CN103792409B - The measuring circuit of fast-changing large electric current - Google Patents
The measuring circuit of fast-changing large electric current Download PDFInfo
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- CN103792409B CN103792409B CN201410021869.4A CN201410021869A CN103792409B CN 103792409 B CN103792409 B CN 103792409B CN 201410021869 A CN201410021869 A CN 201410021869A CN 103792409 B CN103792409 B CN 103792409B
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Abstract
The invention discloses a kind of measuring circuit of fast-changing large electric current, comprise sensing element and operational amplifier; Sensing element is connected in tested current loop; The value of sensing element comprises resistance value and inductance value; The signal output part of operational amplifier connects oscillograph; Measuring circuit also comprises compensating circuit; Compensating circuit comprises compensating resistance and building-out capacitor, in parallel with sensing element after compensating resistance and building-out capacitor series connection; The in-phase input end of operational amplifier is connected between compensating resistance and building-out capacitor; The inverting input of operational amplifier is connected to the negative pole of tested current loop; The compensation condition of compensating circuit is: the value of the value * building-out capacitor of the resistance value=compensating resistance of the inductance value/sensing element of sensing element, the resistance value of the value >> sensing element of compensating resistance. This measuring circuit can be measured current value and be up to per second 10 at 1-100000 ampere, change frequency9HZ, waveform are fast-changing large electric current arbitrarily, its certainty of measurement can reach ten thousand/.
Description
Technical field
The present invention relates to the measuring circuit of fast-changing large electric current.
Background technology
Modern control technology has been applied to each aspect of modern advanced country, industry, agricultural, communications and transportation, national defenceDeng. There is no modern advanced country without modern control technology, and will control well and accurately, first need to measure soon and accurateReally.
In modern control technology, to electric control and important, good electric control needs the survey of accurate electricity at a high speedAmount, comprises the measurement to voltage, electric current. For example, at some special occasions: accurate electric welding machine, that large-scale military equipment all needs is rightFast-changing large electric current is measured accurately. Accurate measurement could produce accurate control. Variation generally refers to fastThe variation of large electric current in millisecond.
The measuring method of fast-changing large electric current at present, substantially divide two kinds:
1, direct series process. By the current sensitive element access current loop of directly connecting, utilize electric current at sensing elementOhmically voltage drop measure. But because current sensitive device is except useful resistance, always with inductance, this makes to pressIn falling, not only comprise resistance drop, also comprise inductive drop, when curent change is fast, inductive drop is very large, makes to measure large at a high speedElectric current time error is very large, and certainty of measurement is difficult to reach 2%.
2, contactless. Actual is to measure current field, and it can only be measured change frequency and be up to per second 106HZ's is largeElectric current, certainty of measurement is difficult to reach 1%.
Summary of the invention
The technical problem to be solved in the present invention is to provide one can measure current value at 1-100000 ampere, change frequencyBe up to per second 109HZ, waveform are the measuring circuit of fast-changing large electric current arbitrarily, its certainty of measurement can reach ten thousand/One.
Technical solution of the present invention is that a kind of measurement electricity of the fast-changing large electric current with following structure is providedRoad, comprises sensing element and operational amplifier; Described sensing element is connected in tested current loop; Described sensing elementValue comprise resistance value and inductance value; The signal output part of described operational amplifier connects oscillograph; Described measuring circuitAlso comprise compensating circuit; Described compensating circuit comprises compensating resistance and building-out capacitor, described compensating resistance and building-out capacitorIn parallel with described sensing element after series connection; The in-phase input end of described operational amplifier be connected to described compensating resistance andBetween building-out capacitor; The inverting input of described operational amplifier is connected to the negative pole of tested current loop; Described compensationThe compensation condition of circuit is: the resistance value=described compensating resistance of the sensing element of the inductance value of described sensing element/describedValue * described in the value of building-out capacitor, the value of described compensating resistance > > resistance value of described sensing element.
Adopt after above structure, the measuring circuit of fast-changing large electric current of the present invention, compared with prior art, hasFollowing advantage:
The measuring circuit of the fast-changing large electric current of the present invention also belongs to series connection pressure decline method in essence, but has added compensating circuitAfter, adopt in this way, fast-changing current waveform is converted to the fast-changing voltage wave on building-out capacitor exactlyShape, as long as keep described in the value * of resistance of the resistance value of the sensing element of the inductance value of described sensing element/described=describedThe value of electric capacity, the value of described resistance > > resistance value of described sensing element, this measuring circuit just can be used for measuring in the leastMicrosecond change up to 100000A electric current, not only accurately but also response fast, the waveform of oscilloscope display is closer to actual waveform.
As another kind of improvement of the present invention, the input impedance of the inverting input of described operational amplifier > > described in 1/The value * S of building-out capacitor, the passband of described operational amplifier > 1GHZ. Adopt after this kind of structure the waveform of oscilloscope displayMore close to actual waveform.
Brief description of the drawings
Fig. 1 is the circuit structure diagram of the measuring circuit of fast-changing large electric current of the present invention.
Fig. 2 is the electrical block diagram that the belt current of the measuring circuit of fast-changing large electric current of the present invention flows to.
Shown in figure: 1, sensing element, 2, operational amplifier, 3, compensating circuit, 4, oscillograph.
Detailed description of the invention
Below in conjunction with the drawings and specific embodiments, the invention will be further described.
Refer to shown in Fig. 1, the measuring circuit of fast-changing large electric current of the present invention comprises that sensing element 1, computing putLarge device 2 and compensating circuit 3. Described sensing element 1 can be large-current electric resistive current sensitive element arbitrarily, as long as internal resistanceLittle, temperature coefficient is little. In the world, the large-current electric resistive current sensitive element that a lot of companies produce can use. This is concreteIn embodiment, described sensing element adopts the partno:3020-01105 element of DATEL company of the U.S..
Described sensing element 1 is connected in tested current loop. The value of described sensing element 1 comprises resistance value and electricitySense value. Described compensating circuit 3 comprises compensating resistance and building-out capacitor, and described compensating resistance and building-out capacitor are connected afterwards and instituteSensing element 1 parallel connection of stating. The in-phase input end of described operational amplifier 2 is connected to described compensating resistance and building-out capacitorBetween. The reverse input end of described operational amplifier 2 is connected to the negative pole in circuit-under-test loop. Described operational amplifier 2Signal output part connect oscillograph 4.
The compensation condition of described compensating circuit 3 is: the electricity of the sensing element of the inductance value of described sensing element/describedThe value of the building-out capacitor described in the value * of the resistance of resistance=described, the value of described compensating resistance > > electricity of described sensing elementResistance. (about 107Doubly)
The input impedance of the inverting input of described operational amplifier 2 > > the value * S of building-out capacitor described in 1/, described inThe passband of operational amplifier > 1GHZ. (S=j ω=j6.2832f, f is frequency, the measuring speed of wishing. )
Refer to shown in Fig. 2, the measuring principle of the measuring circuit of fast-changing large electric current of the present invention is as follows:
Under most of occasions, sensing element is the gold of the temperature coefficient of about 50 micro-ohms (50 μ Ω) very little (0.002%/DEG C)Belong to sheet, but still (can calculate according to physical equation, be generally 10 – 30nH, n=10 with small inductor-9) such small inductor, by U=Ldi/dt is known, at di=100A, and dt=10-5When s, UL=20*10-9*100/10-5=0.2V, being far longer than electric current is 1000ATime, the voltage drop U producing on resistanceR=1000A*50*10-6=0.05V, visible, do not adopt some special measures, with above quickSensing unit is the initial waveform that cannot accurately measure fast-changing large electric current.
In this specific embodiment, the sensing element adopting is to adopt electric current sensor element: DATEL company of the U.S., RCElectronics, inc. all produces resistance type current sensor. For example: the partno:3020-01105 element of DATEL company,When its 1000A, produce 50mV pressure drop, according to its profile, can estimate that with physical equation its inductance is approximately worth, survey of the present inventionAmount circuit compensates:
If the resistance value of described sensing element is R1; The inductance value of described sensing element is L; Described compensating resistanceValue be R2; The value of described building-out capacitor is C.
In actual applications, be exemplified below:
V=250V, Ri=50m Ω, I=5000A square wave, and make L/R1=R2C，R2>>R1, get R2=107R1，
R1=50μΩ，R2=500Ω，L=13nH，C=0.52μF
1. when uncompensated, be only L, R1 connects with power supply, and measuring-signal is V00
2. while having compensation, be that (L+R1) is first in parallel with (R2+C), and then connect with power supply, measuring-signal is V0
The compensation condition requiring is: L/R1=R2C,R2>>R1
Its measuring-signal is
Two measuring-signals can be streamlined any further (Ri > > R1), after simplification, compare again
A does not compensate
Can be reduced toVoo=VR1*（1+T old S）/Ri
B has compensation
Can be reduced toVo=VR1/Ri
C ideal current (not accessing before sensor)
After access resistance sensor, wish: ideal square wave
Can be reduced toVout=VR1/Ri
Consider again actual parameter Ri=50m Ω, R1=50u Ω
Relatively the simplification expression formula of Voo, Vo, Vout, can find: Vo, Vout are duplicate. And Voo pointSon is the many factor (1+ToldS), this means the time that uncompensated Voo need to be longer, and output Voo just can reach high-precisionDegree district. This is a very large distortion to fast-changing large electric current. Here it is, and why uncompensated circuit can not be measured highThe large electric current that speed changes.
That is to say: V00Transient process be Told=0.26mS can only measure mS level curent change. V0Transient process be107Hurry up, its T=10-7Told=0.26*10-10S, so circuit can be surveyed the electric current that nanosecond changes after compensation.
Visible, there is the signal V after compensation0Closer to ideal waveform: VReason=V/Ri (R1 < < Ri). That is to say Vo ratioMore accurately more response is fast for Voo.
Conclusion:
Adopt after compensation method of the present invention, when use, as long as keep L/R1=R2C, R2 > > R1, and computing is putThe requirement of large device is: the input impedance R of the inverting input of described operational amplifieriG>>1/CS，（S=jω=j6.2832f,fFrequency, the measuring speed of wishing), the passband of described operational amplifier > and 1GHZ. This circuit can be used for measuring millimicroThe large electric current (2-10000A) that change second. If change sensing element, even can measure nanosecond change up to100000A electric current, not only accurately but also response fast, the waveform of oscilloscope display is far away closer to actual waveform. Be adapted to especially wantThe occasion of rapid large-current is really controlled in refinement.
Claims (1)
1. a measuring circuit for fast-changing large electric current, comprises sensing element (1) and operational amplifier (2); Described is quickSensing unit (1) is connected in tested current loop; The value of described sensing element (1) comprises resistance value and inductance value; DescribedThe signal output part of operational amplifier (2) connects oscillograph (4); It is characterized in that: described measuring circuit also comprises compensation electricityRoad (3); Described compensating circuit (3) comprises compensating resistance and building-out capacitor, after described compensating resistance and building-out capacitor series connectionIn parallel with described sensing element (1); The in-phase input end of described operational amplifier (2) be connected to described compensating resistance andBetween building-out capacitor; The inverting input of described operational amplifier (2) is connected to the negative pole of tested current loop; Described benefitThe compensation condition of repaying circuit (3) is: the resistance value=described benefit of the sensing element of the inductance value of described sensing element/describedRepay the value of the building-out capacitor described in the value * of resistance, the value of described compensating resistance be described sensing element resistance value 107Doubly.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201410021869.4A CN103792409B (en) | 2014-01-18 | 2014-01-18 | The measuring circuit of fast-changing large electric current |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201410021869.4A CN103792409B (en) | 2014-01-18 | 2014-01-18 | The measuring circuit of fast-changing large electric current |
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| Publication Number | Publication Date |
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| CN103792409A CN103792409A (en) | 2014-05-14 |
| CN103792409B true CN103792409B (en) | 2016-05-11 |
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| CN108693394B (en) * | 2017-04-12 | 2020-06-26 | 上海西门子医疗器械有限公司 | Tube current calculation method and device of X-ray bulb tube |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59126961A (en) * | 1983-01-12 | 1984-07-21 | Fujitsu Ltd | Measuring device of large current |
| CN102445588A (en) * | 2011-11-23 | 2012-05-09 | 中国人民解放军海军工程大学 | Short-time slowly-varying high-current measuring device based on (printed circuit board) PCB type Rogowski coil |
-
2014
- 2014-01-18 CN CN201410021869.4A patent/CN103792409B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59126961A (en) * | 1983-01-12 | 1984-07-21 | Fujitsu Ltd | Measuring device of large current |
| CN102445588A (en) * | 2011-11-23 | 2012-05-09 | 中国人民解放军海军工程大学 | Short-time slowly-varying high-current measuring device based on (printed circuit board) PCB type Rogowski coil |
Non-Patent Citations (3)
| Title |
|---|
| 一种测量脉冲大电流的改进分流器设计;张建永 等;《电子测量技术》;20130630;第36卷(第6期);25-28 * |
| 如何实现快速变化的阶梯电流的测量;韩勇兵;《计量与测试技术》;20130630;第40卷(第6期);31-32 * |
| 陡脉冲大电流的Rogowski测量线圈仿真研究;李维波 等;《高电压技术》;20020831;第28卷(第8期);11-13 * |
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