CN207488351U - Linear photoelectric isolation circuit for inhibiting temperature drift - Google Patents
Linear photoelectric isolation circuit for inhibiting temperature drift Download PDFInfo
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- CN207488351U CN207488351U CN201721304112.1U CN201721304112U CN207488351U CN 207488351 U CN207488351 U CN 207488351U CN 201721304112 U CN201721304112 U CN 201721304112U CN 207488351 U CN207488351 U CN 207488351U
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Abstract
The utility model provides a restrain linear photoelectric isolation circuit of temperature drift, it can include: a signal input source for providing an input signal; the signal conditioning unit is connected with the signal input source and is used for converting the input signal into two signals with the same amplitude and waveform but opposite polarities; the two optical coupling units are connected with the signal conditioning unit and are respectively used for transmitting the two signals; the difference arithmetic unit is connected with the optical coupling unit and is used for carrying out arithmetic processing on the signal output by the optical coupling unit; and the output circuit is connected with the differential operation unit and used for outputting the signal after the operation processing of the differential operation unit. The utility model has the advantages that: the problem of signal gain error caused by temperature deviation and the problem of waveform interference noise in signal isolation transmission are solved, and therefore accurate isolation transmission of signals is achieved. The practical application requirements of the linear photoelectric isolation circuit in the high-voltage industrial field are better met.
Description
Technical field
The utility model is related to high voltage electric equipment testing field more particularly to a kind of linear photoconductors for inhibiting temperature drift
Isolation circuit.
Background technology
In High-Voltage Insulation diagnostic field, high pressure industrial application field, linear photoelectric isolation circuit is often used, and
And require linear photoelectric isolation circuit that there is higher precision.At present frequently with by V-F conversions and simulated light in commercial Application
The mode that fibre combines realizes that linear signal is isolated.But voltage to frequency convert chip is used, since the limitation of its resolution ratio causes to turn
Change that precision is not high, and the voltage range of input signal is smaller.When being isolated simultaneously using linear optical coupling, due to optocoupler line
Property degree and conversion gain be affected by temperature larger, there are larger signal transmission errors, it is therefore desirable to further be calculated with conversion
Method gets rid of the influence of temperature drift.For faint signal to be transmitted, above two form it is all different degrees of cause original
Beginning signal waveform is distorted.Simultaneously for the circuit structure being isolated using isolating transformer, due to the limit of transformer passband
System, can be only applied to that frequency is specific or power frequency under the conditions of.For the high-voltage amplifier of High-Voltage Insulation diagnostic field, not only
It asks transmission signal waveform aberration rate small, while requires the voltage signal magnitude gain stabilization after signal-isolated transmission.Simultaneously because
Dielectric response method in High-Voltage Insulation diagnosis is needed for the test environment of a variety of different temperatures, thus requires isolation circuit
With higher temperature stability.Some above-mentioned requirement shows that existing signal isolation circuit is not well positioned to meet practical need
It asks.
Utility model content
The technical problem to be solved by the utility model is to provide a kind of linear photoelectric isolation electricity for inhibiting temperature drift
Road can improve the signal gain error problem as caused by temperature drift and waveform interference noise problem in signal-isolated transmission, from
And it realizes signal and transmission is accurately isolated.Having better met linear photoelectric isolation circuit should in the reality of high voltage industrial circle
Use demand.
In order to solve the above-mentioned technical problem, the utility model provides a kind of linear photoelectric isolation electricity for inhibiting temperature drift
Road, it may include：
Signal input sources, for providing input signal；
Signal condition unit is connected with the signal input sources, for the input signal to be converted to amplitude and waveform
Identical but opposite polarity two signals；
Two optocoupler units, are connected with the signal condition unit, are respectively used to transmit described two signals；
Calculus of differences unit is connected with described two optocoupler units, and the signal for being exported to the optocoupler unit carries out
Calculation process；
Output circuit is connected with the calculus of differences unit, for by the calculus of differences unitary operation treated letter
It number is exported.
Wherein, the signal condition unit includes operational amplifier and the low-temperature coefficient being connect with the operational amplifier
Resistive element.
Wherein, described two optocoupler units are isolated so that described two by two signals that the conditioning unit exports
Signal is not interfere with each other.
Wherein, the optocoupler unit includes the linear optical coupling of linear optical coupling chip.
Wherein, the calculus of differences unit includes：
Two operational amplifiers are connected respectively with described two optocoupler units, for filtering out connected optocoupler unit output
Signal in high-frequency noise and thermal noise；
Instrumentation amplifier, in-phase end and the reverse side of the instrumentation amplifier receive described two operations respectively
The signal of amplifier output, and eliminate the common-mode error of received signal.
Wherein, the signal condition unit, the linear optical coupling unit, the calculus of differences unit are in the form of differential configuration
It is connected in turn.
Wherein, the operational amplifier is OPA227.
Wherein, the linear optical coupling is HCNR201.
Wherein, the instrument amplifier is AD620.
The advantageous effect of the utility model embodiment is：
The embodiment of the utility model passes through a kind of linear photoelectric isolation circuit for inhibiting temperature drift, on the one hand, improves
The signal gain error problem as caused by temperature drift and waveform interference noise problem in signal-isolated transmission, so as to fulfill letter
Number accurate isolation transmission.Practical application request of the linear photoelectric isolation circuit in high voltage industrial circle is better met；
On the one hand, with by using by V-F conversions, compared with the isolation circuit for the mode that analog optical fiber combines, the utility model uses
Be that the linear optical coupling of differential configuration is transmitted isolation, it is higher for the transmission precision of signal, while high frequency letter will not be introduced
Number transformed error；On the one hand, compared with by the method for normal linear light-coupled isolation, the utility model can significantly improve isolation
The temperature stability of circuit is reduced due to gain error caused by temperature change；On the other hand, with the side by transformer isolation
Method is compared, and the utility model can significantly improve the passband of isolation circuit, widens the scope of application of isolation circuit.
Description of the drawings
It in order to illustrate the embodiment of the utility model or the technical proposal in the existing technology more clearly, below will be to implementing
Example or attached drawing needed to be used in the description of the prior art are briefly described, it should be apparent that, the accompanying drawings in the following description is only
Only it is some embodiments of the utility model, for those of ordinary skill in the art, before not making the creative labor
It puts, can also be obtained according to these attached drawings other attached drawings.
Fig. 1 is a kind of illustrative view of functional configuration of the linear photoelectric isolation circuit of inhibition temperature drift of the utility model.
Fig. 2 is one embodiment physical circuit group of the linear photoelectric isolation circuit of the inhibition temperature drift of the utility model
Into schematic diagram.
Fig. 3 is one embodiment circuit diagram of linear optical coupler module HCNR201 in the utility model.
Fig. 4 is one embodiment schematic diagram of the feedback circuit in linear optical coupler module HCNR201 in the utility model.
Specific embodiment
The explanation of following embodiment is refer to the attached drawing, can be to the particular implementation implemented to example the utility model
Example.
Fig. 1 is a kind of illustrative view of functional configuration for the linear photoelectric isolation circuit for inhibiting temperature drift.In Fig. 1, signal
S0It is sent out by signal input sources 10 after being handled via signal condition unit 20, amplitude is identical with waveform but polarity is opposite for generation two
Signal S1 and signal S2, be respectively fed to linear optical coupling unit 30 and linear optical coupling unit 31, signal S1 and signal S2 is respective
It is not interfere with each other mutually under the action of optocoupler unit, signal S1 is transferred to calculus of differences unit 40, signal by linear optical coupling unit 30
S2 is transferred to calculus of differences unit 40 by linear optical coupling unit 31, two groups of high speed operation amplifiers in calculus of differences unit 40
Signal S1, S2 are carried out by capacitance integral after filtering out high-frequency noise and thermal noise respectively, are respectively fed to calculus of differences unit
The in-phase end and reverse side of instrumentation amplifier in 40 mutually subtract to eliminate common-mode error, eventually form a signal S conveying
To signal output unit 50.
As an example, as in a linear photoelectric isolation circuit embodiments circuit diagram of Fig. 2, signal condition unit is transported
It calculates Amplifier Model and selects OPA227, linear optical coupling model selects HCNR201, and calculus of differences unitary operation Amplifier Model is selected
AD620.The range of temperature of circuit operation is in -20 DEG C to 85 DEG C of section.
The signal conditioning circuit that signal is formed via U1 and U2 generates two amplitudes and wave by operational amplifier OPA227
Shape is identical but opposite polarity signal, be respectively fed in transmission circuit U3 and U4, and capacitance C13 and C15 act as improving at this time
The linearity of signal is transmitted, filters out high-frequency noise and thermal noise, then signal is passed to two branches of differential configuration respectively.
Wherein, the internal frame diagram of linear optical coupling HCNR201 that every branch is included is as shown in figure 3, its operation principle is：
1st, input of 2 pins as isolation signals, for feeding back, 5,6 pins are used to export 3,4 pins.1st, the electric current between 2 pins
It is denoted as IF, the electric current between 3,4 pins between 5,6 pins is denoted as I respectivelyPD1And IPD2.Input signal turns by voltage-to-current
Change, the variation of voltage is embodied on electric current IF, and IPD1 and IPD2 are substantially linear with IF, linear coefficient be denoted as respectively K1 and
K2, i.e.,
K1 and the general very littles of K2, and vary with temperature larger, but the design of chip so that K1 and K2 are equal.Later may be used
To see, in rational periphery circuit design, the ratio K 3 for both being of input/output ratio, linear optical coupling are really influenced
It just can be only achieved the satisfied linearity using this characteristic.
Select some indexs that linear optical coupling HCNR201 is isolated as follows：
* the linearity：HCNR201：0.05%；
* linear coefficient K3：HCNR201：5%；
* temperature coefficient：-65ppm//℃；
* isolation voltage：1414V；
* signal bandwidth：Direct current is to more than 1MHz.
From the above it can be seen that as common optical coupler, what linear optical coupling was really isolated is electric current, to electricity is really isolated
Pressure needs to increase the auxiliary circuits such as operational amplifier at the place of outputting and inputting.Next to the typical electrical of linear optical coupling HCNR201
Road is analyzed, to how to realize feedback in circuit and current-voltage, Voltage-current conversion are derived and illustrated：It is if defeated
Enter terminal voltage for Vin, output end voltage Vout, two electric current carry-over factors that optocoupler ensures are respectively K1, K2.By the electricity of Fig. 3
Road figure extraction part is analyzed, and obtains Fig. 4, as shown in Figure 4：
If the voltage of amplifier negative terminal is Vi, the voltage of amplifier output terminal is Voo, full in the undersaturated the two of amplifier
Foot relation of plane：
Vo=Voo-GVi (1)
Wherein it is the output voltage when amplifier input differential mode is 0, G is the gain of amplifier, general bigger.
Ignore the input current of amplifier negative terminal, it is believed that by the electric current of R1 be IP1, obtained according to the Ohm's law of R1：
It is IF by the electric current at R3 both ends, is obtained according to Ohm's law：
Wherein, Vcc is the voltage of 2 foot of optocoupler, it is contemplated that voltage when LED is connected is basically unchanged, conduct constant here
It treats.According to the characteristic of optocoupler, i.e.,
K1=IP1/IF (4)
The expression formula of sum is substituted into above formula, can be obtained：
Above formula is available through deforming：
K1R1(VDD-Vo0)+K1R1GVi=R3Vin-R3Vi
By expression formula substitute into (3) Shi Ke get：
It is especially big in view of G, then it can do with lower aprons：
In this way, output is as follows with the relationship of input voltage：
As it can be seen that in foregoing circuit Fig. 3, export and input directly proportional, and proportionality coefficient is only determined by K3 and R1, R2,
So generally selecting R1=R2 in reality is used, achieve the purpose that only isolate and not amplify.
It returns in the main circuit diagram of Fig. 2, so the yield value of differential configuration branch one is determined by the ratio of resistance R1 and R5, R6
It is fixed；The yield value of differential configuration branch two determines by the ratio of resistance R7 and R9, R10, and the gain of two groups of branches is identical and resistance
Element is respectively provided with identical temperature coefficient.
Two paths of signals passes through operational amplifier OPA227, warp by being respectively fed in the circuit of U3 and U4 after optocoupler unit
High-frequency noise and thermal noise are filtered out after capacitance integral.
Last two paths of signals is respectively fed to the in-phase end of instrument amplifier AD620 and backward end mutually subtracts to eliminate common mode mistake
Difference exports final signal.
In conclusion the temperature of circuit can be substantially improved in the linear photoelectric isolation circuit in this embodiment of the utility model
Stability is spent, the transmission gain temperature coefficient of typical linear optical coupling can be reduced to 20ppm/ DEG C or so by 65ppm/ DEG C.
It avoids environment temperature and changes the influence that result is transmitted to isolation, can have the ability of higher inhibition temperature drift effects.
Above disclosed is only the utility model preferred embodiment, cannot limit the utility model with this certainly
Interest field, therefore equivalent variations made according to the utility model claims still belong to the range that the utility model is covered.
Claims (9)
1. a kind of linear photoelectric isolation circuit for inhibiting temperature drift, which is characterized in that including：
Signal input sources, for providing input signal；
Signal condition unit is connected with the signal input sources, identical with waveform for the input signal to be converted to amplitude
But opposite polarity two signals；
Two optocoupler units, are connected with the signal condition unit, are respectively used to transmit described two signals；
Calculus of differences unit is connected with described two optocoupler units, and the signal for being exported to the optocoupler unit carries out operation
Processing；
Output circuit is connected with the calculus of differences unit, for by the calculus of differences unitary operation treated signal into
Row output.
2. the linear photoelectric isolation circuit according to claim 1 for inhibiting temperature drift, which is characterized in that the signal tune
Reason unit includes operational amplifier and the low-temperature coefficient resistive element being connect with the operational amplifier.
3. the linear photoelectric isolation circuit according to claim 1 for inhibiting temperature drift, which is characterized in that described two light
Coupling unit is isolated so that described two signals are not interfere with each other by two signals that the conditioning unit exports.
4. the linear photoelectric isolation circuit according to claim 3 for inhibiting temperature drift, which is characterized in that the optocoupler list
Member includes the linear optical coupling of linear optical coupling chip.
5. the linear photoelectric isolation circuit according to claim 1 for inhibiting temperature drift, which is characterized in that the difference fortune
Unit is calculated to include：
Two operational amplifiers are connected respectively with described two optocoupler units, for filtering out the letter of connected optocoupler unit output
High-frequency noise and thermal noise in number；
Instrumentation amplifier, in-phase end and the reverse side of the instrumentation amplifier receive described two operation amplifiers respectively
The signal of device output, and eliminate the common-mode error of received signal.
6. the linear photoelectric isolation circuit according to claim 1 for inhibiting temperature drift, which is characterized in that the signal tune
Reason unit, the linear optical coupling unit, the calculus of differences unit are connected in turn in the form of differential configuration.
7. the linear photoelectric isolation circuit of the inhibition temperature drift according to claim 2 or 4, which is characterized in that the fortune
Calculation amplifier is OPA227.
8. the linear photoelectric isolation circuit according to claim 4 for inhibiting temperature drift, which is characterized in that the linear light
Coupling is HCNR201.
9. the linear photoelectric isolation circuit according to claim 5 for inhibiting temperature drift, which is characterized in that the instrument
Amplifier is AD620.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721304112.1U CN207488351U (en) | 2017-10-11 | 2017-10-11 | Linear photoelectric isolation circuit for inhibiting temperature drift |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721304112.1U CN207488351U (en) | 2017-10-11 | 2017-10-11 | Linear photoelectric isolation circuit for inhibiting temperature drift |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107907728A (en) * | 2017-10-11 | 2018-04-13 | 深圳供电局有限公司 | Linear photoelectric isolation circuit for inhibiting temperature drift |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107907728A (en) * | 2017-10-11 | 2018-04-13 | 深圳供电局有限公司 | Linear photoelectric isolation circuit for inhibiting temperature drift |
| CN107907728B (en) * | 2017-10-11 | 2020-04-24 | 深圳供电局有限公司 | Linear photoelectric isolation circuit for inhibiting temperature drift |
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