CN103630724A - Self-calibration harmonic current transformer based on gapped iron core coil - Google Patents
Self-calibration harmonic current transformer based on gapped iron core coil Download PDFInfo
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Abstract
The invention discloses a self-calibration harmonic current transformer based on a gapped iron core coil. The transformer can output digital quantity and voltage simulation quantity which are linearly proportional to primary current containing harmonics, and can achieve the purposes of measurement and protection. The self-calibration harmonic current transformer comprises a gapped iron core, a primary coil, a measurement secondary coil, a protection secondary coil, a calibration coil, a monitoring secondary coil, an annular shielding box with a slotted inner ring, a first resistor, a second resistor, a third resistor, a sampling resistor, a first operational amplifier, a second operational amplifier, a third operational amplifier, a fourth operational amplifier, a first bidirectional voltage regulator tube, a second bidirectional voltage regulator tube, a third bidirectional voltage regulator tube, a fourth bidirectional voltage regulator tube, a signal conditioning circuit, an analog-to-digital converter, a microprocessor, a digital-to-analog conversion circuit, a calibration current drive circuit, a communication interface, and a first integral summation circuit and a second integral summation circuit which use a lossy integrator.
Description
Technical field
The present invention relates to electromagnetic measurement device, relate in particular to a kind of for measuring and protect the dual-purpose self calibration harmonic current mutual inductor based on band gap iron-core coil.
Background technology
Current transformer is a kind of current sensor, is mainly used in electrical network electric energy metrical, power quality analysis and safeguard protection.Standard GB/T 1208-2006 < < current transformer > > and GB/T20840.8-2007 < < mutual inductor the 8th portions of electronics formula current transformer > > separate provision the technical manual of electromagnetic current transducer and electronic current mutual inductor.Standard GB/T/T14549-1993 < < quality of power supply utility network harmonic wave > > and standard GB/T/T19862-2005 < < power quality monitoring device General Requirement > > separate provision the General Requirement of the permissible value of utility network harmonic wave, detection method and current harmonics monitoring equipment, this harmonic wave sensing accuracy to current transformer has proposed clear and definite requirement.
Current transformer is mainly divided into measuring to be used and two large classes for protection; the current measuring range of Verification of Measuring Current Transformer is generally 1% to 120% of current transformer rated current, and the current detecting scope of protective current transformer, is generally several times to tens times of current transformer rated current.Electromagnetic current transducer adopts iron-core coil to carry out the sensing of primary current, and it is narrower that it measures frequency band, is mainly therefore design under power frequency sine wave condition, calibrates for error and use.Electronic current mutual inductor generally adopts optical devices, air core coil or low-power consumption iron-core coil to carry out the sensing of primary current.Air core coil and low-power consumption iron core coil structure are simple and be easy to realization, are therefore widely adopted.There is not the phenomenon of hysteresis & saturation in air core coil, therefore measures frequency band very wide.But air core coil output signal under power frequency condition is conventionally very little; and be difficult to guarantee that the physical dimension of coil does not change in During Process of Long-term Operation; and the variation of coil geometries is larger on the coefficient of mutual inductance impact of air core coil senser element; cause accuracy not high, so air core coil is generally used as the protective current transformer, senser element that accuracy requirement is not high.The structure of low-power consumption iron-core coil and sensing principle are identical with the iron-core coil that traditional electromagnetic current transducer adopts, and difference is that the output power requiring is different.Low-power consumption iron-core coil has that sensing accuracy is high, output signal is large and the feature such as stable performance, because coil winding is on the soft magnetic material iron core of high magnetic permeability, therefore under same accuracy condition, low-power consumption iron-core coil is more much lower than air core coil to the requirement of coil geometries stability.But low-power consumption iron-core coil hysteresis & saturation and the narrower phenomenon of measurement frequency band still exist, and therefore under power frequency condition, it is used as the Verification of Measuring Current Transformer senser element that accuracy requirement is higher conventionally.Band gap iron-core coil is a kind of current transformer senser element being situated between between air core coil and low-power consumption iron-core coil, the structure of band gap iron-core coil is identical with the structure of low-power consumption iron-core coil, difference is that iron core exists gap, with the gap that nonmagnetic substance is filled, can be considered as air gap.Because coil is wound on the soft magnetic material iron core of high magnetic permeability equally, so band gap iron-core coil is more much lower than air core coil equally to the requirement of coil geometries stability.But because air gap is very little, the subtle change of gas length can produce larger impact to the sensing accuracy of band gap iron-core coil, is not suitable for doing the Verification of Measuring Current Transformer senser element that accuracy requirement is higher.Therefore; a kind of can have advantages of simultaneously air core coil measure bandwidth and be difficult for saturated, low-power consumption iron-core coil output signal large and coil geometries stability requirement is lower; and can overcome the impact that band gap iron-core coil gas length changes, and on same senser element, realize that to measure and protect dual-purpose current transformer be in demand.
Open day is on 02 22nd, 2012, publication number is that the patent documentation of CN102360892A discloses the technical scheme that name is called a kind of current transformer, it comprises iron core, insulation, Secondary Winding and shielding winding, one or several air gap are set on iron core, on iron core, be wound around insulation, outside is wound around Secondary Winding, in Secondary Winding, around several, shield in pairs winding, the electromotive force that main flux is responded to is therein cancelled each other, utilize the electric potential difference that the difference of the magnetic flux that Magnetic Leakage Field of Transformer produces in various piece unshakable in one's determination produces to form circulation, reduce the impact of mutual inductor stray field, iron core is not easy saturated.The weak point of this technical scheme is, the impact that utilizes air gap and potted coil only can reduce stray field makes iron core unsuitable saturated, but cannot overcome, measures the narrow problem of frequency band, can only under power frequency, use.Within open day, be that on 04 14th, 2004, publication number are that the patent documentation of CN 2612041Y discloses the technical scheme that name is called a kind of hollow coil current transformer, it comprises current signal sensing head and current sensing signal treatment circuit, current signal sensing head comprises the non magnetic support frame of annular and the induction of signal coil that electromagnetic wire is coiled into, and induction of signal coil and support frame form inductor etc.The weak point of this technical scheme is, although hollow coil is wound on skeleton, the variation that affects its physical dimension due to factors such as environment temperatures in During Process of Long-term Operation also can exist, and can have a strong impact on current detecting accuracy.
Summary of the invention
Fundamental purpose of the present invention is to provide a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil, and it can export digital quantity and the voltage analog linearly proportional with the primary current that contains harmonic wave, and realizes and measure and protect two kinds of purposes.
The present invention is directed to prior art problem and mainly by following technical proposals, solved, a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil, comprises band gap iron core, primary winding, measurement secondary coil, protection secondary coil, alignment coil, supervision secondary coil, the ring shielding box of interior ring fluting, the first resistance, the second resistance, the 3rd resistance, sampling resistor, the first operational amplifier, the second operational amplifier, the 3rd operational amplifier, four-operational amplifier, the first bi-directional voltage stabilizing pipe, the second bi-directional voltage stabilizing pipe, the 3rd bi-directional voltage stabilizing pipe, the 4th bi-directional voltage stabilizing pipe, signal conditioning circuit, analog to digital converter, microprocessor, D/A converting circuit, calibration current driving circuit, communication interface, use diminishes first integral summing circuit and the second integral summing circuit of integrator, and first integral summing circuit is identical with the circuit structure of second integral summing circuit, measurement secondary coil, protection secondary coil, monitor with secondary coil and alignment coil and be evenly wound on respectively on band gap iron core and be together arranged in the ring shielding box of interior ring fluting, primary winding is the punching bus through band gap iron core, the first operational amplifier, the second operational amplifier, the 3rd operational amplifier and four-operational amplifier form respectively voltage follower, the first resistance, one end of the second resistance and the 3rd resistance respectively with measurement secondary coil, protection is connected with the Same Name of Ends of secondary coil with secondary coil and supervision, the first resistance, the other end of the second resistance and the 3rd resistance respectively with the first operational amplifier, the in-phase input end of the second operational amplifier and the 3rd operational amplifier is connected, measurement secondary coil, protection is connected to the ground and connects with the non-same polarity of secondary coil with secondary coil and supervision, the Same Name of Ends of alignment coil is connected with the output terminal of calibration current driving circuit, one end of sampling resistor is connected with the in-phase input end of the non-same polarity of alignment coil and four-operational amplifier, the other end of sampling resistor is connected to the ground and connects, the first bi-directional voltage stabilizing pipe, the second bi-directional voltage stabilizing pipe, one end of the 3rd bi-directional voltage stabilizing pipe and the 4th bi-directional voltage stabilizing pipe respectively with the first operational amplifier, the second operational amplifier, the in-phase input end of the 3rd operational amplifier and four-operational amplifier is connected, the first bi-directional voltage stabilizing pipe, the second bi-directional voltage stabilizing pipe, the other end of the 3rd bi-directional voltage stabilizing pipe and the 4th bi-directional voltage stabilizing pipe is connected to the ground and connects respectively, the first operational amplifier, the second operational amplifier, the output terminal of the 3rd operational amplifier and four-operational amplifier respectively with the first input end of signal conditioning circuit, the second input end, the 3rd input end and four-input terminal are connected, signal conditioning circuit has four separate input and output voltage conditioning passage and the first output terminals, the second output terminal, the 3rd output terminal and the 4th output terminal respectively with first input end, the second input end, the 3rd input end and four-input terminal are corresponding, the first output terminal, the second output terminal, the 3rd output terminal and the 4th output terminal are connected with four input ends of analog to digital converter respectively, the integrator input end of first integral summing circuit is connected with the first output terminal of signal conditioning circuit, the summing circuit input end of first integral summing circuit is connected with the 4th output terminal of signal conditioning circuit, the integrator input end of second integral summing circuit is connected with the second output terminal and the 4th output terminal of signal conditioning circuit respectively with summing circuit input end, microprocessor respectively with analog to digital converter, D/A converting circuit, signal conditioning circuit and communication interface are connected, the output terminal of D/A converting circuit is connected with the input end of calibration current driving circuit.
Wherein, band gap iron core, primary winding, secondary coil for measurement, secondary coil for protection, monitor with the ring shielding box of secondary coil, alignment coil and interior ring fluting and form primary current sensor; Measure with secondary coil, secondary coil for protection, supervision and be evenly wound on respectively and on band gap iron core, form a toroidal iron core coil with secondary coil and alignment coil.
Below the principle of the technical program is described further.
(1) sensing principle
For the band gap iron-core coil being formed by single turn primary winding, secondary coil, alignment coil and band gap iron core, when primary winding flows through angular frequency, be
sine-wave current
, and the calibration current that flows through of alignment coil is while being zero, according to Ampere circuit law, can obtain:
In formula
and
be respectively core field intensity and equivalent magnetic circuit length,
and
be respectively air-gap field intensity and the gas length of band gap iron core gap.By relational expression
with
substitution (1), has:
In formula
for the magnetic induction density of iron core and air gap,
with
be respectively iron core magnetic permeability and air-gap permeance.In formula (2)
can be considered gas length
correction factor, by select suitable core material and
ratio, can make iron core have in working range
so formula (2) can be expressed as
.Now, for the secondary coil being wound on iron core, its Open Output Voltage is:
Coefficient of mutual inductance in formula
,
and
being respectively core section amasss and the secondary coil number of turn.From formula (3), band gap iron-core coil can be equivalent to and be wound on air-gap magnetic circuit length and be
non magnetic skeleton on air core coil.
To secondary coil Open Output Voltage
carry out analog or digital integration, the RC that hypothetical simulation integration adopts diminishes RC that analogue integrator or digital integration adopt and diminishes in analogue integrator prototype and electric capacity
the resistance that (being the first electric capacity 25 in Fig. 1) is in parallel
(the 5th resistance 23 in Fig. 1) value is enough large, integrator output so
can be expressed as:
By formula (4) substitution formula (3):
No-load voltage ratio constant in formula
.From formula (5), current transformer output
with primary current
become fixing linear ratio relation, no-load voltage ratio constant
with primary current angular frequency
irrelevant.Therefore this mutual inductor is a linear system, when primary current is periodic non-sinusoidal wave, can linear superposition through the each harmonic component of mutual inductor output, i.e. and current transformer output
, this has just realized primary current first-harmonic and each harmonic linear transformation at equal pace.
(2) on-line calibration principle
At primary winding, flow through periodic non-sinusoidal wave electric current
, calibration winding
injector angle frequency
sinusoidal wave calibration current
time, equivalent primary current is
add
calibration current doubly
.Here
for primary current first-harmonic angular frequency, it is suitable to select
value makes
be different from the contained humorous angular frequency of primary current.By formula (3), can obtain secondary coil open-circuit voltage output alignment electric current and cause that the phasor expression formula of component is:
（6）
So obtain coefficient of mutual inductance calculating formula
, wherein
with
be respectively
with
root-mean-square valve.Certainly, also can utilize the expression formula (5) of this linear system to obtain the output of mutual inductor
, to no-load voltage ratio constant
calculate and on-line calibration.
For the calibration current very little
the calibration of lower realization to band gap iron-core coil, can select larger
with
.Suppose
, i.e. secondary coil open-circuit voltage alignment electric current
induction output component equate with primary current first-harmonic output component amplitude, can obtain:
From formula (5) and formula (7), when calibration current is non-vanishing, current transformer is not output as before revising:
In order to guarantee the correct output of mutual inductor between alignment epoch, need to deduct additional components
, in this additional components
, wherein
for calibration current flows through the voltage that sampling resistor produces.
The operational mode of the technical program has two kinds of normal sensing and on-line calibrations.
Under the long-term continuous operation mode of normal sensing, primary winding flows through tested primary current, measurement secondary coil, protection is exported respectively the differential signal of primary current with secondary coil and supervision according to a certain percentage with secondary coil, these signals are connected to respectively the signal input part of analog to digital converter after signal conditioning circuit conditioning, each of signal conditioning circuit independently nursed one's health the input voltage signal of passage after low-pass filter elimination high frequency interference, by scale operation the regulation of electrical circuit wherein, export applicable voltage signal, microprocessor to the measurement of analog to digital converter conversion output with and protect and carry out integration and adjustment by signal digital amount, and through communication interface output and primary current first-harmonic and the proportional measurement of each harmonic with and protection digital signal, the integration of microprocessor and adjustment programme are realized and are measured with and protect the digital integration by two-way output signal, the functions such as the amplitude of digital integration output waveform and phase place adjustment.With secondary coil and protection, with the output voltage of secondary coil, there is under normal circumstances the feature of fixed relationship in secondary coil, measurement for supervision that utilization is wound on same iron core, by the mutual comparison to these three output voltages, realize the monitored for prolonged periods of time of using the working condition of secondary coil with secondary coil and protection to measuring; Meanwhile; through the measurement of conditioning, use and protect the integrator input end of inputting respectively first integral summing circuit and second integral summing circuit with voltage signal; now the summing circuit input terminal voltage signal of first integral summing circuit and second integral summing circuit is zero; the output of first integral summing circuit is measured and is used analog quantity voltage signal; second integral summing circuit output protection analog quantity voltage signal, these two analog voltage signals and primary current first-harmonic and each harmonic proportion relation.
Under the termed run mode in short-term of on-line calibration, primary winding flows through tested primary current, microprocessor drives alignment coil to flow through calibration current by D/A converting circuit and calibration current driving circuit, and the selection of calibration current frequency is different from the contained humorous angular frequency of primary current.Calibration current flows through sampling resistor and produces calibrate voltage signal.Microprocessor goes out the calibration current differential signal of stack separately by using measuring, protect with and monitoring with the Analyze & separate of three-way output signal sampled data; the calibration current differential signal of these stacks is compared with calibrate voltage signal; calculate to measure with secondary coil, protection and use secondary coil and monitor the coefficient of mutual inductance for primary winding with secondary coil, and carry out the on-line calibration of digital quantity sensing error.Microprocessor by the running state information of device with measure with and protection with being exported by communication interface after digital signal merging.Meanwhile, the calibrate voltage signal after conditioning is connected to the summing circuit input end of first integral summing circuit and second integral summing circuit, utilizes summing circuit that the calibration current signal of stack is removed from each analog output.On-line calibration is termed run mode in short-term, and set the interval time between twice on-line calibration by microprocessor, and setting range is dozens of minutes to tens hour.
As preferably, first integral summing circuit is by diminishing integrator and summing circuit forms, diminish integrator and comprise the 4th resistance, the 5th resistance, the first electric capacity and the 5th operational amplifier, summing circuit comprises the 6th resistance, the 7th resistance, the 8th resistance and the 6th operational amplifier, one end of the 4th resistance is connected with the integrator input end of first integral summing circuit, one end of the other end of the 4th resistance and the 5th resistance, the inverting input of one end of the first electric capacity and the 5th operational amplifier is connected, the other end of the other end of the 5th resistance and the first electric capacity is connected with one end of the 6th resistance and the output terminal of the 5th operational amplifier, the other end of the 6th resistance respectively with one end of the 7th resistance, the inverting input of one end of the 8th resistance and the 6th operational amplifier is connected, the other end of the 8th resistance is connected with the output terminal of the 6th operational amplifier, the in-phase input end of the 5th operational amplifier and the 6th operational amplifier is connected to the ground and connects, the other end of the 7th resistance is connected with the summing circuit input end of first integral summing circuit, diminish integrator also as the integrator master pattern of microprocessor integral and calculating.Analogue integrator in first integral summing circuit and second integral summing circuit adopts and diminishes integrator, avoids the amplification spillover of direct current signal.The integrator that microprocessor integral and calculating adopts be take and diminished integrator and obtain as master pattern and through Bilinear transformation method.
As preferably, to measure with the number of turn and the protection of secondary coil and equal with the ratio of the number of turn of secondary coil the current protection multiple that current transformer is set, protection is identical by the number of turn of secondary coil with supervision by the number of turn of secondary coil.The primary current first-harmonic rated current root-mean-square valve of the technical program can reach 2000A; rated frequency is 50Hz; current protection multiple can reach 20, and single harmonic component rated current root-mean-square valve can reach 1/10 of primary current first-harmonic rated current root-mean-square valve, and harmonic measure scope is 100Hz to 2KHz.
As preferably, sampling resistor is pure resistive precision resistance.The calibration current that injects alignment coil flows through pure resistive precision resistance, thereby produces the accurate voltage signal that characterizes calibration current.The resistance of pure resistive precision resistance can value 1K Ω, and its temperature drift rate need be lower than 5ppm/ ℃.
As preferably, D/A converting circuit is by the sinusoidal wave calibration current of calibration current driving circuit output set angle frequency, and calibration current driving circuit is single tube common emitter amplifying circuit.
In alignment coil, inject the sinusoidal wave calibration current of set angle frequency.Select the sinusoidal wave angular frequency of calibration current to be different from the contained humorous angular frequency of primary current; therefore microprocessor can be used from measuring, protects with and monitor with isolating the calibration current differential signal of stack separately three-way output signal; calibrate voltage signal after signal conditioning circuit conditioning and measurement are used, protected with and monitor with the stack calibrate voltage signal that secondary coil is exported and sample; because the cycle of calibration current is set by microprocessor, therefore the sampling number in a calibration current cycle can be fixed.Utilize the sampled data of one-period, just can calculate respectively three secondary coils for the coefficient of mutual inductance of primary winding, and with this regularly to measuring and protecting digital quantity sensing error double-duty to carry out on-line calibration, sensing accuracy is guaranteed for a long time.Calibration current driving circuit adopts single tube cascode level amplifying circuit, has simplified circuit structure meeting in required driving force situation.
As preferably, communication interface is RS485 communication interface.RS-485 interface has the advantages such as good noise immunity, transmission range length and multistation ability.
As preferably, the ring shielding box of interior ring fluting is the shielding box of fluting in the middle of interior ring circumference.Thereby the magnetic flux that primary current is produced is introduced in ring shielding box.
As preferably, band gap iron core is to adopt iron-base nanometer crystal alloy material to be made.Iron-base nanometer crystal alloy material has excellent magnetic property.
As preferably, the iron core equivalent magnetic circuit length of band gap iron core is less than or equal to 100 with the ratio of the gas length in gap.
As preferably, microprocessor is provided with timer, and in the time interval of this Timer Controlling on-line calibration, the time interval setting range of on-line calibration is dozens of minutes to tens hour.The operational mode of this current transformer has two kinds of the long-term continuous operation mode of normal sensing and the termed run mode in short-term of on-line calibration, and the setting range between twice on-line calibration is dozens of minutes to tens hour.
The beneficial effect that the present invention brings is, (1) utilize band gap iron-core coil and self calibration technology realize single current sense device to the measurement of primary current and protect accurate sensing output double-duty, and the output of analog quantity and digital quantity is linearly proportional with the primary current that contains harmonic wave; (2) overcome when air core coil, low-power consumption iron-core coil and normal tape interstitial iron core coil are measured and protect sensing double-duty the primary current that contains harmonic wave as single current sense device limitation separately, have output signal large, measure bandwidth, the feature such as accuracy is high and coil geometries stability requirement is low; (3) by the sinusoidal wave calibration current of characteristic frequency that primary winding is superposeed equivalently, and in each secondary coil output voltage, isolate the mode of calibration current differential signal, online detection measurement secondary coil, protection be the coefficient of mutual inductance between secondary coil and primary winding with secondary coil and supervision, regularly, to measuring and protecting digital quantity sensing error double-duty to carry out on-line calibration, sensing accuracy is guaranteed for a long time; (4) utilize secondary coil, the measurement for supervision that are wound on same iron core with the output voltage of secondary coil, to have under normal circumstances the feature of fixed relationship each other with secondary coil and protection, by the mutual comparison to these three output voltages, realize the monitored for prolonged periods of time of using the working condition of secondary coil with secondary coil and protection to measuring; (5) utilize pure resistive precision resistance to gather calibration current signal, can in summing circuit, deduct accurately calibration current superposed signal contained in analog output, simultaneously also by microprocessor in order to deduct calibration current superposed signal contained in digital integrator output signal; (6) to injecting calibration current, there is no the requirement of accuracy, so in logarithmic mode change-over circuit, the requirement of digital to analog converter figure place is not high yet, so the digital to analog converter that can carry with microprocessor is to reduce costs; (7) adopt in ring shielding box and slot in the middle of ring circumference, the magnetic flux that primary current is produced imports in it smoothly; (8) employing diminishes integrator and sets up direct current signal passage, has therefore avoided the amplification spillover of direct current signal; (9) by RS485, export and comprise transducing signal for measurement, protection transducing signal and band gap iron-core coil running state information numerical information, be very easy to far-end and use and manage.
Accompanying drawing explanation
Fig. 1 is a kind of schematic diagram of the present invention;
Fig. 2 is a kind of structural drawing of primary current sensor of the present invention;
Fig. 3 is a kind of sectional view of primary current sensor of the present invention.
In figure: the 1st, band gap iron core, the 2nd, primary winding, the 3rd, alignment coil, the 4th, measurement secondary coil, the 5th, protection secondary coil, the 6th, supervision secondary coil, the 7th, sampling resistor, 8 is first operational amplifiers, 9 is second operational amplifiers, 10 is the 3rd operational amplifiers, 11 is four-operational amplifiers, the 12nd, digital and analogue signals amplifying circuit, 13 is the first resistance, 14 is the second resistance, 15 is the 3rd resistance, 16 is first bi-directional voltage stabilizing pipes, 17 is second bi-directional voltage stabilizing pipes, 18 is the 3rd bi-directional voltage stabilizing pipes, 19 is the 4th bi-directional voltage stabilizing pipes, the 20th, signal conditioning circuit, the 21st, first integral summing circuit, the 22nd, second integral summing circuit, 23 is the 5th resistance, 24 is the 4th resistance, 25 is the first electric capacity, 26 is the 5th operational amplifiers, 27 is the 6th resistance, 28 is the 8th resistance, 29 is the 7th resistance, 30 is the 6th operational amplifiers, the 31st, microprocessor, the 32nd, communication interface, the 33rd, D/A converting circuit, the 34th, analog to digital converter, the 35th, the ring shielding box of interior ring fluting, the 36th, fluting in the middle of interior ring circumference.
Embodiment
Below by embodiment, and by reference to the accompanying drawings, technical scheme of the present invention is further described in detail.
Embodiment: as shown in Figure 1, Figure 2, Figure 3 shows, the present invention is a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil.
The ring shielding box 35 that band gap iron core (annular) 1, primary winding 2, measurement secondary coil 4, protection secondary coil 5, supervision secondary coil 6, alignment coil 3 and interior ring are slotted forms primary current sensors; Measure with secondary coil 4, secondary coil 5 for protection, supervision and be evenly wound on respectively and on annular band gap iron core 1, form a toroidal iron core coil with secondary coil 6 and alignment coil 3; Sampling resistor 7 is used resistance 1K Ω, temperature drift rate lower than the pure resistive precision resistance of 5ppm/ ℃; Digital and analogue signals amplifying circuit 12 adopts single tube common emitter amplifying circuit; The ring shielding box 35 of interior ring fluting slots 36 in the middle of being provided with interior ring circumference; Communication interface 32 is RS485 communication interface.
First integral summing circuit 21 is identical with the circuit structure of second integral summing circuit 22, first integral summing circuit 21 is by diminishing integrator and summing circuit forms, diminish integrator and comprise the 4th resistance 24, the 5th resistance 23, the first electric capacity 25 and the 5th operational amplifier 26, summing circuit comprises the 6th resistance 27, the 7th resistance 29, the 8th resistance 28 and the 6th operational amplifier 30, and D/A converting circuit 33 comprises digital to analog converter, low-pass filter and voltage follower.Primary winding 2 is the punching bus through toroidal iron core coil, and toroidal iron core coil is placed in the ring shielding box 35 of interior ring fluting; The first operational amplifier 8, the second operational amplifier 9, the 3rd operational amplifier 10 and four-operational amplifier 11 connect into respectively voltage follower; The in-phase input end of the first operational amplifier 8, the second operational amplifier 9 and the 3rd operational amplifier 10 is connected secondary coil 4 for measurement, is protected with secondary coil 5 and monitor the Same Name of Ends of using secondary coil 6 by the first resistance 13, the second resistance 14 and the 3rd resistance 15 respectively; Measure with secondary coil 4, protection and be connected to the ground and connect with the non-same polarity of secondary coil 6 with secondary coil 5 and supervision; The Same Name of Ends of alignment coil 3 is connected with the output terminal of calibration current driving circuit 12, and one end of sampling resistor 7 is connected with the non-same polarity of alignment coil 3 and the in-phase input end of four-operational amplifier 11, and the other end of sampling resistor 7 is connected to the ground and connects; The first bi-directional voltage stabilizing pipe 16, the second bi-directional voltage stabilizing pipe 17, the 3rd bi-directional voltage stabilizing pipe 18 and the 4th bi-directional voltage stabilizing pipe 19 are connected between the in-phase input end and ground (power supply ground) of the first operational amplifier 8, the second operational amplifier 9, the 3rd operational amplifier 10 and four-operational amplifier 11; The output terminal of the first operational amplifier 8, the second operational amplifier 9, the 3rd operational amplifier 10 and four-operational amplifier 11 is connected with first input end, the second input end, the 3rd input end and the four-input terminal of signal conditioning circuit 20 respectively; Signal conditioning circuit 20 has four separate input and output voltage conditioning passages, the first output terminal of signal conditioning circuit 20, the second output terminal, the 3rd output terminal and the 4th output terminal are corresponding with its first input end, the second input end, the 3rd input end and four-input terminal respectively, i.e. input signal u
, u
, u
, u
respectively with output signal u
, u
, u
, u
corresponding; The first output terminal of signal conditioning circuit 20, the second output terminal, the 3rd output terminal and the 4th output terminal are connected with four input ends of analog to digital converter 34 respectively; The integrator input end X1 of first integral summing circuit 21 is connected with the first output terminal of signal conditioning circuit 20, and the summing circuit input end X2 of first integral summing circuit 21 is connected with the 4th output terminal of signal conditioning circuit 20; One end of the 4th resistance 24 is connected with the integrator input end X1 of first integral summing circuit 21, and the other end of the 4th resistance 24 is connected with the inverting input of one end of the 5th resistance 23, one end of the first electric capacity 25 and the 5th operational amplifier 26; The other end of the other end of the 5th resistance 23 and the first electric capacity 25 is connected with one end of the 6th resistance 27 and the output terminal of the 5th operational amplifier 26; The other end of the 6th resistance 27 is connected with the inverting input of one end of the 7th resistance 29, one end of the 8th resistance 28 and the 6th operational amplifier 30 respectively; The other end of the 8th resistance 28 is connected with the output terminal of the 6th operational amplifier 30; The in-phase input end of the 5th operational amplifier 26 and the 6th operational amplifier 30 is connected to the ground and connects; The other end of the 7th resistance 29 is connected with the summing circuit input end X2 of first integral summing circuit 21; The integrator input end X3 of second integral summing circuit 22 is connected with the second output terminal and the 4th output terminal of signal conditioning circuit 20 respectively with summing circuit input end X4; Microprocessor 31 is connected with analog to digital converter 34, D/A converting circuit 33, signal conditioning circuit 20 and communication interface 32 respectively, and the output terminal of D/A converting circuit 33 is connected with the input end of calibration current driving circuit 12.
The present embodiment specific design parameter is: the first-harmonic rated current root-mean-square valve of primary winding 2 is 500A, rated frequency is 50Hz, current protection multiple is 10, the single harmonic component rated current root-mean-square valve of primary winding 2 is 1/10 of primary current first-harmonic rated current r.m.s., and harmonic measure scope is 100Hz to 2KHz; Under rated frequency condition, when primary current is first-harmonic rated current, measure with simulation output rated voltage u
root-mean-square valve be 1V, measuring is 2D41H with the ratings of digital output, protection is 01CFH with the ratings of digital output, data rate is rated frequency 200 times, when primary current is 10 times of first-harmonic rated current, protection is 1V by the root-mean-square valve of simulating output rated voltage; Measuring is 0.5 grade by the accuracy rating of analog output signal, and measuring is 0.2 grade with the class of accuracy of digital output, and protection is 5P level with the class of accuracy of analog output signal and digital output signal.The number of turn of primary winding 2 is 1 circle, and measuring is 200 circles by the number of turn of secondary coil 4, and protection is 20 circles by the number of turn of secondary coil 5, monitors to be 20 circles by the number of turn of secondary coil 6; The iron core of band gap iron core 1 adopts iron-base nanometer crystal alloy material, and its cross section is
, the gas length in gap is
, the iron core equivalent magnetic circuit length of band gap iron core is 50 with the ratio of the gas length in gap; The number of turn of alignment coil 3 is 1256 circles, and calibration current is 1.975KHz frequency
sine-wave current, be 24 hours the interval time between twice on-line calibration; The resistance 1K Ω of sampling resistor 7, its temperature drift rate need be lower than 5ppm/ ℃; Microprocessor 31 adopts the digital signal processor that frequency of operation is 300MHz, analog to digital converter 34 adopts 16, six tunnel ADC, digital to analog converter in D/A converting circuit 33 is 10 DAC, in signal conditioning circuit 20 and D/A converting circuit 33, the cutoff frequency of each low-pass filter is 3KHz, the sample frequency of analog to digital converter 34 is 100KHz, and the digital input amount renewal frequency of D/A converting circuit 33 is 100KHz.
The content not being described in detail in instructions of the present invention belongs to those skilled in the art's known technology.
Should be understood that: above-described embodiment is just to explanation of the present invention, rather than limitation of the present invention, and any innovation and creation that do not exceed within the scope of connotation of the present invention, within all falling into protection scope of the present invention.
Claims (10)
1. the self calibration harmonic current mutual inductor based on band gap iron-core coil, is characterized in that comprising: band gap iron core (1), primary winding (2), measure with secondary coil (4), secondary coil (5) for protection, alignment coil (3), monitor with secondary coil (6), the ring shielding box (35) of interior ring fluting, the first resistance (13), the second resistance (14), the 3rd resistance (15), sampling resistor (7), the first operational amplifier (8), the second operational amplifier (9), the 3rd operational amplifier (10), four-operational amplifier (11), the first bi-directional voltage stabilizing pipe (16), the second bi-directional voltage stabilizing pipe (17), the 3rd bi-directional voltage stabilizing pipe (18), the 4th bi-directional voltage stabilizing pipe (19), signal conditioning circuit (20), analog to digital converter (34), microprocessor (31), D/A converting circuit (33), calibration current driving circuit (12), communication interface (32), use diminishes first integral summing circuit (21) and the second integral summing circuit (22) of integrator, and described first integral summing circuit (21) is identical with the circuit structure of second integral summing circuit (22), measures with secondary coil (4), secondary coil (5) for protection, monitor with secondary coil (6) and alignment coil (3) and be evenly wound on respectively band gap iron core (1) above and be together arranged in the ring shielding box (35) of interior ring fluting, primary winding (2) is the punching bus through band gap iron core (1), the first operational amplifier (8), the second operational amplifier (9), the 3rd operational amplifier (10) and four-operational amplifier (11) form respectively voltage follower, the first resistance (13), one end of the second resistance (14) and the 3rd resistance (15) respectively with measure with secondary coil (4), protection is connected with the Same Name of Ends of secondary coil (6) with secondary coil (5) and supervision, the first resistance (13), the other end of the second resistance (14) and the 3rd resistance (15) respectively with the first operational amplifier (8), the in-phase input end of the second operational amplifier (9) and the 3rd operational amplifier (10) is connected, and measures with secondary coil (4), protection is connected to the ground and connects with the non-same polarity of secondary coil (6) with secondary coil (5) and supervision, the Same Name of Ends of alignment coil (3) is connected with the output terminal of calibration current driving circuit (12), one end of sampling resistor (7) is connected with the non-same polarity of alignment coil (3) and the in-phase input end of four-operational amplifier (11), the other end of sampling resistor (7) is connected to the ground and connects, the first bi-directional voltage stabilizing pipe (16), the second bi-directional voltage stabilizing pipe (17), one end of the 3rd bi-directional voltage stabilizing pipe (18) and the 4th bi-directional voltage stabilizing pipe (19) respectively with the first operational amplifier (8), the second operational amplifier (9), the in-phase input end of the 3rd operational amplifier (10) and four-operational amplifier (11) is connected, the first bi-directional voltage stabilizing pipe (16), the second bi-directional voltage stabilizing pipe (17), the other end of the 3rd bi-directional voltage stabilizing pipe (18) and the 4th bi-directional voltage stabilizing pipe (19) is connected to the ground and connects respectively, the first operational amplifier (8), the second operational amplifier (9), the output terminal of the 3rd operational amplifier (10) and four-operational amplifier (11) respectively with the first input end of signal conditioning circuit (20), the second input end, the 3rd input end and four-input terminal are connected, and signal conditioning circuit (20) has four separate input and output voltage conditioning passage and the first output terminals, the second output terminal, the 3rd output terminal and the 4th output terminal respectively with first input end, the second input end, the 3rd input end and four-input terminal are corresponding, described the first output terminal, the second output terminal, the 3rd output terminal and the 4th output terminal are connected with four input ends of analog to digital converter (34) respectively, the integrator input end of described first integral summing circuit (21) is connected with the first output terminal of signal conditioning circuit (20), the summing circuit input end of described first integral summing circuit (21) is connected with the 4th output terminal of signal conditioning circuit (20), the integrator input end of second integral summing circuit (22) is connected with the second output terminal and the 4th output terminal of signal conditioning circuit (20) respectively with summing circuit input end, microprocessor (31) respectively with analog to digital converter (34), D/A converting circuit (33), signal conditioning circuit (20) and communication interface (32) are connected, and the output terminal of D/A converting circuit (33) is connected with the input end of calibration current driving circuit (12).
2. a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil according to claim 1, it is characterized in that: described first integral summing circuit (21) is by diminishing integrator and summing circuit forms, the described integrator that diminishes comprises the 4th resistance (24), the 5th resistance (23), the first electric capacity (25) and the 5th operational amplifier (26), described summing circuit comprises the 6th resistance (27), the 7th resistance (29), the 8th resistance (28) and the 6th operational amplifier (30), one end of described the 4th resistance (24) is connected with the integrator input end of first integral summing circuit (21), one end of the other end of the 4th resistance (24) and the 5th resistance (23), the inverting input of one end of the first electric capacity (25) and the 5th operational amplifier (26) is connected, the other end of the other end of the 5th resistance (23) and the first electric capacity (25) is connected with one end of the 6th resistance (27) and the output terminal of the 5th operational amplifier (26), the other end of the 6th resistance (27) respectively with one end of the 7th resistance (29), the inverting input of one end of the 8th resistance (28) and the 6th operational amplifier (30) is connected, the other end of the 8th resistance (28) is connected with the output terminal of the 6th operational amplifier (30), the in-phase input end of the 5th operational amplifier (26) and the 6th operational amplifier (30) is connected to the ground and connects, the other end of the 7th resistance (29) is connected with the summing circuit input end of first integral summing circuit (21), the described integrator that diminishes is also as the integrator master pattern of described microprocessor integral and calculating.
3. a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil according to claim 1; it is characterized in that: described for measurement the number of turn of secondary coil (4) with the ratio of the number of turn of secondary coil (5), equal the current protection multiple that current transformer is set with protection, protection uses the number of turn of secondary coil (6) identical by the number of turn of secondary coil (5) with supervision.
4. a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil according to claim 1, is characterized in that: described sampling resistor (7) is pure resistive precision resistance.
5. a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil according to claim 1, it is characterized in that: described D/A converting circuit (33) is by the sinusoidal wave calibration current of calibration current driving circuit (12) output set angle frequency, and described calibration current driving circuit (12) is single tube common emitter amplifying circuit.
6. a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil according to claim 1, is characterized in that: described communication interface is RS485 communication interface.
7. according to a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil described in claim 1 or 2 or 3 or 4 or 5 or 6 or 7, it is characterized in that: the ring shielding box (35) of described interior ring fluting is the shielding box of fluting in the middle of interior ring circumference.
8. a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil according to claim 1, is characterized in that: described band gap iron core (1) is to adopt iron-base nanometer crystal alloy material to be made.
9. according to a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil described in claim 1 or 9, it is characterized in that: the iron core equivalent magnetic circuit length of described band gap iron core (1) is less than or equal to 100 with the ratio of the gas length in gap.
10. a kind of self calibration harmonic current mutual inductor based on band gap iron-core coil according to claim 1, it is characterized in that: described microprocessor (31) is provided with timer, in the time interval of described Timer Controlling on-line calibration, the time interval setting range of described on-line calibration is dozens of minutes to tens hour.
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| CN104764916A (en) * | 2015-03-16 | 2015-07-08 | 中国计量学院 | Electronic voltage transformer based on two capacitors and gap iron core type Rogowski coils |
| CN104764916B (en) * | 2015-03-16 | 2018-04-10 | 中国计量学院 | Electronic type voltage transformer based on double electric capacity and band gap iron core type Rogowski coil |
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| CN106093826B (en) * | 2016-08-10 | 2019-07-12 | 李蕊名 | A kind of band air-gap iron core current transformer measurement structure |
| CN106093826A (en) * | 2016-08-10 | 2016-11-09 | 李蕊名 | A kind of band air-gap iron core current transformer measurement structure |
| CN106093510B (en) * | 2016-08-17 | 2018-08-28 | 山东理工大学 | A kind of mutual inductor secondary side signals Opsonizing method |
| CN106093510A (en) * | 2016-08-17 | 2016-11-09 | 山东理工大学 | A kind of mutual inductor secondary side signals conditioning device and method |
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| CN111239566A (en) * | 2020-03-02 | 2020-06-05 | 西南交通大学 | High-sensitivity high-frequency pulse current sensor |
| CN114814706B (en) * | 2022-06-23 | 2022-11-04 | 武汉磐电科技股份有限公司 | Testing device and method for online self-calibration of mutual inductor |
| CN114814706A (en) * | 2022-06-23 | 2022-07-29 | 武汉磐电科技股份有限公司 | Testing device and method for online self-calibration of mutual inductor |
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