CN105304303B - A kind of accurate alterating and direct current current transformer - Google Patents
A kind of accurate alterating and direct current current transformer Download PDFInfo
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- CN105304303B CN105304303B CN201510642231.7A CN201510642231A CN105304303B CN 105304303 B CN105304303 B CN 105304303B CN 201510642231 A CN201510642231 A CN 201510642231A CN 105304303 B CN105304303 B CN 105304303B
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Abstract
The invention provides a kind of accurate alterating and direct current current transformer.The transformer is based on Zero flux principle, the relatively simple self-oscillation magnetic modulator technology of modulation and demodulation circuit is combined with active ac current transformer technology, wherein self-oscillation magnetic modulator is used to detect direct current flux, and active ac current transformer is used to detect exchange flux.During normal work, no matter for direct current or tested electric current is exchanged, transformer always works in Zero flux state, so as to improve the measurement accuracy of direct current and alternating current simultaneously.In addition, the ripple current that the magnetizing flux of self-oscillation magnetic modulator is sensed due to transformer action in primary and secondary side winding is inhibited using magnetizing flux compensation circuit, inhibited simultaneously using high-pass filter because the useful signal of self-oscillation magnetic modulator extracts the limited ripple current produced in vice-side winding of time constant of circuit, so as to further increase measurement accuracy.
Description
Technical field
The invention belongs to electric current field of precision measurement, more particularly to a kind of accurate alterating and direct current current transformer.
Background technology
The accurate measurement of DC current typically passes through comparator for direct current or zero magnetic based on traditional magnetic modulator technology
Logical DC current transformer is realized, but is limited by the modulating frequency of wherein magnetic modulator, and the quasi-instrument is only used for measurement
Direct current or low-frequency ac.The accurate measurement of alternating current typically then passes through AC current comparator or Zero flux alternating current mutual inductance
Device is realized, but the quasi-instrument is only used for measurement exchange, and is not suitable for direct current.Therefore, for needing to measure straight simultaneously
The application scenario of stream and alternating current, two quasi-instruments are all unable to complete independently.
The transformer of direct current and alternating current can be measured at present simultaneously, but the DC measurement function of this quasi-instrument is big
Traditional magnetic modulator technology is all employed, circuit is complicated, and cost is higher, and it is limited to a certain extent and is used.It is a kind of it is low into
This alternative solution is to do direct current flux detector, mesh using the relatively simple self-oscillation magnetic modulator of modulation and demodulation circuit
The preceding current transformer based on the technology can measure direct current simultaneously and exchange.
But, there are two subject matters in such current transformer：One be due to lack modulation flux compensation magnetic core and around
Group, the modulation magnetic flux of self-oscillation magnetic modulator can be sensed by transformer action in transformer primary side winding and vice-side winding
Ripple current in the ripple current of certain amplitude, primary side winding can disturb tested loop, and the ripple current in vice-side winding
Measurement error can be increased.Two were limited by the sensor response time, and wherein the useful signal of self-oscillation magnetic modulator is extracted
The time constant of circuit can not set too big, and the problem of thus bringing is that the high fdrequency component in useful signal can not effectively be declined
Subtract, the high fdrequency component will produce ripple current directly as error signal drives feedback control circuit, so as to introduce measurement error.
Therefore, such current transformer can't be used for accurate measurement at present.
Fig. 1 is a kind of schematic diagram of the existing alterating and direct current current transformer based on self-oscillation magnetic modulator.Two in Fig. 1
Toroidal core C1 and C2 and three winding W1, W3 and W4 constitute the measurement head of transformer, and winding W5 is usually through transformer
The single turn conductor of measurement head, for flowing through tested electric current IP.Remaining element constitutes the signal conditioning circuit of transformer, for signal
Extract and feedback control.Winding W1, the comparator A1 and exciting curent sampling resistor R1 being wrapped on magnetic core C1 are constituted from exciting
Magnetic modulator is swung, for detecting direct current flux.Low pass filter B2 is used to filtering out exciting curent that (or exciting curent to be in sampling resistor
Pressure drop v2 on R1) in high fdrequency component so as to obtaining useful signal v7.The winding W3 being wrapped on magnetic core C2, which is used to detect, to be handed over
Magnetic flux is flowed, its output signal v8 is added by summing circuit D2 with signal v7, and summing circuit D2 output signal v9 is as by mistake
Difference signal drive feedback controls circuit A3 and its power amplification circuit A4 output secondary currents IS to be used to compensate tested electric current IP productions
Raw magnetic flux, is finally reached Zero flux state.
But, there are two subject matters in such current transformer：One be due to lack modulation flux compensation magnetic core and around
Group, the modulation magnetic flux of self-oscillation magnetic modulator can be by transformer action in transformer primary side winding W5 and vice-side winding W4
The ripple current sensed in the ripple current of certain amplitude, primary side winding W5 can disturb tested loop, and in vice-side winding W4
Ripple current can increase measurement error.Two limited by the transformer response time, and self-oscillation magnetic modulator therein has
Can not set too big with signal extracting circuit B2 time constant, the problem of thus bringing be high fdrequency component in useful signal not
It can be actively damped, the high fdrequency component will be directly as error signal drives feedback control circuit A3 and its power amplification circuit A4
Ripple current is produced, so as to introduce measurement error.Therefore, such transformer can't be used for accurate measurement at present.
The content of the invention
In order to solve, the ac and dc current transformer circuit based on traditional magnetic modulator is complicated, cost is higher lacks
Point, greatly can not while solving the former and deputy side modulation ripple of alterating and direct current current transformer based on emerging self-oscillation magnetic modulator
For the shortcoming of accurate measurement, the invention provides a kind of accurate ac and dc current mutual inductance simple in construction, relative inexpensiveness
Device, including measurement head, the electric current of primary side winding is flowed through for measuring；Self-oscillation magnetic modulator circuit, for detecting DC magnetic
It is logical；Magnetizing flux compensation circuit, the ripple current for offsetting magnetizing flux sensing；And Zero flux AC current transformer electricity
Road, for detecting exchange flux.
According to a preferred embodiment of the invention, the measurement head of accurate alterating and direct current current transformer is by three toroidal cores, two
Individual field winding, exchange flux detection winding, vice-side winding are constituted, and two field windings are respectively wound around two toroidal cores
On, exchange flux detection winding is wrapped on three toroidal cores stacked back-to-back, and vice-side winding is wrapped in exchange
On flux detection winding, the measurement head of accurate alterating and direct current current transformer passes through primary side winding, and primary side winding is flowed through for measuring
Electric current.
According to present invention further optimization embodiment, the physical characteristic and geometric parameter phase of described two toroidal cores
Together, the geometric parameter of the 3rd toroidal core is identical with described two toroidal cores, but physical characteristic can also may be used with identical
With difference, the number of turn of described two field windings is identical, and vice-side winding is wrapped in exchange flux detection winding.
According to present invention further optimization embodiment, self-oscillation magnetic modulator circuit by the first field winding, compare
Device and first resistor are constituted, the Same Name of Ends of output the first field winding of termination of comparator, the non-same polarity of the first field winding
The input of comparator is connect, while be connected with first resistor, the other end ground connection of first resistor.
According to present invention further optimization embodiment, magnetizing flux compensation circuit is by the second field winding, unit gain
Phase inverter and second resistance are constituted, and the input of unity gain inverter is connected with the output end of comparator, and unit gain is anti-phase
The Same Name of Ends of output the second field winding of termination of device, the non-same polarity of the second field winding connects second resistance, second resistance
The other end is grounded.
According to present invention further optimization embodiment, in addition to the first summing circuit, the second summing circuit, LPF
Device, and high-pass filter, two inputs of the first summing circuit connect ungrounded end and the high pass filter of first resistor respectively
The output end of ripple device, the output end of the first summing circuit connects the input of low pass filter, and two of the second summing circuit are defeated
Enter end and connect the output end of low pass filter and the Same Name of Ends of exchange flux detection winding respectively.
According to present invention further optimization embodiment, wherein Zero flux AC current transformer circuit is examined by exchange flux
Survey winding, feedback control circuit, power amplification circuit, vice-side winding and 3rd resistor to constitute, the input of feedback control circuit
The output end of the second summing circuit of end connection, the output end of feedback control circuit connects the input of power amplification circuit, power
Amplifying circuit connects the Same Name of Ends of vice-side winding, the non-same polarity connection 3rd resistor of vice-side winding, the other end of 3rd resistor
Ground connection.
According to present invention further optimization embodiment, wherein feedback control circuit uses the ratio being made up of operational amplifier
Example-integrating circuit.
According to present invention further optimization embodiment, wherein it is defeated to be followed by power amplifier in the proportional, integral circuit
Go out transformer secondary current, the power amplifier is any one of A classes, B classes, AB classes or D classes, or by multiple discrete components
Constitute, or be made up of single integrated device.
According to present invention further optimization embodiment, the low pass filter is passive first order low pass filter, passive
Any one of high-order low-pass filter, active first-order low pass filter and active high-order low-pass filter, the high pass filter
Ripple device is passive first order high-pass filter, passive higher order high pass filters, active first-order high-pass filter and active high-order high pass
Any one of wave filter.
The accurate alterating and direct current current transformer is based on Zero flux principle, and modulation and demodulation circuit is relatively simple from exciting
Swing magnetic modulator technology to be combined with active ac current transformer technology, wherein self-oscillation magnetic modulator is used to detect direct current
Magnetic flux, active ac current transformer is used to detect exchange flux.So, during normal work, no matter for direct current or exchange
Tested electric current, transformer can be operated in Zero flux state all the time, so as to improve the measurement of direct current and alternating current simultaneously
Precision.In addition, employing additional magnetic core and winding is used to compensate what is due to transformer action on primary and secondary side winding sensed
Ripple current, and on the basis of additional magnetic core and winding, employing high-pass filter is used to offset the high frequency in useful signal
Component, so as to reduce due to the limited generation in vice-side winding of time constant that useful signal extracts circuit, i.e. low pass filter
Ripple current.
Brief description of the drawings
In order to illustrate the embodiments of the present invention more clearly, the required accompanying drawing used in embodiment will be made simply below
Introduce.It is clear that the accompanying drawing in following description is only the section Example of the present invention, for those of ordinary skill in the art
For, other embodiments and its accompanying drawing can also be obtained according to these accompanying drawing illustrated embodiments.
Fig. 1 is a kind of schematic diagram of the existing alterating and direct current current transformer based on self-oscillation magnetic modulator；
Fig. 2 is the schematic diagram for the accurate alterating and direct current current transformer that the present invention is provided.
Fig. 3 be the present invention provide accurate ac and dc current transformer measurement DC current when the linearity.
Fig. 4 be the present invention provide accurate ac and dc current transformer measurement alternating current when frequency bandwidth.
Embodiment
Clear, complete description is carried out to the technical scheme of embodiments of the invention below with reference to accompanying drawing, it is clear that retouched
The embodiment stated is only the section Example of the present invention, rather than whole embodiments.Based on embodiments of the invention, this area
Those of ordinary skill's all other embodiment resulting on the premise of creative work is not made, belongs to institute of the present invention
The scope of protection.
Fig. 2 is the schematic diagram for the accurate alterating and direct current current transformer that the present invention is provided.Three toroidal core C1 in figure, C2,
C3 and four winding W1, W2, W3, W4 constitute the measurement head of transformer, and two of which field winding W1 and W2 are respectively wound around ring
On shape magnetic core C1 and C2, exchange flux detection winding W3 is wrapped on three magnetic cores stacked back-to-back C1, C2 and C3, and
Vice-side winding W4 is wrapped on winding W3.Primary side winding W5 is the single turn conductor through transformer measurement head, tested for flowing through
Electric current IP.Stain beside each winding represents Same Name of Ends.
Winding W1, comparator (or operational amplifier) A1 and resistance R1, which constitute self-oscillation magnetic modulator, to be used to detect direct current
Magnetic flux, general principle is the linear pass existed between the average value of the exciting curent based on winding W1 and tested electric current (or magnetic flux)
System.The specific connected mode of self-oscillation magnetic modulator is：Comparator (or operational amplifier) A1 output termination winding W1's
Same Name of Ends, winding W1 non-same polarity connects comparator A1 input, while be connected with resistance R1, resistance R1 another termination
Ground.
Winding W2, unity gain inverter A2 and resistance R2 constitute magnetizing flux compensation circuit, for offsetting in magnetic core C1
The ripple current that is sensed due to transformer action in vice-side winding W4 and primary side winding W5 of magnetizing flux.Magnetizing flux is compensated
The specific connected mode of circuit is：Unity gain inverter A2 input and comparator (or operational amplifier) A1 output end
It is connected, unity gain inverter A2 output termination winding W2 Same Name of Ends, winding W2 non-same polarity connecting resistance R2, resistance R2
The other end ground connection.
High-pass filter B1 effect is to filter out the low frequency in pressure drop v4 of the exciting curent on resistance R2 in winding W2
Component, its output signal v5 passes through the high frequency in pressure drop v2 of the exciting curent in summing circuit D1 and winding W1 on resistance R1
After component is offseted, and the low-pass filtered device B2 of the remaining high fdrequency component in summing circuit D1 output signal v6 further decays
The minimum signal v7 of final output high fdrequency component.
Winding W3 be used for detect exchange flux, its induced signal v8 be added by summing circuit D2 with signal v7 after output
Signal v9 is used as the error signal of system, drive feedback control circuit A3 and its power amplification circuit A4 output compensation electric current IS use
In offsetting the magnetic flux that tested electric current IP is produced, until realizing ampere-turn equilibrium, i.e. IS*W4=IP*W5.Due to winding W4 and W5 circle
Number, it is known that and electric current IS can accurately measurement be obtained by the four-terminal resistance R3 that is in series with winding W4, so as to try to achieve electric current
IP value.
The accurate alterating and direct current current transformer that the present invention is provided is relatively simple from exciting by above-mentioned modulation and demodulation circuit
Swing magnetic modulator technology to be combined with Zero flux AC current transformer technology, so, electric current, above-mentioned self-excitation are tested for direct current
Vibrate magnetic modulator and its useful signal extracts circuit B2 and feedback control circuit A3, power amplification circuit A4 and vice-side winding
W4 constitutes closed loop, and for the tested electric current of exchange, exchange flux detection winding W3 and feedback control circuit A3, power amplification
Circuit A4 and vice-side winding W4 constitutes Zero flux AC current transformer, so that Zero flux state can be in very wide frequency
Set up all the time in band, thus improve the measurement accuracy of direct current and alternating current simultaneously.Above-mentioned magnetizing flux compensation circuit plus
Enter to inhibit the magnetizing flux of self-oscillation magnetic modulator because transformer action is felt in primary side winding W5 and vice-side winding W4
The ripple current answered, and high-pass filter B1 addition then inhibits the useful signal due to self-oscillation magnetic modulator to extract electricity
Road, the i.e. limited ripple current caused by vice-side winding W4 of time constant of low pass filter B2, so as to further increase
Measurement accuracy.
Fig. 3 be the present invention provide accurate ac and dc current transformer measurement DC current when the linearity.Transverse axis in figure
Tested electric current is represented, the longitudinal axis represents the secondary current IS and country's 5kA DC current ratio standards for the transformer that the present invention is provided
Difference current between the output current of device (proportional error in full scale is less than 0.5ppm).Can from figure
Go out, the secondary current difference in full scale ± 600A is about 0.65 μ A, be about relative to secondary rated current ± 0.6A
1.1ppm。
Fig. 4 be the present invention provide accurate ac and dc current transformer measurement alternating current when frequency bandwidth.It is horizontal in figure
Axle represents tested electric current IP frequency, and the longitudinal axis represents the secondary output current IS and the tested electricity of primary side for the transformer that the present invention is provided
The ratio (representing in db form) that IP is converted the electric current for arriving secondary by turn ratio W4/W5 is flowed, wherein tested electric current IP=3Arms is (just
The virtual value of string electric current).It can be seen that the three dB bandwidth for the transformer that the present invention is provided is more than 100kHz.
Obviously, those skilled in the art can carry out the spirit of various changes and modification without departing from the present invention to the present invention
And scope.So, if these modification and variation to the present invention belong to the scope of the claims in the present invention and its equivalent technologies
Within, then including the present invention is also changed and deformed comprising these.
Claims (8)
1. a kind of accurate alterating and direct current current transformer, it is characterised in that including：
Measurement head, primary side winding (W5) electric current (IP) is flowed through for measuring；
Self-oscillation magnetic modulator circuit, for detecting direct current flux；
Magnetizing flux compensation circuit, the ripple current for offsetting magnetizing flux sensing；And
Zero flux AC current transformer circuit, for detecting exchange flux,
The measurement head is by three toroidal cores (C1, C2, C3), two field windings (W1, W2), exchange flux detection windings
(W3), vice-side winding (W4) is constituted, and the first field winding (W1) of two field windings (W1, W2) is wrapped in three toroidal cores
On the first annular magnetic core (C1) of (C1, C2, C3), the second field winding (W2) of two field windings (W1, W2) is wrapped in three
On the second toroidal core (C2) of individual toroidal core (C1, C2, C3), exchange flux detection winding (W3) is wrapped in be stacked in back-to-back
On three toroidal cores (C1, C2, C3) together, and vice-side winding (W4) is wrapped in exchange flux detection winding (W3), essence
The measurement head of close alterating and direct current current transformer passes through primary side winding (W5), and primary side winding (W5) electric current is flowed through for measuring
（IP）, the self-oscillation magnetic modulator circuit is by the first field winding (W1), comparator (A1) and first resistor (R1) structure
Into the output of comparator (A1) terminates the Same Name of Ends of the first field winding (W1), and the non-same polarity of the first field winding (W1) connects
The input of comparator (A1), while be connected with first resistor (R1), the other end ground connection of first resistor (R1).
2. accurate alterating and direct current current transformer according to claim 1, it is characterised in that the first annular magnetic core (C1)
It is identical with geometric parameter with the physical characteristic of the second toroidal core (C2), the 3rd ring of three toroidal cores (C1, C2, C3)
The geometric parameter of shape magnetic core (C3) is identical with the geometric parameter of the first annular magnetic core (C1) and the second toroidal core (C2),
The number of turn of described two field windings is identical.
3. accurate alterating and direct current current transformer according to claim 2, it is characterised in that the magnetizing flux compensation circuit
It is made up of the second field winding (W2), unity gain inverter (A2) and second resistance (R2), unity gain inverter (A2)
Input is connected with the output end of comparator (A1), and the output of unity gain inverter (A2) terminates the second field winding (W2)
Same Name of Ends, the non-same polarity of the second field winding (W2) connects second resistance (R2), the other end ground connection of second resistance (R2).
4. accurate alterating and direct current current transformer according to claim 3, it is characterised in that also including the first summing circuit
(D1), the second summing circuit (D2), low pass filter (B2), and high-pass filter (B1), the two of the first summing circuit (D1)
Individual input connects the ungrounded end of first resistor (R1) and the output end of high-pass filter (B1), the first summing circuit respectively
(D1) input of output end connection low pass filter (B2), two inputs of the second summing circuit (D2) connect low respectively
The output end of bandpass filter (B2) and the Same Name of Ends of exchange flux detection winding (W3).
5. accurate alterating and direct current current transformer according to claim 4, it is characterised in that the Zero flux alternating current is mutual
Sensor circuit is by exchange flux detection winding (W3), feedback control circuit (A3), power amplification circuit (A4), vice-side winding (W4)
And 3rd resistor (R3) is constituted, the input of feedback control circuit (A3) connects the output end of the second summing circuit (D2), instead
Feedback control circuit (A3) output end connection power amplification circuit (A4) input, power amplification circuit (A4) connect secondary around
The Same Name of Ends of group (W4), the non-same polarity connection 3rd resistor (R3) of vice-side winding (W4), another termination of 3rd resistor (R3)
Ground.
6. accurate alterating and direct current current transformer according to claim 5, it is characterised in that the feedback control circuit (A3)
Using the proportional, integral circuit being made up of operational amplifier.
7. accurate alterating and direct current current transformer according to claim 6, it is characterised in that in the proportional, integral circuit
It is followed by power amplifier output mutual inductor secondary current, the power amplifier is any one of A classes, B classes, AB classes or D classes,
Or be made up of multiple discrete components, or be made up of single integrated device.
8. accurate alterating and direct current current transformer according to claim 4, it is characterised in that the low pass filter (B2) is
Passive first order low pass filter, passive high-order low-pass filter, active first-order low pass filter and active high-order low-pass filter
Any one of, high-pass filter (B1) is passive first order high-pass filter, passive higher order high pass filters, active first-order height
Any one of bandpass filter and active higher order high pass filters.
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| CN201510642231.7A CN105304303B (en) | 2015-09-30 | 2015-09-30 | A kind of accurate alterating and direct current current transformer |
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| CN201510642231.7A CN105304303B (en) | 2015-09-30 | 2015-09-30 | A kind of accurate alterating and direct current current transformer |
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| CN105304303B true CN105304303B (en) | 2017-08-04 |
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Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106018912A (en) * | 2016-05-23 | 2016-10-12 | 北京柏艾斯科技有限公司 | High-precision universal alternative and direct current measuring device |
| CN107942124B (en) * | 2017-12-14 | 2024-02-02 | 华中科技大学 | Direct current comparison measuring device |
| CN110161296A (en) * | 2018-03-19 | 2019-08-23 | 深圳市航智精密电子有限公司 | The excitation closed control circuit and its control method of fluxgate current sensor |
| CN108593999A (en) * | 2018-06-30 | 2018-09-28 | 宁波中车时代传感技术有限公司 | A kind of Zero flux current sensor |
| CN111693753A (en) * | 2019-11-29 | 2020-09-22 | 中国计量大学 | Novel direct current measuring device |
| CN112986654B (en) * | 2021-02-10 | 2022-05-03 | 南方电网科学研究院有限责任公司 | Current measuring device of broadband alternating current and direct current |
| CN114280350B (en) * | 2021-12-15 | 2024-04-16 | 浙江巨磁智能技术有限公司 | High-precision current sensor and shunt-based high-current measurement method |
| CN117214502A (en) * | 2023-09-04 | 2023-12-12 | 希斯灵顿(大连)科技有限公司 | Current sensor, detection device and detection system |
| CN117110693A (en) * | 2023-10-25 | 2023-11-24 | 南方电网科学研究院有限责任公司 | Self-excitation type fluxgate current sensor, measuring method and electronic equipment |
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| CN102496446B (en) * | 2011-11-29 | 2014-04-16 | 中国西电电气股份有限公司 | Zero magnetic flux direct-current current transformer |
| JP2013217914A (en) * | 2012-03-12 | 2013-10-24 | Ferrotec Corp | Current sensor, sensor element, and control device |
| CN102866283B (en) * | 2012-09-12 | 2015-05-20 | 北京东方计量测试研究所 | Superimposed large-current bias alternative-current (AC) current measuring device |
| CN102969136B (en) * | 2012-11-17 | 2015-09-16 | 郑州三晖电气股份有限公司 | A kind of big current, High-accuracy direct current current transformer |
| JP6123275B2 (en) * | 2012-12-17 | 2017-05-10 | 富士電機機器制御株式会社 | Current detector |
| CN203503452U (en) * | 2013-07-31 | 2014-03-26 | 河北申科电子股份有限公司 | Zero-magnetic flux high-accuracy current transformer |
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