio of the first output terminal and the second output terminal
Value.
2. the separator of the adjustable two-wire system current sensor exported in proportion according to claim 1, its feature
It is, the resistance value of the sampling resistor is equal with the resistance value of the precision resistance.
3. the separator of the adjustable two-wire system current sensor exported in proportion according to claim 1, its feature
It is, the digital regulation resistance passes through I by a microcontroller2C bus communications data control.
4. the separator of the adjustable two-wire system current sensor exported in proportion according to claim 1, its feature
It is, the output terminal of the operational amplifier is also associated with negative-feedback circuit；The negative-feedback circuit includes triode, and described three
The base stage of pole pipe is connected with the output terminal of operational amplifier, and emitter is grounded by 3rd resistor, and collector is connected with power end.
5. the separator of the adjustable two-wire system current sensor exported in proportion according to claim 1, its feature
It is, current-limiting resistance and zener diode, the current-limiting resistance is also in series between the output terminal and ground of the operational amplifier
Also it is connected with the connecting pin of zener diode with the base stage of triode.
6. the separator of the adjustable two-wire system current sensor exported in proportion according to claim 1, its feature
It is, first output terminal and the second output terminal are equipped with a full-bridge rectifier and decoupling capacitance, the decoupling capacitance
Both ends are also parallel with TVS pipe.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810031835.1A CN108008162A (en) | 2018-01-12 | 2018-01-12 | A kind of separator of the adjustable two-wire system current sensor exported in proportion |
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| CN201810031835.1A CN108008162A (en) | 2018-01-12 | 2018-01-12 | A kind of separator of the adjustable two-wire system current sensor exported in proportion |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109061217A (en) * | 2018-08-01 | 2018-12-21 | 上海理工大学 | Two-wire system optoelectronic sensor for wind speed circuit |
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| CN206517373U (en) * | 2016-09-27 | 2017-09-22 | 武汉永力科技股份有限公司 | A kind of zeroing circuit of operational amplifier |
| CN207798903U (en) * | 2018-01-12 | 2018-08-31 | 东华大学 | A kind of separator of the adjustable two-wire system current sensor exported in proportion |
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2018
- 2018-01-12 CN CN201810031835.1A patent/CN108008162A/en active Pending
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| CN202372568U (en) * | 2011-12-27 | 2012-08-08 | 贵州贵航汽车零部件股份有限公司 | Dynamic data acquisition device |
| CN203705536U (en) * | 2013-11-27 | 2014-07-09 | 杭州电子科技大学 | Circuit for detecting output current of frequency converter in real time |
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