Efficient TMR current sensor and material fixing method thereof

Abstract

The invention discloses a high-efficiency TMR current sensor and a material fixing method thereof. The high-efficiency TMR current sensor comprises a magnetic core and a winding surrounding the magnetic core, the switch is connected in series with the winding; the magnetic core is made of permalloy materials. Performing multi-dimensional simulation analysis on the magnetic core and the state in the air gap of the magnetic core; determining the influence of each data of the magnetic core on the magnetic flux at the air gap; determining a preferred condition of the magnetic core based on the tunneling magnetoresistance effect; and searching a chip template conforming to a preferred condition, and calculating the width d of an air gap opening to complete material fixing. According to the method, the complete structure of the magnetic core, the preferable material required for manufacturing and the preferable size are confirmed, the process comprises multi-dimensional simulation and experimental analysis, high-precision current detection is confirmed, meanwhile, the material fixing policy of the sensor with the small size is determined, and the accurate size is calculated.

Description

Technical Field

[0001] The invention relates to the field of current sensors, in particular to a high-efficiency TMR current sensor and a material determination method thereof. Background Art

[0002] The accuracy of traditional current sensors is usually low. Due to the limitations of their design and manufacturing process, it is particularly difficult to detect tiny currents. They are usually large in size and not easy to integrate into compact circuits or systems. There is often a nonlinear relationship between the output and input current of traditional current sensors, which increases the complexity of calibration and application. The material determination method cannot be refined through conventional means and existing material research. The present invention proposes an open-loop TMR current sensor device based on the tunnel magnetoresistance (TMR) effect, which has the characteristics of high sensitivity, high linearity, low temperature coefficient, etc. By optimizing the material and structural design of the magnetoresistance, the volume of the sensor is reduced, while ensuring the measurement accuracy and response speed of the sensor. In the optimization process, a relatively complete and logically clear material determination method is also adopted, involving multi-dimensional detection and calculation of the effects on the efficacy of the device. Summary of the invention

[0003] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the title of the invention of this application to avoid blurring the purpose of this section, the abstract of the specification and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0004] In view of the fact that the traditional current sensors mentioned above and / or existing in the prior art are generally of low accuracy, are limited by their design and manufacturing processes, are particularly difficult to detect tiny currents, are generally large in size and are not easily integrated into compact circuits or systems, the present invention is proposed.

[0005] Therefore, the technical problem to be solved by the present invention is to reduce the volume of the sensor by optimizing the material and structural design of the magnetoresistance while ensuring the measurement accuracy and response speed of the sensor.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: an efficient TMR current sensor, comprising a magnetic core, and a winding surrounding the magnetic core;

[0007] A switch is connected in series with the winding;

[0008] The magnetic core is made of Permalloy material.

[0009] As a preferred solution of the high-efficiency TMR current sensor described in the present invention, wherein: the magnetic core comprises an outer diameter R, an inner diameter r, and a height h;

[0010] The magnetic core is provided with an air gap, and the opening width is d;

[0011] The outer diameter R and the inner diameter r are positively correlated with the magnetic induction intensity at the air gap;

[0012] The height h is positively correlated with the magnetic induction intensity at the air gap in the range of 5 to 15 mm.

[0013] As a preferred solution of the high-efficiency TMR current sensor of the present invention, wherein: the outer diameter R is 80 mm, the inner diameter r is 60 mm, and the height h is 10 mm;

[0014] The opening width d is 20 mm;

[0015] The winding has 1200 turns.

[0016] As a preferred solution of the high-efficiency TMR current sensor described in the present invention, the TMR chip is placed at the air gap, and the object to be measured is placed at the annular center of the magnetic core.

[0017] The beneficial effects of the present invention are as follows: the magnetoresistance, that is, the complete structure of the magnetic core, as well as the preferred materials and preferred dimensions required for its manufacture are confirmed.

[0018] Given that there is often a nonlinear relationship between the output and input current of traditional current sensors, which increases the complexity of calibration and application, the material determination method cannot be refined through conventional means and existing material research content. Therefore, the technical problem to be solved by the present invention is to adopt a relatively complete and logically clear material determination method, involving multi-dimensional detection and calculation of the impact on the efficacy of the device.

[0019] In order to solve the above technical problems, the present invention also provides the following technical solutions: a high-efficiency TMR current sensor material determination method, comprising the high-efficiency TMR current sensor, and,

[0020] As a preferred solution of the high-efficiency TMR current sensor material determination method described in the present invention, wherein: a multi-dimensional simulation analysis is performed on the state of the magnetic core and its air gap;

[0021] Establish the influence of various core data on the magnetic flux at the air gap;

[0022] Determining the optimal conditions of the magnetic core based on the tunnel magnetoresistance effect;

[0023] Find the chip template that meets the optimal conditions and calculate the air gap opening width d to complete the material determination.

[0024] As a preferred solution of the high-efficiency TMR current sensor material determination method described in the present invention, wherein: by analyzing and simulating the reference factors through Maxwell, a parameter model is first obtained, that is,

[0025] The R is 80 mm, the r is 40 mm, the height h is 10 mm, the opening width d is 20 mm, the magnetic permeability is 100000 H / m, and the conductor current is 1000 A;

[0026] That is, the reference factors include R, r, h, d, magnetic permeability, and wire state.

[0027] As a preferred solution of the material determination method of a high-efficiency TMR current sensor described in the present invention, wherein: size simulation analysis 1, setting the r unchanged, R changes from 80mm to 120mm, that is, the core width becomes 40mm, and the simulation step length is 5mm;

[0028] During the process, the magnetic induction intensity at the air gap first increased and then decreased, with the maximum increase intensity being 1.91 mT and the volume increasing by 1.6 times.

[0029] As a preferred solution of the material determination method of a high-efficiency TMR current sensor described in the present invention, in which: size simulation analysis 2, the core width is set to remain unchanged, R changes from 80mm to 120mm, that is, r becomes 40mm, and the simulation step is 5mm;

[0030] During the process, the magnetic induction intensity at the air gap did not change at first and then decreased, and the volume increased by 0.7 times.

[0031] As a preferred solution of the material determination method of a high-efficiency TMR current sensor described in the present invention, in which: Dimension simulation analysis three, the core width, R, and r are set to remain unchanged, h changes from 5mm to 30mm, and the simulation step length is 5mm;

[0032] During the process, the magnetic induction intensity at the air gap increases continuously within the range of 5 mm to 15 mm, and there is no change after 15 mm. When h is 30 mm, the magnetic induction intensity increases by 2.07 mT compared with h being 10 mm, and the volume increases by 0.2 times.

[0033] As a preferred solution of the material determination method of a high-efficiency TMR current sensor described in the present invention, wherein: in the magnetic permeability simulation analysis, the magnetic core width, R, r, and h are set to remain unchanged, and the magnetic permeability changes from 50000 H / m to 500000 H / m, and the simulation step size is 10000 H / m when the range is 50000 to 100000 H / m, and is 100000 H / m when the range is 100000 to 200000 H / m;

[0034] The magnetic induction intensity increases in direct proportion to the magnetic permeability within the range of 50000 to 200000 H / m of the simulation step of magnetic permeability;

[0035] The growth trend of magnetic induction slows down when the simulation step of magnetic permeability is within the range of 200000 to 500000 H / m;

[0036] After the simulation step of magnetic permeability is greater than 500000 H / m, the growth trend of magnetic flux density is infinitely close to but not equal to 0.

[0037] As a preferred solution of the material determination method of the efficient TMR current sensor described in the present invention, the wire eccentricity simulation analysis is performed, the initial position of the wire is set to be placed at the center of the magnetic core, the center of the magnetic core is taken as the axis, and the change of the magnetic induction intensity of the wire at different Y coordinates is calculated.

[0038] The conductor coordinates vary from -15 mm to 15 mm, the simulation step is 5 mm, and the maximum difference in magnetic induction intensity at different positions is 1.92 mT.

[0039] As a preferred solution of the material determination method of a high-efficiency TMR current sensor described in the present invention, wherein: based on the above simulation process, it is confirmed that the best preferred condition of the magnetic core is a high magnetic permeability metal, the magnetic core material is set to Permalloy, and the TMR chip is TMR2503;

[0040] Substituting the core size into Ampere's loop law and the basic formula of magnetic circuit, the opening width d is obtained to be 20 mm.

[0041] Beneficial effects of the present invention: Through multi-dimensional simulation and experimental analysis, the material selection policy of the sensor with high-precision current detection and small volume is confirmed, and the accurate size is calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0043] Figure 1 A schematic diagram of the structure of a high-efficiency TMR current sensor according to an embodiment of the present invention;

[0044] Figure 2 A Maxwell simulation model of a high-efficiency TMR current sensor according to an embodiment of the present invention;

[0045] Figure 3A curve analysis diagram of magnetic induction intensity at the air gap and magnetic core width of a high-efficiency TMR current sensor according to an embodiment of the present invention;

[0046] Figure 4 A curve analysis diagram of the magnetic induction intensity at the air gap and the inner diameter of the magnetic core of a high-efficiency TMR current sensor according to an embodiment of the present invention;

[0047] Figure 5 A curve analysis diagram of magnetic induction intensity at the air gap and magnetic core height of a high-efficiency TMR current sensor according to an embodiment of the present invention;

[0048] Figure 6 A curve analysis diagram of the magnetic induction intensity at the air gap and the relative magnetic permeability of the magnetic core of a high-efficiency TMR current sensor according to an embodiment of the present invention;

[0049] Figure 7 An analysis diagram of magnetic induction intensity curves at air gaps under different Y coordinates for a high-efficiency TMR current sensor according to an embodiment of the present invention;

[0050] Figure 8 A coordinate diagram showing the relationship between the output voltage of a TMR chip and the strength of an applied magnetic field of a high-efficiency TMR current sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0052] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0053] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0054] Furthermore, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0055] Example 1

[0056] Reference Figure 1 , this embodiment provides a high-efficiency TMR current sensor, including a magnetic core 100, and a winding 100a surrounding the magnetic core 100;

[0057] The switch 100b is connected in series with the winding 100a;

[0058] The magnetic core 100 is made of Permalloy material.

[0059] The basic TMR current sensor structure can achieve seamless connection between large current and small current measurement scenarios through switch switching: when measuring large current, the switch is closed, and the TMR chip will not be saturated under the magnetic field of the large current within the measurement range; when measuring small current, the switch is disconnected, and the switch is subjected to open-circuit voltage, and there will be no problem of excessive open-circuit voltage affecting safety, and the magnetic flux is not reduced at this time, so the accuracy of small current can be guaranteed.

[0060] The high magnetic permeability and saturation magnetic flux density of Permalloy can provide a relatively high magnetic flux density at the air gap 100 c , thus ensuring high feedback efficiency.

[0061] Example 2

[0062] Reference Figure 5 , which is a second embodiment of the present invention, and is based on the previous embodiment, and is different from the previous embodiment in that: the magnetic core 100 comprises an outer diameter R, an inner diameter r, and a height h;

[0063] The magnetic core 100 is provided with an air gap 100c, and the opening width is d;

[0064] The outer diameter R and the inner diameter r are positively correlated with the magnetic induction intensity at the air gap 100c;

[0065] The height h is positively correlated with the magnetic induction intensity at the air gap 100c in the range of 5 to 15 mm.

[0066] The outer diameter R is 80mm, the inner diameter r is 60mm, and the height h is 10mm;

[0067] The opening width d is 20 mm;

[0068] The winding 100a has 1200 turns.

[0069] The TMR chip is placed at the air gap 100 c , and the object to be tested is placed at the annular center of the magnetic core 100 .

[0070] The performance of the open-loop TMR current sensor is affected by the temperature drift, process, stray electromagnetic field and other factors of the TMR element itself. Temperature drift refers to the phenomenon that the sensor has zero drift caused by changes in ambient temperature, that is, when the current to be measured is zero, the output voltage of the TMR sensor is not zero, and due to process limitations, the initial resistance values ​​of the four magnetoresistive elements inside the TMR sensor may be different, and the TMR sensor will output a certain bias voltage;

[0071] Furthermore, a compensation link needs to be designed to offset its voltage offset. The stray magnetic field in the surrounding environment will also cause a bias voltage to exist in the output of the TMR current sensor. Adding a magnetic core to concentrate the magnetic flux will reduce the influence of the stray magnetic field and reduce the influence of the electromagnetic field generated by the external interference source on the TMR current sensor measurement.

[0072] To suppress the saturation phenomenon of the magnetic core, an air gap is opened in the magnetic core. After adding the air gap, the forward interaction force between the magnetic domains is weakened overall. Therefore, when there is no current, the residual magnetism becomes smaller and the voltage bias brought by the magnetic core will also be reduced.

[0073] Combining the existing technical means, it can be simply judged that the more turns the coil has, the better the magnetic field suppression effect. However, when the number of turns reaches a certain level, the suppression effect is not significantly improved. After comprehensive consideration, a 1200-turn coil is selected to connect the switch to form a magnetic field suppression structure.

[0074] Example 3

[0075] Reference Figure 5 , which is the third embodiment of the present invention, and provides an efficient TMR current sensor material determination method. This embodiment is based on the previous embodiment, and is different from the previous embodiment in that:

[0076] Conduct multi-dimensional simulation analysis on the state of the magnetic core and its air gap;

[0077] Establish the influence of various core data on the magnetic flux at the air gap;

[0078] Determining the optimal conditions of the magnetic core based on the tunnel magnetoresistance effect;

[0079] Find the chip template that meets the optimal conditions and calculate the air gap opening width d to complete the material determination.

[0080] Multi-dimensional or multi-size simulation analysis is performed. Each size can determine whether the key point that affects the working efficiency of the magnetoresistance is important and whether it can participate in the core optimization process while ensuring a small volume.

[0081] Since the existing technology does not have a detailed production outline for TMR current sensors, and reference values ​​for new technologies are needed in the small volume field, a template chip that meets the requirements is determined from the established factors involved in the optimization. After the prerequisite for calculating complete data is met, the specifications of the entire magnetic core are qualitatively determined.

[0082] Example 4

[0083] Reference Figure 5 , which is the fourth embodiment of the present invention, is based on the previous embodiment, and is different from the previous embodiment in that: in the measurement of large current, the magnetic core will easily enter the saturation region, after which the linear relationship no longer exists, so it is necessary to suppress the saturation phenomenon of the magnetic core. The most common means of suppressing saturation is to open an air gap in the magnetic core.

[0084] After adding the air gap, the forward interaction force between the magnetic domains is weakened overall. Therefore, when there is no current, the residual magnetism becomes smaller and the voltage bias brought by the magnetic core will also decrease.

[0085] According to the specific technical indicators of this report, the current measurement range of the TMR current sensor of the present invention is 0-1000A, the bandwidth is DC~450Hz, and the transmission voltage range is 6~12V.

[0086] By analyzing and simulating the reference factors through Maxwell, a parameter model is first obtained, that is,

[0087] R is 80mm, r is 40mm, height h is 10mm, opening width d is 20mm, magnetic permeability is 100000H / m, and the conductor current is 1000A;

[0088] That is, the reference factors include R, r, h, d, magnetic permeability, and conductor state.

[0089] The core structure can gather the magnetic field generated by the current-carrying conductor, thereby increasing the magnetic induction intensity obtained at the air gap. The detectable magnetic induction intensity is related to the structure and material of the core, such as the core inner radius, core width, core height, core relative permeability and other factors. Therefore, each factor is analyzed and discussed.

[0090] Example 5

[0091] Reference Figure 5 , which is the fifth embodiment of the present invention, and is based on the previous embodiment, and is different from the previous embodiment in that: size simulation analysis 1, r is set unchanged, R changes from 80mm to 120mm, that is, the width of the magnetic core 100 changes to 40mm, and the simulation step is 5mm;

[0092] During the process, the magnetic flux density at the air gap 100c first increased and then decreased, with the maximum increase intensity reaching 1.91mT and the volume increasing by 1.6 times.

[0093] It can be seen that when the core width changes, the magnetic induction intensity at the air gap will increase first and then decrease, but it actually only changes by 1.91mT. However, the volume becomes larger. For current sensors, a small volume can undoubtedly be applied to more scenarios, so it is not advisable to pay the price of increasing the volume and only get a small increase in magnetic induction intensity. Therefore, the outer diameter of the core is still selected as the initial value of 80mm.

[0094] Example 6

[0095] Reference Figure 5 , which is the sixth embodiment of the present invention, and is based on the previous embodiment, and is different from the previous embodiment in that: in the second dimension simulation analysis, the core width is set unchanged, R changes from 80 mm to 120 mm, that is, r changes to 40 mm, and the simulation step length is 5 mm;

[0096] During the process, the magnetic flux density at the air gap 100c first remained unchanged and then decreased, and the volume increased by 0.7 times.

[0097] It can be seen that when the inner diameter of the magnetic core changes, the magnetic induction intensity at the air gap remains unchanged for a period of time and then decreases. Although the volume of the magnetic core does not increase much, the volume of the overall device increases, which is not conducive to the application of the current sensor. Therefore, the width of the magnetic core is still selected as 20mm, that is, the outer diameter and inner diameter of the magnetic core remain unchanged at the default value.

[0098] Example 7

[0099] Reference Figure 5 , which is the seventh embodiment of the present invention, and is based on the previous embodiment, and is different from the previous embodiment in that: in the dimension simulation analysis three, the core width, R, and r are set unchanged, h is changed from 5 mm to 30 mm, and the simulation step length is 5 mm;

[0100] During the process, the magnetic flux density at the air gap 100c increases continuously within the range of 5mm to 15mm, and there is no change after 15mm. When h is 30mm, the magnetic flux density increases by 2.07mT compared to h is 10mm, and the volume increases by 0.2 times. Similarly, for volume considerations, the core height of 10mm is still selected without height adjustment.

[0101] Example 8

[0102] Reference Figure 5 , which is the second embodiment of the present invention, is based on the previous embodiment, and is different from the previous embodiment in that: the higher the magnetic permeability, the easier the material is magnetized, and the greater the magnetic induction intensity generated.

[0103] When the magnetic permeability is low and an air gap exists, the magnetic field distribution inside the core will be affected, resulting in a relatively low magnetic induction intensity at the air gap.

[0104] As the magnetic permeability increases, the concentration effect of the magnetic core on the magnetic field increases, and the magnetic induction intensity at the air gap will also increase accordingly.

[0105] The simulation step size is 10000 H / m in the range of 50000 to 100000 H / m, which means that in this interval, the magnetic permeability increases by 10000 H / m each time the simulation is performed.

[0106] In the range of 100000~500000H / m, the simulation step is 100000H / m, that is, in this range, the simulated permeability increases by 100000H / m each time.

[0107] When the relative magnetic permeability of the magnetic core is in the range of 50000 to 200000, the magnetic induction intensity at the air gap increases with the increase of the relative magnetic permeability of the magnetic core. The magnetic permeability increases from 10000H / m to 100000H / m.

[0108] Magnetic permeability simulation analysis, setting the core width, R, r, and h unchanged, the magnetic permeability changes from 50000H / m to 500000H / m, the simulation step size is 10000H / m when it is 50000~100000H / m, and 100000H / m when it is 100000~200000H / m;

[0109] The magnetic induction intensity increases in direct proportion to the magnetic permeability within the range of 50000 to 200000 H / m of the simulation step of magnetic permeability;

[0110] The growth trend of magnetic induction slows down when the simulation step of magnetic permeability is within the range of 200000 to 500000 H / m;

[0111] After the simulation step of magnetic permeability is greater than 500000 H / m, the growth trend of magnetic flux density is infinitely close to but not equal to 0.

[0112] When the relative magnetic permeability of the magnetic core exceeds 200,000, the growth trend of the magnetic induction intensity in the air gap slows down.

[0113] Magnetic materials commonly used for magnetic cores include silicon steel sheets, Permalloy, ferrite, iron-based amorphous alloys, etc. Considering the influence of the inherent hysteresis effect of magnetic materials on the sensor output, it is necessary to choose magnetic materials that can be demagnetized quickly to improve the measurement accuracy of the TMR current sensor.

[0114] Therefore, Permalloy with relatively high magnetic permeability is selected as the core material.

[0115] Example 9

[0116] Reference Figure 5 , which is the ninth embodiment of the present invention, is based on the previous embodiment, and is different from the previous embodiment in that: the wire eccentricity simulation analysis is performed, the initial position of the wire is set to be placed at the center of the magnetic core 100, and the center of the magnetic core 100 is taken as the axis, and the change of the magnetic induction intensity of the wire under different Y coordinates is calculated.

[0117] The wire coordinates changed from -15mm to 15mm, the simulation step was 5mm, and the maximum difference in magnetic induction intensity at different positions was 1.92mT.

[0118] It can be seen that when the Y coordinate changes, the magnetic induction intensity at the air gap is not greatly affected, and the maximum difference is 1.92mT. This shows that in the presence of a magnetic core, the eccentricity of the wire has little effect on the magnetic induction intensity at the air gap.

[0119] Example 2

[0120] Reference Figure 5 , which is the second embodiment of the present invention, is based on the previous embodiment, and is different from the previous embodiment in that: within the linear range, the sensor output signal is proportional to the external magnetic field. When the external magnetic field strength reaches HA or -HA, the output voltage and the external magnetic field are no longer linearly related.

[0121] The TMR current sensor needs to meet the accuracy requirements required for reporting, and the sensitivity of the TMR chip needs to be

[0122] As large as possible. After consulting relevant chip data, it was found that the sensitivity of the TMR chip is related to its power supply voltage. The TMR2503 chip was selected as the core measurement element of this design.

[0123] The TMR2503 uses a unique push-pull Wheatstone full-bridge structure design, which contains four unshielded high-sensitivity TMR sensor elements that can sense magnetic fields perpendicular to the chip surface.

[0124] When the external magnetic field changes in the direction perpendicular to the chip surface, the Wheatstone full bridge provides a differential voltage output. In the range of -55℃ to +150℃, the sensitivity and offset voltage of TMR2503 can be maintained at a stable level.

[0125] Example 2

[0126] Reference Figure 5 , which is the second embodiment of the present invention, and is based on the previous embodiment, and is different from the previous embodiment in that: based on the above simulation process, it is confirmed that the best preferred condition of the magnetic core is a high magnetic permeability metal, the material of the magnetic core 100 is set to Permalloy, and the TMR chip is TMR2503;

[0127] After determining the material of the magnetic core, it is necessary to calculate the size of the core air gap opening to provide a theoretical basis for the selection and processing of the magnetic core.

[0128] According to Ampere's circuit law:

[0129] ∮H·dl=I

[0130] Substituting the parameters, we get:

[0131] ∮H·dl=H c ·(2πr 0 -d)+H A ·d=I

[0132] Where HC is the magnetic field strength inside the core, HA is the magnetic field strength in the air gap, and r0 is the average radius of the core center.

[0133] Let B = μ 0 H A =μH C Substituting into formula (1-2), we can get:

[0134]

[0135] According to the data sheet of TMR2503, its saturation magnetic field is 700Oe. Considering a certain margin, 600Oe is taken here. Considering that the maximum current to be measured by the designed TMR current sensor is 1000A, the magnetic permeability of air is 4π×10 -7 H / m, the width of the air gap is d=0.020m. In practice, the opening width of the core is 20mm.

[0136] Substituting the size of the core 100 into Ampere's loop law and the basic formula of the magnetic circuit, the opening width d is obtained to be 20 mm.

[0137] At this point, all important dimensions and materials of the magnetic core have been determined, and the material selection is completed.

[0138] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0139] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0140] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0141] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A high-efficiency TMR current sensor, characterized in that: include, A magnetic core (100), and a winding (100a) surrounding the magnetic core (100); A switch (100b) is connected in series with the winding (100a); The magnetic core (100) is made of Permalloy material.

2. A high efficiency TMR current sensor according to claim 1, characterized in that: The magnetic core (100) comprises an outer diameter R, an inner diameter r, and a height h; The magnetic core (100) is provided with an air gap (100c) with an opening width of d; The outer diameter R, the inner diameter r and the magnetic induction intensity at the air gap (100c) are positively correlated; The height h is positively correlated with the magnetic induction intensity at the air gap (100c) in the range of 5 to 15 mm.

3. A high-efficiency TMR current sensor according to claim 2, characterized in that: The outer diameter R is 80 mm, the inner diameter r is 60 mm, and the height h is 10 mm; The opening width d is 20 mm; The winding (100a) has 1200 turns.

4. A high-efficiency TMR current sensor according to claim 2, characterized in that: The TMR chip is placed at the air gap (100c), and the object to be tested is placed at the annular center of the magnetic core (100).

5. A method for determining the material of a high-efficiency TMR current sensor, acting on the high-efficiency TMR current sensor, characterized in that: Conduct multi-dimensional simulation analysis on the state of the magnetic core and its air gap; Establish the influence of various core data on the magnetic flux at the air gap; Determining the optimal conditions of the magnetic core based on the tunnel magnetoresistance effect; Find the chip template that meets the optimal conditions and calculate the air gap opening width d to complete the material determination.

6. A high-efficiency TMR current sensor material determination method according to claim 5, characterized in that: By analyzing and simulating the reference factors through Maxwell, a parameter model is first obtained, that is, The R is 80 mm, the r is 40 mm, the height h is 10 mm, the opening width d is 20 mm, the magnetic permeability is 100000 H / m, and the conductor current is 1000 A; That is, the reference factors include R, r, h, d, magnetic permeability, and wire state.

7. A high-efficiency TMR current sensor material determination method according to claim 7, characterized in that: Dimension simulation analysis 1, setting r unchanged, R changes from 80 mm to 120 mm, that is, the width of the magnetic core (100) changes to 40 mm, and the simulation step length is 5 mm; During the process, the magnetic flux density at the air gap (100c) first increases and then decreases, with the maximum increase in intensity reaching 1.91 mT, and the volume increasing by 1.6 times.

8. A high-efficiency TMR current sensor material determination method according to claim 8, characterized in that: Size simulation analysis 2, setting the core width unchanged, R changes from 80mm to 120mm, that is, r becomes 40mm, and the simulation step length is 5mm; During the process, the magnetic flux density at the air gap (100c) first remained unchanged and then decreased, and the volume increased by 0.7 times.

9. A high-efficiency TMR current sensor material determination method according to claim 9, characterized in that: Size simulation analysis three, set the core width, R, r unchanged, h changes from 5mm to 30mm, and the simulation step length is 5mm; During the process, the magnetic flux density at the air gap (100c) increases continuously within the range of 5 mm to 15 mm, and there is no change after 15 mm. When h is 30 mm, the magnetic flux density increases by 2.07 mT compared to h being 10 mm, and the volume increases by 0.2 times.

10. A high-efficiency TMR current sensor material determination method according to claim 9, characterized in that: The magnetic permeability simulation analysis sets the core width, R, r, and h unchanged, and the magnetic permeability changes from 50,000 H / m to 500,000 H / m. The simulation step size is 10,000 H / m when the range is 50,000 to 100,000 H / m, and 100,000 H / m when the range is 100,000 to 200,000 H / m. The magnetic induction intensity increases in direct proportion to the magnetic permeability within the range of 50000 to 200000 H / m of the simulation step of magnetic permeability; The growth trend of magnetic induction slows down when the simulation step of magnetic permeability is within the range of 200000 to 500000 H / m; After the simulation step of magnetic permeability is greater than 500000 H / m, the growth trend of magnetic flux density is infinitely close to but not equal to 0.

11. A high-efficiency TMR current sensor material determination method according to claim 9, characterized in that: Conductor eccentricity simulation analysis is performed by setting the initial position of the conductor to be at the center of the magnetic core (100), taking the center of the magnetic core (100) as the axis, and calculating the change in magnetic induction intensity of the conductor at different Y coordinates. The conductor coordinates vary from -15 mm to 15 mm, the simulation step is 5 mm, and the maximum difference in magnetic induction intensity at different positions is 1.92 mT.

12. A high-efficiency TMR current sensor material determination method according to claim 9, characterized in that: Based on the above simulation process, it is confirmed that the best optimal condition for the magnetic core is a high magnetic permeability metal, the material of the magnetic core (100) is set to be Permalloy, and the TMR chip is TMR2503; Substituting the size of the magnetic core (100) into Ampere's circuit law and the basic formula of magnetic circuit, it is obtained that the opening width d is 20 mm.

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