CN203981755U - A kind of idle current detecting circuit - Google Patents
A kind of idle current detecting circuit Download PDFInfo
- Publication number
- CN203981755U CN203981755U CN201420470900.8U CN201420470900U CN203981755U CN 203981755 U CN203981755 U CN 203981755U CN 201420470900 U CN201420470900 U CN 201420470900U CN 203981755 U CN203981755 U CN 203981755U
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- China
- Prior art keywords
- optocoupler
- circuit
- phototriode
- led4
- current
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Abstract
A kind of idle current detecting circuit is measured for the reactive current of three-phase circuit, and it comprises that on-off circuit and the reactive current of controlling optocoupler conducting and cut-off form circuit; Described on-off circuit is with line voltage U
bCcontrol phototriode conducting, the cut-off of optocoupler for input signal, in the time of the conducting of phototriode, wired current signal passes through, and the current signal being passed through is measured reactive current signal; Be characterized in 1, owing to having adopted optocoupler to make line voltage U
bCvoltage signal and line current signal I
abetween without electrically contacting, avoided phase mutual interference between the two, reduce the measuring error of reactive current; 2, circuit structure is simple, easily debugging, and production cost is low; 3,, because circuit structure is simple, in the forming process of reactive current, without accumulated error, the measuring accuracy of reactive current is higher.
Description
Technical field
the utility model relates to a kind of idle current detecting circuit, measures for the reactive current to three-phase circuit.
Background technology
Line current in three-phase circuit is as line current I
ain comprise active current and reactive current, active current have resistive load form, reactive current is generally formed by inductive load; The mathematic(al) representation of active current is I
acos φ, the mathematic(al) representation of reactive current is I
asin φ,
φ in formula is line current I
aand the phase differential between active current; The existence of reactive current not only affects going out rate and also increasing the line loss of circuit-line of generating plant, therefore needs to carry out reactive-current compensation (also claiming reactive power compensation) to reduce the loss of electric energy; The compensation method of reactive power has two kinds conventionally, a kind of method is the phase difference detecting between the powerfactorcosφ of three-phase circuit or line current and corresponding active current, according to powerfactorcosφ or phase difference to automatic switching capacitive load power capacitor in three-phase circuit so that powerfactorcosφ close to 1 or phase difference close to 0; According to the big or small switching power capacitor of powerfactorcosφ or phase difference exist defect be when electric current in three-phase circuit hour, easily occur that over-compensation is that the electric current of single power capacitor is greater than inductance current, at this moment there will be repeatedly the phenomenon of throwing, cutting power capacitor, affect the serviceable life of power capacitor.Another kind method is to calculate reactive current according to phase difference and single-string galvanometer, throws, cuts power capacitor according to the size of reactive current, can avoid like this phenomenon appearance of repeatedly throwing, cutting power capacitor; But according to the complicated structure of the idle current detecting circuit of this method design, accumulated error is larger simultaneously.
Utility model content
The technical problems to be solved in the utility model is to provide a kind of idle current detecting circuit, and this circuit structure is simple and can measure exactly the reactive current in three-phase circuit.
The technical solution of the utility model is that a kind of idle current detecting circuit comprises that on-off circuit and the reactive current of controlling optocoupler conducting and cut-off form circuit;
Described on-off circuit comprises the light emitting diode of optocoupler LED1-LED4, the light emitting diode of optocoupler LED1, LED2 is connected in series, the light emitting diode of optocoupler LED3, LED4 is connected in series, the light-emitting diodes tube cathode of optocoupler LED1 and the light-emitting diodes tube anode of optocoupler LED3 connect the C phase of three-phase circuit, and the light-emitting diodes tube anode of optocoupler LED2 and the light-emitting diodes tube cathode of optocoupler LED4 connect the B phase of three-phase circuit by resistance R 1;
Described reactive current forms the phototriode that circuit comprises optocoupler LED1-LED4, the phototriode collector of optocoupler LED1 is connected with secondary coil one end of power pack B2 with the phototriode emitter of optocoupler LED2, the phototriode collector of optocoupler LED3 and the phototriode emitter of optocoupler LED4 be connected with the secondary coil other end of power pack B2, the phototriode emitter of optocoupler LED1 and the phototriode collector of optocoupler LED2, one end of the phototriode collector connecting resistance R3 of the phototriode emitter of optocoupler LED3 and optocoupler LED4, the center tap of the secondary coil of another termination power pack B2 of resistance R 3, the primary coil of power pack B2 is accepted the A line current signal I of three-phase circuit
a, one end of resistance R 3 is successively by resistance R 4, capacitor C 1 ground connection, and resistance R 4 is reactive current signal output part with the tie point of capacitor C 1.
The feature of this idle current detecting circuit is, by line voltage U
bCvoltage signal control conducting and the cut-off of optocoupler LED1 and optocoupler LED2 and optocoupler LED3 and optocoupler LED4, in the specific conducting of optocoupler interval, gather line current I
asignal, thus the line current I in conducting interval obtained
athe mean value of signal is reactive current signal; Its beneficial effect is, 1, owing to having adopted optocoupler to make line voltage U
bCvoltage signal and line current signal I
abetween without electrically contacting, avoided phase mutual interference between the two, reduce the measuring error of reactive current; 2, circuit structure is simple, easily debugging, and production cost is low; 3, because circuit structure is simple, in the forming process of reactive current, without accumulated error, the measuring accuracy of reactive current is higher.
Brief description of the drawings
Fig. 1 is the circuit theory diagrams of the first embodiment of the present utility model.
Fig. 2 is the oscillogram of explanation the utility model measuring principle.
Mark in Fig. 2 represents respectively: 1-voltage signal U
bCwaveform, the phototriode conducting of 2-optocoupler LED1, LED2, the waveform of cut-off state, the phototriode conducting of 3-optocoupler LED3, LED4, the waveform of cut-off state, 4-line current signal I
athe waveform of its current signal Ua during for pure resistive loads, 5-line current signal I
athe waveform of its current signal Ua during for inductive load electricity, the waveform of 6-reactive current signal.
Embodiment
Now contrast brief description of the drawings embodiment of the present utility model.
Idle current detecting circuit comprises an on-off circuit of controlling optocoupler conducting, cut-off, in optocoupler conducting interval to line current signal I
athe reactive current gathering forms circuit.
Described on-off circuit is with line voltage U
bCfor input signal is controlled phototriode conducting, the cut-off of optocoupler, it comprises the light emitting diode of optocoupler LED1-LED4, the light emitting diode of optocoupler LED1, LED2 is connected in series, the light emitting diode of optocoupler LED3, LED4 is connected in series, the light-emitting diodes tube cathode of optocoupler LED1 and the light-emitting diodes tube anode of optocoupler LED3 connect the C phase of three-phase circuit, and the light-emitting diodes tube anode of optocoupler LED2 and the light-emitting diodes tube cathode of optocoupler LED4 connect the B phase of three-phase circuit by resistance R 1; Resistance R 1 is used for the electric current of restricted passage light emitting diode.
Described reactive current forms the phototriode that circuit comprises optocoupler LED1-LED4, the phototriode collector of optocoupler LED1 is connected with secondary coil one end of power pack B2 with the phototriode emitter of optocoupler LED2, the phototriode collector of optocoupler LED3 and the phototriode emitter of optocoupler LED4 be connected with the secondary coil other end of power pack B2, the phototriode emitter of optocoupler LED1 and the phototriode collector of optocoupler LED2, one end of the phototriode collector connecting resistance R3 of the phototriode emitter of optocoupler LED3 and optocoupler LED4, the center tap of the secondary coil of another termination power pack B2 of resistance R 3, the primary coil of power pack B2 is accepted the A line current signal I of three-phase circuit
a, one end of resistance R 3 is successively by resistance R 4, capacitor C 1 ground connection, and resistance R 4 is reactive current signal output part with the tie point of capacitor C 1.Resistance R 4 is used for reactive current signal to carry out filtering with capacitor C 1, AC compounent in filtering reactive current signal.
The iron core of described power pack B2 is E type siliconized plate, in the middle of it, the sectional area of iron core is 100 square millimeters, the number of turn of primary coil is 10 circles, and the upper and lower limit number of turn of secondary coil is respectively 100 circles, and the current signal Ua of secondary monolateral output is 0-6V and line current signal I
awithout phase differential.The resistance of resistance R 3 is 1K ohm, and the resistance of resistance R 4 is 10K ohm, and capacitor C 1 is that the negative pole of two 100-330 microfarad electrochemical capacitors connects series connection formation; The model of described optocoupler LED1-LED4 is TLP521.
Now in conjunction with Fig. 2, measuring principle of the present utility model is described, line voltage U
bCvoltage signal U
bcwaveform 1 while being positive half cycle, the phototriode of optocoupler LED1, LED2 is in conducting, the phototriode of optocoupler LED3, LED4 is in cut-off, its conducting, cut-off state are as shown in waveform 2; Voltage signal U
bcwaveform 1 while being negative half period, the phototriode of optocoupler LED3, LED4 is in conducting, the phototriode of optocoupler LED, LED2 is in cut-off; Optocoupler conducting, cut-off state as shown in waveform 3, the conducting interval that the dash area in waveform 2,3 is optocoupler.
Known in the time that A line current is pure resistive electric current according to the characteristic of three-phase circuit, the leading line voltage U of its phase place
bC90 degree, line current signal I
acurrent signal Ua waveform as shown in waveform 4; In the conducting interval of optocoupler, there is current signal Ua by form mean value Up in resistance R 3, as shown in dash area in waveform 2,3.In the time having perceptual current component in line current, between its phase place and pure resistive line current, there is a phase difference; Waveform 5 is depicted as the current signal Ua waveform in the time that line current has inductive current component; In the conducting interval of optocoupler, the waveform forming in resistance R 3 corresponding to the current signal of waveform 5 is as shown in waveform 6;
The expression formula of current signal Ua is: Ua=U
am(Sin ω t-φ); (1)
U in formula 1
amfor the maximal value of current signal Ua, φ is the phase differential between its phase place and pure resistive line current while having perceptual current component in line current, the angular frequency that ω is alternating circuit;
The current signal Ua in the conducting interval (seeing pi/2 to the 3 pi/2 section on time shaft) to optocoupler carries out filtering processing and can obtain its mean value, and filtering processing is equivalent to calculate positive area and negative amass poor of shade in waveform 6; Average Up can be represented by the formula:
Up=（2/π）U
amSinφ；（2）
The radian value in the conducting district that in formula 2, π is optocoupler;
Due to current signal Ua and line current proportional, so can find out that from formula 2 mean value Up is reactive current signal, it changes with phase difference by sine function relation.When the numerical value of mean value Up is that timing represents that reactive current is perception, when the numerical value of mean value Up represents that reactive current is capacitive when negative.
Claims (2)
1. an idle current detecting circuit, comprises that on-off circuit and the reactive current of controlling optocoupler conducting and cut-off form circuit;
Described on-off circuit comprises the light emitting diode of optocoupler LED1-LED4, the light emitting diode of optocoupler LED1, LED2 is connected in series, the light emitting diode of optocoupler LED3, LED4 is connected in series, the light-emitting diodes tube cathode of optocoupler LED1 and the light-emitting diodes tube anode of optocoupler LED3 connect the C phase of three-phase circuit, and the light-emitting diodes tube anode of optocoupler LED2 and the light-emitting diodes tube cathode of optocoupler LED4 connect the B phase of three-phase circuit by resistance R 1;
Described reactive current forms the phototriode that circuit comprises optocoupler LED1-LED4, the phototriode collector of optocoupler LED1 is connected with secondary coil one end of power pack B2 with the phototriode emitter of optocoupler LED2, the phototriode collector of optocoupler LED3 and the phototriode emitter of optocoupler LED4 be connected with the secondary coil other end of power pack B2, the phototriode emitter of optocoupler LED1 and the phototriode collector of optocoupler LED2, one end of the phototriode collector connecting resistance R3 of the phototriode emitter of optocoupler LED3 and optocoupler LED4, the center tap of the secondary coil of another termination power pack B2 of resistance R 3, the primary coil of power pack B2 is accepted the A line current signal I of three-phase circuit
a, one end of resistance R 3 is successively by resistance R 4, capacitor C 1 ground connection, and resistance R 4 is reactive current signal output part with the tie point of capacitor C 1, the model of described optocoupler LED1-LED4 is TLP521.
2. idle current detecting circuit according to claim 1, it is characterized in that, the iron core of described power pack B2 is E type siliconized plate, and in the middle of it, the sectional area of iron core is 100 square millimeters, the number of turn of primary coil is 10 circles, and the upper and lower limit number of turn of secondary coil is respectively 100 circles.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420470900.8U CN203981755U (en) | 2014-08-20 | 2014-08-20 | A kind of idle current detecting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420470900.8U CN203981755U (en) | 2014-08-20 | 2014-08-20 | A kind of idle current detecting circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203981755U true CN203981755U (en) | 2014-12-03 |
Family
ID=51979189
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420470900.8U Expired - Fee Related CN203981755U (en) | 2014-08-20 | 2014-08-20 | A kind of idle current detecting circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203981755U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104122433A (en) * | 2014-08-20 | 2014-10-29 | 高玉琴 | Reactive current detection circuit |
| CN112415255A (en) * | 2020-11-14 | 2021-02-26 | 陕西航空电气有限责任公司 | Improved active current sampling circuit |
-
2014
- 2014-08-20 CN CN201420470900.8U patent/CN203981755U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104122433A (en) * | 2014-08-20 | 2014-10-29 | 高玉琴 | Reactive current detection circuit |
| CN112415255A (en) * | 2020-11-14 | 2021-02-26 | 陕西航空电气有限责任公司 | Improved active current sampling circuit |
| CN112415255B (en) * | 2020-11-14 | 2023-10-24 | 陕西航空电气有限责任公司 | Improved active current sampling circuit |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20141203 Termination date: 20160820 |