CN101561458B - Method and device for measuring current on line - Google Patents
Method and device for measuring current on line Download PDFInfo
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- CN101561458B CN101561458B CN2009100855992A CN200910085599A CN101561458B CN 101561458 B CN101561458 B CN 101561458B CN 2009100855992 A CN2009100855992 A CN 2009100855992A CN 200910085599 A CN200910085599 A CN 200910085599A CN 101561458 B CN101561458 B CN 101561458B
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Abstract
The invention discloses a method and a device for measuring current in a circuit on line. The method can calculate the current of a measured circuit after measuring voltage values of certain circuit element in the measured circuit in a state of normal working and in a state with additional voltage. The invention also discloses the device for implementing the method to measure the current in the circuit on line. By using the method and the device, the current path is not needed to be switched off and the normal work of the measured circuit is not interrupted, the current value in the measure circuit can be displayed through calculation after direct measurement of a circuit element selected from the measured circuit, thereby greatly facilitating the maintenance and the diagnosis of the circuit; and simultaneously, the device has the advantage of simple circuit design.
Description
Technical field
The invention belongs to electronic measuring technology field, relate to a kind of on-line measurement method of current and device in particular.
Background technology
,, need be concatenated into reometer in the current return in the past, again reometer taken out after the measurement, thereby not only influence the operate as normal of circuit in order to measure electric current, also very inconvenient in the operation.To this; People constantly seek new measuring method; Just put down in writing a kind of measuring method like Chinese patent 200610157793.3 " on-line measurement straight-flow system and method "; Though this method need not insert reometer in the current return again, in measuring engineering, still need the running current of turn-off circuit, thereby still the work in tested loop is caused interference.Chinese patent CN85107432.A " on-line direct current current measuring method and online reometer " has disclosed another kind of measuring method, and this method can directly be measured current in loop, and needn't interrupt the work of circuit-under-test; But its shortcoming is a measuring equipment electric current identical with working current to be provided; When the electric current that will measure reaches 100MA～1A, just no longer be suitable for portable apparatus, when the electric current that will measure reaches 1A～20A; Then will make the power supply of testing apparatus become very complicated; In addition, this measuring method also exists and influenced by extraneous factor, the defective of functional reliability difference.
Summary of the invention
Problem to prior art exists the object of the present invention is to provide a kind of on-line measurement method of current, and the device of realizing this method.
Technical scheme of the present invention is following:
A kind of on-line measurement method of current is specially:
1) in circuit-under-test, choose one have linear impedance element;
2) keep under the normal operating conditions at circuit-under-test; Measure the voltage at selected element two ends; And at selected element two ends and connect a testing power supply, measure the voltage at selected element two ends once more, and measure electric current in the loop that constitutes by testing power supply and selected element;
3) current value that will measure through calculating.
Carrying out above-mentioned steps 2) before, at first confirm the character of working current in the selected element, then according to the character of measured electric current, carry out the step 2 of back again), step 3).
When measured electric current is direct current, at first measure the voltage at selected element two ends with voltage measuring apparatus, obtain a magnitude of voltage V1; Then, at selected element two ends and connect a DC test power supply, make to produce a measuring current I1 in the loop that constitutes by this DC test power supply and selected element, and measure the voltage at selected element two ends simultaneously, obtain a magnitude of voltage V2; At last, through formula: I=I1 * V1/ (V2-V1) calculates the working direct current in the circuit-under-test.
When measured electric current is direct current; Also can measure as follows: with the testing power supply of output square-wave pulse signal; Behind the series current measurement mechanism; Be connected in parallel on the two ends of selected element; While is the shunt voltage measurement mechanism at selected element two ends, and voltage Vtl, electric current I tl when measuring voltage Vth, the electric current I th when exporting the square wave high level respectively and exporting the square wave low level calculate the working direct current I in the selected element through formula I=(Ith*Vtl-Vth*Itl)/(Vth-Vtl) at last.
When measured electric current is direct current, also can measure as follows: at first, measure the voltage at selected element two ends, obtain a magnitude of voltage V1 with voltage measuring apparatus; Then; With sending sinusoidal wave alternating-current measurement power supply and being connected on frequency-selecting current measuring device on the alternating-current measurement power supply and being connected in parallel on the two ends of selected element; Measure measuring current It, measure the voltage Vt at selected element two ends, calculate resistance value Z=Vt/It with the frequency-selecting voltage measuring apparatus; At last, calculate the working current I in the selected element through formula I=V1/R, wherein R is the real part of Z.
When measured electric current was interchange, its measuring process was: at first, measure the voltage V at selected element two ends with the frequency-selecting voltage measuring apparatus; Then; With sending sinusoidal wave alternating-current measurement power supply and being connected on frequency-selecting current measuring device on the testing power supply and being connected in parallel on the two ends of selected element; Measure measuring current It, measure the voltage Vt at selected element two ends, calculate resistance value Z=Vt/It with the frequency-selecting voltage measuring apparatus; At last, calculate the working current I in the selected element through formula I=V/Z, Z wherein, Vt, It, V, I are vector.
When measured electric current includes the alternating component of multiple frequency, at first, utilize the frequency-selecting voltage measuring apparatus to measure voltage V1, V2...Vn under each frequency of selected element two ends respectively; Then; With sending sinusoidal wave alternating-current measurement power supply and being connected on frequency-selecting current measuring device on the testing power supply and being connected in parallel on the two ends of selected element; Measure electric current I t, measure the voltage Vt at selected element two ends, calculate resistance value Z=Vt/It with the frequency-selecting voltage measuring apparatus; At last, calculate electric current I 1, I2...In under each frequency, and calculate the working current I in the selected element through formula I=Vd/R+ ∑ Ii through formula I=V/Z, wherein i=1,2...n, Z, Vt, It, V, I are vector.
When measured electric current not only includes alternating component but also flip-flop is arranged; At first, with the testing power supply of output square-wave pulse signal, behind the series current measurement mechanism; Be connected in parallel on the two ends of selected element; While is the shunt voltage measurement mechanism at selected element two ends, and voltage Vtl, electric current I tl when measuring voltage Vth, the electric current I th when exporting the square wave high level respectively and exporting the square wave low level are through formula I
1=(Ith*Vtl-Vth*Itl)/(Vth-Vtl) calculate the working direct current I in the selected element
1
Then; Measure the voltage V at selected element two ends with the frequency-selecting voltage measuring apparatus; Be connected in parallel on the two ends of selected element with sending sinusoidal wave alternating-current measurement power supply with being connected on frequency-selecting current measuring device on the testing power supply, measure measuring current It, measure the voltage Vt at selected element two ends simultaneously with the frequency-selecting voltage measuring apparatus; Calculate resistance value Z=Vt/It, calculate the working current I in the selected element through formula I=V/Z
2
At last, through formula I=I
1+ I
2Calculate the working current I in the selected element, wherein, Z, Vt, It, V, I
2, I is vector.
Further, when including alternating component in the working current of selected element, the frequency that the said alternating-current measurement power supply that sends sine wave is selected for use is different from the frequency that comprises alternating component in the measured electric current.
Further, said selected element is a section lead, resistance, inductance or the electric capacity in the circuit-under-test.
Implement the device of a kind of on-line measurement electric current of said method; This device comprises testing power supply, frequency-selecting voltage measuring apparatus, frequency-selecting current measuring device, signal processing unit, display; Wherein, Testing power supply can be exported direct current square-wave pulse signal and AC sine wave signal; Signal processing unit is used for the signal that frequency-selecting voltage measuring apparatus and frequency-selecting current measuring device measure is carried out calculation process, and the working current value that will measure to obtain, display are used to the waveform that shows measurement result and measure signal.
Further, the calculation process of said signal processing unit comprises the calculating of calculating to measured current effective value (root-mean-square value), absolute calculation, absolute average.
Further, measure calculate resistance value Z after, to being connected in parallel on selected element voltage measurement mechanism; Be input to the digital signal of computing machine, use the wave filter of characteristic, make signal Processing as Z; To obtain the data stream of electric current I; And direct as required display waveform, or calculate effective value (root-mean-square value), absolute value, absolute average, show again.
Further, said testing power supply is a constant current source.
Further, the approximate constant current source of said testing power supply for being constituted behind the resistance of selected element impedance by a power series one resistance.
Further; Said signal processing unit also comprises the working current in the described selected element is carried out error analysis; Be specially:, calculate error and demonstration by conventional means, when error is excessive according to the measuring error of electric current, voltage measuring apparatus and the computing formula of electric current; Through sound, light alarm, remind the user to adjust method of testing or alternative testing element.
On-line measurement method of current of the present invention and device; During use; Need not break off circuit-under-test, need not interrupt the operate as normal of circuit-under-test, directly through after a circuit component of choosing in the circuit-under-test is tested; Just can show the current value in the circuit-under-test through calculating, be very easy to the maintenance and the diagnosis of circuit.
Description of drawings
Fig. 1 is a principle of the invention synoptic diagram;
Fig. 2 is the measuring principle synoptic diagram of working direct current;
Fig. 3 is the measuring principle synoptic diagram of working alternating current;
Fig. 4 is the principle schematic of AC and DC working current;
Fig. 5 is a measurement mechanism structural drawing of the present invention;
Fig. 6 a is the circuit structure diagram that testing power supply adopts constant current source;
Fig. 6 b is the circuit structure diagram that testing power supply adopts approximate constant current source.
Embodiment
Fig. 1 is a principle schematic of the present invention.
Shown in figure, principle of work of the present invention is under the condition of element operate as normal to be tested, measures the voltage at its two ends; At its two ends and after connecing testing power supply, measure the voltage at selected element two ends once more, and measure simultaneously by testing power supply and current in loop that selected element constitutes; At last, the current value that will measure through calculating.
As shown in Figure 2, when measured working current was direct current, concrete steps were:
At first, measure the voltage at selected element two ends, obtain a magnitude of voltage V1 with D.C. voltmeter; Then, at selected element two ends and connect a DC test power supply, measure the current in loop that constitutes by DC test power supply and selected element, obtain a measuring current I1, and measure the voltage at selected element two ends simultaneously, obtain a magnitude of voltage V2 with DC ammeter; At last, through formula: I=I1 * V1/ (V2-V1) calculates the working direct current in the circuit-under-test.
Testing power supply wherein can also adopt the testing power supply of output square-wave pulse signal, and at this moment, measuring process is:
Behind the testing power supply series direct current reometer with the output square-wave pulse signal; Be connected in parallel on the two ends of selected element; While is the parallel connection direct voltage table at selected element two ends; Voltage Vtl, electric current I tl when measuring voltage Vth, the electric current I th when exporting the square wave high level respectively and exporting the square wave low level calculate the working direct current I in the selected element through formula I=(Ith*Vtl-Vth*Itl)/(Vth-Vtl) at last.
Referring to Fig. 4, when measured working current is direct current, can also adopt the alternating-current measurement power supply, measuring process is:
At first, measure the voltage at selected element two ends, obtain a magnitude of voltage V1 with D.C. voltmeter; Then; With sending sinusoidal wave alternating-current measurement power supply and being connected on frequency-selecting reometer on the alternating-current measurement power supply and being connected in parallel on the two ends of selected element; Measure measuring current It, measure the voltage Vt at selected element two ends, calculate resistance value Z=Vt/It with frequency selective voltmeter; At last, calculate the working current I in the selected element through formula I=V1/R.Wherein R is the real part of Z.
As shown in Figure 3, when measured working current was interchange, concrete steps were:
At first, measure the voltage V at selected element two ends with frequency selective voltmeter; Then, be connected in parallel on the two ends of selected element with being connected on frequency-selecting reometer on the testing power supply, measure measuring current It, measure the voltage Vt at selected element two ends, calculate resistance value Z=Vt/It with frequency selective voltmeter with sending sinusoidal wave alternating-current measurement power supply; At last, calculate the working current I in the selected element through formula I=V/Z, Z wherein, Vt, It, V, I are vector.
Because element to be tested in working order down, there are working current and voltage to exist.And be electric current and the voltage that the test impedance produces by testing power supply, must make a distinction with working current and voltage.Therefore, it should be noted that during measurement: the testing power supply frequency of operation is different with element frequency of operation to be tested, distinguishes with selective frequency meter, measures measuring current, voltage and WV respectively.
Make to the electric current that the test impedance produces, the frequency of voltage and be different from the working current of element to be tested, electric voltage frequency.Distinguish the different value of these two kinds of electric currents, voltage again with frequency selective voltmeter, reometer, the electric current, the voltage that have therefore just reached electric current, voltage and the element work to be tested of test impedance do not disturb mutually.Be actually working current according to element to be tested, frequency that electric voltage frequency is selected testing power supply realizes.
As special case, when measured electric current included the alternating component of multiple frequency, its measuring process was:
At first, utilize frequency selective voltmeter to measure voltage V1, V2...Vn under each frequency of selected element two ends respectively; Then, be connected in parallel on the two ends of selected element with being connected on frequency-selecting reometer on the testing power supply, measure electric current I t, measure the voltage Vt at selected element two ends, calculate resistance value Z=Vt/It with frequency selective voltmeter with sending sinusoidal wave alternating-current measurement power supply; At last, calculate electric current I 1, I2...In under each frequency, and calculate the working current I in the selected element through formula I=Vd/R+ ∑ Ii through formula I=V/Z, wherein i=1,2...n, Z, Vt, It, V, I are vector.
As shown in Figure 4, when measured working current had both comprised flip-flop, when comprising alternating component again, concrete steps are:
At first; Testing power supply with the output square-wave pulse signal; Behind the series direct current reometer, be connected in parallel on the two ends of selected element, simultaneously parallel connection direct voltage table at selected element two ends; Voltage Vtl, electric current I tl when measuring voltage Vth, the electric current I th when exporting the square wave high level respectively and exporting the square wave low level are through formula I
1=(Ith*Vtl-Vth*Itl)/(Vth-Vtl) calculate the working direct current I in the selected element
1
Then; Measure the voltage V at selected element two ends with frequency selective voltmeter; Be connected in parallel on the two ends of selected element with sending sinusoidal wave alternating-current measurement power supply with being connected on frequency-selecting reometer on the testing power supply, measure measuring current It, measure the voltage Vt at selected element two ends simultaneously with frequency selective voltmeter; Calculate resistance value Z=Vt/It, calculate the working current I in the selected element through formula I=V/Z
2
At last, through formula I=I
1+ I
2Calculate the working current I in the selected element, wherein, Z, Vt, It, V, I
2, I is vector.
Shown in Figure 5 is actual design structural drawing according to an online current sensing means of principle of the invention design.
As shown in the figure, this installs by testing power supply, the current detecting input stage, and the voltage detecting input stage, computing controller CPU, these several parts of display are formed.
Wherein,
(1) testing power supply: form testing power supply by DAC waveform generator U1, variable gain amplifier U2, output amplifier U3.According to the control of computing machine, DAC can send the AC signal of various frequencies.U2 regulates the size of output power, to adapt to various test requests.Output stage can be designed to constant current output, shown in Fig. 6 a.Also can be designed to constant voltage and add resistance output, shown in Fig. 6 b.The testing power supply of constant current output is smaller to the influence of circuit, and is complicated but circuit is wanted, and operational amplifier will have higher WV, to avoid nonlinear generation.It is just simple many that constant voltage adds the resistance mode, also do not have nonlinear restriction, but will notice that the influence to circuit-under-test can not be too big, and the internal resistance that also is power supply is than big many of the impedance absolute value of selected testing element.In principle, the interchange of testing power supply output can be a random waveform, only otherwise the test of disturbing WV just can, neither contain the frequency content of WV.In the reality, can select sine wave for use.
(2) form the current detecting input stage by sampling resistor R, variable gain amplifier U4, ADC digital analog converter U5a.Sampling resistor R becomes voltage signal to the current conversion of passing through.Regulate U4 to obtain best test effect, ADC converts analog test signal to digital signal, deliver to computing controller CPU after, be for data processing by the software of computing controller.Software bandpass filtering among the CPU and current detecting input stage are formed electric current frequency-selecting measurement mechanism jointly.Therefore the frequency-selecting frequency can be provided with through the parameter that wave filter is set very easily, can make things convenient for and records It accurately.If wave filter is a low-pass filter, then form the dc current measurement device.
(3) form the voltage detecting input stage by variable gain amplifier U6, ADC digital analog converter U5b.Regulate U6 to obtain best test effect.Voltage detecting input stage and data processing software can be accomplished multiple test function jointly.In this instrument, mainly contain:
1. low-pass filter is accomplished the direct current measurement function.
2. BPF. is accomplished the frequency-selecting measurement function.
3. FFT, fast fourier transform is accomplished the frequency sweep function.
4. through being arranged to the wave filter that filtering characteristic is impedance 1/Z, in order to test and monitor current.
Be noted that especially above function can use simultaneously.
(4) display: be used to show net result.
The explanation of software for calculation:
(1) calculating of Z: the AC signal that the testing power supply output frequency is ft is set, and the filter frequencies of frequency-selecting current measuring device and frequency-selecting voltage measuring apparatus is set to f.Test I t and Vt calculate Z=Vt/It, and both the ratio of the amplitude of Vt, It and both phase places was poor.Concrete computing method are a lot, belong to this professional domain technician's basic skills, do not spoken more at this.Will note in the test: 1. the working current in the detected element can not contain the ft frequency content.Can scan the frequency content of detected element working current in advance, when the testing power supply frequency is set, avoid these frequencies.2. U5a and U5b must synchronized samplings.If share an ADC, when selecting electric current, voltage tester with switch, the starting point that detects voltage and current is necessary identical for the phase place of testing power supply.As requested, also can show Z.
(2) calculating of detected element working current:
1. frequency-selecting voltage measuring apparatus frequency is set for frequency f, measures the voltage V on the detected element through the detected element electric current, electric current I=V/Z, wherein Z, V, I are vectors.When measuring V, testing power supply should not contain the f frequency content, and harmonic wave should not contain the f frequency content yet, can turn off testing power supply yet.When tested working current was direct current, it was the dc voltage measurement device that the frequency-selecting voltage measuring apparatus is set, and also promptly wave filter is set to low-pass filter, measures V, took out the real part R of Z (Z=R+jX, a kind of expression way of vector Z) again, I=V/R.
If when direct current and a plurality of alternating component are arranged in the loop of 2. being tested, use said method, measure a plurality of alternating currents, vector addition obtains total current.Narration is as follows: when the alternating current of a plurality of frequencies passed through the loop with DC current, the subscript of a plurality of frequencies interchanges was followed successively by i=1,2...n, is designated as d under the direct current.By D.C. voltmeter or frequency-selecting frequency is that zero frequency span is measured Vd, and the frequency-selecting frequency is that the voltage that the selective frequency meter of f1, f2...fn is measured respectively under each frequency is: V1, V2...Vn, and I=Vd/R+ ∑ Ii then, i=1....n, wherein: ft ≠ fi, i=1...n.This total current I also is a vector, can be as required, and display waveform, effective value (root-mean-square value), absolute value, absolute average etc.Also can observe the electric current that shows each frequency content, this is the frequency domain amperometry in the electronics just.
3. the digital filter in the frequency-selecting voltage measuring apparatus of the selected element voltage of test, be arranged to the wave filter that characteristic is impedance 1/Z, the signal of process filter process is exactly the electric current that selected element passes through, the amperometry of both time domain waveforms, or time domain.Display mode can be as required, display waveform, effective value (root-mean-square value), absolute value, absolute average etc.
4. be provided with and measure power supply output square-wave signal, frequency-selecting voltage measuring apparatus and frequency-selecting current measuring device are direct-current measuring device, when the high level of output square wave; Measuring voltage is Vth; Measuring electric current is Ith, and when the low level of output square wave, measuring voltage is Vtl; Measuring electric current is Itl, calculates R with formula R=(Vth-Vtl)/(Ith+Itl).The voltage at said element two ends is: V=(Ith*Vtl-Vth*Itl)/(Ith+Itl), I=V/R calculates electric current through formula, also can directly be I=V/R formula abbreviation: I=(Ith*Vtl-Vth*Itl)/(Vth-Vtl).
It is simple many that the online current sensing means of direct current is wanted, also low many of price.Mainly be electric current, voltage measuring apparatus all is a direct-current measuring device, and testing power supply also only needs to produce square wave.The frequency of square wave is selected, and should guarantee that electric current, voltage signal begin to measure also after stable again will guarantee enough test durations.This will confirm according to the design of ADC and entire circuit.Computing method are with aforementioned identical.
Because online current test method is indirect measurement, is the test result of calculation of a plurality of amounts, and is general; Can be bigger than individual event test error; Therefore it is necessary error being calculated and shown, when error is excessive, and display error numerical value not only; And inform the user through acousto-optic etc., so that the user adjusts method of testing or alternative testing element.The computing formula of error is derived by the error of each test item in the computing formula of electric current and the formula.This technology is those skilled in the art's a ABC, does not just do detailed argumentation at this.
Claims (13)
1. on-line measurement method of current is specially:
1) in circuit-under-test, choose one have linear impedance element;
2) keep under the normal operating conditions at circuit-under-test; Use frequency selective voltmeter to measure the voltage at selected element two ends; Then at selected element two ends and connect a testing power supply, and use frequency selective voltmeter to measure the voltage at selected element two ends and use the frequency-selecting reometer to measure electric current in the loop that constitutes by testing power supply and selected element;
3) current value that will measure through calculating;
Carrying out said step 2) before, at first confirm the character of working current in the selected element, according to the character of measured electric current, carry out said step 2 more then), step 3).
2. the method for claim 1 is characterized in that, when measured electric current is direct current, said step 2), step 3) is specially:
Measure the voltage at selected element two ends with voltage measuring apparatus, obtain a magnitude of voltage V1; Said selected element is a resistance, then, at selected element two ends and connect a DC test power supply, makes to produce a measuring current I1 in the loop that is made up of this DC test power supply and selected element, and measures the voltage at selected element two ends simultaneously, obtains a magnitude of voltage V2; At last, through formula: I=I1 * V1/ (V2-V1) calculates the working direct current in the circuit-under-test.
3. the method for claim 1 is characterized in that, when measured electric current is direct current, said step 2), step 3) is specially:
Testing power supply with the output square-wave pulse signal; Behind the series current measurement mechanism; Be connected in parallel on the two ends of selected element, said selected element is a resistance, simultaneously the shunt voltage measurement mechanism at selected element two ends; Voltage Vtl, electric current I tl when measuring voltage Vth, the electric current I th when exporting the square wave high level respectively and exporting the square wave low level calculate the working direct current I in the selected element through formula I=(Ith*Vtl-Vth*Itl)/(Vth-Vtl) at last.
4. the method for claim 1 is characterized in that, when measured electric current is direct current, said step 2), step 3) is specially:
At first, measure the voltage at selected element two ends, obtain a magnitude of voltage V1 with voltage measuring apparatus; Said selected element is a resistance; Then; With sending sinusoidal wave alternating-current measurement power supply and being connected on frequency-selecting current measuring device on the alternating-current measurement power supply and being connected in parallel on the two ends of selected element; Measure measuring current It, measure the voltage Vt at selected element two ends, calculate resistance value Z=Vt/It with the frequency-selecting voltage measuring apparatus; At last, calculate the working current I in the selected element through formula I=V1/R, wherein R is the real part of Z.
5. the method for claim 1 is characterized in that, when measured electric current when exchanging, said step 2), step 3) is specially:
At first, measure the voltage V at selected element two ends with the frequency-selecting voltage measuring apparatus; Then; With sending sinusoidal wave alternating-current measurement power supply and being connected on frequency-selecting current measuring device on the testing power supply and being connected in parallel on the two ends of selected element; Measure measuring current It; Saidly send the frequency that sinusoidal wave alternating-current measurement power supply selects for use and be different from the frequency that comprises alternating component in the measured electric current, measure the voltage Vt at selected element two ends, calculate resistance value Z=Vt/It with the frequency-selecting voltage measuring apparatus; At last, calculate the working current I in the selected element through formula I=V/Z, Z wherein, Vt, It, V, I are vector.
6. the method for claim 1 is characterized in that, said selected element is a section lead, resistance, inductance or the electric capacity in the circuit-under-test.
7. the method for claim 1; It is characterized in that; Use the four-wire system method of testing, current testing device is arranged on said selected element two ends with after said testing power supply is connected; Voltage test device is arranged on the two ends of said selected element simultaneously, and voltage test device is connected with the lead-in wire of current testing device through selected element with testing power supply.
8. implement the device that aforesaid right requires a kind of on-line measurement electric current of the arbitrary described method of 1-7; It is characterized in that; This device comprises testing power supply, frequency-selecting voltage measuring apparatus, frequency-selecting current measuring device, signal processing unit, display; Wherein, testing power supply can be exported direct current square-wave pulse signal and AC sine wave signal, and signal processing unit is used for the signal that frequency-selecting voltage measuring apparatus and frequency-selecting current measuring device measure is carried out calculation process; The working current value that will measure to obtain, display are used to the waveform that shows measurement result and measure signal.
9. device as claimed in claim 8 is characterized in that, the calculation process of said signal processing unit comprises the calculating of calculating to measured current effective value, absolute calculation, absolute average.
10. device as claimed in claim 8 is characterized in that, measure calculate resistance value Z after; To being connected in parallel on selected element voltage measurement mechanism, be input to the digital signal of computing machine, use the wave filter of characteristic as 1/Z; Make signal Processing, obtaining the data stream of electric current I, and direct display waveform as required; Or calculate effective value, absolute value, absolute average, show again.
11. device as claimed in claim 8 is characterized in that, said testing power supply is a constant current source.
12. device as claimed in claim 8 is characterized in that, the approximate constant current source of said testing power supply for being made up of behind the resistance of selected element impedance a power series one resistance.
13. device as claimed in claim 8; It is characterized in that said signal processing unit also comprises the working current in the described selected element is carried out error analysis, is specially: according to the measuring error of electric current, voltage measuring apparatus and the computing formula of electric current; Calculate error and demonstration by conventional means; When error is excessive,, remind the user to adjust method of testing or alternative testing element through sound, light alarm.
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| CN102608410B (en) * | 2011-12-12 | 2015-03-25 | 中国电力科学研究院 | Pulse generation circuit, voltage measuring circuit and voltage measuring method |
| CN102721852B (en) * | 2012-06-21 | 2014-08-20 | 天地融科技股份有限公司 | Method and device for measuring working current of electronic device |
| CN106556729A (en) * | 2015-09-27 | 2017-04-05 | 北京嘉岳同乐极电子有限公司 | A kind of current measuring device |
| CN110470887A (en) * | 2019-09-02 | 2019-11-19 | 珠海格力智能装备有限公司 | Detection device and detection method |
| CN110488084A (en) * | 2019-09-26 | 2019-11-22 | 京信通信系统（中国）有限公司 | Pcb board branch current detection device and system |
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|---|---|---|---|---|
| CN85107432A (en) * | 1985-09-26 | 1987-04-08 | 齐桓电子工业公司 | On-line direct current current measuring method and online reometer |
| CN201011504Y (en) * | 2006-11-28 | 2008-01-23 | 李彩珍 | Current sensor |
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