CN202330528U - Current sensor with double-shaft fluxgate - Google Patents
Current sensor with double-shaft fluxgate Download PDFInfo
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- CN202330528U CN202330528U CN2011204815925U CN201120481592U CN202330528U CN 202330528 U CN202330528 U CN 202330528U CN 2011204815925 U CN2011204815925 U CN 2011204815925U CN 201120481592 U CN201120481592 U CN 201120481592U CN 202330528 U CN202330528 U CN 202330528U
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Abstract
The utility model discloses a current sensor with a double-shaft fluxgate, relating to devices used for measuring current. The current sensor with the double-shaft fluxgate comprises a fluxgate detecting probe, a zero-magnetic-flux current mutual inductor and a signal processing circuit, wherein the fluxgate detecting probe is composed of two inner annular magnetic cores a and b, an excitation winding and an induction winding; the zero-magnetic-flux current mutual inductor is composed of an outer annular magnetic core and a secondary side winding; a feedback winding is additionally arranged to wind up the two inner annular magnetic cores a and b and the outer annular magnetic core; the signal processing circuit is divided into an excitation circuit part and a detection circuit part; the excitation circuit part comprises an excitation signal generating circuit, a voltage comparer and a power amplifying circuit; and the detection circuit part comprises an RLC (Radio Link Control) resonant circuit, a differential amplifying circuit, a band-pass filtering circuit, a phase sensitive detection circuit, a differential smooth filtering circuit, a voltage-controlled current source and a sampling resistor. According to the utility model, as a closed loop composed of the feedback winding is adopted, the measurement errors of the conventional fluxgate current sensors are removed.
Description
Technical field
The technical scheme of the utility model relates to and is used for equipment measuring current, specifically twin shaft fluxgate current sensor.
Background technology
Along with the development of Power Electronic Technique, the range of application of high precision electric current transducer is more extensive.Especially the noncontact current sensor has DEVELOPMENT PROSPECT widely on commercial Application.The noncontact current measurement can guarantee surveying work personnel's the personal safety and the stable operation of system.Current measuring method mainly comprises: divider resistance, current transformer, Hall current sensor, Rogowski coil (Luo-coil), fluxgate current sensor and magneto-impedance effect Magnetic Sensor.Wherein Hall current sensor and fluxgate current sensor can detect AC and DC.Hall current sensor can detect the electric current of several kiloamperes, and accuracy rating is between 0.5% and 2%, and is bigger but the accuracy of detection of Hall current sensor is influenced by temperature and external magnetic field, and this has just limited the range of application of Hall element.
Existing fluxgate sensor is mainly used in low-intensity magnetic field and detects, such as aspects such as terrestrial magnetic field detection, iron ore detection, displacement detecting and Non-Destructive Testings.Compare with Hall element, the fluxgate current sensor has the advantage of low temperature drift and low drift.
Reported the structure of several kinds of fluxgate current sensors in the world, Davide Azzoni etc. measure the saturation time interval and the load current of coil inductance in the fluxgate current sensor through using microcontroller, reach the purpose of measuring DC current.Utilizations such as G Velasco-Quesada instead swash topological sum efficient switch pipe converter and have made a kind of low-power consumption fluxgate current sensor.The complex structure of these fluxgate current sensors, cost of manufacture is high, has bigger measuring error.CN1310801 discloses a kind of magnet sensor arrangement and current sensor apparatus.The shortcoming of this device is: (1) this device adopts rod core, contains very big and the irrelevant fundametal compoment of environmental magnetic field information in the output signal of single excellent type fluxgate sensor, and this is the part that sensor signal processing circuit need be removed; (2) this device is used two active components, has increased extra driving circuit, causes apparatus structure complicated, and cost increases; (3) this device adopts Open-loop sensors, long and insufficient bandwidth of the response time that the magnetic loss in the magnetic circuit causes, and relatively large with the gain drift of temperature correlation, sensitivity is lower.CN201689125U has disclosed a kind of zero flux current sensor, comprises shell and cover plate.Be provided with first magnet ring and second magnet ring that are superimposed with each other in the shell, its shortcoming is: (1) owing to the no external power source of this device, detected signal is inevitable faint, causes detection difficult; (2) this crust of the device need be used multiple material, and cost is higher, and manufacture craft is comparatively complicated; (3) this device can only be measured alternating current, function singleness, and range of application is narrower.
In view of the existing technical shortcoming of above-mentioned existing fluxgate current sensor, finally cause existing fluxgate current sensor in actual measurement, to have bigger measuring error.
The utility model content
The utility model technical matters to be solved is: twin shaft fluxgate current sensor is provided; The closed-loop path of having adopted the feedback winding to form; Eliminated the measuring error of existing fluxgate current sensor, and product simple in structure, cost is low and function is many.
The utility model solves this technical problem the technical scheme that is adopted: twin shaft fluxgate current sensor; Comprise fluxgate detection probe, zero-flux current transformer and signal processing circuit; Wherein, the fluxgate detection probe is made up of two interior toroidal core a and b, excitation winding and induction winding, and two interior toroidal core a and b discharge side by side; The excitation winding is that a lead is after twining 100 circles on the interior toroidal core a; On interior toroidal core b, twine 100 circles with opposite direction again, the induction winding is intertwined two interior toroidal core a and b that are arranged side by side, and twines 70 circles; Zero-flux current transformer is made up of an outer ring magnetic core and secondary side winding; Secondary side winding is wrapped in separately on the outer ring magnetic core, twines 300 circles, and outer ring magnetic core size is more bigger than two interior toroidal core a and b; Can two interior toroidal core a and b intactly be surrounded; Being enclosed within two interior toroidal core a and b is the outside of twin shaft fluxgate magnetic core, and other has a feedback winding that two interior toroidal core a and b and three magnetic cores of outer ring magnetic core are wound up in the lump, twines 50 circles; Signal processing circuit is divided into exciting circuit and testing circuit two parts; Exciting circuit partly comprises exiting signal generating circuit, voltage comparator and power amplification circuit, and testing circuit partly comprises RLC resonant circuit, differential amplifier circuit, bandwidth-limited circuit, phase-sensitive detection circuit, difference smoothed filter circuit, voltage-controlled current source and sample resistance; Excitation winding one end is connected and other end ground connection with power amplification circuit in the exciting circuit; The induction winding adds electric capacity with inductance that self exists and resistance makes it to constitute the RLC resonant circuit in the testing circuit; Secondary side winding one end connects voltage-controlled current source and other end ground connection, and feedback winding one end is connected with voltage-controlled current source and an end of other end connection sample resistance, and the exiting signal generating circuit in the exciting circuit connects voltage comparator; Voltage comparator connects power amplification circuit again; RLC resonant circuit in the testing circuit connects differential amplifier circuit, and differential amplifier circuit connects bandwidth-limited circuit again, and bandwidth-limited circuit connects phase-sensitive detection circuit again; Phase-sensitive detection circuit connects the difference smoothed filter circuit again; The difference smoothed filter circuit connects voltage-controlled current source again, the other end ground connection of sample resistance, the exiting signal generating circuit in the exciting circuit also with testing circuit in phase-sensitive detection circuit be connected.
Above-mentioned twin shaft fluxgate current sensor, said interior toroidal core a and the used material of b are the ultracrystallite magnetic material, and its saturation magnetic flux density is Bs=1.2T, and coercivity H＜3A/m, saturation magnetostriction coefficient are s=10
-8～10
-6, magnetic permeability is 15000～150000H/m, core loss (100KHz, 0.3T) P
Fe=80W/Kg.
Above-mentioned twin shaft fluxgate current sensor, the used material of said outer ring magnetic core is a ferrite, its saturation magnetic flux density B
s=510mT, coercive force H
c＜14A/m, magnetic permeability are 2500～3500H/m, core loss (100KHz, 0.2T) P
Cv=600KW/m
3
Above-mentioned twin shaft fluxgate current sensor, the used material of said whole windings is enameled wire, and diameter is 0.3mm.
Above-mentioned twin shaft fluxgate current sensor adopts chip SN74HC4060 in the said exiting signal generating circuit, the used chip of voltage comparator is LM339; Power amplification circuit is chip used to be two LF356; Differential amplifier circuit is selected the AD623 chip for use, and bandwidth-limited circuit is selected the OP27A chip for use, and phase-sensitive detection circuit is selected the CD4098 chip for use; The difference smoothed filter circuit is selected the LF353 chip for use, and two chips that feedback circuit comprises all are CA3080.
The beneficial effect of the utility model is:
(1) principle
The fluxgate basic functional principle is based on the nonlinear characteristic of core material referring to Fig. 1, and core material is selected high magnetic permeability, low-coercivity for use, is prone to saturated soft magnetic material, and excitation winding and induction winding uniform winding are on toroidal core.Frequency causes magnetic core magnetic flux alternate for the f alternating current excitation winding of flowing through, and when ac-excited ampere turns was enough big, magnetic core presented periodically saturated and undersaturated condition.As tested primary current I
p＞0, the voltage that Secondary Winding induces comprises the harmonic component of frequency for (2n-1) f and 2nf, and even-order harmonic wherein comprises the information of primary current, therefore can measure primary current through special circuit structure.Among the figure, Is is an exciting current, and Ws is the excitation winding, and WA is the induction winding, and Ip is tested primary current, and circle is a toroidal core.Primary current passes in toroidal core, and the magnetic field of generation is assembled by toroidal core, detects then.If the output of the size in magnetic field and testing circuit has good linear relationship, just can reflect the size of current in the lead according to the output signal of testing circuit.
(2) compared with prior art, the outstanding substantive distinguishing features of the utility model is:
The probe portion of the utility model twin shaft fluxgate current sensor is a magnetic core; The lead that passes toroidal core feeds electric current and produces magnetic field later on; Detected and detect electric current by specific sensing element through special electronic device and the consequent magnetic effect that drives magnetic hysteresis loop; The fluxgate detection probe is the magnetic field that primary current produces, i.e. detection of primary electric current through detecting tested electric current.The toroidal core material selection high magnetic permeability, low-coercivity and be prone to saturated soft magnetic material; Excitation winding and induction winding uniform winding are on toroidal core, and frequency causes toroidal core magnetic flux alternate for the f alternating current excitation winding of flowing through, and when ac-excited ampere turns was enough big, toroidal core presented the saturated and undersaturated condition of periodicity; When primary current Ip＞0, the voltage that the induction winding induces comprises the harmonic component of frequency for (2n-1) f and 2nf, and wherein therefore the information that comprises primary current of even-order harmonic can pass through special circuit structure measurement primary current.The fluxgate current sensor has the advantage of low temperature drift and low drift.Because the magnetic core of fluxgate current sensor is operated in periodic saturated and unsaturated state,, guaranteed the higher measuring accuracy of fluxgate current sensor simultaneously so the magnetic field skew is effectively suppressed.The twin shaft fluxgate current sensor of the utility model owing to feed back the closed-loop path that winding is formed, has been eliminated the measuring error of conventional fluxgate current sensor.
In high-frequency range, secondary side winding and tested electric current produce transformer action, on secondary side winding, induce induction current, and induction current and tested electric current have a linear relationship, through measuring size and the frequency that the induced electricity rheology can obtain tested electric current.
In low-frequency range, (comprise direct current); Through twin shaft fluxgate principle, record the second harmonic in the magnetic field that tested electric current produces, extract after the second harmonic; Harmonic wave and tested size of current have a linear relationship, just can obtain the size of tested electric current through experimental analysis.
For have ± 3 ‰ ultralow nonlinearity erron and low-down temperature float and drift; The utility model twin shaft fluxgate current sensor has adopted closed-loop system; The analog signal output of circuit is fed back to the tickler winding in the twin shaft fluxgate current sensor, and feedback current produces feedback magnetic field, has offset tested external magnetic field; Make the inner magnetic core of twin shaft fluxgate current sensor be operated near zero magnetic field, so just constituted the closed-loop system of fluxgate signal processing circuit.Non-excitation external magnetic field in the closed-loop system in the magnetic core remains near zero, the zero field operation state in the closed-loop system that Here it is.Null field is much smaller with respect to the non-excitation external magnetic field in the open loop magnetic core, and this has just been reduced by the influence of measuring magnetic field to external world, helps the raising of the linearity, and has suppressed effectively that temperature is floated and zero drift phenomenon.
In addition; RLC resonant circuit, differential amplifier circuit, bandwidth-limited circuit, phase-sensitive detection circuit, difference smoothed filter circuit and feedback circuit role in the utility model twin shaft fluxgate current sensor signal treatment circuit are: the fluxgate magnetic core is when saturation depth changes; The degree of stability of the higher harmonic components of its output signal is more far short of what is expected than second harmonic, is difficult to use.Adopted the method for quadratic harmonics to extract fluxgate output signal so the utility model twin shaft fluxgate current sensor is designed to the fluxgate driving circuit, promptly the second harmonic component in the selective extraction fluxgate signal all filters other harmonic components.The excitation square-wave signal is through power amplification circuit driven magnetic open gate detection probe, the Magnetic Field H that tested electric current produced
0Convert induced signal into through the fluxgate detection probe, through the RLC resonant circuit, can amplify the induced signal second harmonic component, other harmonic components can be suppressed.Differential amplifier circuit can obtain the difference mode signal of the inductive coil two end signals output behind the resonance.Through other harmonic components beyond the bandwidth-limited circuit filtering second harmonic component.Phase-sensitive rectifier circuit makes the ac signal after frequency-selecting is amplified change dc signal into, and can characterize the polarity of tested magnetic signal.The fluctuating signal of difference smoothed filter circuit after with phase depending on rectification changes stable direct current signal into.Direct-flow signal voltage value stool and urine can be reflected by the size of measuring magnetic field, and then reflected the size of tested electric current.
(3) compared with prior art, the remarkable advantage of the utility model is:
The utility model twin shaft fluxgate current sensor has and is merely ± 3 ‰ ultralow nonlinearity errons, and low-down temperature is floated and drift, and the input signal noise when detecting direct current or exchanging is effectively suppressed.
The twin shaft fluxgate magnetic core of the utility model twin shaft fluxgate current sensor adopts the ultracrystallite material; It has high magnetic permeability, low-coercivity, high squareness ratio, core loss is low and high-temperature stability is good advantage; And saturation induction density is higher, and wearing quality and corrosion stability are all strong.
The utility model twin shaft fluxgate current sensor combines twin shaft fluxgate magnetic core and zero-flux current transformer magnetic core, and both energy measurement DC current and low-frequency ac electric current were gone back the energy measurement high-frequency ac current.
Zero-flux current transformer in the utility model twin shaft fluxgate current sensor is to be that current transformer core surrounds two interior toroidal core a and b is twin shaft fluxgate magnetic core a and b with the outer ring magnetic core; Play the effect of external magnetic field shielding; Effectively suppressed the influence of outside electromagnetic interference, thereby improved the precision of measurement result significantly current sensor measurement work.
Description of drawings
Below in conjunction with accompanying drawing and embodiment the utility model is further specified.
Fig. 1 is the simplification schematic diagram of the utility model twin shaft fluxgate current sensor.
Fig. 2 is the diagrammatic cross-section of the fluxgate detection probe structure of the utility model twin shaft fluxgate current sensor.
Fig. 3 is the signal flow graph of the signal processing circuit of the utility model twin shaft fluxgate current sensor.
Fig. 4 is the structural representation of the signal processing circuit of the utility model twin shaft fluxgate current sensor.
Fig. 5 is the exiting signal generating circuit synoptic diagram of the utility model twin shaft fluxgate current sensor.
Fig. 6 is the voltage comparator and the power amplification circuit synoptic diagram of the utility model twin shaft fluxgate current sensor.
Fig. 7 is the RLC resonant circuit synoptic diagram of the utility model twin shaft fluxgate current sensor.
Fig. 8 is the differential amplifier circuit synoptic diagram of the utility model twin shaft fluxgate current sensor.
Fig. 9 is the bandwidth-limited circuit synoptic diagram of the utility model twin shaft fluxgate current sensor.
Figure 10 is the phase-sensitive detection circuit synoptic diagram of the utility model twin shaft fluxgate current sensor.
Figure 11 is the difference smoothed filter circuit synoptic diagram of the utility model twin shaft fluxgate current sensor.
Figure 12 is the voltage-controlled current source synoptic diagram of the utility model twin shaft fluxgate current sensor.
Figure 13 is the graph of a relation of voltage and tested electric current on the sample resistance of the utility model twin shaft fluxgate current sensor.
Figure 14 is the relative error curve map of the utility model twin shaft fluxgate current sensor.
Among the figure, 1. interior toroidal core a, 2. interior toroidal core b, 3. outer ring magnetic core, 4. induction winding W
S1,2, 5. secondary side winding W
S3, 6. feed back winding W
F1,2,3, 7. encourage winding W
E1,2, 8. exiting signal generating circuit, 9. voltage comparator, 10. power amplification circuit, the 11.RLC resonant circuit, 12. differential amplifier circuits, 13. bandwidth-limited circuits, 14. phase-sensitive detection circuits, 15. difference smoothed filter circuits, 16. voltage-controlled current sources, 17. sample resistances,
Embodiment
Embodiment illustrated in fig. 2 showing, the fluxgate detection probe of the utility model twin shaft fluxgate current sensor is by interior toroidal core a (1) and interior toroidal core b (2), excitation winding W
E1,2(7) and induction winding W
S1,2(4) constitute, interior toroidal core a (1) and interior toroidal core b (2) be discharging side by side, excitation winding W
E1,2(7) be that a lead forms excitation winding W later at last 100 circles that twine of interior toroidal core a (1)
E1,2(7) W
E1Part goes up at interior toroidal core b (2) with opposite direction and twines 100 circles formation excitation winding W
E1,2(7) W
E2Part, induction winding W
S1,2(4) two interior toroidal core a (1) that are arranged side by side and interior toroidal core b (2) are intertwined, twine 70 circles, wherein the induction winding W on interior toroidal core a (1)
S1,2(4) part is called W
S1, the induction winding W on the interior toroidal core b (2)
S1,2(4) part is called W
S2The zero-flux current transformer of the utility model twin shaft fluxgate current sensor is by an outer ring magnetic core (3) and secondary side winding W
S3(5) constitute secondary side winding W
S3(5) be wrapped in separately on the outer ring magnetic core (3); Twine 300 circles; Outer ring magnetic core (3) size is more bigger than interior toroidal core a (1) and interior toroidal core b (2); Can interior toroidal core a (1) and interior toroidal core b (2) intactly be surrounded, being enclosed within two interior toroidal core a and b is the outside of twin shaft fluxgate magnetic core, and other has a feedback winding W
F1,2,3(6) interior toroidal core a (1) and interior toroidal core b (2) and (3) three magnetic cores of outer ring magnetic core are wound up in the lump, twine 50 circles, wherein feed back winding W
F1,2,3(6) part that is wrapped on the interior toroidal core a (1) is called W
F1, feedback winding W
F1,2,3(6) part that is wrapped on the interior toroidal core b (2) is called W
F2, feedback winding W
F1,2,3(6) part that is wrapped on the outer ring magnetic core (3) is called W
F3
Embodiment illustrated in fig. 3 showing; The signal flow of the signal processing circuit of the utility model twin shaft fluxgate current sensor is: by the excitation square-wave signal of exiting signal generating circuit (8) generation; Through power amplification circuit (10) afterwards; Make magnetic core reach periodic hypersaturated state, be input to the excitation winding W on the fluxgate detection probe
E1,2(7) in, produce and detect magnetic field.After the magnetic field that the tested electric current in former limit produces is detected by the fluxgate detection probe of this moment, on fluxgate detection probe inductive coil, can produce and to react the even-order harmonic component of treating the measuring magnetic field size.Harmonic component gets into RLC resonant circuit (11) afterwards, amplifies required frequency signal, suppresses other harmonic components of signal.Signal is input to differential amplifier circuit (12) afterwards, suppresses common-mode signal.Because the fluxgate magnetic core noise has the odd harmonic characteristic, and its maximum harmonic component be first-harmonic with third harmonic just in signal second harmonic component both sides, therefore in order to suppress noise, signal entering bandwidth-limited circuit (13).Signal gets into phase-sensitive detection circuit (14) after bandwidth-limited circuit (13) output; Phase sensitive detection is in that synchronous signal is under the condition of benchmark with same frequency; Periodically alternating signal carries out full-wave rectification, passes through difference smothing filtering (15) afterwards, confirms the amplitude size of signal.Another effect of phase-sensitive detection circuit (14) is the influence that can thoroughly eliminate odd harmonic.Through difference smothing filtering (15) afterwards, obtain induced voltage signal, come the Control and Feedback electric current, the magnetic flux of feedback current generation and the magnetic flux of tested electric current generation are offseted, reach zero magnetic flux state by voltage-controlled current source (16).At last,, measure the electric current in the feedback winding, and then reflect the size of tested electric current through measuring the voltage on the sample resistance (17).
Embodiment illustrated in fig. 4 showing, the signal processing circuit of the utility model twin shaft fluxgate current sensor is divided into exciting circuit and testing circuit two parts.Exciting circuit partly comprises exiting signal generating circuit (8), voltage comparator (9) and power amplification circuit (10), and testing circuit partly comprises RLC resonant circuit (11), differential amplifier circuit (12), bandwidth-limited circuit (13), phase-sensitive detection circuit (14), difference smoothed filter circuit 15, voltage-controlled current source (16) and sample resistance (17); Excitation winding W
E1,2(7) promptly figure in W
E1And W
E2An end be connected and the other end ground connection induction winding W with power amplification circuit (10) in the exciting circuit
S1,2(4) promptly figure in W
S1And W
S2, induction winding W
S1,2(4) inductance that self exists and the electric capacity of resistance and interpolation constitute the RLC resonant circuit (11) in the testing circuit, secondary side winding W
S3(5) one ends connect voltage-controlled current source (16) and other end ground connection, feedback winding W
F1,2,3(6) promptly the string among the figure is one group W
F1, W
F2And W
F3An end be connected with voltage-controlled current source (16); The other end connects an end of sample resistance (17), and the exiting signal generating circuit in the exciting circuit (8) connects voltage comparator (9), and voltage comparator (9) connects power amplification circuit (10) again; RLC resonant circuit (11) in the testing circuit connects differential amplifier circuit (12); Differential amplifier circuit (12) connects bandwidth-limited circuit (13) again, and bandwidth-limited circuit (13) connects phase-sensitive detection circuit (14) again, and phase-sensitive detection circuit (14) connects difference smoothed filter circuit 15 again; Difference smoothed filter circuit 15 connects voltage-controlled current source (16) again, the other end ground connection of sample resistance (17).
It is f that two pins of the chip SN74HC4060 of exiting signal generating circuit (8) are drawn frequency respectively
1And 2f
1Signal, frequency is f
1Signal be input in the voltage comparator (9) as excitation, frequency is 2f
1Signal be input in the phase-sensitive detection circuit (14), as the reference signal of phase sensitive detection.From exiting signal generating circuit (8) signal of output be from zero to a certain on the occasion of square wave, the signal of actual needs is to have negative square wave excitation is just arranged, and after voltage comparator among Fig. 4 (9), with obtaining negative square-wave signal is just arranged.Owing to the f that comes out from chip SN74HC4060 pin
1Square-wave signal power is less; Be input to the magnetic field that produces behind the drive coil and can not make magnetic core reach periodic hypersaturated state, also just do not reach the requirement of fluxgate pumping signal circuit, so will signal be input in the power amplification circuit (10); Through after the power amplification, be input to excitation winding W
E1,2(7) in, produce and detect magnetic field.
Detect the field signal entering testing circuit part that magnetic field and tested electric current are produced.The square-wave signal of exiting signal generating circuit (8) output encourages this twin shaft fluxgate current sensor with this signal.According to the fluxgate principle, answer on the coil and can generation can react the even-order harmonic component of treating the measuring magnetic field size at twin shaft fluxgate current sensor.The purpose of testing circuit is exactly to come out required input.
Induction winding W
S1,2(4) promptly figure in W
S1And W
S2Self there are resistance R and inductance L, add capacitor C and make induction winding W
S1,2(4) loop forms RLC resonant circuit (11), and signal amplifies required frequency signal through RLC resonant circuit (11) afterwards, suppresses other harmonic components of signal, and signal is input to differential amplifier circuit (12) afterwards, suppresses common-mode signal.Because fluxgate detection probe noise has the odd harmonic characteristic, and its maximum harmonic component is that first-harmonic and third harmonic are just in signal second harmonic component both sides, so will use bandwidth-limited circuit (13).Bandwidth-limited circuit (13) is phase-sensitive detection circuit (14) afterwards; Phase sensitive detection is in that synchronous signal is under the condition of benchmark with same frequency; Periodically alternating signal carries out full-wave rectification, confirms the amplitude size of signal again through difference smoothed filter circuit 15.Another effect of phase-sensitive detection circuit (14) is the influence that can thoroughly eliminate odd harmonic.Through phase-sensitive detection circuit (14) afterwards, obtain induced voltage signal, come the Control and Feedback electric current, the magnetic flux of feedback current generation and the magnetic flux of tested electric current generation are offseted, reach zero magnetic flux state by voltage-controlled current source (16).At last,, measure the electric current in the feedback winding, and then reflect the size of tested electric current through measuring the voltage on the sample resistance (17).
In Fig. 4, Ip is tested primary current, and If is a feedback current, two frequency multiplication fundamental signal 2f
1Be the reference signal frequency of phase-sensitive detection circuit, be 2 times of fluxgate detection probe exciting signal frequency.Φ in the drawings
pBe the magnetic flux that tested electric current produces, Φ e is the magnetic flux that pumping signal produced, and Rm is sample resistance (17).
The formation that shows the exiting signal generating circuit (8) of the utility model twin shaft fluxgate current sensor embodiment illustrated in fig. 5; Respectively the crystal oscillator of 8M is carried out 8k and 4k frequency division in this circuit; Producing frequency is the square wave of 1kHz and 2kHz; The chip of the SN74HC4060 that selects for use its external crystal oscillator is the highest can reach 20M, can fully satisfy the utility model requirement.
The formation that shows the voltage comparator (9) and the power amplification circuit (10) of the utility model twin shaft fluxgate current sensor embodiment illustrated in fig. 6; Voltage comparator (9) and power amplification circuit (10) comprise three chips; The used chip of voltage comparator (9) is LM339; Power amplification circuit (10) is chip used to be two LF356, and other elements are as shown in the figure, and L1 is excitation winding W among the figure
E1,2(7).
The formation that shows the RLC resonant circuit (11) of the utility model twin shaft fluxgate current sensor embodiment illustrated in fig. 7; Because fluxgate detection probe noise ratio signal is much bigger by force; So will improve the signal to noise ratio (S/N ratio) of prime amplifier input end as far as possible, so that prime amplifier can bear the accuracy of noise and holding signal amplification.Consider that the output impedance of fluxgate detection probe is main with inductance, therefore make it to constitute a RLC resonant circuit (11).Induction winding W
S1,2(4) promptly its inductance of L (t) among the figure is 257.1mH, and resistance R is induction winding W
S1,2(4) own resistance, resistance value are 150.6 Ω, and the value of capacitor C is 24.6nF.E (t) is induction winding W
S1,2(4) electromotive force that induces, V (t) are the second harmonic electromotive force among the induction electromotive force e (t) under the ideal situation.Utilize the selecting frequency characteristic of RLC resonant circuit (11), the signal to noise ratio (S/N ratio) of second harmonic is effectively strengthened at resonant capacitance of secondary coil output terminal parallel connection.
The formation that shows the differential amplifier circuit (12) of the utility model twin shaft fluxgate current sensor embodiment illustrated in fig. 8, differential amplifier circuit (12) can effectively suppress common-mode signal, wherein selects the AD623 chip for use.Input signal noise when detecting electric current for effective inhibition, the utility model has designed a high performance symmetric difference amplifying circuit (12), has further suppressed noise.Through the fluxgate signal behind the differential amplifier circuit (12), second harmonic signal and noise all obtain amplifying.Centre frequency obtains useful second harmonic signal for the 2f1 BPF. can filter noise.
The formation that shows the bandwidth-limited circuit (13) of the utility model twin shaft fluxgate current sensor embodiment illustrated in fig. 9; Fluxgate detection probe noise has the odd harmonic characteristic; And its maximum harmonic component-first-harmonic and third harmonic are just in signal second harmonic component both sides; So use bandwidth-limited circuit (13), wherein select the OP27A chip for use.Bandwidth-limited circuit (13) extracts and has amplified second harmonic signal, has removed signal noise effectively.
The formation that shows the phase-sensitive detection circuit (14) of the utility model twin shaft fluxgate current sensor embodiment illustrated in fig. 10; Phase sensitive detection is in that synchronous signal is under the condition of benchmark with same frequency; Periodically alternating signal carries out full-wave rectification, confirms the amplitude size of signal again through smothing filtering.Another effect of phase-sensitive detection circuit is the influence that can thoroughly eliminate odd harmonic.Another effect of this phase-sensitive detection circuit (14) is the influence that can thoroughly eliminate odd harmonic.Selected chip CD4098BE can trigger monostalbe trigger again for two in this circuit, and HCF4053 is 32 tunnels analogy switches.The external RC resistance-capacitance network of monostalbe trigger can carry out the adjustment of pulse delay and pulse width.Utilize the external resistance-capacitance network of monostalbe trigger of CD4098BE to go to adjust the pulse width of reference signal, promptly regulate the size of R401 resistance value among this figure, the pulse width of adjustment need to equal the angle of phase shift; Remove to trigger another monostalbe trigger of CD4098 then with the negative edge of this pulse; Adjustment and the external RC resistance-capacitance network of this monostalbe trigger; Promptly regulate the size of R402 resistance value among this figure; The frequency and the phase place of its output pulse and phase sensitive detection input signal are consistent, and then the square-wave signal of pin 10 outputs is all consistent with phase sensitive detection frequency input signal and phase place among the CD4098.
The formation that shows the difference smoothed filter circuit 15 of the utility model twin shaft fluxgate current sensor embodiment illustrated in fig. 11, this circuit is the operational amplifier of external RC resistance-capacitance network, and the function of difference smothing filtering is arranged.Two signals insert the in-phase end and the end of oppisite phase of operational amplifier respectively, output DC simulation signal, and the magnetic field intensity of change fluxgate magnetic core axial component finds that the direct current signal of output can change along with the variation of magnetic field intensity, wherein selects the LF353 chip for use.
Embodiment illustrated in fig. 12 showing, voltage-controlled current source (16) comprises two chips, all is CA3080.In order to improve scope and the precision of measuring electric current, must design this voltage-controlled current source (16), the magnetic flux of its feedback current generation and the magnetic flux of tested electric current generation are offset, make it reach zero magnetic flux state, in this circuit
Become the fluxgate detection probe and the zero-flux current transformer of twin shaft fluxgate current sensor by above-mentioned device embodiment illustrated in fig. 2, wherein the formation of fluxgate detection probe is, interior toroidal core a (1) and interior toroidal core b (2) be discharging side by side, excitation winding W
E1,2(7) be that a lead forms excitation winding W later at last 100 circles that twine of interior toroidal core a (1)
E1,2(7) W
E1Part goes up at interior toroidal core b (2) with opposite direction and twines 100 circles formation excitation winding W
E1,2(7) W
E2Part, induction winding W
S1,2(4) two interior toroidal core a (1) that are arranged side by side and interior toroidal core b (2) are intertwined, twine 70 circles, wherein the induction winding W on interior toroidal core a (1)
S1,2(4) part is called W
S1, the induction winding W on the interior toroidal core b (2)
S1,2(4) part is called W
S2Zero-flux current transformer is by an outer ring magnetic core (3) and secondary side winding W
S3(5) constitute secondary side winding W
S3(5) be wrapped in separately on the outer ring magnetic core (3); Twine 300 circles; Outer ring magnetic core (3) size is more bigger than interior toroidal core a (1) and interior toroidal core b (2); Can interior toroidal core a (1) and interior toroidal core b (2) intactly be surrounded, being enclosed within two interior toroidal core a and b is the outside of twin shaft fluxgate magnetic core, and other has a feedback winding W
F1,2,3(6) interior toroidal core a (1) and interior toroidal core b (2) and (3) three magnetic cores of outer ring magnetic core are wound up in the lump, twine 50 circles, wherein feed back winding W
F1,2,3(6) part that is wrapped on the interior toroidal core a (1) is called W
F1, feedback winding W
F1,2,3(6) part that is wrapped on the interior toroidal core b (2) is called W
F2, feedback winding W
F1,2,3(6) part that is wrapped on the outer ring magnetic core (3) is called W
F3Interior toroidal core a (1) and the used material of b (2) are the ultracrystallite magnetic material, and its saturation magnetic flux density is Bs=1.2T, and coercivity H＜3A/m, saturation magnetostriction coefficient are s=10
-8～10
-6, magnetic permeability is 15000～150000H/m, core loss (100KHz, 0.3T) P
Fe=80W/Kg; The used material of outer ring magnetic core (3) is a ferrite, its saturation magnetic flux density B
s=510mT, coercive force H
c＜14A/m, magnetic permeability are 2500～3500H/m, core loss (100KHz, 0.2T) P
Cv=600KW/m
3All the used material of winding is enameled wire, and diameter is 0.3mm.The signal processing circuit of twin shaft fluxgate current sensor adopts the above-mentioned exiting signal generating circuit that shows embodiment illustrated in fig. 5 (8); Voltage comparator that shows embodiment illustrated in fig. 6 (9) and power amplification circuit (10); The RLC resonant circuit (11) that shows embodiment illustrated in fig. 7; The differential amplifier circuit that shows embodiment illustrated in fig. 8 (12); The phase-sensitive detection circuit that shows embodiment illustrated in fig. 10 (14); Difference smoothed filter circuit that shows 15 embodiment illustrated in fig. 11 and the voltage-controlled current source that shows embodiment illustrated in fig. 12 (16).By above-mentioned embodiment illustrated in fig. 4, connect above-mentioned fluxgate detection probe, zero-flux current transformer and all signal processing circuits, excitation winding W
E1,2(7) be connected in the middle of the exciting circuit induction winding W
S1, 2(4) be connected in the middle of the testing circuit secondary side winding W
S3(5) one ends connect voltage-controlled current source, other end ground connection, feedback winding W
F1,2,3(6) one ends are connected with voltage-controlled current source (16), and the other end connects 10 ohm sample resistance (17).Device becomes twin shaft fluxgate current sensor thus.
The twin shaft fluxgate current sensor that said apparatus is become carries out the experiments of measuring of DC current, and tested electric current is measured the voltage on the sample resistance (17) from-30A～30A.Matlab carries out least square curve fitting with the data that obtain input business software, obtains voltage and the relation of tested electric current on the sample resistance of twin shaft fluxgate current sensor shown in Figure 13.The fit equation of this curve is: Uout=99.5Ip+15, and this formula is represented the quantitative relation between tested electric current and the current sensor output voltage, can obtain, and the linearity of this current sensor is 99.5, and drift is 15mA, and output voltage is limited in ± 3V.
Theoretical value with output voltage deducts actual value; Just the relative error in the time of can obtaining this current sensor measurement scope for-30A～30A divided by actual value again; Visible shown in the relative error curve map of Figure 14 the utility model twin shaft fluxgate current sensor; At-30A in the range of 30A, relative error is limited in ± 3 ‰ in.
Remove excitation winding W
E1,2(7) be that a lead forms excitation winding W later at last 100 circles that twine of interior toroidal core a (1)
E1,2(7) W
E1Part goes up at interior toroidal core b (2) with opposite direction and twines 100 circles formation excitation winding W
E1,2(7) W
E2Part, induction winding W
S1,2(4) two interior toroidal core a (1) that are arranged side by side and interior toroidal core b (2) are intertwined, twine 70 circles, wherein the induction winding W on interior toroidal core a (1)
S1,2(4) part is called W
S1, the induction winding W on the interior toroidal core b (2)
S1,2(4) part is called W
S2Outside, other are with embodiment 1.
The twin shaft fluxgate current sensor that said apparatus is become carries out the experiments of measuring of low-frequency ac electric current, and measuring method and process be with embodiment 1, and tested electric current is from-30A～30A, the voltage on the measurement sample resistance (17).
Remove excitation winding W
E1,2(7) be that a lead forms excitation winding W later at last 100 circles that twine of interior toroidal core a (1)
E1,2(7) W
E1Part goes up at interior toroidal core b (2) with opposite direction and twines 100 circles formation excitation winding W
E1,2(7) W
E2Part, induction winding W
S1,2(4) two interior toroidal core a (1) that are arranged side by side and interior toroidal core b (2) are intertwined, twine 70 circles, wherein the induction winding W on interior toroidal core a (1)
S1,2(4) part is called W
S1, the induction winding W on the interior toroidal core b (2)
S1,2(4) part is called W
S2Outside, other are with embodiment 1.
The twin shaft fluxgate current sensor that said apparatus is become carries out the experiments of measuring of high-frequency ac current, and measuring method and process are with embodiment 1, and tested power frequency reaches as high as 20KHz, the voltage on the measurement sample resistance (17).
Starting material that use in the foregoing description and parts all obtain through being purchased approach, and all circuit diagrams also are existing known technologies, the assemble method of twin shaft fluxgate current sensor, and measuring method and process are institute's easy master in present technique field.
Claims (1)
1. twin shaft fluxgate current sensor; It is characterized in that: comprise fluxgate detection probe, zero-flux current transformer and signal processing circuit; Wherein, the fluxgate detection probe is made up of two interior toroidal core a and b, excitation winding and induction winding, and two interior toroidal core a and b discharge side by side; The excitation winding is that a lead is after twining 100 circles on the interior toroidal core a; On interior toroidal core b, twine 100 circles with opposite direction again, the induction winding is intertwined two interior toroidal core a and b that are arranged side by side, and twines 70 circles; Zero-flux current transformer is made up of an outer ring magnetic core and secondary side winding; Secondary side winding is wrapped in separately on the outer ring magnetic core, twines 300 circles, and outer ring magnetic core size is more bigger than two interior toroidal core a and b; Can two interior toroidal core a and b intactly be surrounded; Being enclosed within two interior toroidal core a and b is the outside of twin shaft fluxgate magnetic core, and other has a feedback winding that two interior toroidal core a and b and three magnetic cores of outer ring magnetic core are wound up in the lump, twines 50 circles; Signal processing circuit is divided into exciting circuit and testing circuit two parts; Exciting circuit partly comprises exiting signal generating circuit, voltage comparator and power amplification circuit, and testing circuit partly comprises RLC resonant circuit, differential amplifier circuit, bandwidth-limited circuit, phase-sensitive detection circuit, difference smoothed filter circuit, voltage-controlled current source and sample resistance; Excitation winding one end is connected and other end ground connection with power amplification circuit in the exciting circuit; The induction winding adds electric capacity with inductance that self exists and resistance makes it to constitute the RLC resonant circuit in the testing circuit; Secondary side winding one end connects voltage-controlled current source and other end ground connection, and feedback winding one end is connected with voltage-controlled current source and an end of other end connection sample resistance, and the exiting signal generating circuit in the exciting circuit connects voltage comparator; Voltage comparator connects power amplification circuit again; RLC resonant circuit in the testing circuit connects differential amplifier circuit, and differential amplifier circuit connects bandwidth-limited circuit again, and bandwidth-limited circuit connects phase-sensitive detection circuit again; Phase-sensitive detection circuit connects the difference smoothed filter circuit again; The difference smoothed filter circuit connects voltage-controlled current source again, the other end ground connection of sample resistance, the exiting signal generating circuit in the exciting circuit also with testing circuit in phase-sensitive detection circuit be connected.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204815925U CN202330528U (en) | 2011-11-28 | 2011-11-28 | Current sensor with double-shaft fluxgate |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204815925U CN202330528U (en) | 2011-11-28 | 2011-11-28 | Current sensor with double-shaft fluxgate |
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| Publication Number | Publication Date |
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| CN202330528U true CN202330528U (en) | 2012-07-11 |
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ID=46442504
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011204815925U Withdrawn - After Issue CN202330528U (en) | 2011-11-28 | 2011-11-28 | Current sensor with double-shaft fluxgate |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102401853A (en) * | 2011-11-28 | 2012-04-04 | 河北工业大学 | Double-shaft fluxgate current sensor |
| CN104734156A (en) * | 2013-12-20 | 2015-06-24 | 张绍华 | Active quantum filter |
| CN105785116A (en) * | 2016-03-09 | 2016-07-20 | 张国宁 | Anti-power-theft high-voltage user load intelligent measurement analyzer |
| CN106405189A (en) * | 2016-08-14 | 2017-02-15 | 河北工业大学 | Current sensor with temperature stability and measuring method thereof |
| CN106716149A (en) * | 2014-09-26 | 2017-05-24 | 旭化成微电子株式会社 | Hall electromotive force signal detection circuit and current sensor |
| CN108205077A (en) * | 2016-12-16 | 2018-06-26 | 联合汽车电子有限公司 | Current sensing means, current detecting system and electric current detecting method |
| RU2718758C1 (en) * | 2016-12-19 | 2020-04-14 | Сафран Электроникс Энд Дифенс | Inductive current sensor |
| CN113075442A (en) * | 2021-03-30 | 2021-07-06 | 国网宁夏电力有限公司电力科学研究院 | Current mutual inductance circuit and current transformer |
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2011
- 2011-11-28 CN CN2011204815925U patent/CN202330528U/en not_active Withdrawn - After Issue
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102401853A (en) * | 2011-11-28 | 2012-04-04 | 河北工业大学 | Double-shaft fluxgate current sensor |
| CN104734156A (en) * | 2013-12-20 | 2015-06-24 | 张绍华 | Active quantum filter |
| CN106716149A (en) * | 2014-09-26 | 2017-05-24 | 旭化成微电子株式会社 | Hall electromotive force signal detection circuit and current sensor |
| CN105785116A (en) * | 2016-03-09 | 2016-07-20 | 张国宁 | Anti-power-theft high-voltage user load intelligent measurement analyzer |
| CN106405189A (en) * | 2016-08-14 | 2017-02-15 | 河北工业大学 | Current sensor with temperature stability and measuring method thereof |
| CN108205077A (en) * | 2016-12-16 | 2018-06-26 | 联合汽车电子有限公司 | Current sensing means, current detecting system and electric current detecting method |
| RU2718758C1 (en) * | 2016-12-19 | 2020-04-14 | Сафран Электроникс Энд Дифенс | Inductive current sensor |
| CN113075442A (en) * | 2021-03-30 | 2021-07-06 | 国网宁夏电力有限公司电力科学研究院 | Current mutual inductance circuit and current transformer |
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