CN104459596B - The balanced compensated transformer measurement circuit of mutual inductor spurious impedance - Google Patents
The balanced compensated transformer measurement circuit of mutual inductor spurious impedance Download PDFInfo
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- CN104459596B CN104459596B CN201410691794.0A CN201410691794A CN104459596B CN 104459596 B CN104459596 B CN 104459596B CN 201410691794 A CN201410691794 A CN 201410691794A CN 104459596 B CN104459596 B CN 104459596B
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- mutual inductor
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Abstract
The invention discloses a kind of transformer measurement circuits that mutual inductor spurious impedance is balanced compensated, belong to analog signal measuring circuit technical field.Its technical solution includes that resistance R1 is provided between an output end of mutual inductor and the inverting input of operational amplifier circuit, resistance R4 is provided between the output end of the operational amplifier circuit and its in-phase input end, it is provided with resistance R5 between in-phase input end after the one resistance R2 of another output end series connection of mutual inductor with the operational amplifier circuit, the inverting input of the operational amplifier circuit is connected with resistance R3 with output end, applies DC voltage Vref between R2, R5；The secondary side equiva lent impedance R0 of wherein resistance R1, R2, R3, R4, R5 and mutual inductor meets the following conditions：R4/R3=R5/ (R1+R2+R0).The zero load that the technology really realizes mutual inductor measures, it is only necessary to which the information of primary side can be passed to secondary side, so as to significantly improve the measurement accuracy of mutual inductor by some energy of very little.
Description
Technical field
The present invention relates to analog signal measuring circuit technical fields, more particularly, to the measurement of mutual inductor spurious impedance compensation
Circuit.
Background technology
Modern society, electric power energy are widely used, safety utilization of electric power (circuit protection), fair electricity consumption (accurate metering and billing),
Rational utilization of electricity (energy-saving and emission-reduction) etc., is required to based on accurately measuring the parameters such as electric current.However power generation, power transformation, transmission of electricity,
Size of current great disparity in distribution and the circuit of electricity consumption has from several peaces to tens of thousands of Andu.For ease of metering, protection and control, need
The unified electric current of comparison is converted to, in addition the voltage on circuit is generally relatively high, and it is breakneck such as directly to measure, it is necessary to
There is sensing element to be converted to measuring apparatus acceptable weak signal.
The measurement sensing element of electric current, the most commonly used is current transformers, and structure is relatively simple, by the primary of mutually insulated
High current easily can be converted to measurement by the compositions such as winding, secondary winding, iron core and framework, shell, connecting terminal
Equipment acceptable low current signal, and play the role of electrical isolation, it ensure that the safe and reliable steady operation of measuring apparatus.
In addition production technology is relatively easy and technology maturation, at low cost, can also accomplish the preferable measurement accuracy that compares, thus extensive
Using.
Current transformer is realized according to electromagnetic induction principle, as the principle of transformer.As shown in Figure 1, applying
The primary current I1 of alternation is generated in first winding in the electromotive force E1 of first winding both ends (L1, L2), I1 is produced in the core
The magnetic flux ￠ 1 of raw alternation, the magnetic flux ￠ 1 of alternation respectively once with induced electromotive force E1 ' that alternation is induced in secondary winding
With E2.E2 forms induced current I2 in the closed loop that secondary winding and load Z are constituted.In turn, I2 is similarly produced in the core
The magnetic flux ￠ 2 of raw alternation, the magnetic flux ￠ 2 of alternation also respectively once with induced electromotive force that alternation is induced in secondary winding
E1 " and E2 '.According to Lenz's law and law of conservation of energy, ￠ 2 always hinders the variation of ￠ 1, and E1 ', E1 " are reversed with E1, E2 '
Reversed with E2, exactly this obstruction, just so that the signal of primary then electric current I1 passes to secondary side current I2, this transmission is practical
Upper is exactly a kind of transmission of energy.
Ideal mutual inductor and its measuring circuit, first and second winding is without internal resistance, and iron core is without magnetic resistance, iron core infinite,
The impedance of secondary output is zero, in this way, the energy that primary current generates in mutual inductor, loss-free in the least can pass to secondary
Then there is I1N1=I2n2 namely I2/I1=N1/n2 in side.
However, in practice, this is impossible, and at least prior art condition is also much not achieved.It is actual for one
Mutual inductor and its measuring circuit, first and second winding has impedance, and (mainly resistance and induction reactance, capacitive reactance can be ignored not completely
Meter), especially secondary winding pricks that number is more, and line footpath is thin, thus spurious impedance is big.Iron core has magnetic resistance and impedance, for instrument mutual inductance
Device, secondary side, which often also has, to be loaded, thus actual mutual inductor, there are no small error, including angular difference and ratio it is poor.From
Current transformer generate since, explore by being continually striving to, understand substantially, the error of mutual inductor, substantially by it is following because
Element is constituted：
1, excitation loss and iron loss.Primary side current I1 must have one part of current I01 to magnetize iron core so that iron core
Middle generation magnetic flux, I01N1 are known as abampere circle or excitation magnetomotive force；In addition I1 also has one part of current I02, because magnetic flux passes through
When iron core, forms vortex in core interior and consume, this partition losses, referred to as iron loss.Core material permeability is bigger, required
I01 it is smaller, error is smaller.Iron core resistance is bigger, and inducting, vortex is smaller, and I02 is smaller, and error is smaller.
2, secondary load size and property.Secondary load includes the spurious impedance of secondary winding.Error and secondary load at
Direct ratio, but after load increase, iron-core magnetic induction intensity becomes larger, and magnetic conductivity slightly improves, so error is slightly less than direct ratio increase.
3, the number of turns of secondary winding.Error and secondary winding the number of turns square are inversely proportional.Therefore increase secondary winding the number of turns,
The error of mutual inductor can be reduced.But secondary winding internal resistance, secondary circuit total impedance can be increased while increasing secondary winding the number of turns
Become larger, adds somewhat to error.
4, the frequency of power grid.Frequency is bigger, and error is bigger, this itself is again related with core characteristics.
5, primary current size.To all it reduce than poor, angular difference when electric current becomes larger.However current variation is very big, it will usually 0
Change between rated current, thus, transformer error is nonlinear.
Due to current transformer material itself and measuring principle influence, the measurement accuracy of current transformer is improved,
Always work of the scientific and technological circle in ongoing effort.The existing technology for improving transformer precision includes mainly --- and research is more preferable
Core material, since the mild steel of early stage, develop into later more clock ferrites, alloy material, powder core material, amorphous and
Nano-crystal soft magnetic alloy etc. technology.These are improved, and are provided to reach several purposes：It improves magnetic conductivity, improve saturation magnetic strength
Intensity is answered, residual magnetic flux density is reduced, reduces coercivity, improving iron core impedance, a word exactly improves the performance of iron core；
Increase core section, shorten the length of magnetic path, make iron core be operated in magnetic induction intensity it is not high under conditions of；Increase coil turn.Increase
Ledger line circle ampere-turn can accordingly reduce than difference and angular difference；The influence for limiting secondary load, minimizes secondary load；Design Zero flux
Mutual inductor, fully reducing excitation influences.
Existing mutual inductor exports measuring circuit although being zero load circuit, but be not zero load in fact, because mutually
The spurious impedance R0 of sensor is actual load, cannot be eliminated herein, drives the voltage E2 of the output loading of mutual inductor simultaneously
It is not zero.Secondly, this circuit is influenced, potentially unstable by amplifier quality.Third, the output of mutual inductor are directly connected to transport
The input put, amplifier are easily interfered by outside.
Invention content
For overcome the deficiencies in the prior art, the present invention proposes a kind of mutual inductor measuring that mutual inductor spurious impedance is balanced compensated
Circuit is measured, the purpose is to improve the measurement accuracy for measuring mutual inductor.
In order to solve the above technical problems, basic technical scheme proposed by the present invention is：A kind of mutual inductor spurious impedance
Balanced compensated transformer measurement circuit, it is characterised in that：Between the output end and the inverting input of operational amplifier circuit of mutual inductor
It is provided with resistance R1, resistance R4 is provided between the output end of the operational amplifier circuit and its in-phase input end, in the another of mutual inductor
Resistance R5 is provided between the in-phase input end of the operational amplifier circuit after one output end series connection, one resistance R2, the operational amplifier circuit
Inverting input is connected with resistance R3 with output end, and DC offset voltage Vref, wherein resistance is arranged in the junction of R2 and R5
The secondary side equiva lent impedance R0 of R1, R2, R3, R4, R5 and mutual inductor meets the following conditions：R4/R3=R5/ (R1+R2+R0), fortune
The output signal U o put is the signal that the present invention obtains.
In the balanced compensated transformer measurement circuit of mutual inductor spurious impedance of the present invention, including operational amplifier circuit, it should
Filter circuit is set between the inverting input of operational amplifier circuit and its output end.
In the balanced compensated transformer measurement circuit of mutual inductor spurious impedance of the present invention, the filter circuit includes
The resistance R6 and capacitance C1 being cascaded.
In the balanced compensated transformer measurement circuit of mutual inductor spurious impedance of the present invention, the secondary side of mutual inductor is defeated
The both ends concatenation phase-shift compensation circuit gone out.
In the balanced compensated transformer measurement circuit of mutual inductor spurious impedance of the present invention, phase-shift compensation electricity
Road includes the resistance R7 being cascaded and capacitance C2.
In the balanced compensated transformer measurement circuit of mutual inductor spurious impedance of the present invention, the resistance R7 resistance values
At 20K~50K ohm.
In the balanced compensated transformer measurement circuit of mutual inductor spurious impedance of the present invention, the capacitance C2 is
0.1~0.3 μ F.
The beneficial effects of the invention are as follows：
1, the zero load for really realizing mutual inductor measures, it is only necessary to some energy of very little, it can be primary side
Information, passes to secondary side, this required portion of energy consumes in excitation and iron loss, so as to significantly improve survey
Accuracy of measurement.
It 2, can since the circuits such as capacitance-resistance filter can be increased between mutual inductor output and amplifier relative to existing circuit
To protect amplifier well so that circuit operation becomes more stable reliable.
3, its size can be arranged in DC offset voltage Vref according to demand so that the circuit invention can both be applied in list
In power circuit, it can also apply in two-supply circuit, using flexible.
4, circuit is simple, of low cost, and relative to available circuit, actual cost does not almost increase.Increased resistance, each
Including processing charges, it is no more than 3 points of RMB；Relative to Zero flux mutual inductor, increased cost can be ignored not completely
Meter.
5, production is simple, and consistency is good.Because only simply increasing several capacitance resistance wares, existing circuit board is given birth to
Production. art, these increased circuits, assembly line easy to implement, automation production.
Description of the drawings
Fig. 1 is mutual inductor basic principle figure；
Fig. 2 is the circuit diagram of the embodiment one of the balanced compensated transformer measurement circuit of mutual inductor spurious impedance；
Fig. 3 is the circuit diagram of the embodiment two of the balanced compensated transformer measurement circuit of mutual inductor spurious impedance.
Specific implementation mode
Below with reference to attached drawing 1 to attached drawing 3, the present invention is described further, but should not with this come limit the present invention
Protection domain.
Embodiment one
Compares figure 2, in the present embodiment, the output end of mutual inductor secondary side equivalent circuit 10 connects operational amplifier circuit, the mutual inductance
Electromotive force of the device secondary side equivalent circuit 10 including equivalent current source I2 and the both ends equiva lent impedance R0, I2 is E2, and E2 is that driving is mutual
Voltage needed for the secondary lateral load of sensor (including the internal driving of secondary side, i.e. spurious impedance R0).In the anti-of the operational amplifier circuit
Resistance R1 is set between phase input terminal c and the output end b of mutual inductor secondary side equivalent circuit 10, in the reverse phase of the operational amplifier circuit
Connect connection resistance R3 between input terminal c and its output end e, between the output end e and its in-phase input end d of the operational amplifier circuit
Be arranged resistance R4, mutual inductor secondary side equivalent circuit 10 another output port f connect a resistance R2 after with operational amplifier circuit
Resistance R5 is set between in-phase input end d, in the junction of R2 and R5 setting DC offset voltage Vref.
In addition, in order to compensation circuit, phase-shift compensation circuit, the shifting are concatenated at the both ends that the secondary side of mutual inductor exports
Phase compensation circuit includes the resistance R7 being cascaded and capacitance C2, and the resistance R7 resistance values are in 30K ohm, capacitance C2
0.1μF。
The signal Uo (=Ueg) relative to DC offset voltage Vref of the amplifier output is big with primary side current
The corresponding signal of small and phase, this be we need for the signal that is further processed.
Specifically, R4/R3=R5/ (R1+R2+R0)；
According to the empty short feature of amplifier, the potential that 2 points of c, d is equal, i.e.,
Ued=Uec
According to the feature that amplifier void is broken, have
Uec/R3=Uca/ (R1+R0)=Ufg/R2；Ued/R4=Udg/R5；
It is easy to release by the formula above formula
Udg=Uca+Ufg；
And
Ueg=Uec+Uca+Uaf+Ufg=Ued+Udg
So E2=Uaf=0.
So Uo=I2* (R3+R1+R0+R2)+E2=I2* (R3+R1+R0+R2)
In this way so that the voltage E2 of the load of driving mutual inductor is zero, load voltage E2 is zero, and load is also just zero, to
It is truly realized zero load measurement.
The present embodiment really realizes zero load measurement, it is only necessary to some energy of very little, it can be the letter of primary side
Breath, passes to secondary side, and so as to significantly improve measurement accuracy, this required portion of energy is consumed in excitation and iron
In damage.
Embodiment two
Compared with embodiment one, the present embodiment only difference is that the inverting input c of the operational amplifier circuit and its is defeated
Filter circuit 30 is arranged in e between outlet, which includes the resistance R6 being cascaded and capacitance C1, the filtered electrical
Road can preferably filter out high-frequency interferencing signal with table, can protect amplifier well so that circuit operation becomes relatively reliable steady
It is fixed.
According to the disclosure and teachings of the above specification, those skilled in the art in the invention can also be to above-mentioned embodiment party
Formula is changed and is changed.Therefore, the invention is not limited in specific implementation modes disclosed and described above, to the present invention's
Some modifications and changes should also be as falling into the scope of the claims of the present invention.In addition, although being used in this specification
Some specific terms, these terms are merely for convenience of description, does not limit the present invention in any way.
Claims (7)
1. a kind of transformer measurement circuit that mutual inductor spurious impedance is balanced compensated, it is characterised in that：One output end of mutual inductor
It is provided with resistance R1 between the inverting input of operational amplifier circuit, is set between the output end of the operational amplifier circuit and its in-phase input end
It is equipped with resistance R4, is arranged between the in-phase input end after the one resistance R2 of another output end series connection of mutual inductor with the operational amplifier circuit
There are resistance R5, inverting input and the output end of the operational amplifier circuit to be connected with resistance R3, setting is straight in the junction of R2 and R5
The secondary side equiva lent impedance R0 of stream offset voltage Vref, wherein resistance R1, R2, R3, R4, R5 and mutual inductor meets the following conditions：
R4/R3=R5/ (R1+R2+R0).
2. the balanced compensated transformer measurement circuit of mutual inductor spurious impedance as described in claim 1, it is characterised in that：It is described
Filter circuit is arranged between the inverting input of the operational amplifier circuit and its output end in operational amplifier circuit.
3. the balanced compensated transformer measurement circuit of mutual inductor spurious impedance as claimed in claim 2, it is characterised in that：It is described
Filter circuit includes the resistance R6 being cascaded and capacitance C1.
4. the balanced compensated transformer measurement circuit of mutual inductor spurious impedance as described in claim 1, it is characterised in that：Mutually
The both ends of the secondary side output of sensor concatenate phase-shift compensation circuit.
5. the balanced compensated transformer measurement circuit of mutual inductor spurious impedance as claimed in claim 4, it is characterised in that：It is described
Phase-shift compensation circuit include the resistance R7 being cascaded and capacitance C2.
6. the balanced compensated transformer measurement circuit of mutual inductor spurious impedance as claimed in claim 5, it is characterised in that：It is described
Resistance R7 resistance values at 20K~50K ohm.
7. the balanced compensated transformer measurement circuit of mutual inductor spurious impedance as claimed in claim 5, it is characterised in that：It is described
Capacitance C2 be 0.1~0.3 μ F.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201410691794.0A CN104459596B (en) | 2014-11-26 | 2014-11-26 | The balanced compensated transformer measurement circuit of mutual inductor spurious impedance |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201410691794.0A CN104459596B (en) | 2014-11-26 | 2014-11-26 | The balanced compensated transformer measurement circuit of mutual inductor spurious impedance |
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| CN104459596A CN104459596A (en) | 2015-03-25 |
| CN104459596B true CN104459596B (en) | 2018-07-13 |
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| CN101086917A (en) * | 2006-06-09 | 2007-12-12 | 郑州大学 | Compensation method of voltage mutual inductor and secondary loop voltage reduction error and compensation device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7525297B2 (en) * | 2005-12-01 | 2009-04-28 | Falco Ltd. | Current transformer with impedance compensation and associated methods |
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2014
- 2014-11-26 CN CN201410691794.0A patent/CN104459596B/en active Active
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|---|---|---|---|---|
| CN101086917A (en) * | 2006-06-09 | 2007-12-12 | 郑州大学 | Compensation method of voltage mutual inductor and secondary loop voltage reduction error and compensation device |
| CN102682985A (en) * | 2012-05-16 | 2012-09-19 | 深圳市深泰明科技有限公司 | High-voltage electronic type voltage transformer |
| CN103928226A (en) * | 2013-01-14 | 2014-07-16 | 上海浦东金盛互感器厂 | Error compensation single-core three-winding current transformer and split core type current transformer |
| CN103941065A (en) * | 2013-01-17 | 2014-07-23 | 上海浦东金盛互感器厂 | Method used for reducing residual impedance effect of voltage transformer and inductive voltage divider primary winding |
| CN203590195U (en) * | 2013-12-10 | 2014-05-07 | 中国石油化工股份有限公司 | Improved simulation integrating circuit based on PCB Rogowski coil current transformer |
| CN203838223U (en) * | 2014-03-28 | 2014-09-17 | 云南电力试验研究院（集团）有限公司电力研究院 | Hall current transformer |
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