CN1542456A - Current measuring method - Google Patents
Current measuring method Download PDFInfo
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- CN1542456A CN1542456A CNA2003101050527A CN200310105052A CN1542456A CN 1542456 A CN1542456 A CN 1542456A CN A2003101050527 A CNA2003101050527 A CN A2003101050527A CN 200310105052 A CN200310105052 A CN 200310105052A CN 1542456 A CN1542456 A CN 1542456A
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- current
- voltage
- measurement
- signal
- electric current
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Abstract
The present invention belongs to the field of electronic measurement technology, and is especially one new kind of current measuring method. Without need of outer work power supply, one current transformer CT, current/voltage converting circuit and other circuit are used to obtain the work power supply for the measurement device and relative measured current signal. The present invention features that only one current transformer CT, one current/voltage converting circuit comprising shunt regulator, rectifying filter, sampling circuit, delayed comparator, driver circuit and voltage stabilizer, and one signal processing and displaying unit are used to obtain the work power supply for the measurement device and one pulse voltage signal with duty ratio corresponding to the measured current for current measurement via the duty ratio measurement. The present invention has wide measurement range, and is especially suitable for where no work power supply is provided.
Description
Technical field
The invention belongs to electronic measuring technology field, relate to a kind of new method of measuring electric current.This method is particularly suitable for using being difficult to provide under the operate outside power supply occasion.
Background technology
Electric current is one of basic physical amount.At present, the method for known measurement electric current is a lot, as:
1. utilize electromagnetic type or magneto-electric pointer reometer, it is based on condition that electromagnetic action principle and electromagnetic torque and mechanical force moment balance each other and realizes current measurement;
2. utilize Hall current sensor, it is based on the relation between the electric current in the size of Hall voltage and the current and realizes current measurement;
3. the voltage drop that produces when utilizing electric current to pass through resistance, it is based on Europe female law and realizes current measurement;
4. utilize fibre optic current sensor, it is the method that adopts the magnetostriction materials coated fiber, or realizes current measurement based on Faraday effect, piezoelectricity elasto-optical effect;
5. utilize the photoelectric mixed-mode current sense, it is changed based on air-core current transformer CT and electricity/light conversion, light/electricity, and the light pulse signal of employing Optical Fiber Transmission after electricity/light conversion, realize current measurement, as HUST's journal, 2000, Vol.28, the measurement current methods of being introduced among the No.3:90-92. " a kind of photoelectric mixed-mode current sensor "; Or the like.
Utilize the method for above-mentioned measurement electric current to measure electric current: or need the outside to provide working power (comprising electric main, accumulator, solar cell etc.) for measurement mechanism; Or utilize the energy of tested electric current to provide working power for measurement mechanism, at this moment needing to carry out the current/voltage conversion with a current transformer CT and interlock circuit to provide working power for device separately, with another current transformer CT (or other current sense device, material) obtains the relevant signal of tested electric current, the method of this measurement electric current is being difficult to provide the occasions such as high voltage of operate outside power supply to use usually, as HUST's journal, 2000 Vol.28, the measurement current methods of being introduced among the No.3:90-92. " a kind of photoelectric mixed-mode current sensor "; Or the like.
Only utilize a current transformer CT and interlock circuit to obtain the pulse voltage signal that the working power of measurement mechanism self and dutycycle and tested electric current have one-to-one relationship simultaneously, recently realize the method for current measurement by the duty of measuring pulse voltage signal, do not appear in the newspapers as yet.
Summary of the invention
The purpose of this invention is to provide a kind of new method of measuring electric current, this method only utilizes a current transformer CT and interlock circuit can obtain the pulse voltage signal that the working power of measurement mechanism self and dutycycle and tested electric current have one-to-one relationship simultaneously, recently realize current measurement by the duty of measuring pulse voltage signal, for being difficult to provide the current measurement under the operate outside power supply occasion that a kind of effective method is provided, also provide a kind of new technology for current instruments or Design of device.
Technical scheme of the present invention is current/voltage translation circuit and signal Processing and the display that adopts a current transformer CT and be made up of parallel regulator, rectifier filer, sample circuit, hysteresis comparator, driving circuit, voltage stabilizer, tested electric current is done the current/voltage conversion, obtain the pulse voltage signal that the working power of measurement mechanism self and dutycycle and tested electric current have one-to-one relationship simultaneously, recently realize current measurement by the duty of measuring pulse voltage signal.
The principle of this method foundation is to utilize sample circuit that the input voltage of voltage stabilizer is taken a sample, hysteresis comparator is by detecting the voltage from sample circuit, voltage pulse output, this pulse voltage is controlled parallel regulator through driving circuit and with on-off mode the secondary current of current transformer CT is shunted, even the input voltage that makes voltage stabilizer is when tested electric current variation range is big, also remain in the proper range, thereby export the working power of stable voltage as measurement mechanism self; Because the load of voltage stabilizer, be that signal Processing and display are dead loads, so variation along with tested electric current, the dutycycle of the hysteresis comparator voltage pulse output of control parallel regulator work is also inevitable to be changed thereupon, make the dutycycle and the tested electric current of hysteresis comparator voltage pulse output signal have relation one to one, the pulse voltage signal of hysteresis comparator output is inputed to signal Processing and display, thereby realize current measurement.It is characterized in that: comprise a current transformer CT and by parallel regulator, rectifier filer, sample circuit, hysteresis comparator, driving circuit, current/voltage translation circuit and signal Processing and display that voltage stabilizer is formed, the parallel connection of secondary windings of the ac input end of parallel regulator and rectifier filer and current transformer CT, the input end of voltage stabilizer and the input end of sample circuit link to each other with the output terminal of rectifier filer, the signal output part of sample circuit links to each other with the signal input part of hysteresis comparator, the output terminal of hysteresis comparator links to each other with the signal input part of display with the control end of driving circuit and signal Processing, the power input of driving circuit links to each other with the output terminal of voltage stabilizer, thereby only realize obtaining the pulse voltage signal that the working power of measurement mechanism self and dutycycle and tested electric current have one-to-one relationship simultaneously with a current transformer CT and described current/voltage translation circuit, by measuring the method for pulse voltage signal dutycycle, realize current measurement, provide working power and other current sense device or material and need not the outside.
In the method, because parallel regulator is with on-off mode work, so when tested electric current variation range was big, the hear rate of parallel regulator was also less; In addition,, the input/output voltage difference of voltage stabilizer is still remained in the OK range when tested electric current variation range is big, reduce the hear rate of voltage stabilizer by suitably choosing the threshold voltage of hysteresis comparator.Therefore, this method is measured the wide ranges of electric current.
The present invention compares with the existing method of measuring electric current, and its effect and benefit are:
1. only obtain the pulse voltage signal that the working power of device self and dutycycle and tested electric current have one-to-one relationship simultaneously with a current transformer CT and current/voltage translation circuit, realize current measurement, provide working power and other current sense device or material and need not the outside;
2. be particularly suitable for being difficult to provide the occasions such as high voltage of operate outside power supply to use;
3. provide a kind of new technology for current instruments or Design of device;
4. it is wide to measure range of current, and cost is lower, realizes easily.
Description of drawings
Accompanying drawing 1 is a kind of theory diagram of measuring the electric current new method.
Among the figure: 1 current transformer CT; 2 parallel regulators; 3 rectifier filers; 4 voltage stabilizers; 5 signal Processing and display; 6 sample circuits; 7 hysteresis comparators; 8 driving circuits; 9 current carrying conductors.
Accompanying drawing 2 is a kind of circuit diagrams of measuring the electric current new method.
Accompanying drawing 3 is IC in the accompanying drawing 2
2Output voltage U
0With the sample circuit output voltage U '
InBetween graph of a relation.
Accompanying drawing 4 is IC in the accompanying drawing 2
2Output voltage U
0And the graph of a relation between the time t.
Embodiment
Below in conjunction with accompanying drawing, be described in detail the specific embodiment of the present invention and most preferred embodiment.
As shown in Figure 1, its principle of work of measuring electric current is: the electric current in the current carrying conductor 9 (that is tested electric current) is behind current transformer CT1, parallel regulator 2, rectifier filer 3 and voltage stabilizer 4, and the output burning voltage is the interlock circuit power supply; When the electric current in the current carrying conductor 9 changes, the input voltage of voltage stabilizer 4 also will change, by sample circuit 6 this voltage is taken a sample, hysteresis comparator 7 is by detecting the signal from sample circuit 6, export a pulse voltage, this pulse voltage through the conducting of driving circuit 8 control parallel regulators 2 with end, guarantee under the situation that tested electric current changes, the input voltage of voltage stabilizer 4 remains in the suitable scope, output voltage stabilization; Since voltage stabilizer 4 load---signal Processing and display 5 are dead loads, so variation along with tested electric current, the dutycycle of the hysteresis comparator 7 voltage pulse output signals of control parallel regulator 2 work is also inevitable to be changed thereupon, make the dutycycle and the tested electric current of hysteresis comparator 7 voltage pulse output signals have relation one to one, the pulse voltage signal of hysteresis comparator 7 outputs is inputed to signal Processing and display 5, thereby realize current measurement.
By following description, provide embodiments of the invention to accompanying drawing 2～accompanying drawing 4.
In accompanying drawing 2, SSR
1-1And SSR
1-2Be respectively the input end and the output terminal of solid-state relay, the two forms parallel regulator, IC
1Be three terminal integrated voltage stabilizer, D
1～D
4And C
2Form rectifier filer, resistance R
9And R
10Form sample circuit, operational amplifier IC
2With resistance R
2, R
3, R
4Form hysteresis comparator, triode Q
1, Q
2Deng formation driving circuit, R
YBe voltage dependent resistor (VDR), R
1With C
1Form higher hamonic wave and absorb circuit.The IC that provides at accompanying drawing 3
2Output voltage U
0With the sample circuit output voltage U '
InBetween graph of a relation in, U
2And U
1Be respectively the upper and lower threshold voltage of hysteresis comparator, their size is by resistance R
2, R
3, R
4And IC
1Output voltage U
CCDecision, U
1Be in order to satisfy IC
1The requirement of minimum I/O pressure reduction, U
2Be in order to guarantee IC
1Input voltage be no more than permissible value, make IC
1Hear rate is lower than the hear rate of its permission.
The principle of work of circuit is shown in the accompanying drawing 2:
Hysteresis comparator by detect voltage U from sample circuit '
InAfter, IC
2Voltage pulse output, this pulse voltage is through triode Q
1Drive SSR
1-1, make SSR
1-2With on-off mode work, to the secondary current I of CT
2Shunt, thereby make IC
1Input voltage U
InChange U '
InAlso change thereupon.As U '
In≤ U
1The time, IC
2The output high level; As U '
In〉=U
2The time, IC
2Output low level; As U '
InBy U
1→ U
2The time, IC
2The output high level; As U '
InBy U
2→ U
1The time, IC
2Output low level.Because by IC
2, R
2, R
3, R
4The hysteresis comparator and the SSR that form
1-1Branch road and SSR
1-2The negative feedback that forms between branch road makes U '
InEven when tested electric current variation range is big, also all the time at U
1～U
2Between change, thereby make IC
1Output voltage stabilization, make IC simultaneously
2The dutycycle of the pulse voltage signal of output and tested electric current have relation one to one.
For the ease of further specifying, establish: U '
InBy U
1Rise to U
2Time be T
1, U '
InBy U
2Drop to U
1Time be T
2(IC at this moment
2The pulse voltage signal of output as shown in Figure 4); With IC
1Bias current I
BAnd IC
2Working current be integrated into load (i.e. " signal Processing and display ") electric current I
LIn, and ignore I
BVariation (I
BActual change is very small, at Δ U
InDuring＜5V, Δ I
B＜0.2mA); SSR
1-1Electric current during conducting is I
G, the electric current the during conducting of LED branch road is I
D, I
D=I
G(this very easy realization).
A. as U '
In〉=U
2The time, IC
2Output low level, Q
2By, Q
1Conducting, SSR
1-1Conducting makes SSR
1-2Become conducting state from cut-off state.This moment is because SSR
1-2On-state voltage drop (being lower than 2V) less than U
InSo, the secondary current I of CT
2Fully by SSR
1-2Bypass, capacitor C
2Beginning is SSR separately
1-1Branch road and electric, elapsed time T
2After, U '
In=U
1
According to the fundamental relation formula: Δ Q=C * Δ U and Δ Q=I * Δ t, wherein Δ Q is C
2In the charge variation amount, C is C
2Electric capacity, I and Δ t are respectively discharge (or charging) average current and the time thereof.
Following relation is arranged in this course:
C×(U
2-U
1)＝(I
L+I
G)×T
2 (1)
It is worthy of note: SSR
1-2During conducting, because the unidirectional buffer action of diode in the rectifier bridge makes SSR
1-2Can be to C
2The middle electric charge that stores is shunted.
B. work as U
In≤ U
1The time, IC
2The output high level, Q
2Conducting, Q
1By, SSR
1-1End, make SSR
1-2Become cut-off state from conducting state, at this moment the secondary current I of CT
2To C
2In the time of charging is again LED branch road and electric, elapsed time T
1After, U '
In=U
2
Following relation is arranged in this course:
I
2* T
1=C * (U
2-U
1)+(I
L+ I
D) * T
1(annotate: I
2Be the mean value of CT secondary current)
With I
D=I
G, the substitution following formula gets:
I
2×T
1＝C×(U
2-U
1)+(I
L+I
G)×T
1 (2)
Above-mentioned A, B process cycle back and forth carry out, and make U '
InAll the time at U
1～U
2Between change, make IC
1Keep suitable I/O pressure reduction, output voltage stabilization is for load provides stable working power.
Get by formula (1) and formula (2) again:
T
1/ (T
1+ T
2)=(I
L+ I
G)/I
2(3) in the formula (3), I
LAnd I
GBe known constant (because signal Processing and display can be thought dead load), and T
1/ (T
1+ T
2) be again IC just
2The dutycycle of voltage pulse output signal makes it represent with D, then:
According to formula (4) as can be known, I
2There is relation one to one with D, that is tested electric current and IC
2The dutycycle of voltage pulse output signal is one to one, so, at I
LAnd I
GUnder the known condition, as long as measure dutycycle D, just can obtain I
2, according to the no-load voltage ratio of current transformer CT, just can obtain measured current I again
1Value.This part work is finished by " signal Processing and display " unit.
This shows, shown in accompanying drawing 1 and the accompanying drawing 2 only with a current transformer CT and current/voltage translation circuit and signal Processing and the display formed by parallel regulator, rectifier filer, sample circuit, hysteresis comparator, driving circuit, voltage stabilizer, by tested electric current being carried out the method for current/voltage conversion, can obtain the pulse voltage signal that the working power of measurement mechanism self and dutycycle and tested electric current have one-to-one relationship simultaneously, thereby realize the measurement of electric current.The method of this measurement electric current, measurement range is wide, realizes easily, is particluarly suitable for being difficult to provide the occasions such as high voltage of operate outside power supply to be used, and also provides a kind of new technology for current instruments or Design of device simultaneously.
When the method for stating is in the use carried out current measurement,, also must note the influence of following factor, and take corresponding measure in order to guarantee to measure accurately:
1. in order to reduce because of SSR
1-2The difference of the current transformer CT secondary current phase place of correspondence during each conducting (or shutoff), and make IC
2The dutycycle of voltage pulse output signal to the error that measurement brings, should be measured a plurality of dutycycles when current transformer CT secondary current is constant and change as far as possible, utilizes its mean value to calculate tested current value.
2. because the working power of measurement mechanism adopts current transformer CT and current/voltage-converted circuit to realize, and in current transformer CT when work, need certain exciting current, have loss, so, have only when tested electric current during greater than a certain value, measurement mechanism just can obtain stable working power, at this moment just can measure.Therefore, when using said method to measure electric current, one section work dead band (promptly when tested electric current during less than a certain value, can't measure) is arranged.In order to reduce the work dead band, the one, adopt low power design technique to reduce the working current of signal Processing and display unit, that is reduce load current I
L, the 2nd, select the iron core of the iron core of high permeability, low iron loss for use, as nanocrystalline iron core as current transformer CT.
3. the error of current measurement being brought for the exciting current that reduces current transformer CT and loss, can adopt the method for calibration, promptly according to tested electric current and dutycycle condition one to one, with the reometer that degree of accuracy is high the current value that records with said method is calibrated, thereby obtain " data set "---(dutycycle, current value), " data set " is cured to " signal Processing and display " unit of forming by single-chip microcomputer, this unit just can directly provide the exact value of tested electric current automatically by the dutycycle that records by the method for tabling look-up.
In addition, as the case may be, " signal Processing and the display " unit in the accompanying drawing 2, also available " signal Processing and wireless receiving and dispatching " unit substitutes, and it is specially adapted to occasions such as telemeasurement.
Claims (2)
1. method of measuring electric current, adopt current transformer CT and current/voltage translation circuit and signal Processing and display, obtain the working power of measurement mechanism self and the coherent signal of tested electric current, realize current measurement, it is characterized in that: comprise a current transformer CT and current/voltage translation circuit and signal Processing and the display formed by parallel regulator, rectifier filer, sample circuit, hysteresis comparator, driving circuit, voltage stabilizer; The parallel connection of secondary windings of the ac input end of parallel regulator and rectifier filer and current transformer CT, the input end of voltage stabilizer and the input end of sample circuit link to each other with the output terminal of rectifier filer, the signal output part of sample circuit links to each other with the signal input part of hysteresis comparator, the output terminal of hysteresis comparator links to each other with the signal input part of display with the control end of driving circuit and signal Processing, and the power input of driving circuit links to each other with the output terminal of voltage stabilizer; Only realize obtaining the pulse voltage signal that the working power of measurement mechanism self and dutycycle and tested electric current have one-to-one relationship simultaneously with a current transformer CT and described current/voltage translation circuit, by measuring the method for pulse voltage signal dutycycle, realize current measurement.
2. the method for measurement electric current according to claim 1, its feature are that also described parallel regulator adopts solid-state relay.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200310105052 CN1226633C (en) | 2003-11-07 | 2003-11-07 | Current measuring method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200310105052 CN1226633C (en) | 2003-11-07 | 2003-11-07 | Current measuring method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1542456A true CN1542456A (en) | 2004-11-03 |
| CN1226633C CN1226633C (en) | 2005-11-09 |
Family
ID=34333607
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200310105052 Expired - Fee Related CN1226633C (en) | 2003-11-07 | 2003-11-07 | Current measuring method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1226633C (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102075103A (en) * | 2010-12-08 | 2011-05-25 | 天津市翔晟远电力设备实业有限公司 | Energy-gaining device adapted to large-scale current changes |
| CN102981034A (en) * | 2012-11-23 | 2013-03-20 | 安徽鑫龙电器股份有限公司 | Measuring meter for measuring current and voltage values |
| CN103983835A (en) * | 2014-05-22 | 2014-08-13 | 南京深科博业电气股份有限公司 | Direct current small-current transformer and method for measuring current of direct current small-current transformer |
| CN104113224A (en) * | 2013-12-19 | 2014-10-22 | 西安电子科技大学 | Radio frequency energy acquisition circuit system |
| CN110646659A (en) * | 2019-09-26 | 2020-01-03 | 浙江榆阳电子有限公司 | Sampling precision and hysteresis control lifting circuit |
| WO2021003719A1 (en) * | 2019-07-10 | 2021-01-14 | Abb Schweiz Ag | Sensing apparatus and sensing method |
-
2003
- 2003-11-07 CN CN 200310105052 patent/CN1226633C/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102075103A (en) * | 2010-12-08 | 2011-05-25 | 天津市翔晟远电力设备实业有限公司 | Energy-gaining device adapted to large-scale current changes |
| CN102981034A (en) * | 2012-11-23 | 2013-03-20 | 安徽鑫龙电器股份有限公司 | Measuring meter for measuring current and voltage values |
| CN104113224A (en) * | 2013-12-19 | 2014-10-22 | 西安电子科技大学 | Radio frequency energy acquisition circuit system |
| CN104113224B (en) * | 2013-12-19 | 2017-03-08 | 西安电子科技大学 | A kind of RF energy obtains Circuits System |
| CN103983835A (en) * | 2014-05-22 | 2014-08-13 | 南京深科博业电气股份有限公司 | Direct current small-current transformer and method for measuring current of direct current small-current transformer |
| WO2021003719A1 (en) * | 2019-07-10 | 2021-01-14 | Abb Schweiz Ag | Sensing apparatus and sensing method |
| CN114041062A (en) * | 2019-07-10 | 2022-02-11 | Abb瑞士股份有限公司 | Sensing device and sensing method |
| CN110646659A (en) * | 2019-09-26 | 2020-01-03 | 浙江榆阳电子有限公司 | Sampling precision and hysteresis control lifting circuit |
| CN110646659B (en) * | 2019-09-26 | 2021-07-30 | 浙江榆阳电子有限公司 | Sampling precision and hysteresis control lifting circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1226633C (en) | 2005-11-09 |
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