CN102183736B - Device and method for measuring low-intensity magnetic field - Google Patents

Abstract

The invention discloses a device and a method for measuring a low-intensity magnetic field. The device comprises a reference coil, a current sampling resistor, a direct current power supply, a modulating coil, a magnetic resistor, an alternating current power supply and a monitoring unit; the reference coil and the current sampling resistor are connected in series, and form a current loop with the direct current power supply to generate a reference magnetic field; the modulating coil and the magnetic resistor are connected in series, and form a current loop with the alternating current power supply to generate a modulating magnetic field; the reference coil and the modulating coil are close to each other and keep a constant relative position state; the magnetic resistor is at a position where the reference magnetic field and the modulating magnetic field can be sensed simultaneously; and the monitoring unit tests direct current flowing through the reference coil by the current sampling resistor, tests direct current voltage components at two ends of the magnetic resistor under various amplitudes or polarities by changing amplitude or polarity of the direct current power supply respectively, and calculates the intensity and direct of the measured magnetic field by the components of the tested direct current and direct voltage. The device for testing the low-intensity magnetic field is simple in structure and low in cost; and the test result is not influenced by temperature.

Description

A kind of weak magnetic measurement device and method

Technical field

The present invention relates to electronic measuring technology field, more particularly, relate to a kind of weak magnetic measurement device and method.

Background technology

The measuring method of low-intensity magnetic field mainly contains in the prior art: fluxgate method, nuclear magnetic resonance method, optical magnetic resonance method, superconductive quantum interference method and magnetic rotation effect method etc., though these method measuring accuracy and sensitivity are very high, ubiquity structural manufacturing process complexity, the problem that cost is high.

In addition, the Hall effect method also is a kind of method commonly used in the prior art, this method is simple in structure, with low cost, but in measuring process, has ettingshausen effect, Nernst effect, lining discipline-leduc effect, and the not exclusively symmetrical caused not equipotential electromotive force of electrode position, wherein ettingshausen effect can't be eliminated, and when magnetic direction can not change, the equipotential electromotive force can't not eliminated, in addition, also there is bigger temperature coefficient in Hall element.

Therefore, if can propose the higher and temperature influence not of a kind of measuring accuracy and sensitivity, while structural manufacturing process weak magnetic measurement device and method simple, with low cost, to be of great immediate significance, high-precision weak magnetic measurement is used widely in the electronic surveying field.

Summary of the invention

In view of this, the invention provides the higher and temperature influence not of a kind of measuring accuracy and sensitivity, structural manufacturing process weak magnetic measurement device and method simple, with low cost simultaneously, technical scheme is as follows:

A kind of weak magnetic measurement device comprises: reference coil, current sampling resistor, direct supply, modulation coil, mistor, AC power and measurement and control unit; Wherein:

Described reference coil and described current sampling resistor are connected, and constitute current return with described direct supply, produce with reference to magnetic field;

Described modulation coil and described mistor are connected, and constitute current return with described AC power, produce modulated magnetic field;

Described reference coil and described modulation coil are close and keep the relative position state constant;

Described mistor is positioned at the position that can sense simultaneously with reference to magnetic field and modulated magnetic field, and induction is by measuring magnetic field, with reference to magnetic field and modulated magnetic field;

Described measurement and control unit connects the two ends of described current sampling resistor, two ends, direct supply and the AC power of mistor, detect the DC current that flows through reference coil by current sampling resistor, by changing direct supply amplitude or polarity, detect the DC voltage component at mistor two ends under different direct supply amplitudes or polarity respectively, and by the DC current of the reference coil that records and the DC voltage component at mistor two ends, calculate by the size and Orientation of measuring magnetic field.

Preferably, in the above-mentioned weak magnetic measurement device, described reference coil is coaxial with described modulation coil.

A kind of weak magnetic measurement method is applied to comprise in the above-mentioned weak magnetic measurement device:

AC power output comprises the alternating current of n different frequency component and gives modulation coil, and wherein n is not less than 1 natural number, and the difference that any two frequency sums reach in n different frequency is not equal to all the other any frequencies;

Measurement and control unit control direct supply output amplitude and polarity make reference coil flow through the DC current of default amplitude and direction, and flow through the DC current values of reference coil by the current sampling resistor detection;

Measurement and control unit detects the DC voltage component at mistor two ends;

Measurement and control unit changes direct supply output amplitude or polarity, flows through size or the direction of reference coil DC current with change, and detects the DC current values that flows through reference coil again by current sampling resistor;

Measurement and control unit detects the DC voltage component at mistor two ends again;

Measurement and control unit calculates by the size and Orientation of measuring magnetic field according to the DC voltage component at the mistor two ends that successively record for twice.

By above technical scheme as can be seen, the present invention has made up the weak magnetic measurement device that a cover mainly is made of mistor, during measurement, detect the DC current that flows through reference coil by current sampling resistor, by changing direct supply amplitude or polarity, detect the DC voltage component at mistor two ends under different direct supply amplitudes or polarity respectively, and by the DC current of the reference coil that records and the DC voltage component at mistor two ends, calculate by the size and Orientation of measuring magnetic field.The present invention in the advantage such as simple in structure, highly sensitive and with low cost of having utilized that mistor has, can the filtering temperature to the influence of weak magnetic measurement, the precision of measurement is higher.

Description of drawings

In order to be illustrated more clearly in technical scheme of the present invention, the accompanying drawing of required use is done to introduce simply in will describing embodiment below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

The structural representation of a kind of weak magnetic measurement device that Fig. 1 provides for the embodiment of the invention;

The process flow diagram of a kind of weak magnetic measurement method that Fig. 2 provides for the embodiment of the invention.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that obtains under the creative work prerequisite.

Referring to shown in Figure 1, a kind of weak magnetic measurement device that the embodiment of the invention provides can comprise:

Reference coil C _R, current sampling resistor R _S, direct supply E _DC, modulation coil C _M, mistor R _M, AC power E _ACWith measurement and control unit PU.

Wherein, described reference coil C _RWith described current sampling resistor R _SThe series connection, and with described direct supply E _DCConstitute current return, produce with reference to magnetic field; Described modulation coil C _MWith described mistor R _MThe series connection, and with described AC power E _ACConstitute current return, produce modulated magnetic field; Described reference coil C _RWith described modulation coil C _MNear and keep the relative position state constant; Described mistor R _MBe positioned at the position that can sense simultaneously with reference to magnetic field and modulated magnetic field, induction is by measuring magnetic field, with reference to magnetic field and modulated magnetic field; Described measurement and control unit PU connects described current sampling resistor R _STwo ends, mistor R _MTwo ends, direct supply E _DCWith AC power E _AC, by current sampling resistor R _SReference coil C is flow through in detection _RDC current, by changing direct supply E _DCAmplitude or polarity detect mistor R under different direct supply amplitudes or polarity respectively _MThe DC voltage component at two ends, and the reference coil C by recording _RDC current and mistor R _MThe DC voltage component at two ends calculates by the size and Orientation of measuring magnetic field.

In other embodiments, described reference coil C _RWith described modulation coil C _MCoaxial.

The concrete measuring principle of the weak magnetic measurement device that the embodiment of the invention provides is as follows:

Modulation coil C _MWith reference coil C _RThere is coefficient of mutual inductance, then flows through modulation coil C _MElectric current is:

$i_M=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Mi}}\sin ({\mathrm{\ω}}_{i}t+{\mathrm{\α}}_i)---\left(1\right)$

In the formula, I _Mi, ω _i, α _iBe respectively and flow through modulation coil C _MAmplitude, angular frequency, the phase place of alternating current i secondary frequency components, n is the number of the contained different frequency component of alternating current, n is not less than 1 natural number, any two frequency sums in n the different frequency, and difference be not equal to all the other any frequencies.

Modulation coil C _MThe magnetic induction density that produces is:

$B_M={\mathrm{\σ}}_M\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Mi}}\sin ({\mathrm{\ω}}_{i}t+{\mathrm{\α}}_i)---\left(2\right)$

In the formula, σ _MFor with modulation coil C _MThe constant that structural parameters are relevant with dielectric permeability.

Flow through reference coil C _RElectric current be:

$i_R=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Ri}}\sin ({\mathrm{\ω}}_{i}t+{\mathrm{\β}}_i)+I_{R0}---\left(3\right)$

In the formula, I _Ri, β _i, I _R0Be respectively and flow through reference coil C _RAmplitude, phase place, the DC current of induction current i secondary frequency components.

Reference coil C _RThe magnetic induction density that produces is:

$B_R={\mathrm{\σ}}_R[\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Ri}}\sin ({\mathrm{\ω}}_{i}t+{\mathrm{\β}}_i)+I_{R0}]---\left(4\right)$

In the formula, σ _RFor with reference coil C _RThe constant that structural parameters are relevant with dielectric permeability.

Under the low-intensity magnetic field condition, the magnetoresistance of mistor is expressed as:

R＝R ₀(1+k _sB ²) (5)

In the formula, R ₀Be the zero field ressitance value relevant with temperature, R is the resistance value when magnetic field is arranged, and B is the responsive magnetic induction density of mistor, k _sBe the reluctancy relevant with the carrier mobility of material and material shape and temperature.

If be B by the magnetic induction density of measuring magnetic field ₀, at reference coil C _RThe magnetic field B that produces _R, modulation coil C _MThe magnetic field B that produces _MAnd tested magnetic field B ₀Effect under, mistor R _MResistance is:

$R_M=R_0[1+k_s{(B_0+B_R+B_M)}^2]$

$=R_0\{1+k_s[B_0+{\mathrm{\σ}}_R\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Ri}}\sin ({\mathrm{\ω}}_{i}t+{\mathrm{\β}}_i)---\left(6\right)$

$+{\mathrm{\σ}}_R{I}_{R0}+{\mathrm{\σ}}_M\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Mi}}\sin ({\mathrm{\ω}}_{i}t+{\mathrm{\α}}_i){]}^2\}$

Mistor R _MThe detection voltage at two ends is:

$u_{R_M}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Mi}}\sin ({\mathrm{\ω}}_{i}t+{\mathrm{\α}}_i)(R_M+R_W)$

$+M_{{\mathrm{MR}}_M}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Mi}}{\mathrm{\ω}}_i\cos ({\mathrm{\ω}}_{i}t+{\mathrm{\α}}_i)---\left(7\right)$

$+M_{{\mathrm{RR}}_M}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Ri}}{\mathrm{\ω}}_i\cos ({\mathrm{\ω}}_{i}t+{\mathrm{\β}}_i)$

In the formula,

Be respectively modulation coil C _MWith reference coil C _RWith mistor R _MThe coefficient of mutual inductance in voltage detecting loop, R _WBe mistor R _MLead resistance.

The difference that reaches owing to any two frequency sums in n the different frequency is not equal to all the other any frequencies, so, mistor R _MThe DC component that voltage is detected at two ends is:

$U_1=R_0{k}_s({\mathrm{\σ}}_R{I}_{R0}+B_0)[{\mathrm{\σ}}_R\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Ri}}{I}_{\mathrm{Mi}}\cos ({\mathrm{\α}}_i-{\mathrm{\β}}_i)+{\mathrm{\σ}}_M\underset{i=0}{\overset{\∞}{\mathrm{\Σ}}}{I_{\mathrm{Mi}}}^2]---\left(8\right)$

Only change direct supply E _DCAmplitude or polarity, make and flow through reference coil C _RDC current be I _R1, modulation coil C then _MWith reference coil C _RThe alternating current size constant, the phase differential between them is also constant, mistor R _MThe DC component that voltage is detected at two ends is:

$U_2=R_0{k}_s({\mathrm{\σ}}_R{I}_{R1}+B_0)[{\mathrm{\σ}}_R\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{I}_{\mathrm{Ri}}{I}_{\mathrm{Mi}}\cos ({\mathrm{\α}}_i-{\mathrm{\β}}_i)+{\mathrm{\σ}}_M\underset{i=0}{\overset{\∞}{\mathrm{\Σ}}}{I_{\mathrm{Mi}}}^2]---\left(9\right)$

According to formula (8), (9), (8)/(9) can get tested D.C. magnetic field B ₀For:

$B_0=\frac{{\mathrm{\σ}}_R(U_2{I}_{R0}-U_1{I}_{R1})}{U_1-U_2}---\left(10\right)$

By formula (10) as can be seen, weak magnetic measurement device provided by the invention can detect by the size and Orientation of measuring magnetic field, and measurement result and mistor temperature are irrelevant.

From above-described embodiment as can be seen, the embodiment of the invention has made up the weak magnetic measurement device that a cover mainly is made of mistor, during measurement, detect the DC current that flows through reference coil by current sampling resistor, by changing direct supply amplitude or polarity, detect the DC voltage component at mistor two ends under different direct supply amplitudes or polarity respectively, and by the DC current of the reference coil that records and the DC voltage component at mistor two ends, calculate by the size and Orientation of measuring magnetic field.The embodiment of the invention in the advantage such as simple in structure, highly sensitive and with low cost of having utilized that mistor has, can the filtering temperature to the influence of weak magnetic measurement, the precision of measurement is higher.

Referring to shown in Figure 2, the embodiment of the invention also provides a kind of weak magnetic measurement method that is applied to the disclosed weak magnetic measurement device of above-described embodiment, can may further comprise the steps:

S201, AC power output comprises the alternating current of n different frequency component and gives modulation coil, and wherein n is not less than 1 natural number, and the difference that any two frequency sums reach in n different frequency is not equal to all the other any frequencies.

S202, measurement and control unit control direct supply output amplitude and polarity make reference coil flow through the DC current of default amplitude and direction, and flow through the DC current values of reference coil by the current sampling resistor detection.

S203, measurement and control unit detects the DC voltage component at mistor two ends.

S204, measurement and control unit change direct supply output amplitude or polarity, flow through size or the direction of reference coil DC current with change, and detect the DC current values that flows through reference coil again by current sampling resistor.

S205, measurement and control unit detect the DC voltage component at mistor two ends again.

S206, measurement and control unit calculates by the size and Orientation of measuring magnetic field according to the DC voltage component at the mistor two ends that successively record for twice.

For the disclosed weak magnetic measurement method of the embodiment of the invention, because it is based on above-mentioned weak magnetic measurement device proposition, that therefore describes is fairly simple, and concrete implementation process, measuring principle and computing formula get final product referring to weak magnetic measurement device embodiment disclosed above.

To the above-mentioned explanation of the disclosed embodiments, make this area professional and technical personnel can realize or use the present invention.Multiple modification to these embodiment will be apparent concerning those skilled in the art, and defined General Principle can realize under the situation that does not break away from the spirit or scope of the present invention in other embodiments herein.Therefore, the present invention will can not be restricted to these embodiment shown in this article, but will meet the wideest scope consistent with principle disclosed herein and features of novelty.

Claims (3)

1. a weak magnetic measurement device is characterized in that, comprising: reference coil, current sampling resistor, direct supply, modulation coil, mistor, AC power and measurement and control unit; Wherein:

Described reference coil and described current sampling resistor are connected, and constitute current return with described direct supply, produce with reference to magnetic field;

Described modulation coil and described mistor are connected, and constitute current return with described AC power, produce modulated magnetic field;

Described reference coil and described modulation coil are close and keep the relative position state constant;

Described mistor is positioned at the position that can sense simultaneously with reference to magnetic field and modulated magnetic field, and induction is by measuring magnetic field, with reference to magnetic field and modulated magnetic field;

The output of described AC power comprises the alternating current of n different frequency component and gives described modulation coil, and n is not less than 1 natural number, and the difference that any two frequency sums reach in n different frequency is not equal to all the other any frequencies;

Described measurement and control unit connects the two ends of described current sampling resistor, two ends, direct supply and the AC power of mistor, detect the DC current that flows through reference coil by current sampling resistor, by changing direct supply amplitude or polarity, detect the DC voltage component at mistor two ends under different direct supply amplitudes or polarity respectively, and by the DC current of the reference coil that records and the DC voltage component at mistor two ends, calculate by the size and Orientation of measuring magnetic field.

2. weak magnetic measurement device according to claim 1 is characterized in that, described reference coil is coaxial with described modulation coil.

3. a weak magnetic measurement method is applied to it is characterized in that in the weak magnetic measurement device as claimed in claim 1 or 2, comprising:

AC power output comprises the alternating current of n different frequency component and gives modulation coil, and wherein n is not less than 1 natural number, and the difference that any two frequency sums reach in n different frequency is not equal to all the other any frequencies;

Measurement and control unit control direct supply output amplitude and polarity make reference coil flow through the DC current of default amplitude and direction, and flow through the DC current values of reference coil by the current sampling resistor detection;

Measurement and control unit detects the DC voltage component at mistor two ends;

Measurement and control unit changes direct supply output amplitude or polarity, flows through size or the direction of reference coil DC current with change, and detects the DC current values that flows through reference coil again by current sampling resistor;

Measurement and control unit detects the DC voltage component at mistor two ends again;

Measurement and control unit calculates by the size and Orientation of measuring magnetic field according to the DC voltage component at the mistor two ends that successively record for twice.

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