CN203630195U - Giant magnetoresistance current sensor - Google Patents
Giant magnetoresistance current sensor Download PDFInfo
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- CN203630195U CN203630195U CN201320777510.0U CN201320777510U CN203630195U CN 203630195 U CN203630195 U CN 203630195U CN 201320777510 U CN201320777510 U CN 201320777510U CN 203630195 U CN203630195 U CN 203630195U
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Abstract
The utility model discloses a novel giant magnetoresistance current sensor, and relates to a device for current measurement. The current sensor consists of an electromagnetic conversion module, a signal amplification module, and a feedback compensation module. The electromagnetic conversion module comprises a magnetism-collection ring magnetic core, a primary-side winding, and a giant magnetoresistance chip. The signal amplification module comprises an operational amplifier and a push-pull power amplifier. The feedback compensation module is a feedback winding. The whole measurement loop of the sensor forms a closed-loop system. The giant magnetoresistance chip and the magnetism-collection ring magnetic core form a closed structure, thereby ironing out the defects that a giant magnetoresistance current sensor in the prior art is very liable to be disturbed by a stray external magnetic field during measurement and cannot eliminate temperature excursion and null shift completely, and the measurement precision is affected by the existing of inherent magnetic hysteresis in a magnetic device.
Description
Technical field
The technical solution of the utility model relates to the device for measuring electric current, specifically giant magnetoresistance current sensor.
Background technology
Along with the development of Power Electronic Technique, the application of high precision, broadband current sensor is more and more extensive.Last decade incoming current sensor has been obtained larger development.According to the difference of measuring principle, current sensor is divided into based on Ohm law, the law of electromagnetic induction, Hall effect, Luo-coil and fluxgate several substantially; According to the difference of method using, current sensor can be divided into contact and contactless two types.Can guarantee staff's personal safety and the stable operation of system because non-contact current sensor carries out current measurement, range of application is more extensive.Non-contact current sensor is generally the measurement based on magnetic field.Existing Measurement Method for Magnetic Field has fluxmeter, Fluxgate Technique and magneto-dependent sensor.Magneto-dependent sensor, owing to having advantages of that integrated level is high, volume is little and simple in structure, is subject to increasing attention.Current magneto-dependent sensor mainly contains Hall element and giant magnetoresistance element.Wherein, Hall current sensor can detect the electric current of several kiloamperes, and accuracy rating is between 0.5% to 2%, but Hall element sensitivity is low, and temperature is floated with drift serious, aspect high-acruracy survey, is restricted.Existing giant magnetoresistance sensor is mainly used in the fields such as magnetic encoder, electronic compass, disk read-write magnetic head and electromagnetic nondestructive.Compared with Hall element, giant magnetoresistance sensor has advantages of Low Drift Temperature and low drift, and highly sensitive, has unrivaled advantage in high-precision current context of detection.
Reported in the world the structure of several giant magnetoresistance current sensors, Z.Qian etc., in order to solve the problem of isolation of the application of electromagnetic electric current mutual inductor in electric system, have proposed a kind of current sensor based on giant magnetoresistance effect.The people such as Istv á n Jedlicska eliminate magnetic hysteresis impact by Numerical method, output characteristics linearization degree is improved, increased the measuring accuracy of giant magneto-resistance sensor, designed sensor is guaranteeing that under the prerequisite that precision does not reduce, measurement range almost approaches saturation point.In order to reach the object of the current detecting based on a magnetic field, Erik R.Olson and Robert D.Lorenz are studied the dynamic perfromance of current－carrying conductor surrounding magnetic field, proposed a kind of spatial coherence module, i.e. 5% steady bandwidth criterion, for optimizing magnetic field detectors position.Meanwhile, two people's application realize tested current signal are extracted and separating unknown Perturbation signal based on an integrated current sensors of magnetic field giant magnetoresistance detector array Erik R.Olson with Robert D.Lorenz.But in the time only magnetic field being measured with giant magnetoresistance element, there is following problem: giant magnetoresistance element is very responsive to magnetic field in prior art, is very easily disturbed by spuious external magnetic field when measurement; Cannot eliminate that temperature is floated and drift completely; There is intrinsic hysteresis in magnetic device, affects measuring accuracy.
Utility model content
Technical problem to be solved in the utility model is: giant magnetoresistance current sensor is provided, its whole measuring circuit forms closed-loop system, giant magnetoresistance chip and magnetism gathering rings magnetic core form the structure of a sealing, and the giant magnetoresistance current sensor that has overcome prior art is very easily disturbed, cannot eliminate completely temperature by spuious external magnetic field and floats with drift, magnetic device and exist intrinsic hysteresis to affect the defect of measuring accuracy in the time measuring.
The utility model solves this technical problem adopted technical scheme: giant magnetoresistance current sensor, formed by electromagnetic conversion module, signal amplification module and feedback compensation module three parts, wherein, electromagnetic conversion module comprises magnetism gathering rings magnetic core, former limit winding and giant magnetoresistance chip, signal amplification module comprises operational amplifier and push-pull amplifier, and feedback compensation module is feedback winding, former limit winding is through magnetism gathering rings magnetic core, feedback winding is evenly on magnetism gathering rings magnetic core, feedback winding one end is connected with push-pull amplifier, the feedback winding other end connects a sampling resistor, giant magnetoresistance chip and magnetism gathering rings magnetic core and feedback winding form the measuring sonde of closed-loop system formula, after assemble in the magnetic field that magnetism gathering rings magnetic core produces primary current, act on giant magnetoresistance chip, giant magnetoresistance chip is after the effect of experiencing magnetic field, to have voltage signal output, the voltage signal of this output is sent into operational amplifier, operational amplifier is connected with push-pull amplifier, after the voltage signal process operational amplifier of above-mentioned output and push-pull amplifier amplify, be added on sampling resistor, form feedback current, this feedback current produces feedback magnetic field through feedback winding, electromagnetic conversion module thus, signal amplification module and feedback compensation module three parts form measuring circuit closed-loop system.
Above-mentioned giant magnetoresistance current sensor, the constituent material of described magnetism gathering rings magnetic core is permalloy material, its resistivity is 0.56 μ Ω m, Curie point is 400 ℃, saturation induction density is Bs=0.7T, coercivity H under saturation induction density is not more than 1.6A/m, and the magnetic permeability that DC magnetic performance meets in 0.08A/m magnetic field intensity is not less than 37.5mH/m; Magnetism gathering rings magnetic core is annular magnetic roller, and the internal diameter of this magnet ring is that 20mm, external diameter are that 25mm, the high 7mm of being, gas length are that 5mm, xsect are the long rectangle for 7mm and the wide 5mm of being.
Above-mentioned giant magnetoresistance current sensor, described giant magnetoresistance chip is GMR chip, adopts the VA110F3 of east Wei Ci Science and Technology Ltd.
Above-mentioned giant magnetoresistance current sensor, the number of turn of described former limit winding is 1 circle.
Above-mentioned giant magnetoresistance current sensor, the number of turn of described feedback winding is 120 circles.
Above-mentioned giant magnetoresistance current sensor, described sampling resistor is 20 ohm.
Above-mentioned giant magnetoresistance current sensor, the model of described operational amplifier is INA118, the model of push-pull amplifier is L165.
Above-mentioned giant magnetoresistance current sensor, related parts and starting material all obtain by known approach, and the method for assembling is that those skilled in the art can grasp.
The beneficial effects of the utility model are: compared with prior art, outstanding substantive distinguishing features of the present utility model is:
(1) principle of the work of the utility model giant magnetoresistance current sensor and flow process are: the primary current in the winding of former limit is after assemble through magnetism gathering rings magnetic core in the magnetic field that produces of tested electric current, act on giant magnetoresistance chip, this giant magnetoresistance chip is after the effect of experiencing magnetic field, to have voltage signal output, after the voltage signal process operational amplifier of this output and power amplifier amplify, be added on sampling resistor, form feedback current, this feedback current produces feedback magnetic field through feedback winding, in the time of the equal and opposite in direction in the magnetic field that feedback magnetic field and former limit winding produce, feedback current no longer reduces, just reach the duty of zero magnetic flux, primary current now and the relation of feedback current be: N
1i
p=N
2i
c.Accurately record thus the current value of tested electric current.
(2) described above, in the time of the equal and opposite in direction in feedback magnetic field and the magnetic field of former limit winding generation, just reach the duty of zero magnetic flux.Because any variation of tested electric current all can destroy this balance that closed-loop system reaches, once and magnetic field out of trim, giant magnetoresistance chip just has voltage signal output, this signal is after amplifying, have immediately corresponding feedback current be offset current flow through feedback winding unbalance magnetic field is compensated, to reach new balance.Because the required time of above-mentioned equilibrium process is less than 1 μ s, therefore determine the response speed faster that has of the utility model giant magnetoresistance current sensor.
(3) the utility model giant magnetoresistance current sensor has adopted closed-loop system, the magnetic field output terminal that primary current is produced produces output voltage in giant magnetoresistance chip, after amplifying, be added on sampling resistor, form feedback current, feedback current produces feedback magnetic field, offset tested external magnetic field, magnetism gathering rings magnetic core is operated near zero magnetic field, so just formed the closed-loop system of the current sensor based on giant magnetoresistance.Zero magnetic field is much smaller with respect to external magnetic field in open loop magnetic core, and this has just been reduced by the impact of measuring magnetic field to external world, is conducive to the raising of the giant magnetoresistance current sensor linearity, and has effectively suppressed that temperature is floated and zero drift phenomenon.
Compared with prior art, marked improvement of the present utility model is:
(1) the utility model giant magnetoresistance current sensor only has the nonlinearity errons ultralow for ± 7 ‰, and low-down temperature is floated and drift, and input signal noise in the time detecting direct current or exchange is effectively suppressed.
(2) closed-loop system that magnetism gathering rings magnetic core enough becomes with feedback winding has overcome giant magnetoresistance chip unintentional nonlinearity degree and temperature is floated phenomenon, has avoided the extra compensating module of measuring system.
(3) the utility model giant magnetoresistance current sensor combines the closed loop of giant magnetoresistance chip, magnetism gathering rings magnetic core and zero magnetic flux, can measure DC current and low-frequency ac electric current, can also measure high-frequency ac current.
(4) the utility model giant magnetoresistance current sensor has reduced the error causing due to the intrinsic hysteresis of magnetic device.The introducing of magnetism gathering rings magnetic core has improved the sensitivity of sensor, can record the low current signal of mA rank, has improved the ability that sensor is measured high precision weak current.
(5) the utility model giant magnetoresistance current sensor has response speed faster.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the utility model is further illustrated.
Fig. 1 is the structural representation of the utility model giant magnetoresistance current sensor.
Fig. 2 is the composition frame chart of the utility model giant magnetoresistance current sensor.
The waveform of primary current and the oscillogram of offset current when Fig. 3 (a) is the 100kHz of the utility model giant magnetoresistance current sensor.
The waveform of primary current and the oscillogram of offset current when Fig. 3 (b) is the 500kHz of the utility model giant magnetoresistance current sensor.
Fig. 4 is the Bode diagram that the small-signal analysis of the utility model giant magnetoresistance current sensor obtains.
Fig. 5 is the 0-8A scope direct current measurement result curve figure of the utility model giant magnetoresistance current sensor.
Fig. 6 is the relative error curve map of the utility model giant magnetoresistance current sensor.
Fig. 7 is the 0-13A scope direct current measurement result curve figure of the utility model giant magnetoresistance current sensor.
Fig. 8 is that the hysteresis of the utility model giant magnetoresistance current sensor is to the influence curve figure of sensor.
Embodiment
Embodiment illustrated in fig. 1 showing, former limit winding Wp is through magnetism gathering rings magnetic core C, feedback winding Wc is on magnetism gathering rings magnetic core C, feedback winding Wc one end is connected with push-pull amplifier, the feedback winding Wc other end connects a sampling resistor Rm, giant magnetoresistance chip GMR and magnetism gathering rings magnetic core C and feedback winding Wc form the measuring sonde of closed-loop system formula, after assemble in the magnetic field that magnetism gathering rings magnetic core C produces primary current Ip, act on giant magnetoresistance chip GMR, giant magnetoresistance chip GMR is after the effect of experiencing magnetic field, to have voltage signal output, the voltage signal of this output is sent into operational amplifier, operational amplifier is connected with push-pull amplifier, after the voltage signal process operational amplifier of above-mentioned output and push-pull amplifier amplify, be added on sampling resistor Rm, form feedback current Ic, this feedback current Ic produces feedback magnetic field through feedback winding Wc, form thus the structure of the giant magnetoresistance current sensor of the present embodiment with measuring circuit closed-loop system.Because the magnetic field that feedback winding Wc produces is contrary with the magnetic direction that primary current Ip produces, thereby weaken magnetic field, former limit, giant magnetoresistance chip GMR output is reduced gradually, feedback current Ic is corresponding reducing also, in the time of the equal and opposite in direction of the magnetic field of former limit winding Wp and feedback winding Wc generation, feedback current Ic no longer reduces, and reaches zero magnetic flux state.The size in magnetic field and the output of testing circuit have good linear relationship, therefore can reflect the size of current in wire according to the output signal of testing circuit.
Embodiment illustrated in fig. 2 showing, giant magnetoresistance current sensor is made up of electromagnetic conversion module, signal amplification module and feedback compensation module three parts, by electromagnetic conversion module output voltage signal, the voltage signal of this output is sent into signal amplification module, form feedback current through entering feedback compensation module after amplifying, produce feedback magnetic field.Electromagnetic conversion module, signal amplification module and feedback compensation module three parts form measuring circuit closed-loop system thus.
Embodiment shown in Fig. 3 has set up realistic model to whole measuring circuit closed-loop system, and in model, compensating umber of turn is 10, and tested current amplitude is 20A.In the time that frequency is 100kHz and 500kHz, primary current and the offset current waveform under two kinds of frequencies is respectively if Fig. 3 (a) is with as shown in 3 (b).Can find out, in the time that frequency is 100kHz, the output of current sensor is undistorted, and in the time of 500kHz, waveform is out of shape a little.
Embodiment shown in Fig. 4 carries out to current sensor the Bode diagram that small-signal analysis obtains, and as known in the figure, the bandwidth of giant magnetoresistance current sensor of the present utility model is higher, can reach MHz.
The giant magnetoresistance current sensor of the present embodiment, by electromagnetic conversion module, signal amplification module and feedback compensation module three part compositions, wherein, the number of turn is that the former limit winding Wp of 1 circle passes magnetism gathering rings magnetic core C, the number of turn is that the feedback winding Wc of 120 circles is on magnetism gathering rings magnetic core C, the push-pull amplifier that feedback winding Wc one end is L165 with model is connected, the feedback winding Wc other end connects a resistance R m of sampling, giant magnetoresistance chip GMR and magnetism gathering rings magnetic core C and feedback winding Wc form the measuring sonde of closed-loop system formula, after assemble in the magnetic field that magnetism gathering rings magnetic core C produces primary current Ip, act on giant magnetoresistance chip GMR, giant magnetoresistance chip GMR is after the effect of experiencing magnetic field, to have voltage signal output, the voltage signal of this output is sent into the operational amplifier that model is INA118, model is that the push-pull amplifier that the operational amplifier of INA118 is L165 with model is connected, the voltage signal of above-mentioned output is that the operational amplifier of INA118 and model are after the push-pull amplifier of L165 amplifies through model, be added on the resistance R m of 20 ohm of samplings, form feedback current Ic, this feedback current Ic produces feedback magnetic field through feedback winding Wc, form thus the structure of the giant magnetoresistance current sensor of the present embodiment with measuring circuit closed-loop system.Because the magnetic field that feedback winding Wc produces is contrary with the magnetic direction that primary current Ip produces, thereby weaken magnetic field, former limit, giant magnetoresistance chip GMR output is reduced gradually, feedback current Ic is corresponding reducing also, in the time of the equal and opposite in direction of the magnetic field of former limit winding Wp and feedback winding Wc generation, feedback current Ic no longer reduces, and reaches zero magnetic flux state.The size in magnetic field and the output of testing circuit have good linear relationship, therefore can reflect the size of current in wire according to the output signal of testing circuit.
The constituent material of above-mentioned magnetism gathering rings magnetic core C is permalloy material, its resistivity is 0.56 μ Ω m, Curie point is 400 ℃, saturation induction density is Bs=0.7T, coercivity H under saturation induction density is not more than 1.6A/m, and the magnetic permeability that DC magnetic performance meets in 0.08A/m magnetic field intensity is not less than 37.5mH/m; Magnetism gathering rings magnetic core is annular magnetic roller, and the internal diameter of this magnet ring is that 20mm, external diameter are that 25mm, the high 7mm of being, gas length are that 5mm, xsect are the long rectangle for 7mm and the wide 5mm of being; Giant magnetoresistance chip is GMR chip, adopts the VA110F3 of east Wei Ci Science and Technology Ltd..
Comparative example 1
Except measuring sonde is only giant magnetoresistance chip GMR, do not have outside feedback compensation module, other are with embodiment 1.
Comparative example 2
Except measuring sonde is only giant magnetoresistance chip GMR and magnetism gathering rings magnetic core C composition, do not have outside feedback compensation module, other are with embodiment 1.
(1) when measured current I p scope is from 0 to 8A time, respectively the current sensor of above embodiment 1, comparative example 1 and 2 three kinds of structures of comparative example is measured, the input-output characteristic curve that experiment obtains as shown in Figure 5, as can be seen here, in the time only having giant magnetoresistance chip GMR as measuring sonde, it is low that electric current passes the sensitivity of sensor, poor linearity, and measuring accuracy is lower; In the time forming measuring sonde by giant magnetoresistance chip GMR and magnetism gathering rings magnetic core C, be open cycle system, the sensitivity of current sensor improves, but easily saturated, and measurement range is narrower, and the linearity is poor; When be made up of the measuring sonde of closed-loop system formula giant magnetoresistance chip GMR and magnetism gathering rings magnetic core C and feedback winding Wc, the sensitivity of current sensor improves, and measurement range is identical with giant magnetoresistance chip GMR, and the linearity is better.
(2) deduct actual value by the theoretical value of output voltage, just the relative error can obtain this current sensor measurement scope and be 0A～8A divided by actual value again time, as shown in the relative error curve map of Fig. 6 the utility model giant magnetoresistance current sensor, at 0A in the range of 8A, relative error is limited in ± 7 ‰ in.
(3) in order to analyze the impact of hysteresis on current sensor, respectively the current sensor of embodiment 1, comparative example 1 and 2 three kinds of structures of comparative example is studied.First tested electric current is increased to 13A from 0, measures respectively the output of the current sensor of three kinds of structures, then electric current is down to 0A from 13A, again measures the output of the current sensor of three kinds of structures, and input-output characteristic curve as shown in Figure 7.The output error of the current sensor of three kinds of structures as shown in Figure 8.As seen from the figure, the closed-loop system of the utility model giant magnetoresistance current sensor can reduce the error being caused by hysteresis, has guaranteed measuring accuracy and the linearity of sensor.
Above-mentioned comparative illustration, the utility model giant magnetoresistance current sensor has ± 7 ‰ ultralow nonlinearity erron, the closed-loop system that magnetism gathering rings magnetic core enough becomes with feedback winding has overcome giant magnetoresistance chip unintentional nonlinearity degree and temperature is floated phenomenon, avoid the extra compensating module of measuring system, and reduced the error causing due to the intrinsic hysteresis of magnetic device.The introducing of magnetism gathering rings magnetic core has improved the sensitivity of current sensor, can record the low current signal of mA rank, has improved the ability that current sensor is measured high precision weak current.The result of small-signal analysis has shown that the utility model giant magnetoresistance current sensor has very high bandwidth, and the frequency range of measurement can reach MHz.
Parts and starting material related in above-described embodiment all obtain by known approach, and the method for assembling is that those skilled in the art can grasp.
Claims (5)
1. giant magnetoresistance current sensor, it is characterized in that: formed by electromagnetic conversion module, signal amplification module and feedback compensation module three parts, wherein, electromagnetic conversion module comprises magnetism gathering rings magnetic core, former limit winding and giant magnetoresistance chip, signal amplification module comprises operational amplifier and push-pull amplifier, and feedback compensation module is feedback winding, former limit winding is through magnetism gathering rings magnetic core, feedback winding is evenly on magnetism gathering rings magnetic core, feedback winding one end is connected with push-pull amplifier, the feedback winding other end connects a sampling resistor, giant magnetoresistance chip and magnetism gathering rings magnetic core and feedback winding form the measuring sonde of closed-loop system formula, after assemble in the magnetic field that magnetism gathering rings magnetic core produces primary current, act on giant magnetoresistance chip, giant magnetoresistance chip is after the effect of experiencing magnetic field, to have voltage signal output, the voltage signal of this output is sent into operational amplifier, operational amplifier is connected with push-pull amplifier, after the voltage signal process operational amplifier of above-mentioned output and push-pull amplifier amplify, be added on sampling resistor, form feedback current, this feedback current produces feedback magnetic field through feedback winding, electromagnetic conversion module thus, signal amplification module and feedback compensation module three parts form measuring circuit closed-loop system.
2. giant magnetoresistance current sensor according to claim 1, it is characterized in that: described magnetism gathering rings magnetic core is annular magnetic roller, the internal diameter of this magnet ring is that 20mm, external diameter are that 25mm, the high 7mm of being, gas length are that 5mm, xsect are the long rectangle for 7mm and the wide 5mm of being.
3. giant magnetoresistance current sensor according to claim 1, is characterized in that: the number of turn of described former limit winding is 1 circle.
4. giant magnetoresistance current sensor according to claim 1, is characterized in that: the number of turn of described feedback winding is 120 circles.
5. giant magnetoresistance current sensor according to claim 1, is characterized in that: described sampling resistor is 20 ohm.
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| CN201320777510.0U CN203630195U (en) | 2013-11-29 | 2013-11-29 | Giant magnetoresistance current sensor |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103616550A (en) * | 2013-11-29 | 2014-03-05 | 河北工业大学 | Giant magnetoresistance current sensor |
| CN105353193A (en) * | 2015-11-27 | 2016-02-24 | 华中科技大学 | Low direct current clamp-shaped measuring device |
| CN105774573A (en) * | 2015-01-13 | 2016-07-20 | 福特全球技术公司 | Bi-directional current sensing using unipolar sensors with closed loop feedback |
| CN109298233A (en) * | 2018-11-30 | 2019-02-01 | 国网电力科学研究院武汉南瑞有限责任公司 | A kind of alterating and direct current flow sensor |
| CN109709369A (en) * | 2019-03-06 | 2019-05-03 | 宁波泰丰源电气有限公司 | A kind of electric energy meter electronic mutual inductor |
-
2013
- 2013-11-29 CN CN201320777510.0U patent/CN203630195U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103616550A (en) * | 2013-11-29 | 2014-03-05 | 河北工业大学 | Giant magnetoresistance current sensor |
| CN105774573A (en) * | 2015-01-13 | 2016-07-20 | 福特全球技术公司 | Bi-directional current sensing using unipolar sensors with closed loop feedback |
| CN105353193A (en) * | 2015-11-27 | 2016-02-24 | 华中科技大学 | Low direct current clamp-shaped measuring device |
| CN109298233A (en) * | 2018-11-30 | 2019-02-01 | 国网电力科学研究院武汉南瑞有限责任公司 | A kind of alterating and direct current flow sensor |
| CN109709369A (en) * | 2019-03-06 | 2019-05-03 | 宁波泰丰源电气有限公司 | A kind of electric energy meter electronic mutual inductor |
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