CN205210163U - Huge magnetoresistive effect current sensor - Google Patents
Huge magnetoresistive effect current sensor Download PDFInfo
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- CN205210163U CN205210163U CN201520955913.9U CN201520955913U CN205210163U CN 205210163 U CN205210163 U CN 205210163U CN 201520955913 U CN201520955913 U CN 201520955913U CN 205210163 U CN205210163 U CN 205210163U
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Abstract
The embodiment of the utility model discloses huge magnetoresistive effect current sensor, include: the electromagnetic conversion module includes annular magnetic core, passes the primary side winding and the giant magnetoresistance chip of annular magnetic core, the bias current source is connected including bias current source and the bias winding of winding on the magnetic core, the both ends of bias winding to the biasing module, signal processing module, including operational amplifier and reference voltage production circuit, reference voltage produces the circuit and is used for producing the DC voltage of setting for the size, and two inputs of operational amplifier are continuous with two outputs of giant magnetoresistance chip respectively, and reference voltage produces the output of circuit and connects the end at operational amplifier's non inverting input, power module links to each other with electromagnetic conversion module and signal processing module, in order to provide the power. The utility model provides a giant magnetoresistance chip be unipolarity output characteristic, the immeasurability alternating current, simultaneously when being than the low -intensity magnetic field by survey magnetic field, the giant magnetoresistance chip has the hysteresis effect, arouses the problem of great output error.
Description
Technical field
The utility model relates to sensor technology, particularly relates to a kind of giant magnetoresistance effect current sensor.
Background technology
Along with the development of Power Electronic Technique, the demand of compact high performance current sensor increases gradually.Traditional electric current detecting method comprises shunt, current transformer, Luo-coil, Hall element; Novel detection technique comprises fluxgate sensor, giant magneto-resistance sensor and Fibre Optical Sensor.Wherein shunt measuring method can not realize electric isolution, and power consumption is higher; Current transformer can only carry out the measurement of alternating current, and magnetic core is easily by saturated impact, and survey frequency is lower, and volume is comparatively large, expensive; Hall current sensor can detect the electric current of relatively large journey, and measuring accuracy is between 0.5% and 2%, but its measuring accuracy affects comparatively large by environment temperature and external magnetic field, which limits its range of application; Luo-coil survey frequency scope is comparatively large, but immeasurability direct current, and expensive.Fibre optic current sensor volume is little, lightweight, and there is not magnetic saturation impact, electromagnetism interference performance is good, but its complex structure, involve great expense.Fluxgate sensor utilizes high permeability magnetic core under the saturation activation of alternating magnetic field, and the nonlinear relationship between its magnetic induction density and magnetic field intensity carrys out a kind of sensor in the tested magnetic field of indirect inspection.It is high that fluxgate sensor has resolution, Low Drift Temperature, the advantages such as low drift, but its signal processing circuit is more loaded down with trivial details, is mainly used in the measurement of direct current low-intensity magnetic field.Compared with above-mentioned current sensor, giant magnetoresistance current sensor has the advantages such as high bandwidth, high sensitivity, low-power consumption, good reliability and volume are little, it reaches the requirement of current sensor future developing trend, in the detection technique in future, giant magnetoresistance current sensor will be applied more and more extensive, plays the superiority of itself.
But, when tested magnetic field more weak and positive and negative alternately change time, due to the coupling that giant magnetoresistance neighboring ferromagnetic interlayer is more weak, make giant magnetoresistance chip list reveal obvious hysteresis effect.Giant magnetoresistance chip used is in addition unipolar output characteristic, and when being measured as alternating current, output waveform is similar to full-wave rectification and exports, and the easy distortion of waveform exported like this, causes larger output error.
Utility model content
In view of this, the utility model provides a kind of giant magnetoresistance effect current sensor, can not measure alternating current to solve giant magnetoresistance chip because of unipolar output characteristic, simultaneously when tested magnetic field be comparatively low-intensity magnetic field time, giant magnetoresistance chip has hysteresis effect, causes the problem of larger output error.
The utility model embodiment provides a kind of closed loop giant magnetoresistance effect sensor, comprising:
Electromagnetic conversion module, comprises toroidal core, through former limit winding and the giant magnetoresistance chip of toroidal core;
Biasing module, comprise bias current sources and be wrapped in the biased winding on magnetic core, the two ends of described biased winding connect described bias current sources;
Signal processing module, comprise operational amplifier and generating circuit from reference voltage, described generating circuit from reference voltage is for generation of the DC voltage of setting size, the in-phase input end of described operational amplifier is connected with two output terminals of described giant magnetoresistance chip respectively with inverting input, and the output terminal of described generating circuit from reference voltage is connected to the in-phase input end of described operational amplifier;
Power module, is connected with described signal processing module with described electromagnetic conversion module, for providing power supply for described giant magnetoresistance effect current sensor.
A kind of giant magnetoresistance effect current sensor that the utility model provides, by arranging biased winding for producing bias magnetic field at magnetic core on toroidal core, because giant magnetoresistance chip is unipolar output characteristic, when being measured as alternating current, output waveform is similar to full-wave rectification and exports, make the magnetic field acting on giant magnetoresistance chip all bring up to linear zone by the superposition in magnetic field, achieve double-polarity control.And strengthening magnetic field makes giant magnetoresistance chip reduce hysteresis error.
Accompanying drawing explanation
By reading the detailed description done non-limiting example done with reference to the following drawings, other features, objects and advantages of the present utility model will become more obvious:
A kind of giant magnetoresistance effect current sensor structure schematic diagram that Fig. 1 provides for the utility model embodiment one;
The giant magnetoresistance effect current sensor that Fig. 2 provides for the utility model embodiment one is with or without hysteresis graph during bias magnetic field;
The input-output characteristic curve figure of giant magnetic effect current sensor under the Open loop and closed loop structure that Fig. 3 provides for the utility model embodiment one;
Fig. 4 be the utility model embodiment current sensor of proposing two confessions when without magnetic core without magnetic shielding sheet, only have magnetic core and have magnetic core to have a magnetic shielding sheet Distribution of Magnetic Field analogous diagram;
The current sensor that Fig. 5 provides for the utility model embodiment two have magnetic core to have magnetic shielding sheet and under having magnetic core without the condition of magnetic shielding sheet along air gap height direction magnetic induction density change curve;
The current sensor that Fig. 6 provides for the utility model embodiment two adds the Distribution of Magnetic Field analogous diagram of the extraneous stray magnetic field of 2mT under only having magnetic core and having magnetic core to have magnetic shielding sheet two kinds of conditions;
The comprising modules block diagram of the giant magnetoresistance effect current sensor that Fig. 7 provides for the utility model embodiment two.
Embodiment
Below in conjunction with drawings and Examples, the utility model is described in further detail.Be understandable that, specific embodiment described herein only for explaining the utility model, but not to restriction of the present utility model.It also should be noted that, for convenience of description, illustrate only the part relevant to the utility model in accompanying drawing but not full content.
Embodiment one
A kind of giant magnetoresistance effect current sensor structure schematic diagram that Fig. 1 provides for the utility model embodiment one.The utility model embodiment provides a kind of giant magnetoresistance effect current sensor, and this current sensor is applicable to be not easy to the situation that electric current measured by direct disconnecting circuit reometer in Circuits System.As shown in Figure 1, this giant magnetoresistance effect current sensor comprises:
Electromagnetic conversion module, comprises toroidal core 11, through former limit winding 13 and the giant magnetoresistance chip 14 of toroidal core 11;
Biasing module, the biased winding 42 comprising bias current sources 41 and be wrapped on magnetic core 11, the two ends of biased winding 42 connect bias current sources 41;
Signal processing module, comprise operational amplifier 21 and generating circuit from reference voltage 22, generating circuit from reference voltage 22 is for generation of the DC voltage of setting size, the in-phase input end of operational amplifier 21 is connected with two output terminals of giant magnetoresistance chip 14 respectively with inverting input, and the output terminal of generating circuit from reference voltage 22 is connected to the in-phase input end of operational amplifier 21;
Power module, is connected with signal processing module with electromagnetic conversion module, for providing power supply (not shown) for giant magnetoresistance effect current sensor.
So-called giant magnetoresistance effect, refers to the resistivity of magnetic material when there being external magnetic field than without the phenomenon that there is great variety during external magnetic field.Giant magnetoresistance effect current sensor can measure electric current by directly measuring the long straight conductor raw magnetic field of miscarriage that powers on.When in certain wire during curent change, the magnetic field that electric current produces changes thereupon, and giant magnetoresistance also changes, and utilizing bridge structure the change of resistance to be exported is a voltage signal.Owing to having linear variability law between giant magnetoresistance and magnetic field, the voltage proportional of output in tested electric current, thus realizes the measurement function of current signal.
The magnetic field that the current signal of former limit winding 13 is produced by electric current is converted to voltage signal by electromagnetic conversion module.Toroidal core 11 is assembled the magnetic field of former limit winding 13 generation and is acted on giant magnetoresistance chip 14.Because magnetic field distributes according to the concentric circles being the center of circle with former limit winding 13, the shape of magnetic core 11 is preferably annular, can strengthen the magnetic induction density of magnetic core 11 like this.
But giant magnetoresistance chip 14 is unipolar output characteristic, when being measured as alternating current, output waveform is similar to full-wave rectification and exports.Simultaneously when tested magnetic field be comparatively low-intensity magnetic field time, due to the coupling that giant magnetoresistance neighboring ferromagnetic interlayer is more weak, make giant magnetoresistance chip 14 show obvious hysteresis effect, cause larger output error.
In order to realize double-polarity control and reduce hysteresis error, this embodiment introduces unique bias magnetic field structure, biased winding 42 is for generation of bias magnetic field, the magnetic field acting on giant magnetoresistance chip 14 is made all to bring up to linear zone by the superposition in magnetic field, because when magnetic field is very weak, the linear relationship of the voltage that giant magnetoresistance chip 14 produces and magnetic field size is not very strong, makes magnetic field be strengthened to the strong state of linear relationship by bias magnetic field superposition.Like this when without tested magnetic field, giant magnetoresistance chip 14 exports a DC offset voltage, and when there being tested electric current, the output voltage of giant magnetoresistance chip 14 is the voltage having superposed again the magnetic field produced by tested electric current and produce on the basis of former bias voltage.Bias current sources 41 provides electric current for biased winding 42 thus produces bias magnetic field.
The giant magnetoresistance effect current sensor that Fig. 2 provides for the utility model embodiment one is with or without hysteresis graph during bias magnetic field.Test with or without the giant magnetic effect current sensor under bias magnetic field two kinds of structures, the first positive stroke of tested electric current is increased to 14A from 0A, measures the output voltage signal under different electric current respectively.Then, electric current revesal is down to 0A from 14A, again measures the output signal of different electric current lower sensor.As shown in Figure 2, c curve is the curve of output that under having bias magnetic field, the positive stroke of tested electric current is corresponding, d curve is the curve of output that under having bias magnetic field, tested electric current revesal is corresponding, e curve is without curve of output corresponding to the positive stroke of electric current tested under bias magnetic field, and f curve is without curve of output corresponding to electric current revesal tested under bias magnetic field.As can be seen from test curve, the coincidence factor of curve c and d is greater than curve e and f.The introducing of bias magnetic field can reduce the error caused by hysteresis greatly.
Giant magnetoresistance chip 14 has two output terminals, and the voltage difference of two output terminals is the magnitude of voltage that giant magnetoresistance chip 14 produces.Two output terminals of giant magnetoresistance chip 14 are connected with inverting input with the in-phase input end of the operational amplifier 21 of signal processing module respectively.Because the voltage that giant magnetoresistance chip 14 exports is very little, when the magnetic field that former limit winding 13 produces changes, can not display from the output voltage of giant magnetoresistance chip 14.The output signal of giant magnetoresistance chip 14 is amplified by operational amplifier 21, can learn the changes of magnetic field situation of former limit winding 13 more accurately thus measure the current value of former limit winding 13.Generating circuit from reference voltage 22 can produce the voltage of setting, by the region of operational amplifier 21 output voltage control in setting.
Such as, when former limit winding 13 electric current is 1A, giant magnetoresistance chip 14 exports the voltage of 1V, and the change of former limit winding 13 electric current 0.1A causes giant magnetoresistance chip 14 output voltage to be changed to 0.1V, this is distant difference, is easy to because machine error or reading error produce the error exported.And the 1V that giant magnetoresistance chip 14 exports is amplified ten times for 10V by operational amplifier 21, then when former limit winding 13 electric current has the change causing operational amplifier 21 output voltage values 1V during the change of 0.1A, reduce the error exported.
Power module is used for powering for whole giant magnetoresistance effect current sensor.Power module is connected with the power pins of the giant magnetoresistance chip 14 of electromagnetic conversion module, for giant magnetoresistance chip 14 is powered; Be connected with the operational amplifier 21 of signal processing module, for operational amplifier 21 provides power supply.
Preferably, operational amplifier 21 is differential operational amplifier;
The positive output end of giant magnetoresistance chip 14 is connected with the in-phase input end of operational amplifier 21, and the negative output terminal of giant magnetoresistance chip 14 is connected with the inverting input of operational amplifier 21;
The output voltage of generating circuit from reference voltage 22 is equal with the bias voltage that biased winding 42 produces on giant magnetoresistance chip 14.
The voltage difference that operational amplifier 21 input end access giant magnetoresistance chip 14 two output terminals export, add the in-phase input end that generating circuit from reference voltage 22 is connected on operational amplifier 21 simultaneously, voltage voltage difference and generating circuit from reference voltage 22 produced is superimposed, then amplifies the voltage after superposition.The generating circuit from reference voltage 22 of operational amplifier 21 in-phase input end, for eliminating the bias voltage of bias magnetic field generation, makes sensor finally export the voltage obtaining a bipolar output, and also namely exporting to have just has negative voltage.
Signal processing module also comprises: push-pull power amplifier 23, and the input end of push-pull power amplifier 23 is connected with the output terminal of operational amplifier 21.
The output signal of operational amplifier 21 is amplified by push-pull power amplifier 23 further, makes the measurement result of current sensor more accurate.
Power module comprises power generation circuit;
Power generation circuit is used for being respectively giant magnetoresistance chip 14, generating circuit from reference voltage 22, operational amplifier 21 and push-pull power amplifier 23 according to supply voltage and produces the operating voltage adapted.
The power supply of giant magnetoresistance chip 14, operational amplifier 21 and push-pull power amplifier 23 is different.Such as, giant magnetoresistance chip 14 can be the power voltage supply of 5V with voltage, and operational amplifier 21 can use the power supply of 15V.Do not have voltage to be the direct voltage source of 5V or 15V in life, various required voltage can be exported with the power supply that voltage is 220V by power generation circuit.
In addition, current sensor also comprises:
Feedback compensation module, comprises and is wrapped in feedback winding 51 on described magnetic core and a sampling resistor 52, and one end of feedback winding 51 connects the output terminal of push-pull power amplifier 23, other end series connection sampling resistor 52 ground connection.
Feedback winding 51 forms closed-loop system with former limit winding 13, and working sensor, in Zero flux state, effectively improves range and the noiseproof feature of sensor.The structure of product is relatively simple, cost is low and function is many.The duty of Zero flux is just reached during the magnetic field equal and opposite in direction that feedback winding 51 produces with former limit winding 13.Any change due to tested electric current all can destroy this balance that closed-loop system reaches, and once magnetic field out of trim, giant magnetoresistance chip 14 just has voltage signal to export, this signal is after amplifying, have corresponding feedback current and offset current to flow through feedback winding 51 immediately to compensate unbalance magnetic field, to reach new balance.Time needed for above-mentioned equilibrium process is less than 1 μ s, therefore determines the utility model closed loop giant magnetoresistance effect current sensor and has response speed faster.
As shown in Figure 3, the input-output characteristic curve figure of giant magnetic effect current sensor under the Open loop and closed loop structure that provides for the utility model embodiment one of Fig. 3.Curve g is the input-output curve of giant magnetic effect current sensor under open loop structure, and curve h is the input-output curve of giant magnetic effect current sensor under closed loop configuration.Can find out, the linearity of curve h is better than curve g, and for inputting identical electric current, the output voltage that curve h is corresponding is less than curve g.Closed loop configuration effectively can improve anti-interference and the range ability of sensor.
A kind of giant magnetoresistance effect current sensor that the utility model embodiment provides, toroidal core is wound around biased winding be used for producing bias magnetic field to giant magnetoresistance chip, make the magnetic field acting on giant magnetoresistance chip all bring up to linear zone by the superposition in magnetic field, achieve double-polarity control and reduce hysteresis error.Feedback compensation winding and former limit winding form closed-loop system, and working sensor, in Zero flux state, effectively improves range and the noiseproof feature of sensor.
Embodiment two
The present embodiment two is further described giant magnetoresistance current sensor on the basis of above-described embodiment.With reference to figure 1, with air gap on toroidal core 11;
Electromagnetic conversion module also comprises: two the magnetic shielding sheets 12 being positioned over toroidal core 11 air gap two ends.
Because giant magnetoresistance is to the extremely sensitive characteristic in magnetic field, make them be subject to the impact of extraneous stray magnetic field simultaneously.The field source of these stray magnetic fields comprises the electric equipment such as motor and transformer, or current－carrying conductor around sensor etc.Stray magnetic field can cause sensor to produce larger output error, have impact on the accuracy of current measurement result.The toroidal core 11 and the magnetic shielding sheet 12 that arrange band air gap effectively can shield stray magnetic field, strengthen the impact in magnetic field, former limit, reduce output error.
Toroidal core 11 with air gap is just the ring of a C shape, and magnetic shielding sheet 12 is added in the two ends of air gap.
Giant magnetoresistance chip 14 is positioned over the air gap place of toroidal core 11.
In order to strengthen the sensitivity of giant magnetoresistance chip 14 for former limit winding magnetic field, the sensitive axes direction of giant magnetoresistance chip 14 is consistent with the air gap height direction of toroidal core 11.
Magnetic direction is the direction of toroidal core 11, so the sensitive axes direction of giant magnetoresistance chip 14 will be made consistent with toroidal core 11 air gap direction.
The area of magnetic shielding sheet 12 is more than or equal to the area of side adjacent with magnetic shielding sheet 12 in each side of giant magnetoresistance chip 14.
Giant magnetoresistance chip 14 will be placed on the inside of two magnetic shielding sheets 12, and object is the sensitivity in order to improve current sensor equally.
The material of magnetic core 11 and magnetic shielding sheet 12 is permalloy material.
By magnetic resistance formula R
m=l/ μ S is known, and the magnetic permeability of magnetic resistance and material is inversely proportional to, and therefore generally will select high-permeability material.In order to increase the range of sensing range, the permeability magnetic material of high saturation magnetic induction should being selected, simultaneously in order to obtain accurate testing result in real time, low magnetic hysteresis, low-coercivity material be selected.Conventional magnetic shielding material comprises: electromagnetic soft iron, siliconized plate, permalloy, non-crystaline amorphous metal etc.Wherein non-crystaline amorphous metal magnetic permeability is the highest, but price costly, electromagnetic soft iron and siliconized plate low price, but magnetic permeability is lower.From the viewpoint of performance and cost, the present invention have selected the material of permalloy material as magnetic core 11 and magnetic shielding sheet 12.Its resistivity is 0.56 μ Ω m, and Curie point is 400 DEG C, and saturation induction density is B
s=0.7T, the coercive force H under saturation induction density
cbe not more than 1.6A/m, the magnetic permeability that DC magnetic performance meets in 0.08A/m magnetic field intensity is not less than 37.5mH/m, meets the requirement of magnetic shielding to material.
The present embodiment, when former limit winding current is 20A, utilizes finite element software to giant magnetic effect current sensor respectively when having magnet ring without unshielded of magnetic core, only and have magnetic core to have Distribution of Magnetic Field situation when magnetic shielding sheet to carry out simulation analysis.
Fig. 4 be the utility model embodiment current sensor of proposing two confessions when without magnetic core without magnetic shielding sheet, only have magnetic core and have magnetic core to have a magnetic shielding sheet Distribution of Magnetic Field analogous diagram.Can be seen by Distribution of Magnetic Field situation, magnetic field intensity draws near according to the distance to former limit winding and gradually strengthens, the introducing of toroidal core and magnetic shielding sheet can improve the magnetic induction density at giant magnetoresistance chip position place greatly, and increase magnetic gain coefficient, namely transducer sensitivity will increase significantly.
Same, when former limit winding 13 electric current is 20A, utilize finite element software respectively when having magnetic core without magnetic shielding sheet and having magnetic core to have a magnetic shielding sheet, to carry out simulation analysis along air gap height direction magnetic induction density to giant magnetic effect current sensor.The current sensor that Fig. 5 provides for the utility model embodiment two have magnetic core to have magnetic shielding sheet and under having magnetic core without the condition of magnetic shielding sheet along air gap height direction magnetic induction density change curve.As shown in Figure 5, a is along air gap height direction magnetic induction density change curve under having magnetic core without the condition of magnetic shielding sheet, b is that significantly, curve b magnetic induction density is more stable along air gap height direction magnetic induction density change curve under having magnetic core to have the condition of shielding sheet.Adding magnetic shielding sheet as seen from Figure 5 can make magnetic field, air gap place more stable, thus adds the precision of sensor.The central point representing air gap zero point of Fig. 5 middle distance axle.
The current sensor that Fig. 6 provides for the utility model embodiment two adds the Distribution of Magnetic Field analogous diagram of the extraneous stray magnetic field of 2mT under only having magnetic core and having magnetic core to have magnetic shielding sheet two kinds of conditions.By the simulation result of two kinds of conditions can find out two kinds of structures to external world stray magnetic field all there is higher shield effectiveness.By contrast, the introducing of magnetic shielding sheet has more superior shield effectiveness, has magnetic core to have the sensor accuracy under magnetic shielding chip architecture higher.
A kind of giant magnetoresistance effect current sensor that the utility model embodiment two provides, while adding biased winding, by arranging space and introduce magnetic shielding sheet on toroidal core, effectively reduce the interference of extraneous stray magnetic field, add the magnetic gain coefficient of sensor, thus the precision of designed current sensor and sensitivity are improved significantly.And the material of selected magnetic core and magnetic shielding sheet is permalloy material, increases the sensitivity of giant magnetoresistance effect current sensor further, reduces output error.
On the basis of above-described embodiment, the present embodiment giant magnetoresistance effect current sensor is made up of five part of module, as shown in Figure 7.The comprising modules block diagram of the giant magnetoresistance effect current sensor that Fig. 7 provides for the utility model embodiment two.With reference to figure 1 and Fig. 7, in the present embodiment, the composition frame chart of closed loop giant magnetoresistance effect current sensor comprises electromagnetic conversion module 1, biasing module 4, signal processing module 2, feedback compensation module 5 and power module 3 five part, five part of module composition loop closed-loop systems.Tested electric current is by electromagnetic installing die change block 1 output voltage signal.Biasing module 4 provides constant bias magnetic field for giant magnetoresistance chip 14, to realize the object measured alternating current and improve hysteresis error.Giant magnetoresistance core 14 output voltage signal is removed the bias voltage that bias magnetic field produces by signal processing module 2, and carries out amplification process to output signal.Voltage signal after amplification is carried out ground connection by feedback winding 51 and sampling resistor 52 by feedback compensation module 5, forms feedback current, after system reaches Zero flux state, indirectly can record the tested current signal in former limit by fed-back current signals.Power module 3 is used for as whole current sensor provides power supply.
Detailed process is: former limit winding 13 is through toroidal core 11, and the magnetic field that the electric current flowing through former limit winding 13 produces acts on giant magnetoresistance chip 14 after being assembled by toroidal core 11 and magnetic shielding sheet 12.Giant magnetoresistance chip 14 is after sensing magnetic fields, voltage signal will be had export, the voltage signal of this output sends into operational amplifier 21, operational amplifier 21 is connected with push-pull power amplifier 23, the voltage signal of above-mentioned output is after operational amplifier 21 and push-pull power amplifier 23 amplify, by feedback winding 51 and sampling resistor 52 ground connection, form feedback current, this feedback current produces feedback magnetic field through feedback winding 51.The magnetic field produced due to feedback winding 51 is contrary with the magnetic direction that former limit winding 13 electric current produces, thus reduce magnetic field, air gap place, giant magnetoresistance chip is exported and reduces gradually, when the magnetic field equal and opposite in direction that two coils produce, feedback current no longer increases, and whole system reaches mobile equilibrium.If N
pfor the coil turn of former limit winding 13, I
pfor primary current, N
ffor feeding back the coil turn of winding 51, I
ffor feedback current, there is N
pi
p=N
fi
f.Therefore by measuring the electric current I in feedback winding
findirectly can draw measured current I
p, wherein I
fobtain by the voltage on sampling resistor.
Note, above are only preferred embodiment of the present utility model and institute's application technology principle.Skilled person in the art will appreciate that the utility model is not limited to specific embodiment described here, various obvious change can be carried out for a person skilled in the art, readjust and substitute and protection domain of the present utility model can not be departed from.Therefore, although be described in further detail the utility model by above embodiment, but the utility model is not limited only to above embodiment, when not departing from the utility model design, can also comprise other Equivalent embodiments more, and scope of the present utility model is determined by appended right.
Claims (10)
1. a giant magnetoresistance effect current sensor, is characterized in that, comprising:
Electromagnetic conversion module, comprises toroidal core, through former limit winding and the giant magnetoresistance chip of toroidal core;
Biasing module, comprise bias current sources and be wrapped in the biased winding on magnetic core, the two ends of described biased winding connect described bias current sources;
Signal processing module, comprise operational amplifier and generating circuit from reference voltage, described generating circuit from reference voltage is for generation of the DC voltage of setting size, the in-phase input end of described operational amplifier is connected with two output terminals of described giant magnetoresistance chip respectively with inverting input, and the output terminal of described generating circuit from reference voltage is connected to the in-phase input end of described operational amplifier;
Power module, is connected with described signal processing module with described electromagnetic conversion module, for providing power supply for described giant magnetoresistance effect current sensor.
2. current sensor according to claim 1, is characterized in that, described operational amplifier is differential operational amplifier;
The positive output end of described giant magnetoresistance chip is connected with the in-phase input end of described operational amplifier, and the negative output terminal of described giant magnetoresistance chip is connected with the inverting input of described operational amplifier;
The output voltage of described generating circuit from reference voltage is equal with the bias voltage that described biased winding produces on described giant magnetoresistance chip.
3. current sensor according to claim 1, is characterized in that, described signal processing module also comprises: push-pull power amplifier, and the input end of described push-pull power amplifier is connected with the output terminal of described operational amplifier.
4. current sensor according to claim 3, is characterized in that, also comprises:
Feedback compensation module, comprise and be wrapped in feedback winding on described magnetic core and a sampling resistor, one end of described feedback winding connects the output terminal of described push-pull power amplifier, and the other end is connected described sampling resistor ground connection.
5. current sensor according to claim 3, is characterized in that, described power module comprises power generation circuit;
Described power generation circuit is used for being respectively described giant magnetoresistance chip, described generating circuit from reference voltage, described operational amplifier and described push-pull power amplifier according to supply voltage and produces the operating voltage adapted.
6. the current sensor according to any one of claim 1-5, is characterized in that, with air gap on described magnetic core;
Described electromagnetic conversion module also comprises: two the magnetic shielding sheets being positioned over described magnetic core air gap two ends.
7. current sensor according to claim 6, is characterized in that, described giant magnetoresistance chip is positioned over the air gap place of described magnetic core.
8. current sensor according to claim 6, is characterized in that, the sensitive axes direction of described giant magnetoresistance chip is consistent with the air gap height direction of described magnetic core.
9. current sensor according to claim 6, is characterized in that, the area of described magnetic shielding sheet is more than or equal to the area of side adjacent with described magnetic shielding sheet in the described each side of giant magnetoresistance chip.
10. current sensor according to claim 6, is characterized in that, the material of described magnetic core and described magnetic shielding sheet is permalloy material.
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