CN108459193A - Alternating current measuring device - Google Patents
Alternating current measuring device Download PDFInfo
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- CN108459193A CN108459193A CN201810298444.6A CN201810298444A CN108459193A CN 108459193 A CN108459193 A CN 108459193A CN 201810298444 A CN201810298444 A CN 201810298444A CN 108459193 A CN108459193 A CN 108459193A
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- current
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
The invention discloses a kind of alternating current measuring devices.It includes：Magnetic circuit, oscillating circuit, timer counter circuit, current calculation module and electric current display module.Magnetic circuit includes magnetic core, first winding and secondary winding.The magnetic circuit is converted for impedance.Oscillating circuit is connected with the secondary winding, for generating frequency of oscillation.Timer counter circuit is connected with the oscillating circuit, the periodic frequency mean value for obtaining tested current first harmonics.Current calculation module is connected with the timer counter circuit, goes out tested current value according to the periodic frequency mean value computation of the tested current first harmonics.Electric current display module is connected with the current calculation module, for showing the calculated tested current value of the current calculation module.The principle of the alternating current measuring device is relatively complicated, is not apparent, therefore the alternating current measuring device is not easy to be attacked by people, and safety is improved.
Description
Technical field
The present invention relates to a kind of power system measuring field, more particularly to a kind of alternating current measuring device.
Background technology
In order to ensure power system security economical operation, it is necessary to carry out monitoring and measuring to the operating condition of power equipment.
Main technical schemes in terms of ac current measurement include：Traditional current transformer and Rogowski coil.
Traditional current transformer is the flat of winding magnetic potential on the closed magnetic circuit constituted based on high magnetic conduction soft magnetic materials
Weighing apparatus principle and realize the measurement to alternating current.Fig. 1 is that the alternating current of the traditional current transformer of the prior art measures original
Reason figure.Reference numeral meaning in Fig. 1 is as follows：I1：Primary current；N1：The number of turns；I2：Secondary current；Ie：Exciting current；
N2：Secondary the number of turns；B：Magnetic flux.
Its magnetic potential balance equation is as follows：I1·N1=(I2+Ie)·N2.Due to：Ie＜ ＜ I2, namely：
It enables again：N=N2/N1, then have following equation establishment：
Here it is the measuring principles of our common current transformers.
Fig. 2 is the ac current measurement schematic diagram of the Rogowski coil of the prior art.Rogowski coil is to be based on a kind of spiral winding
System, hollow core structures loop coil.The output v (t) of its coil is connected to an integrating circuit input terminal for having consumption, integral
It is directly proportional to tested electric current that device exports Vout (t).Its main feature is as follows：One electric current is incuded winding (secondary winding) coiling
On a non-magnet material skeleton, secondary winding works in the mode almost opened a way, output voltage and exciting current it
Between relationship it is as follows：Wherein：A is the sectional area of helical loop；N is the number of turns；μ0It is air magnetic conductance
Rate；L is the length of magnetic path (length of helical loop)；I (t) is the electric current (tested electric current) in current－carrying conductor
Traditional current transformer and Rogowski coil all has the following problems：
1, principle is all very simple, and technology is very easy to obtain, this results in measurement process to be easy (such as to be stolen by criminal
Electric person) attack, and then influence measurement result.
2 because secondary winding the number of turns all relatively more (thousands of circles), material cost is not low, and coiling when
It waits since it is desired that meet the needs of uniform coiling process costs also not low.
Being disclosed in the information of the background technology part, it is only intended to increase understanding of the overall background of the invention, without answering
It has been the prior art well known to persons skilled in the art when being considered as recognizing or imply that the information is constituted in any form.
Invention content
The purpose of the present invention is to provide a kind of alternating current measuring devices, and principle is relatively complicated, be not it is aobvious and
It is clear to, therefore the alternating current measuring device is not easy to be attacked by people, safety is improved.
To achieve the above object, the present invention provides a kind of alternating current measuring devices.It includes：Magnetic circuit, oscillating circuit,
Timer counter circuit, current calculation module and electric current display module.Magnetic circuit includes magnetic core, first winding and secondary winding.
The magnetic circuit is converted for impedance.Oscillating circuit is connected with the secondary winding, for generating frequency of oscillation.Timer counter circuit
It is connected with the oscillating circuit, the periodic frequency mean value for obtaining tested current first harmonics.Current calculation module with it is described fixed
When counting circuit be connected, tested current value is gone out according to the periodic frequency mean value computation of the tested current first harmonics.Electric current is shown
Module is connected with the current calculation module, for showing the calculated tested current value of the current calculation module.
In a preferred embodiment, the magnetic core is made of the soft magnetic materials of air-gap-free.
In a preferred embodiment, the magnetic core is ultracrystalline magnetic core or FERRITE CORE.
In a preferred embodiment, the oscillating circuit is Colpitts oscillating circuits.
In a preferred embodiment, the formula of the current calculation module calculating current is y=1E-06x3-
0.0004x2+ 0.0952x+1.4202, wherein x are the periodic frequency mean values of tested current first harmonics, and y is the tested electric current
Value.
Compared with prior art, alternating current measuring device according to the present invention has the advantages that：The alternation
The principle of current measuring device is relatively complicated, and inventor is found that the frequency of magnetic circuit secondary side oscillating circuit and tested alternation
Current related, the alternating current measuring device designed using the principle is not easy to be attacked by people, and safety is improved, in addition,
Secondary winding part the number of turns of its magnetic circuit is in several circles between tens of circles, and the number of turns is seldom, and cost is reduced.
Description of the drawings
Fig. 1 is the alternating current measuring principle figure of the traditional current transformer of the prior art.
Fig. 2 is the ac current measurement schematic diagram of the Rogowski coil of the prior art.
Fig. 3 is alternating current measuring principle figure according to an embodiment of the present invention.
Fig. 4 is hysteresis loop according to an embodiment of the present invention.
Fig. 5 is the typical curve of current first harmonics periodic frequency mean value and exciting current according to an embodiment of the present invention
Figure.
Specific implementation mode
Below in conjunction with the accompanying drawings, the specific implementation mode of the present invention is described in detail, it is to be understood that the guarantor of the present invention
Shield range is not restricted by specific implementation.
Unless otherwise explicitly stated, otherwise in entire disclosure and claims, term " comprising " or its change
It changes such as "comprising" or " including " etc. and will be understood to comprise stated element or component, and do not exclude other members
Part or other component parts.
The present invention provides a kind of ac current measurement devices, and principle is relatively complicated, and technology is not easy to obtain, and measure
Process is not easy to be attacked, and the safety is improved.And secondary winding the number of turns of the device is fewer, number circle to tens circles, therefore material
Expect that cost is relatively low, and compares when coiling and save the time.
Fig. 3 is alternating current measuring principle figure according to an embodiment of the present invention.
As shown, the alternating current measuring device includes magnetic circuit 11, oscillating circuit 12, timer counter circuit 13, electricity
Stream calculation module 14, electric current display module 15 etc..Magnetic circuit 11 can be made of the common soft magnetic materials of any type and winding.Around
Group part is divided into first winding and secondary winding.First winding is single turn or number circle, secondary winding (can generally be fetched by several circles
Circle is to tens of circles) coiling forms.
Ac current source is used for generating the tested alternating current I1 of simulation, the core portion of magnetic circuit 11 by air-gap-free soft magnetism
Material (such as ultracrystallite, manganese-zinc ferrite) is constituted, and the first winding of magnetic circuit 11 can be 1~2 circle, the circle of 4 circle of secondary winding~30
Between.There are two the effects of magnetic circuit 11：When the buffer action of signal, second is that impedance change action.Phase inverter U1A, capacitance C1
With C2, resistance R1 (several kilohms of resistance value or more) and R2 (several kilohms of resistance value or more), the impedance Z structure looked by magnetic circuit secondary side
At a Colpitts oscillator.ZD1 (zener diode) mainly plays limited amplitude protection, and two-way TVS pipe may be used and make
For zener diode.
Since 11 secondary side of magnetic circuit is almost opened a way, according to General mutual inductor equivalent model it is found that the variation of tested electric current I1
The magnetic permeability of magnetic circuit, magnetic circuit dynamic permeadility μ=dB/dH can be changed.
Fig. 4 is the hysteresis loop of the embodiment.When hysteresis loop indicates magnetic field intensity cyclically-varying, ferromagnetic substance
The closure magnetization curve of hysteresis.It show during ferromagnetic substance remagnetization magnetic flux density B and magnetic field intensity H it
Between relationship.Because magnetic flux density B is directly proportional to excitation voltage, magnetic field intensity H is directly proportional to exciting current, when electric current is smaller
When, magnetic field intensity H is smaller, and B and H can approximate linear changes in proportion.At this time magnetic circuit dynamic permeadility μ maintain substantially it is constant not
Become.And after electric current increases to a certain degree, magnetic flux enters saturation region, and magnetic flux density B is no longer pressed with the variation of magnetic field intensity H
Original slope is changed, but is in slow growing trend.
According to inductance formula：Wherein, H is magnetic field intensity (amperes per meter)；L is magnetic
Road length；N is the number of turns；A accumulates for core cross-section.
Because magnetic field intensity H is directly proportional to electric current, inductance L is inversely proportional with magnetic field intensity H, thus the size of inductance L and electricity
Stream is inversely proportional.
For a Colpitts oscillator, the frequency of oscillationIn present embodiment, C=C1*
C2/(C1+C2)。
As described above, inductance L is a parameter by current-modulation.For an AC signal (bipolar signal)
Quantization can generally use the mean value (being namely averaged after rectification) of virtual value or signal absolute value.The mean value of absolute value
Operation compared with virtual value wants complicated, the mean value of absolute value only relate to basic operation and effectively operation be then square, mean value and
Extracting operation operates.The ingenious of alternating current measuring principle of present embodiment is：Frequency is not positive and negative, that is to say, that
Frequency output signal is completely instead of absolute value circuit or rectification circuit, as long as and by being timed counting again to frequency of oscillation
Mean value is taken to can be obtained by one and the relevant frequency values of an exciting current, then in turn that is：Electric current
The mean value of frequency can directly reflect the size of tested electric current in the integral multiple time of primitive period.
Fig. 5 is the typical case of current first harmonics periodic frequency mean value and ac-excited electric current according to an embodiment of the present invention
Curve graph.By the principle of least square, following functional relation can be fitted：Y=1E-06x3-0.0004x2+0.0952x+
1.4202, wherein y are ac-excited electric currents；X is current first harmonics periodic frequency mean value.In practical application, pass through timer counter
Module 13 calculates current first harmonics periodic frequency mean value, then by look-up table in current calculation module 14 or function method by week
The average frequency value of phase property measures current values result accordingly to obtain.It is finally shown by electric current display module 15 and is tested electric current
Value.
In conclusion the principle of alternating current measuring device of the present invention is not apparent, therefore the alternation
Current measuring device is not easy to be attacked by people.The safety is improved, in addition, secondary winding part the number of turns of its magnetic circuit is relatively seldom,
Cost reduction.
The description of the aforementioned specific exemplary embodiment to the present invention is in order to illustrate and illustration purpose.These descriptions
It is not wishing to limit the invention to disclosed precise forms, and it will be apparent that according to the above instruction, can much be changed
And variation.The purpose of selecting and describing the exemplary embodiment is that explaining the specific principle of the present invention and its actually answering
With so that those skilled in the art can realize and utilize the present invention a variety of different exemplary implementation schemes and
Various chooses and changes.The scope of the present invention is intended to be limited by claims and its equivalents.
Claims (5)
1. a kind of alternating current measuring device, which is characterized in that including：
Magnetic circuit, including magnetic core, first winding and secondary winding, the magnetic circuit are converted for impedance；
Oscillating circuit is connected with the secondary winding, for generating frequency of oscillation；
Timer counter circuit is connected with the oscillating circuit, the periodic frequency mean value for obtaining tested current first harmonics；
Current calculation module is connected with the timer counter circuit, according to the periodic frequency mean value of the tested current first harmonics
Calculate tested current value；And
Electric current display module is connected with the current calculation module, for showing that the current calculation module is calculated tested
Current value.
2. alternating current measuring device according to claim 1, which is characterized in that the magnetic core by air-gap-free soft magnetism material
Material is constituted.
3. alternating current measuring device according to claim 2, which is characterized in that the magnetic core is ultracrystalline magnetic core or iron
Ferrite core.
4. alternating current measuring device according to claim 1, which is characterized in that the oscillating circuit is that Colpitts shakes
Swing circuit.
5. alternating current measuring device according to claim 1, which is characterized in that the current calculation module calculating current
Formula be y=1E-06x3-0.0004x2+ 0.0952x+1.4202, wherein x are that the periodic frequency of tested current first harmonics is equal
Value, y is the tested current value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810298444.6A CN108459193B (en) | 2018-04-04 | 2018-04-04 | Alternating current measuring device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810298444.6A CN108459193B (en) | 2018-04-04 | 2018-04-04 | Alternating current measuring device |
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| CN108459193A true CN108459193A (en) | 2018-08-28 |
| CN108459193B CN108459193B (en) | 2020-09-11 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110542871A (en) * | 2019-10-10 | 2019-12-06 | 华北电力大学 | magnetic characteristic measurement system and method for magnetic material |
| CN112034397A (en) * | 2020-07-21 | 2020-12-04 | 华北电力大学 | Transformer frequency response signal detection method based on power frequency zero crossing point |
| CN112230047A (en) * | 2020-10-10 | 2021-01-15 | 浙江巨磁智能技术有限公司 | Method for measuring current by utilizing magnetic saturation oscillation |
| CN112230048A (en) * | 2020-10-10 | 2021-01-15 | 浙江巨磁智能技术有限公司 | Method for measuring current by combining fluxgate oscillation and magnetic saturation oscillation |
| CN113777530A (en) * | 2021-09-10 | 2021-12-10 | 华北电力大学（保定） | Open-circuit fault diagnosis method for rotating diode of inner rotor type three-phase brushless exciter |
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| CN112230047A (en) * | 2020-10-10 | 2021-01-15 | 浙江巨磁智能技术有限公司 | Method for measuring current by utilizing magnetic saturation oscillation |
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| CN112230048B (en) * | 2020-10-10 | 2023-12-08 | 浙江巨磁智能技术有限公司 | Method for measuring current by composite fluxgate oscillation and magnetic saturation oscillation |
| CN112230047B (en) * | 2020-10-10 | 2023-12-08 | 浙江巨磁智能技术有限公司 | Method for measuring current by utilizing magnetic saturation oscillation |
| CN113777530A (en) * | 2021-09-10 | 2021-12-10 | 华北电力大学（保定） | Open-circuit fault diagnosis method for rotating diode of inner rotor type three-phase brushless exciter |
| CN113777530B (en) * | 2021-09-10 | 2023-07-11 | 华北电力大学（保定） | Open-circuit fault diagnosis method for rotating diode of inner rotor type three-phase brushless exciter |
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