CN107894576B - Integrated low-power-consumption three-axis magnetic field sensor with high Z-direction resolution - Google Patents

Abstract

The invention discloses an integrated low-power-consumption triaxial magnetic field sensor with high Z-direction resolution, which comprises an insulating substrate, track-changing soft magnetic blocks and four magnetic measurement units, wherein the four magnetic measurement units are arranged on the surface of the insulating substrate in a centrosymmetric manner, the track-changing soft magnetic blocks are symmetrically arranged on the four magnetic measurement units by taking the central points of the four magnetic measurement units as centers, and one part of each magnetic measurement unit is positioned right below the track-changing soft magnetic block. Aiming at the problems of insufficient Z-direction resolution, low compensation efficiency and the like in the existing scheme, the invention realizes high-efficiency track change of a Z-direction magnetic field by adopting the track change soft magnetic block and four centrosymmetric magnetic measurement units, can realize aggregation amplification and planarization measurement of a three-axis magnetic field, effectively improves the three-axis orthogonality and the resolution of the Z-direction magnetic field, can realize high-resolution measurement of weak three-axis magnetic field signals and high-efficiency compensation of magnetic hysteresis, and has the advantages of low energy consumption and low cost.

Description

An all-in-one low-power three-axis magnetic field sensor with high Z-direction resolution

technical field

The invention relates to weak magnetic signal detection technology, in particular to an integrated low power consumption three-axis magnetic field sensor with high Z-direction resolution.

Background technique

The three-axis magnetic sensor can directly obtain the three-component information of the magnetic field, and is widely used in military and national economic fields such as target detection, geomagnetic navigation, geological exploration, and biomedicine. At the same time, with the continuous improvement of the requirements for weak magnetic field detection and miniaturization of the carrying platform, the magnetic sensor technology presents a development trend of high resolution, small size, and low power consumption.

With the development of micro-electromechanical systems (MEMS) technology, the integrated three-axis magnetic sensor manufactured by MEMS technology has shown great advantages in terms of volume, weight, power consumption and reliability, and can effectively solve the problem of traditional assembly methods. The problem of poor orthogonality of the three-axis magnetic sensor, but the existing MEMS three-axis magnetic field sensor still has certain deficiencies, especially in the high-resolution measurement of the Z-direction magnetic field and hysteresis nonlinear suppression.

The biggest difficulty in the integrated manufacturing of the three-axis magnetic sensor lies in the high-resolution measurement of the Z-direction magnetic field. Although the three-axis magnetic sensor based on the Hall magnetic sensitive unit and Lorentz force resonance can guarantee the orthogonality well, the resolution is generally not high; To achieve high-resolution measurement requirements, but the MR sensitive unit is usually only sensitive to the magnetic field in the X or Y direction in the plane, but not sensitive to the magnetic field in the Z direction. In general, the integrated three-axis magnetic field sensor has better orthogonality than the assembled three-axis magnetic field sensor, and the miniaturization of the MR sensor can also be realized by using micro-machining technology; but the MR sensitive unit only detects the magnetic field in the plane Sensitive, insensitive to magnetic fields perpendicular to the plane. There are two main ways to solve this problem:

1. Prepare the magnetic sensitive unit on the inclined surface of the substrate, such as: 1. Etch a pit or a boss on the substrate, prepare the MR sensitive unit on the inclined side, and use the circuit unit to synthesize the output signals of each sensitive unit Obtain Z-direction magnetic field after treatment (patent application number is US20120068698 US Patent Document); 2. Anisotropically etch the second surface on the first surface of the single crystal silicon substrate, and form a silicon The included angle (54.74°) determined by the crystal structure, and then the MR sensitive unit is prepared on the second surface. Since the MR sensitive unit forms a certain included angle with the substrate plane, the Z-direction magnetic field can be measured. However, the performance of the MR sensitive unit on the slope is poor due to the oblique incidence in the preparation process of the above scheme, which greatly affects the Z-direction magnetic field measurement.

2. The Z-direction magnetic field in the vertical plane is diverted to the plane by using the magnetic flux track structure, and then the high-resolution MR magnetic sensor unit is used for measurement, which is expected to realize three-axis high orthogonality and high resolution at the same time. There are also many proposals for measuring the Z-direction magnetic field based on the above ideas. Such as: 1. Separate soft magnetic concentrators are prepared on both sides of the MR sensitive unit, and a small part of the Z-direction magnetic force line is twisted and guided into the plane for measurement (the US patent document with the patent number US7505233B2), but the Z-direction magnetic field of this scheme is turned The efficiency is very low, generally only a few percent; 2. The magnetic orbit concentrators on both sides of the MR sensitive unit are located in a pit, and the magnetic field orbit in the Z direction is realized through the magnetic concentrators in the pit and on the slope of the pit ( Publication number is the Chinese patent document of CN103116143A); 3, the base that is loaded with MR sensitive unit is placed on the base that is provided with a pit, and soft magnetic block is placed in the pit (publication number is the Chinese patent document of CN103323795A), relatively The previous scheme effectively improved the resolution of the Z-direction magnetic field, but the further improvement of the Z-direction magnetic field resolution was limited due to the limited thickness of the soft magnetic block in the pit and the fact that the soft magnetic block was far away from the plane of the MR sensitive unit.

Aiming at the problem that hysteresis restricts the improvement of the accuracy of magnetic field sensors, some units have carried out relevant research on reducing the nonlinear influence of hysteresis. The Institute of Systems Engineering and Computing in Portugal designed the magnetic structure of the MTJ free layer to reduce the hysteresis of the MTJ magnetic field response curve and effectively improved the performance of the magnetic sensor. However, it is difficult to accurately control the nanostructure of the MTJ free layer, and the effect limited; based on the mathematical model of the hysteresis loop, the University of Erlangen-Nuremberg in Germany has established a nonlinear algorithm for reducing hysteresis, which effectively reduces the nonlinear influence of hysteresis, but its calculation results will make the magnetic field measurement The value produces a certain error; the National University of Defense Technology (the Chinese patent document with the publication number CN103323794A) directly proceeds from the physical mechanism of the hysteresis, and designs a planar microcoil for magnetic field compensation. The coil has the advantages of simple structure and convenient preparation, and effectively reduces the hysteresis of the magnetic field sensor. However, the planar coil structure of this scheme is loose, and the compensation efficiency of the outer coil decreases rapidly, and there are problems such as low compensation efficiency and large space occupation. .

Contents of the invention

The technical problem to be solved by the present invention: Aiming at the problems of insufficient Z-direction resolution and low compensation efficiency in the existing solutions, a method is provided to realize the high Z-direction magnetic field by using track-changing soft magnetic blocks and four centrally symmetrical magnetic measurement units. Efficiency change track can realize the aggregation amplification and planar measurement of the three-axis magnetic field, which effectively improves the three-axis orthogonality and the resolution of the Z-direction magnetic field, and can realize high-resolution measurement of weak three-axis magnetic field signals, high-efficiency hysteresis compensation, An integrated low-power three-axis magnetic field sensor with low energy consumption and low cost and high Z-direction resolution.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

An integrated low-power three-axis magnetic field sensor with high Z-direction resolution, including an insulating substrate, a track-changing soft magnetic block, and four magnetic measurement units, the four magnetic measurement units are symmetrically arranged on the surface of the insulating substrate The track-changing soft magnetic block is symmetrically placed on the four magnetic measuring units with the center points of the four magnetic measuring units as the center, and a part of each magnetic measuring unit is located directly below the track-changing soft magnetic block.

Preferably, the magnetic measurement unit includes a magnetic flux concentrator, a compensation coil and a magnetic sensitive unit, the magnetic flux concentrator is a ring structure with a central axis in the middle, a gap is provided on the central axis, and the compensation coil winds Located on both sides of the gap on the central axis, the magnetic sensitive unit is a Wheatstone bridge composed of two sensitive magnetoresistances and two reference magnetoresistances, the two sensitive magnetoresistances are arranged in the gap of the insulating substrate, The two reference magnetoresistors are located in the magnetic field shielding area below the magnetic flux concentrator, and the two drive electrodes of the compensation coil, the two drive electrodes of the magnetic sensitive unit and the output electrodes are all arranged on an insulating substrate.

Preferably, the gaps are arranged at an angle of 45° to the central axis, and the gaps in all the magnetic measurement units face the same direction.

Preferably, the magnetic flux concentrator is made by growing a high-permeability film on an insulating substrate, or by electroplating or sputtering on an insulating substrate.

Preferably, the widths of both ends of the central axis gradually become smaller toward the middle.

Preferably, the compensation coil includes an upper layer coil and a lower layer coil, the upper layer coil is located on the upper surface of the central axis, the lower layer coil is located on the lower surface of the central axis, the upper layer coil and the lower layer coil jointly form a ring coil structure and are wound at both ends of the axis.

Preferably, the upper layer coil and the lower layer coil are formed by electroplating and film formation.

Preferably, both the sensitive magnetoresistance and the reference magnetoresistance are tunnel magnetoresistance sensors TMR.

Preferably, the track-changing soft magnetic block is fixed on the planar structure formed by the magnetic flux concentrator and the compensation coil by means of epoxy glue bonding.

Preferably, the insulating substrate is intrinsic silicon on which an insulating layer is deposited on the surface through gas-phase chemical reaction.

The integrated low-power three-axis magnetic field sensor with high Z-direction resolution of the present invention has the following advantages:

1. The present invention includes an insulating base, a track-changing soft magnetic block and four magnetic measuring units, and the four magnetic measuring units are symmetrically arranged on the surface of the insulating base, and the track-changing soft magnetic block uses four magnetic measuring units The center point is symmetrically placed on the four magnetic measurement units, and a part of each magnetic measurement unit is located directly under the track-changing soft magnetic block. The track-changing soft magnetic block and four magnetic measuring units are used to achieve high Z-direction magnetic field. Efficiency change track realizes the aggregation and amplification of the three-axis magnetic field and planar measurement, which can effectively improve the orthogonality of the three axes and the resolution of the Z-direction magnetic field.

2. The structure of the present invention can be prepared by MEMS technology, and has the advantages of small volume and simple realization.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the front view of the embodiment of the present invention.

FIG. 2 is a schematic diagram of the cross-sectional structure along line A-A of FIG. 1 .

FIG. 3 is a schematic structural diagram of a magnetic sensitive unit according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of a magnetic measurement unit according to an embodiment of the present invention.

Legend: 1. Insulation base; 2. Orbit-changing soft magnetic block; 3. Magnetic measurement unit; 31. Magnetic field line concentrator; 311. Central axis; 312. Gap; 32. Compensation coil; 321. Upper layer coil; 322. Lower layer Coil; 33, magnetic sensitive unit; 331, sensitive magnetic resistance; 332, reference magnetic resistance.

Detailed ways

As shown in Figure 1, the integrated low-power three-axis magnetic field sensor with high Z-direction resolution of the present embodiment includes an insulating substrate 1, a track-changing soft magnetic block 2 and four magnetic measurement units 3 (magnetic measurement unit 3#1 ～magnetic measurement unit 3#4), four magnetic measurement units 3 (magnetic measurement unit 3#1～magnetic measurement unit 3#4) are symmetrically arranged on the surface of the insulating substrate 1, and the track-changing soft magnetic block 2 is composed of four The center point of the magnetic measurement unit 3 is symmetrically placed on the four magnetic measurement units 3 , and a part of each magnetic measurement unit 3 is located directly below the track-changing soft magnetic block 2 . The integrated low-power three-axis magnetic field sensor of this embodiment uses the track-changing soft magnetic block 2 and four magnetic measurement units 3 to realize high-efficiency track changing of the Z-direction magnetic field, and realizes the aggregation and amplification of the three-axis magnetic field and planar measurement. It can effectively improve the three-axis orthogonality and the resolution of the Z-direction magnetic field.

In this embodiment, the insulating substrate 1 is intrinsic silicon on which an insulating layer is deposited on the surface through a vapor phase chemical reaction.

As shown in Figure 2, the track-changing soft magnetic block 2 is a block-shaped structure made of high-permeability soft-magnetic material, and the track-changing soft magnetic block 2 is fixed on the magnetic force line concentrator 31 and the compensation coil 32 by epoxy glue bonding. composed of planar structures. Based on this structure, the parameters such as the height of the track-changing soft magnetic block 2 can not be restricted by the thick film preparation capability in the MEMS process (it can be increased from the original tens of microns to several millimeters), which is conducive to improving the Z-direction magnetic field. The orbit changing efficiency can overcome the disadvantage of low Z-direction magnetic field resolution caused by insufficient orbit changing efficiency.

As shown in Fig. 1, Fig. 2, Fig. 3 and Fig. 4, the magnetic measurement unit 3 includes a magnetic force line concentrator 31, a compensation coil 32 and a magnetic sensitive unit 33, and the magnetic force line concentrator 31 is an annular structure with a central axis 311 in the middle, There is a gap 312 on the central axis 311, and the compensation coil 32 is wound on both sides of the gap 312 on the central axis 311. The magnetic sensitive unit 33 is a Wheatstone bridge composed of two sensitive magnetic resistances 331 and two reference magnetic resistances 332. , two sensitive magnetoresistors 331 are arranged in the gap 312 of the insulating substrate 1, two reference magnetoresistors 332 are located below the magnetic field line concentrator 31 (the location is in the magnetic field shielding area, the magnetic field is shielded and cannot be sensitive to the magnetic field), and the compensation coil 32 two driving electrodes (for accessing the compensation current for the compensation coil 32), two driving electrodes of the magnetic sensitive unit 33 (for supplying power to the magnetic sensitive unit 33) and output electrodes (for outputting the magnetic sensitive unit 33 detection signals) are arranged on the insulating substrate 1. The magnetic measurement unit 3 has the following advantages: 1. the compensation coil 32 is wound on the central axis 311 of the magnetic field line concentrator 31, the compensation coefficient is large, and the compensation current and power consumption are small; 2. the gap between the compensation coil 32 and the central shaft 311 is The two sides of 312 make the two sides of the gap 312 of the magnetic flux concentrator 31 form a secondary side, which can make the magnetic field of the compensation coil 32 form a loop, improve the compensation coefficient of the compensation coil 32, and reduce the power consumption of the compensation coil 32.

Referring to Fig. 3, four magnetic measurement units 3 (magnetic measurement unit 3#1～magnetic measurement unit 3#4) include four magnetic sensitive units 33 (magnetic sensitive unit 33#1～magnetic sensitive unit 33#4), each A magneto-sensitive unit 33 is a Wheatstone bridge composed of two sensitive magnetoresistances 331 and two reference magnetoresistances 332 . Sensitive magnetoresistors 331 are two non-adjacent magnetoresistors in the Wheatstone bridge, which are located in the gap and can be sensitive to magnetic fields, and their resistance value becomes R ₀ +ΔR. The reference magnetoresistance 332 is another two non-adjacent magnetoresistances in the Wheatstone bridge, located below the magnetic force concentrator, subjected to the shielding insensitive magnetic field of the magnetic force concentrator, and its resistance value R does _not change; in this embodiment , two sensitive magnetoresistances 331 and two reference magnetoresistances 332 form a half-bridge Wheatstone bridge. Under the action of the power supply voltage _Vc , the output of a single magnetic sensitive unit 33 is shown in formula (1):

In formula (1), V _o represents the output of a single magnetic sensitive unit 33, R ₀ is the resistance value of the reference magnetic resistance 332, R ₀ +△R is the resistance value of the sensitive magnetic resistance 331, △R is the sensitive magnetic resistance 331 and Referring to the resistance difference (sensing resistance) of the magnetic resistor 332 , V _c is the power supply voltage input to the magnetic sensitive unit 33 .

Referring to Fig. 1, Fig. 3 and Fig. 4, each magnetic measuring unit 3 comprises six electrodes in total: two driving electrodes of the compensation coil 32 (for accessing the compensation current for the compensation coil 32), two electrodes of the magnetic sensitive unit 33 The driving electrodes (for supplying power to the magnetic sensitive unit 33 ) and the output electrodes (for outputting the detection signal of the magnetic sensitive unit 33 ), the four magnetic measurement units 3 include twenty-four electrodes in total. The electrodes of the magnetic sensitive unit 33#1～magnetic sensitive unit 33#4 are as follows: the two drive electrodes of the magnetic sensitive unit 33#1 are _Vc and GND, and the two output electrodes of the magnetic sensitive unit 33# ₁ are V11 and V ₁₂ , the two driving electrodes of the magnetic sensitive unit 33#2 are V _c and GND, the two output electrodes of the magnetic sensitive unit 33#1 are V ₂₁ and V ₂₂ , the two driving electrodes of the magnetic sensitive unit 33#3 are V _c and GND, the two output electrodes of the magnetic sensitive unit 33#1 are V ₃₁ and V ₃₂ , the two drive electrodes of the magnetic sensitive unit 33#4 are V _c and GND, the two output electrodes of the magnetic sensitive unit 33#1 The electrodes are V ₄₁ and V ₄₂ . There is no doubt that the driving electrodes of the magnetic sensitive unit 33#1 ~ magnetic sensitive unit 33#4 can be powered independently or in parallel as required. The principle is the same as this embodiment, so in This will not be repeated here.

As shown in FIG. 1 and FIG. 4 , the gap 312 is arranged at an angle of 45° to the central axis 311 , and the gaps 312 in all the magnetic measurement units 3 face the same direction. The directions of the gaps 312 on the four magnetic field line concentrators 31 are in the same direction, so that the sensitive directions of the sensitive magnetoresistances 331 of all the magnetic sensitive units 33 can be in the same direction (perpendicular to the long side direction of the gaps 312), avoiding the same insulating substrate 1, the difficulty in preparing the sensitive magnetoresistance 331 with different sensitive directions greatly reduces the difficulty of preparing the sensitive magnetoresistance 331 , and at the same time eliminates the mutual influence between the sensitive magnetoresistance 331 with different sensitive directions.

In this embodiment, the magnetic force line concentrator 31 is made by growing a high-permeability film on the insulating substrate 1 , and it can also be made by electroplating or sputtering on the insulating substrate 1 as required. Prepared by MEMS technology, it has the advantages of small volume and simple implementation. In this embodiment, the four magnetic flux concentrators 31 (magnetic flux concentrator 31#1 to magnetic flux concentrator 31#4) of the four magnetic measuring units 3 (magnetic measuring unit 3#1 to magnetic measuring unit 3#4) have the same structure , with gaps 312 in the middle, all made of high permeability soft magnetic materials (such as NiFe, CoZrNb, etc.), and distributed symmetrically about the plane center of the insulating substrate 1 .

As shown in FIG. 1 and FIG. 4 , the width of both ends of the central axis 311 gradually decreases toward the middle, which can effectively enhance the magnetic force concentration effect of the magnetic force concentrator 31 and improve the resolution of the magnetic field sensor. In this embodiment, both ends of the central axis 311 are provided with symmetrical wedge-shaped structures, and the width of the two ends of the central axis 311 gradually decreases toward the middle through the symmetrical wedge-shaped structures, so that the two ends are thick and the middle is small. Enhance the concentration effect of magnetic field lines and improve the resolution of the magnetic field sensor.

As shown in Figure 2, the compensation coil 32 includes an upper layer coil 321 and a lower layer coil 322, the upper layer coil 321 is located on the upper surface of the central axis 311, the lower layer coil 322 is located on the lower surface of the central axis 311, the upper layer coil 321 and the lower layer coil 322 form a ring together The coil-like structure is wound on both ends of the central shaft 311 . The compensation coil 32 is directly wound on the central axis 311 of the magnetic flux concentrator 31 , the compensation magnetic field generated at the gap 312 is relatively large, and the required compensation current is relatively small, thereby reducing power consumption. The compensation coil 32 generates a corresponding magnetic field so that the magnetic field at the gap 312 is in a relatively stable state, which can reduce the influence of hysteresis and nonlinear factors.

In this embodiment, the upper layer coil 321 and the lower layer coil 322 are made by electroplating film formation, the thickness of the electroplating film is relatively large, the step coverage on the side of the coil is good, the coil resistance is small, and the power consumption is low. However, the preparation method of the upper layer coil 321 and the lower layer coil 322 is not limited to the electroplating method.

In this embodiment, both the sensitive magnetoresistance 331 and the reference magnetoresistance 332 are tunnel magnetoresistance sensors TMR.

In this embodiment, the track-changing soft magnetic block 2 and four magnetic measurement units 3 (magnetic measurement unit 3#1 to magnetic measurement unit 3#4) jointly constitute the basic structure of the three-axis magnetic field sensor, and the measurement of the three-axis magnetic field The decoupling principle is as follows:

The magnetic fields measured by the four magnetic measurement units 3 (magnetic measurement unit 3#1 to magnetic measurement unit 3#4) are shown in formula (2):

In formula (2), B ₁ ~ B ₄ are the magnetic fields measured by magnetic measurement unit 3#1 ~ magnetic measurement unit 3#4 respectively, G is the magnetic field magnification of the magnetic flux concentrator, B _ext-x , B _ext-y , B _ext-z are the three components of the measured magnetic field; k is the orbital coefficient, which is jointly determined by the orbital soft magnetic block 2 and the four magnetic measurement units 3, and represents the efficiency of the Z-direction magnetic field turning into a planar magnetic field .

The calculation formula of the three-component magnetic field can be obtained by decoupling as shown in formula (3):

In formula (3), B _ext-x , B _ext-y , B _ext-z are the three components of the measured magnetic field, and B ₁ ~ B ₄ are the magnetic measurement unit 3#1 ~ magnetic measurement unit 3#4 The measured magnetic field, G is the magnetic field magnification of the magnetic force line concentrator; k is the orbital coefficient, which is determined by the orbital soft magnetic block 2 and the four magnetic measurement units 3, indicating the efficiency of the Z-direction magnetic field turning into a planar magnetic field . Therefore, the use of the track-changing soft magnetic block 2 and the four magnetic measurement units 3 can realize the high-efficiency track change of the Z-direction magnetic field, realize the aggregation and amplification of the three-axis magnetic field and planar measurement, and can effectively improve the three-axis orthogonality and Z resolution of the magnetic field.

The above descriptions are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions under the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principles of the present invention should also be regarded as the protection scope of the present invention.

Claims (9)

1. An integrated low-power three-axis magnetic field sensor with high Z-direction resolution, characterized in that it includes an insulating substrate (1), a track-changing soft magnetic block (2) and four magnetic measurement units (3). The four magnetic measurement units (3) are symmetrically arranged on the surface of the insulating substrate (1), and the track-changing soft magnetic block (2) is symmetrically placed on the four sides with the center points of the four magnetic measurement units (3) as the center. On each magnetic measurement unit (3), a part of each magnetic measurement unit (3) is located directly below the track-changing soft magnetic block (2); the magnetic measurement unit (3) includes a magnetic field line concentrator (31), a compensation coil (32) and a magnetic sensitive unit (33), the magnetic field line concentrator (31) is a ring structure with a central axis (311) in the middle, and a gap (312) is provided on the central axis (311), the The compensation coil (32) is wound on both sides of the gap (312) of the central axis (311), and the magnetic sensitive unit (33) is composed of two sensitive magnetoresistances (331) and two reference magnetoresistances (332) Wheatstone bridge, the two sensitive magnetoresistances (331) are arranged in the gap (312) of the insulating substrate (1), and the two reference magnetoresistances (332) are located in the magnetic field shielding below the magnetic field line concentrator (31) In the area, the two drive electrodes of the compensation coil (32), the two drive electrodes of the magnetic sensitive unit (33) and the output electrodes are all arranged on the insulating substrate (1). 2. The integrated low-power three-axis magnetic field sensor with high Z-direction resolution according to claim 1, characterized in that: the gap (312) is arranged at an angle of 45° to the central axis (311), and all magnets The gaps ( 312 ) in the measuring unit ( 3 ) face in the same direction. 3. The integrated low-power three-axis magnetic field sensor with high Z-direction resolution according to claim 1, characterized in that: the magnetic field line concentrator (31) is grown on the insulating substrate (1) through a high magnetic permeability film made, or made by electroplating or sputtering on an insulating substrate (1). 4. The integrated three-axis magnetic field sensor with high Z-direction resolution and low power consumption according to claim 1, characterized in that: the width of both ends of the central axis (311) gradually decreases toward the middle. 5. The integrated low-power three-axis magnetic field sensor with high Z-direction resolution according to claim 1, characterized in that: the compensation coil (32) includes an upper layer coil (321) and a lower layer coil (322), the The upper coil (321) is located on the upper surface of the central axis (311), the lower coil (322) is located on the lower surface of the central axis (311), and the upper coil (321) and the lower coil (322) together form a ring coil structure And wound around the two ends of the central axis (311). 6. The integrated low-power three-axis magnetic field sensor with high Z-direction resolution according to claim 5, characterized in that: the upper layer coil (321) and the lower layer coil (322) are made by electroplating and film formation . 7. The integrated low-power three-axis magnetic field sensor with high Z-direction resolution according to claim 2, characterized in that: the sensitive magnetoresistance (331) and the reference magnetoresistance (332) are both tunnel magnetoresistance sensors TMR. 8. The integrated low-power three-axis magnetic field sensor with high Z-direction resolution according to claim 1, characterized in that: the track-changing soft magnetic block (2) is fixed on the magnetic force line by epoxy glue bonding The concentrator (31) and the compensating coil (32) are on a planar structure. 9. The integrated low-power three-axis magnetic field sensor with high Z-direction resolution according to any one of claims 1 to 8, characterized in that: the insulating substrate (1) is deposited on the surface by a gas-phase chemical reaction layer insulating layer of intrinsic silicon.