CN204287289U - High-precision current voltage transitions sample circuit - Google Patents
High-precision current voltage transitions sample circuit Download PDFInfo
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- CN204287289U CN204287289U CN201420677206.3U CN201420677206U CN204287289U CN 204287289 U CN204287289 U CN 204287289U CN 201420677206 U CN201420677206 U CN 201420677206U CN 204287289 U CN204287289 U CN 204287289U
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- operational amplifier
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Abstract
The utility model relates to a kind of high-precision current voltage transitions sample circuit.It includes current source, the first resistance, the second resistance, the 3rd resistance, the 4th resistance and integrated operational amplifier; The two ends of the first resistance described in two terminations of current source, a termination power ground of the first resistance, the other end also receives the negative input of integrated operational amplifier together with one end of the second resistance; The output terminal of the integrated operational amplifier described in another termination of the second resistance; The positive input of one termination integrated operational amplifier of the 3rd resistance, another termination power ground; The output terminal of the 4th resistance one termination integrated operational amplifier, another termination power ground.Owing to adding integrated operational amplifier, sampling precision in circuit is improved greatly, thus the protection precision of intelligent protection electrical equipment is improved, measure display precision and improve, avoid misoperation phenomenon, ensure that the reliability of power supply.
Description
Technical field
The utility model belongs to a kind of low-voltage electrical apparatus sample circuit, particularly relates to a kind of high-precision current voltage transitions sample circuit.
Background technology
Along with low-voltage electrical apparatus develops into intellectualization times; require more and more higher for low-voltage variation electrical equipment; be not limited only to current protection and residual current protecting, also will have had the functions such as the measurement of electrical energy parameter, communication, frequency analysis, so require it is very high to the sampling precision of current data.The collection of all signals is all from main circuit current, voltage signal, and finally all will convert voltage signal to.Traditional current-voltage conversion method is as shown in Figure 1: connect sampling resistor at two ends, Current Transformer Secondary side, the then magnitude of voltage at Direct Sampling resistance two ends exactly.But sampling resistor has the effect of dividing potential drop and shunting, and except sampling resistor, also there is equivalent resistance problem in the circuit of other parts, when circuit equivalent resistance changes, and during motor stable operation, also may there is the fluctuation of setting current.Cause data acquisition mistake, sampling precision declines greatly, causes miscount, and make intelligent protection electrical equipment occur error in judgement, misoperation phenomenon appears in isolating switch, causes circuit to suffer unnecessary loss.
Summary of the invention
The utility model provides a kind of high-precision current voltage transitions sample circuit high to current data sampling precision for solving in known technology the technical matters that exists.
The technical scheme that the utility model is taked for the technical matters existed in solution known technology is: it includes current source (Is), the first resistance (Rs), the second resistance (Rf), the 3rd resistance (Rg), the 4th resistance (RL) and integrated operational amplifier (A); The two ends of the first resistance (Rs) described in two terminations of described current source (Is), one termination power ground of described the first resistance (Rs), the other end also receives the negative input of described integrated operational amplifier (A) together with one end of described the second resistance (Rf); The output terminal of the integrated operational amplifier (A) described in another termination of described the second resistance (Rf); The positive input of the integrated operational amplifier (A) described in one termination of the 3rd described resistance (Rg), another termination power ground; The output terminal of the described integrated operational amplifier (A) described in the 4th resistance (RL) one termination, another termination power ground.
The advantage that the utility model has and good effect are: owing to being add integrated operational amplifier on the basis of traditional sampling circuit, utilize the principle of work of its " empty short, empty disconnected ", original circuit advantage is still existed, makes shortcoming be improved simultaneously and even eliminate.Sampling precision in circuit is improved greatly, thus the protection precision of intelligent protection electrical equipment is improved, measure display precision and improve, avoid misoperation phenomenon, ensure that the reliability of power supply.
Accompanying drawing explanation
Fig. 1 is the sample circuit schematic diagram of prior art;
Fig. 2 is sample circuit schematic diagram of the present utility model.
Embodiment
For summary of the invention of the present utility model, Characteristic can be understood further, hereby exemplify following examples, and coordinate accompanying drawing to be described in detail as follows:
As shown in Figure 2, the two ends of the two termination first resistance Rs of current source Is, namely one end of the first resistance Rs connects power supply ground, and the other end also receives the negative input of integrated operational amplifier A together with one end of the second resistance Rf; The output terminal of another termination integrated operational amplifier A of the second resistance Rf; The positive input of the one termination integrated operational amplifier A of the 3rd resistance Rg, another termination power ground; The output terminal of the 4th resistance RL mono-termination integrated operational amplifier A, another termination power ground.Ri is the equivalent resistance in circuit.
Under desirable amplifier condition: U
+=U
-=0;
Input resistance: Ri=0;
Thus, If=Is;
Therefore output voltage: Uo=-IsRf;
Because the equivalent resistance Ri in side circuit in circuit can not be zero, but as long as sampling the first resistance Rs is more larger than circuit equivalent resistance Ri, conversion accuracy is higher, and sampling precision is higher.
Claims (1)
1. a high-precision current voltage transitions sample circuit, is characterized in that: it includes current source (Is), the first resistance (Rs), the second resistance (Rf), the 3rd resistance (Rg), the 4th resistance (RL) and integrated operational amplifier (A); The two ends of the first resistance (Rs) described in two terminations of described current source (Is), one termination power ground of described the first resistance (Rs), the other end also receives the negative input of described integrated operational amplifier (A) together with one end of described the second resistance (Rf); The output terminal of the integrated operational amplifier (A) described in another termination of described the second resistance (Rf); The positive input of the integrated operational amplifier (A) described in one termination of the 3rd described resistance (Rg), another termination power ground; The output terminal of the described integrated operational amplifier (A) described in the 4th resistance (RL) one termination, another termination power ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420677206.3U CN204287289U (en) | 2014-11-13 | 2014-11-13 | High-precision current voltage transitions sample circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420677206.3U CN204287289U (en) | 2014-11-13 | 2014-11-13 | High-precision current voltage transitions sample circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204287289U true CN204287289U (en) | 2015-04-22 |
Family
ID=52870438
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420677206.3U Active CN204287289U (en) | 2014-11-13 | 2014-11-13 | High-precision current voltage transitions sample circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN204287289U (en) |
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2014
- 2014-11-13 CN CN201420677206.3U patent/CN204287289U/en active Active
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