阅读说明：本技术 一种基于层状磁电复合材料的磁电罗盘及其应用 (Magnetoelectric compass based on layered magnetoelectric composite material and application thereof ) 是由 胡忠强 吴金根 刘明 徐奕维 于 2021-06-29 设计创作，主要内容包括：一种基于层状磁电复合材料的磁电罗盘及其应用,包括压电材料、磁致伸缩材料、柔性电极片、胶黏剂、线圈、旋转平台、校准算法；磁致伸缩材料在外磁场的作用下产生长度方向的应变,并通过胶黏剂传递给压电材料,压电材料产生电信号输出,继而实现对外界交流磁场的传感。本发明的磁场传感器,相比于常见的磁场传感器,具有价格低廉、性能稳定等优点,细长型的器件结构与校准算法的数据处理大大提高了传感器对磁场方向的探测灵敏度。本发明的磁场传感器,可以用于面内交流磁场大小和方向的测试,在工业设备的磁场测定中具有重大的应用前景。(A magnetoelectric compass based on a layered magnetoelectric composite material and application thereof comprise a piezoelectric material, a magnetostrictive material, a flexible electrode plate, an adhesive, a coil, a rotating platform and a calibration algorithm; the magnetostrictive material generates strain in the length direction under the action of an external magnetic field and transmits the strain to the piezoelectric material through the adhesive, and the piezoelectric material generates an electric signal to output, so that the sensing of an external alternating current magnetic field is realized. Compared with the common magnetic field sensor, the magnetic field sensor has the advantages of low price, stable performance and the like, and the detection sensitivity of the sensor to the magnetic field direction is greatly improved through the slender device structure and the data processing of the calibration algorithm. The magnetic field sensor can be used for testing the size and the direction of an in-plane alternating current magnetic field and has great application prospect in the magnetic field measurement of industrial equipment.)

1. A magnetoelectric compass based on a layered magnetoelectric composite material is characterized by comprising a piezoelectric material (1), a magnetostrictive material (2), a flexible electrode plate (3), an adhesive (4), a coil (5) and a rotating platform (6); the piezoelectric material (1) is in a strip rectangular sheet structure, and electrodes are arranged on the surface of the piezoelectric material; the magnetostrictive material (2) is in a strip rectangular sheet structure, the length of the magnetostrictive material is greater than that of the piezoelectric material, and the piezoelectric material (1) is positioned between the two layers of magnetostrictive materials (2) to form a magnetoelectric composite material; the flexible electrode slice (3) is positioned between the piezoelectric material (1) and the magnetostrictive material (2); the coil (5) is wound on the magnetoelectric composite material; the magnetoelectric composite material and the coil (5) are fixed on the rotating platform (6).

2. The magnetoelectric compass based on layered magnetoelectric composite material according to claim 1, characterized in that the piezoelectric material (1) is a single crystal or polycrystalline ceramic material, in particular AlN, quartz, LiNbO₃、BaTiO₃、ZnO、Pb(Zr，Ti)O₃、Pb(Mg，Nb)O₃-PbTiO₃、Pb(Zn，Nb)O₃-PbTiO₃、Pb(Ni，Nb)O₃-Pb(Zr，Ti)O₃Or BiScO₃-PbTiO₃One kind of (1).

3. The magnetoelectric compass based on layered magnetoelectric composite materials according to claim 1, characterized in that electrodes on the piezoelectric material (1) are covered on both sides in the thickness direction, and the electrode material is one of Au, Ag, Al, Cu, Pt, W, Fe, Co, Ni or Ti.

4. The magnetoelectric compass based on the layered magnetoelectric composite material according to claim 1, characterized in that the magnetostrictive material (2) is an alloy or an oxide having magnetostrictive effect or a magnetostrictive composite material formed by compounding the alloy or the oxide with a polymer; in particular Metglas, Tb-Dy-Fe alloy [ Terfenol-D (Tb)_0.27-0.30Dy_0.73-0.70Fe_1.90-1.95)]Nickel iron oxide NiFe₂O₄CoFe, CoFe oxide₂O₄Ni-Mn-Ga alloy Ni₂MnGa or a magnetostrictive composite material formed by compounding the magnetostrictive material with a polymer; the adhesive (4) is epoxy resin.

5. The magnetoelectric compass based on the layered magnetoelectric composite material according to claim 1, characterized in that the flexible electrode sheet (3) is a long rectangular sheet structure, the size of which matches the piezoelectric material (1), the conductive material is one of Au, Ag, Al, Cu, Pt or Ni, and the base material of the flexible electrode sheet (3) is one of polyethylene glycol terephthalate PET, polydimethylsiloxane PDMS, polyethylene PE, polyvinyl chloride PVC or polypropylene PP.

6. The magnetoelectric compass based on the layered magnetoelectric composite material according to claim 1, characterized in that the length of the elongated rectangular sheet structure of the piezoelectric material (1) is 10-30mm, the width is 1-4mm, the thickness is 0.1-0.5mm, and the polarization direction is the thickness direction; the length of the long strip rectangular sheet structure of the magnetostrictive material (2) is 80-120mm, the width is 1-4mm, and the thickness is 0.1-0.5 mm.

7. The magnetoelectric compass based on the layered magnetoelectric composite material according to claim 1, characterized in that the coil (5) surrounds the magnetoelectric composite material composed of the piezoelectric material (1), the magnetostrictive material (2) and the flexible electrode sheet (3), the axial direction thereof is the length direction of the magnetoelectric composite material, and the length thereof is greater than the length of the magnetoelectric composite material.

8. The magnetoelectric compass based on layered magnetoelectric composite material according to claim 1, characterized in that the magnetoelectric composite material and the coil (5) are fixed on a rotating platform (6), and the rotating platform (6) is controlled by a stepping motor.

9. The application of the magnetoelectric compass based on the layered magnetoelectric composite material is characterized in that the magnetoelectric compass based on the layered magnetoelectric composite material according to any one of claims 1 to 9 comprises the following steps:

step 1, acquiring test data of the obtained magnetoelectric compass;

step 2, when a group of test data is obtained, the response voltage lowest value is used for corresponding theta₀To determine the extent of the actual magnetic field direction: (theta)₀-Δθ，θ₀+ Δ θ), Δ θ being the deviation of the actual magnetic field direction from the measured magnetic field direction; selecting as many angles as possible in the range, and respectively calculating a group of magnetic field intensity data by taking each angle as a magnetic field directionAnd drawing the corresponding magnetic field angle and magnetic field intensity data in a polar coordinate system, wherein the angle of the magnetic field direction corresponding to the curve closest to the circle is the direction of the actual magnetic field.

10. The application of the magnetoelectric compass based on the layered magnetoelectric composite material, according to claim 9, is characterized in that each measurement generates two data: the included angle between the length direction of the magnetoelectric composite material and the direction of the magnetic field and the response voltage; the calculation formula of the magnetic field intensity is as follows: h_ac＝V_ME/(α_ME·t_p| cos θ |), each measurement point satisfies: the angles used in calculating the magnetic field strength were: theta₁，θ₂，…，θ_nWith a response voltage of V_ME，1，V_ME，2，…，V_ME，n(ii) a Based on theta₁，θ₂，…，θ_nAnd V_ME，1，V_ME，2，…，V_ME，nThe calculated magnetic field intensity of each test point is equal and is the actual magnetic field intensity; when the magnetic field direction is shifted by Δ θ due to the error, the angle used to calculate the magnetic field strength is: theta₁+Δθ，θ₂+Δθ，…，θ_n+ Δ θ, the calculated magnetic field strength is: the calculated deviation of the magnetic field strength increases significantly as Δ θ increases, whereas the deviation of the magnetic field strength decreases if Δ θ decreases.

Technical Field

The invention belongs to the technical field of sensors, and particularly relates to a magnetoelectric compass based on a layered magnetoelectric composite material and application thereof.

Background

There are many kinds of magnetic field detection sensors including fluxgates, detection coils, hall sensors, magnetodiodes, superconducting quantum interferometers, anisotropic magnetoresistive sensors, giant magnetoresistive sensors, tunneling magnetoresistive sensors, magnetoelectric sensors, and the like. Among the sensors, the magnetoelectric sensor formed by compounding the magnetostrictive material and the piezoelectric/ferroelectric material has the advantages of reliable performance, low price, flexible design, easy manufacture and the like, and has great application potential. The magnetoelectric sensor realizes the sensing of a magnetic field based on a magnetoelectric coupling effect, and the magnetostrictive material and the piezoelectric/ferroelectric material interact through a 'magnetism-elasticity-electricity' coupling theory to realize the mutual conversion from the electric polarization to the magnetization. Due to the 'magneto-elastic-electric' coupling effect of taking strain as a medium, the magnetoelectric sensor based on the principle usually only responds to a direct current magnetic field or an alternating current magnetic field in a certain specific direction, and if the magnetoelectric sensor is used for detecting a magnetic field in any direction, the structure of the magnetoelectric composite material needs to be optimized and improved.

Disclosure of Invention

The invention aims to provide a magnetoelectric compass based on a layered magnetoelectric composite material and application thereof so as to solve the problems.

In order to achieve the purpose, the invention adopts the following technical scheme:

a magnetoelectric compass based on a layered magnetoelectric composite material comprises a piezoelectric material, a magnetostrictive material, a flexible electrode plate, an adhesive, a coil and a rotating platform; the piezoelectric material is in a strip rectangular sheet structure, and electrodes are arranged on the surface of the piezoelectric material; the magnetostrictive material is in a strip rectangular sheet structure, the length of the magnetostrictive material is greater than that of the piezoelectric material, and the piezoelectric material is positioned between the two layers of magnetostrictive materials to form a magnetoelectric composite material; the flexible electrode plate is positioned between the piezoelectric material and the magnetostrictive material; the coil is wound on the magnetoelectric composite material; the magnetoelectric composite material and the coil are fixed on the rotating platform.

Further, the piezoelectric material is a single crystal or polycrystalline ceramic material, specifically AlN, quartz, LiNbO₃、BaTiO₃、 ZnO、Pb(Zr,Ti)O₃、Pb(Mg,Nb)O₃-PbTiO₃、Pb(Zn,Nb)O₃-PbTiO₃、Pb(Ni,Nb)O₃-Pb(Zr,Ti)O₃Or BiScO₃-PbTiO₃One kind of (1).

Further, the electrodes on the piezoelectric material cover two surfaces in the thickness direction, and the electrode material is one of Au, Ag, Al, Cu, Pt, W, Fe, Co, Ni or Ti.

Further, the magnetostrictive material is an alloy or an oxide with magnetostrictive effect or a magnetostrictive composite material formed by compounding the alloy or the oxide with a polymer; in particular Metglas, Tb-Dy-Fe alloy [ Terfenol-D (Tb)_{0.27- 0.30}Dy_0.73-0.70Fe_1.90-1.95)]Nickel iron oxide NiFe₂O₄CoFe, CoFe oxide₂O₄Ni-Mn-Ga alloy Ni₂MnGa or a magnetostrictive composite material formed by compounding the magnetostrictive material with a polymer; the adhesive is epoxy resin.

Furthermore, the flexible electrode plate is of a strip rectangular sheet structure, the size of the flexible electrode plate is matched with that of the piezoelectric material, the conductive material is one of Au, Ag, Al, Cu, Pt or Ni, and the substrate material of the flexible electrode plate is one of polyethylene glycol terephthalate (PET), Polydimethylsiloxane (PDMS), Polyethylene (PE), polyvinyl chloride (PVC) or polypropylene (PP).

Furthermore, the length of the long rectangular sheet structure of the piezoelectric material is 10-30mm, the width is 1-4mm, the thickness is 0.1-0.5mm, and the polarization direction is the thickness direction; the length of the long strip rectangular sheet structure of the magnetostrictive material is 80-120mm, the width is 1-4mm, and the thickness is 0.1-0.5 mm.

The application of the magnetoelectric compass based on the layered magnetoelectric composite material comprises the following steps:

step 1, acquiring test data of the obtained magnetoelectric compass;

step 2, when a group of test data is obtained, the response voltage lowest value is used for corresponding theta₀To determine the extent of the actual magnetic field direction: (theta)₀-Δθ，θ₀+ Δ θ), Δ θ being the deviation of the actual magnetic field direction from the measured magnetic field direction; selecting as many angles as possible in the range, calculating a group of magnetic field intensity data by taking each angle as the magnetic field direction, drawing the corresponding magnetic field angle and magnetic field intensity data in a polar coordinate system, wherein the angle of the magnetic field direction corresponding to the curve closest to the circle is the actual magnetic fieldThe direction of (a);

further, each measurement yields two data: the included angle between the length direction of the magnetoelectric composite material and the direction of the magnetic field and the response voltage; formula for calculating magnetic field intensity H_ac＝V_ME/(α_ME·t_p| cos θ |), each measurement point satisfies: the angles used in calculating the magnetic field strength were: theta₁，θ₂，…，θ_nWith a response voltage of V_ME,1，V_ME,2，…，V_ME,n(ii) a Based on theta₁，θ₂，…，θ_nAnd V_ME,1，V_ME,2，…， V_ME,nThe calculated magnetic field intensity of each test point is equal and is the actual magnetic field intensity; when the magnetic field direction is shifted by Δ θ due to the error, the angle used to calculate the magnetic field strength is: theta₁+Δθ，θ₂+Δθ，…，θ_n+ Δ θ, the calculated magnetic field strength is: the calculated deviation of the magnetic field strength increases significantly as Δ θ increases, whereas the deviation of the magnetic field strength decreases if Δ θ decreases.

Compared with the prior art, the invention has the following technical effects:

the magnetoelectric compass device based on the layered magnetoelectric composite material has the advantages of improving the performance to the maximum extent, reducing the usage amount of the material, along with low price, stable performance and the like. The invention combines the magnetoelectric composite material with the rotary platform, overcomes the defect that the magnetoelectric composite material only has response to a magnetic field in a certain direction, and can simultaneously detect the size and the direction of an in-plane alternating current magnetic field. In addition, the magnetoelectric composite material has a long and thin structure, has a strong beam magnetic effect, is very sensitive to the direction of a magnetic field, and can realize high-sensitivity detection on the strength and the direction of the magnetic field by matching with a rotating platform.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

FIG. 2 is a schematic structural diagram of a magnetoelectric composite material according to the present invention;

FIG. 3 is a graph showing the results of the experimental tests of the present invention.

FIGS. 4(a) -4 (e) are experimental test results of the present invention;

fig. 5(a) -5 (b) are experimental test results of the calibration algorithm of the present invention.

Wherein: 1. a piezoelectric material; 2. a magnetostrictive material; 3. a flexible electrode sheet; 4. an adhesive; 5. a coil; 6. rotating the platform; 7. and (5) calibrating an algorithm.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

referring to fig. 1 to 2, a magnetoelectric compass based on a layered magnetoelectric composite material includes a piezoelectric material 1, a magnetostrictive material 2, a flexible electrode sheet 3, an adhesive 4, a coil 5, and a rotating platform 6; the piezoelectric material 1 is in a strip rectangular sheet structure, and electrodes are arranged on the upper surface and the lower surface of the piezoelectric material; the magnetostrictive material 2 is in a strip rectangular sheet structure, the length of the magnetostrictive material is greater than that of the piezoelectric material, and the piezoelectric material 1 with the flexible electrode plate 3 attached is positioned between the two layers of magnetostrictive materials 2 to form a magnetoelectric composite material; the coil 5 is wound on the magnetoelectric composite material; the magnetoelectric composite material and the coil 5 are fixed on the rotating platform 6.

The piezoelectric material 1 is a single crystal or polycrystalline ceramic material, specifically AlN, quartz, LiNbO₃、BaTiO₃、ZnO、 Pb(Zr,Ti)O₃、Pb(Mg,Nb)O₃-PbTiO₃、Pb(Zn,Nb)O₃-PbTiO₃、Pb(Ni,Nb)O₃-Pb(Zr,Ti)O₃Or BiScO₃-PbTiO₃One kind of (1).

The piezoelectric material 1 is in a long rectangular sheet structure, electrodes on the piezoelectric material 1 cover two opposite surfaces in the thickness direction, and the used material is one of Au, Ag, Al, Cu, Pt, W, Fe, Co, Ni or Ti.

The magnetostrictive material 2 is an alloy or an oxide having a magnetostrictive effect or a magnetostrictive composite material formed by compounding the alloy or the oxide with a polymer. They may be Metglas, Tb-Dy-Fe alloy [ Terfenol-D (Tb)_0.27-0.30Dy_{0.73- 0.70}Fe_1.90-1.95)]Nickel iron oxide (NiFe)₂O₄) Cobalt iron oxide (CoFe)₂O₄) Nickel manganese gallium alloy (Ni)₂MnGa), or a magnetostrictive composite material formed by compounding the above magnetostrictive material with a polymer, the magnetostrictive material 2 has a long rectangular sheet structure, and the length thereof is longer than that of the piezoelectric material 1.

The flexible electrode plate 3 is of a strip rectangular sheet structure, the size of the flexible electrode plate is matched with that of the piezoelectric material 1, the conductive material is one of Au, Ag, Al, Cu, Pt or Ni, and the substrate material of the flexible electrode plate 3 is one of polyethylene glycol terephthalate (PET), Polydimethylsiloxane (PDMS), Polyethylene (PE), polyvinyl chloride (PVC) or polypropylene (PP).

The adhesive 4 is a material with high strength, excellent adhesion performance and good stability, and epoxy resin and the like can be used.

The length of the strip rectangular sheet structure of the piezoelectric material 1 is 10-30mm, the width is 1-4mm, the thickness is 0.1-0.5mm, and the polarization direction is the thickness direction; the length of the long strip rectangular sheet structure of the magnetostrictive material 2 is 80-120mm, the width is 1-4mm, and the thickness is 0.1-0.5 mm.

The coil 5 can be an enameled wire or a conducting wire with a plastic sheath, and the diameter of the conducting part is 0.05-5 mm. The coil 5 surrounds the magnetoelectric composite material formed by the piezoelectric material 1, the magnetostrictive material 2 and the flexible electrode plate 3 to form a solenoid, the axial direction of the solenoid is the length direction of the magnetoelectric composite material, and the length of the solenoid is greater than that of the magnetoelectric composite material.

The core of the magnetoelectric compass is a magnetoelectric composite material (magnetoelectric sensor), and after the coil 5 is electrified with direct current, a direct current bias magnetic field in the length direction is provided for the coil. Due to magnetismThe slender structure design of the magnetoelectric composite material has the advantages that the magnetic field response signal in the width direction of the magnetoelectric composite material can be ignored, and the magnetoelectric composite material only has the response signal to the magnetic field along the length direction of the magnetoelectric composite material. Therefore, the intensity of the external alternating current magnetic field can pass through H_AC,‖＝V_ME/(α_ME·t_p) Performing a calculation in which V_MEIs the response voltage, alpha, of the magnetoelectric composite material_MEIs the magnetoelectric electric field coefficient, t, of the magnetoelectric composite material_pIs the thickness of the piezoelectric material 1. The magnetoelectric voltage coefficient of the magnetoelectric composite material can be determined according to Adjusting, wherein n is the percentage of the thickness of the magnetostrictive material to the total thickness, t is the total thickness of the magnetoelectric composite material, and d_33,mAnd s_33,mRespectively the piezomagnetic coefficient and the elastic compliance constant of the magnetostrictive material, d_31,pAnd s_11,pRespectively, the piezoelectric constant and the elastic compliance constant, k, of the piezoelectric material_coIs the interfacial coupling coefficient, i.e., the percentage of strain imparted to the piezoelectric layer by the magnetostrictive layer.

When the magnetoelectric compass works, the magnetoelectric composite material and the coil rotate for a circle in the plane of an alternating current magnetic field to be measured under the action of the rotating platform. The relationship between the response voltage and the included angle of the magnetic field of the magnetoelectric composite material is V_ME＝α_ME·t_p·H_ACAnd (c) cos theta, wherein theta is an included angle between the length direction of the magnetoelectric composite material and the direction of the alternating current magnetic field. The strength and the direction of an alternating current magnetic field can be obtained through analysis according to response voltage data collected by one rotation of the magnetoelectric composite material through the relational expression, and the detection precision is related to the stepping angle precision of the rotary platform.

The calibration algorithm 7 can further improve the detection accuracy of the magnetic field angle, and the principle is as follows: when rotating in a plane, a gap always exists between two adjacent measured angles, so that the direction of the magnetic field has an error, and the magnitude of the error is determined by the gap. In order to eliminate the error caused by the gap, on the one hand, the gap angle can be directly reduced, but this will require the accuracy of the instrument and will greatly increase the time taken for measurement; alternatively, some calibration algorithm may be added to process the measurement data. Each measurement yields two data: the angle between the length direction of the magnetoelectric composite material and the direction of the magnetic field and the response voltage. Formula for calculating magnetic field intensity H_ac＝V_ME/(α_ME·t_p| cos θ |), because the magnetic field strength is not changed all the time when the magnetoelectric composite material rotates, theoretically, each measurement point should satisfy: the angles used in calculating the magnetic field strength were: theta₁，θ₂，…，θ_nWith a response voltage of V_ME,1， V_ME,2，…，V_ME,n. Theoretically, based on θ₁，θ₂，…，θ_nAnd V_ME,1，V_ME,2，…，V_ME,nAnd the calculated magnetic field intensity of each test point is equal and is the actual magnetic field intensity. When the magnetic field direction is shifted by Δ θ due to the error, the angle used to calculate the magnetic field strength is: theta₁+Δθ，θ₂+Δθ，…，θ_n+ Δ θ, the calculated magnetic field strength is: due to the presence of delta theta, the calculated magnetic field strength at each test point is no longer equal and the deviation of the calculated magnetic field strength increases significantly as delta theta increases. Conversely, if Δ θ is smaller, the deviation of the magnetic field strength is smaller. By using this principle, the measurement accuracy of the magnetic field direction can be further improved. When obtaining a set of test data, the test data can be obtained by first responding to electricityPressing theta corresponding to the lowest value₀To determine the extent of the actual magnetic field direction: (theta)₀-Δθ，θ₀+ Δ θ) (Δ θ is the deviation of the actual magnetic field direction from the measured magnetic field direction). Selecting as many angles as possible in the range, respectively calculating a group of magnetic field intensity data by taking each angle as the magnetic field direction, drawing the corresponding magnetic field angle and magnetic field intensity data in a polar coordinate system, wherein the angle of the magnetic field direction corresponding to the curve closest to the circle is the direction of the actual magnetic field.

A manufacturing method of a magnetoelectric compass based on a layered magnetoelectric composite material comprises the following steps:

step 1, providing a piezoelectric material 1, processing the piezoelectric material into a required size and shape, and ultrasonically cleaning the piezoelectric material by using ultrapure water;

step 2, plating electrodes on the upper surface and the lower surface of the piezoelectric material 1 in a silver paste annealing, evaporation or magnetron sputtering mode and the like;

step 3, polarizing the piezoelectric material 1 in the thickness direction after electrodes are manufactured;

step 4, two flexible electrode plates 3 are attached to two upper end surfaces and two lower end surfaces of the piezoelectric material 1 and used for conducting electric signals;

step 5, providing a magnetostrictive material 2, processing the magnetostrictive material into a required size and a required shape, and cleaning the magnetostrictive material with alcohol;

step 6, adhering the piezoelectric material 1 laminated with the flexible electrode plate 3 between two layers of magnetostrictive materials by using an adhesive 4, wherein the piezoelectric material 1 is positioned at the central position of the magnetostrictive material 2 in the length direction;

step 7, welding a lead at the output end of the flexible electrode plate 3 so as to lead out a signal conveniently;

step 8, winding the coil 5 on the magnetoelectric composite material to form a solenoid, wherein the length direction of the magnetoelectric composite material is overlapped with the axial direction of the coil;

and 9, fixing the magnetoelectric composite material and the coil 5 on the rotating platform 6, wherein the fixed position is the central position of the magnetoelectric composite material.

Step 10, the calibration algorithm 7 is combined with data processing.

FIG. 4 shows the results of the experimental tests of the present invention: (a) the magnetoelectric compass device adopts the working principle that the magnetoelectric composite material rotates for a circle in a plane where a magnetic field is positioned; (b) when the bias direct-current magnetic field is 8Oe, the magnetoelectric coefficient of the magnetoelectric composite material under the alternating-current magnetic field with different frequencies; (c) the device has the strength precision of 0.001Oe according to the sensitivity test result of the magnetic field strength under the alternating current magnetic fields of 10Hz, 100Hz and 1 kHz; (d) the device outputs a voltage signal under an alternating current magnetic field with the size of 3.1Oe and the frequency of 100Hz along the horizontal direction; (e) the device accurately measures the actual direction of the alternating current magnetic field by determining the vertical direction of the alternating current magnetic field, and the angular sensitivity of the alternating current magnetic field is obtained by directly testing the device under the alternating current magnetic field of 100Hz, and the angular precision is +/-0.1 degrees.

FIG. 5 is an experimental test result of the calibration algorithm of the present invention: (a) according to the invention, a calculation result is obtained by reversely deducing the magnetic field strength according to the measured magnetic field angle; (b) in order to calculate the relationship between the standard deviation of the magnetic field intensity and the angle precision of the magnetic field, the angle precision of the alternating current magnetic field is +/-0.02 degrees after calibration under the alternating current magnetic field of 100 Hz.

The above embodiments of the present invention are merely examples for illustrating the present invention, and are not intended to limit the embodiments of the present invention. Variations and modifications in other variations will occur to those skilled in the art upon reading the foregoing description. Not all embodiments are exhaustive. All obvious changes and modifications of the present invention are within the scope of the present invention.