Hall current sensor

Abstract

A Hall current sensor, comprising: a magnetic core (10), wherein an air gap (11) is formed in one side of the magnetic core (10); a Hall element (12), wherein the Hall element (12) is disposed in the air gap (11); and a ferrite structure, wherein the ferrite structure is disposed in the air gap (11), and the ferrite structure clamps the Hall element (12) in the air gap (11), so as to reduce the air gap of a magnetic circuit and keep the Hall element (12) perpendicular to the direction of a magnetic induction line in the air gap (11). The Hall current sensor can significantly improve the detection precision, anti-interference capability and position error resistance capability of open-loop and closed-loop magnetic sensors in leakage current, small current and other weak magnetic scenarios, thereby realizing low-cost, high-precision and fast-response current sensing.

Description

Hall current sensor TECHNICAL FIELD

[0001] The present application belongs to the field of semiconductor integrated circuit design and manufacturing, and particularly relates to a Hall current sensor. BACKGROUND

[0002] With the popularization of electricity, electricity safety becomes a very important part in power application. Whether in the field of consumer electricity or in the field of industrial electricity, safety is always a topic that cannot be avoided.

[0003] The power supply line of a general device or electric appliance contains two lines, three lines or four lines. Taking 220V household power supply as an example, when the electric appliance is normally working, the fire line current and the zero line current are equal and opposite, the magnetic field of the two lines cancels out each other, and the symmetric closed cross section on the line presents zero magnetic flux. When electric shock occurs, the fire line introduces an additional current to the ground (this current is the leakage current), at this time, the fire line current increases and the zero line current remains unchanged, the zero magnetic flux state of the cross section is broken, the external magnetic field changes in proportion to the size of the leakage current, and the change can be monitored by a magnetic sensor. When the threshold is exceeded, the power supply is shut down, so as to protect the human body and equipment and avoid further harm to the human body.

[0004] For the human body, the safe current is 10mA, and the current exceeding this threshold will cause human body injury or death. The degree of harm of electric shock to the human body mainly depends on the size of the current passing through the human body and the length of the power-on time, so the precision and response speed of the small current test become two important indicators of the leakage current sensor. The leakage current sensor currently mainly uses mutual inductor, closed loop Hall and open loop, closed loop flux gate principle for design.

[0005] In the prior art, leakage detection generally has several different principle leakage current sensors. The first is a transformer, which measures the leakage current by a set of primary and secondary coils to proportionally amplify the current imbalance of zero and live lines, but it can only be used for AC detection and is not suitable for the increasingly widespread DC leakage detection. The second is a magnetic flux gate current sensor structure. The open-loop and closed-loop magnetic flux gate leakage current sensors use the nonlinear relationship between the magnetic induction intensity and the magnetic field intensity of the high-permeability magnetic core in the measured magnetic field under the saturation excitation of the alternating magnetic field to measure the weak magnetic field. Among them, the single magnetic ring structure is suitable for DC and low-frequency AC detection, and the double magnetic ring structure is suitable for AC and DC detection, and the detection accuracy is very high, but it often faces problems such as complex signal processing, high cost, and high power consumption. The third is a closed-loop Hall current sensor, which balances the magnetic field generated by the measured current through a set of secondary coils, so that the magnetic field at the air gap is zero, and a high-sensitivity Hall element is used to monitor this zero point. The size of the compensation current through the secondary coil at this zero point reflects the size of the measured current. Compared with ordinary closed-loop Hall current sensors, the leakage current sensor often adds many algorithms, such as power-on self-zeroing, to improve detection accuracy. There are few products using closed-loop Hall principle for leakage current detection, and the detection accuracy is low and the price is high. The fourth is an open-loop Hall current sensor, which is generally used for large current detection. The open-loop Hall current sensor detects the magnetic field at the air gap of the peripheral magnetic core of the current-carrying wire through a Hall element or a Hall IC to feedback the current size.

[0006] When a traditional open-loop Hall current sensor scheme is applied to weak magnetic detection scenarios such as leakage current and small current, the Hall voltage change caused by the small change of the external magnetic field (mA-level current change at the test end) is overwhelmed by the output noise of the Hall sensor. This phenomenon is manifested externally as poor resolution of mA-level current or inability to distinguish mA-level current. When the relative position of the inner coil of the magnetic core and the current-carrying wire changes, the magnetic permeability of the magnetic loop is unevenly distributed due to the difference in the relative magnetic permeability of the magnetic core and the air, and the magnetic field at the air gap also changes greatly, causing the sensor output value to change (hereinafter referred to as position error), and the test result is unreliable. Moreover, the existence of the earth's magnetic field and the magnetic field generated by the surrounding electrical appliances when they are working also affect the accuracy of small current testing under this scheme. Therefore, the traditional open-loop Hall principle current sensor design scheme cannot be used for leakage current detection.

[0007] It should be noted that the above introduction to the technical background is only to facilitate a clear and complete description of the technical solutions of the present application and to facilitate the understanding of those skilled in the art. The above technical solutions cannot be considered as known to those skilled in the art merely because they are described in the background section of the present application. SUMMARY

[0008] In view of the above-mentioned defects of the prior art, the purpose of the present application is to provide a Hall current sensor for solving the problems of low accuracy and high design cost of the Hall principle current sensor for leakage current detection in the prior art.

[0009] To achieve the above-mentioned purpose and other related purposes, the present application provides a Hall current sensor, comprising: a magnetic core, one side of which is provided with an air gap; a Hall element, which is arranged in the air gap; and a ferrite structure, which is arranged in the air gap, clamps the Hall element in the air gap, reduces the air gap of the magnetic circuit, and makes the Hall element keep perpendicular to the direction of magnetic induction lines in the air gap.

[0010] Optionally, the Hall element comprises a ferrite base, a patterned InSb film arranged on the ferrite base, and a protective layer arranged on the ferrite base and the InSb film, the InSb film of the Hall element is connected with an external soft plate, and the external soft plate is arranged outside the air gap to realize circuit connection of the Hall element.

[0011] Optionally, it further comprises a conditioning chip connected with the Hall element through the external soft plate for power supply and signal processing of the Hall element, and the external soft plate comprises a connecting soft plate and a pad structure connected with the connecting soft plate.

[0012] Optionally, it further comprises a magnetic shielding structure made of permalloy, which comprises a first shielding part and a second shielding part, and the first shielding part and the second shielding part are assembled into an integrated structure after being sleeved on the periphery of the magnetic core.

[0013] Optionally, the side of the magnetic shielding structure is provided with a notch, and the external soft plate extends to the outside of the magnetic shielding structure through the notch.

[0014] Optionally, it further comprises an outer shell covering the periphery of the magnetic shielding structure, the external soft plate and the conditioning chip.

[0015] Optionally, the magnetic core is a special-shaped nanocrystalline magnetic core, and the width of the special-shaped nanocrystalline magnetic core gradually increases from both ends of the air gap to the direction away from the air gap, so as to enhance the magnetic induction intensity at the air gap.

[0016] Optionally, the ferrite structure comprises two ferrite pieces with complementary angles, the outer end faces of the two ferrite pieces are respectively connected with the magnetic core, and the inner end faces of the two ferrite pieces clamp the Hall element, so that the Hall element keeps perpendicular to the direction of magnetic induction lines in the air gap.

[0017] Optionally, the ferrite pieces are wedge-shaped ferrite pieces, the air gap has an angle of inclination between the two end faces and the vertical plane of the magnetic induction lines, the angle of inclination is equal to the wedge angle of the wedge-shaped ferrite pieces, the right angle face of the two wedge-shaped ferrite pieces clamps the Hall element, and the inclined faces of the two wedge-shaped ferrite pieces are connected to the two end faces of the air gap, respectively.

[0018] Optionally, the angle of inclination between the two end faces of the air gap and the vertical plane of the magnetic induction lines is between 5° and 20°, and the wedge angle of the wedge-shaped ferrite pieces is between 5° and 20°.

[0019] Optionally, the ferrite structure includes a wedge-shaped ferrite piece, the air gap has an angle of inclination between the first end face and the vertical plane of the magnetic induction lines, and the second end face is perpendicular to the magnetic induction lines, the angle of inclination is equal to the wedge angle of the wedge-shaped ferrite piece, and after the wedge-shaped ferrite piece and the Hall element are embedded in the air gap, the Hall element is clamped between the right angle face of the wedge-shaped ferrite piece and the second end face of the air gap, so that the Hall element is perpendicular to the direction of the magnetic induction lines in the air gap.

[0020] Optionally, the angle of inclination between the first end face of the air gap and the vertical plane of the magnetic induction lines is between 5° and 20°, and the wedge angle of the wedge-shaped ferrite piece is between 5° and 20°.

[0021] Optionally, the cross-sectional length of the air gap is less than or equal to 5 mm, and the width is less than or equal to 5 mm, and after the Hall element and the ferrite structure are arranged in the air gap, the remaining air gap height is less than or equal to 0.2 mm.

[0022] Optionally, the thickness of the Hall element is less than or equal to 0.1 mm.

[0023] Optionally, the Hall current sensor includes one of an open-loop Hall leakage current sensor and a closed-loop Hall leakage current sensor.

[0024] As described above, the Hall current sensor of the present application has the following beneficial effects:

[0025] The application provides a thin air gap magnetic concentration sensor, a Hall sensor chip with a thin film structure, a magnetic core with a thin air gap magnetic concentration structure to increase the magnetic field change caused by the initial current, and the magnetic core can effectively shield and attenuate two axes of the external space magnetic field interference, and the third axis interference magnetic field is attenuated by using an external high magnetic permeability shielding structure, and the magnetic shielding structure can also attenuate the other two axis magnetic fields, so that the magnetic field gain and the signal-to-noise ratio of the measured magnetic field can be effectively improved. The stray magnetic field (including the geomagnetic field and the magnetic field generated by the external current with a distance of more than 5 cm) around the sensor and the position error have an influence on the test accuracy of less than 0.5 mA, and the output range can be programmed to adjust, and the conditioning circuit can still be added at the back end of the conditioning chip to realize the preset mode output. The application can significantly improve the detection accuracy, anti-interference ability and anti-position error ability of the open loop and closed loop magnetic sensor in the weak magnetic field scene of leakage current and small current, and realize low-cost, high-precision and fast-response current sensing.

[0026] The Hall leakage current sensor of the application has high resolution for small current, strong anti-interference ability, and certain resistance to position error, so as to ensure the accuracy of small current detection and realize the leakage current detection effect. The open loop current sensor scheme of the application can ensure the detection accuracy in the detection of leakage current, small current and other small magnetic fields, and realize low-cost and fast-response leakage current detection. Compared with the transformer, the application can be applied to direct current testing; compared with the magnetic flux gate current sensor, the manufacturing cost can be greatly reduced, and the same accuracy level can be reached. This scheme is suitable for open loop and closed loop Hall leakage current sensors and related magnetic sensing problems, reduces the design threshold of the leakage current sensor, and meets the leakage current detection requirements. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings included to provide a further understanding of the embodiments of the application and constitute a part of the specification, which serve to explain the principles of the application together with the text. Obviously, the accompanying drawings in the following description only show some embodiments of the application.

[0028] Fig. 1-2 shows the magnetic core structure schematic diagram of the Hall current sensor of the embodiment of the application.

[0029] Fig. 3 shows the Hall element and external soft plate structure schematic diagram of the Hall current sensor of the embodiment of the application.

[0030] Fig. 4 shows the wedge-shaped ferrite sheet structure schematic diagram of the Hall current sensor of the embodiment of the application.

[0031] Fig. 4 shows the magnetic core structure schematic diagram of the Hall current sensor of the embodiment of the application.

[0032] Figure 5 shows the assembly of the Hall current sensor according to an embodiment of the present application.

[0033] Figure 6 shows the assembly of the Hall current sensor according to an embodiment of the present application.

[0034] Figure 7 shows the assembly of the Hall current sensor according to an embodiment of the present application.

[0035] Figure 8 shows the connection of the Hall element and the conditioning chip on the PCB of the Hall current sensor according to an embodiment of the present application.

[0036] Figure 9 shows the magnetic shielding structure of the Hall current sensor according to an embodiment of the present application.

[0037] Figure 10 shows the housing structure of the Hall current sensor according to an embodiment of the present application.

[0038] Figure 11 shows the magnetic core and wedge-shaped ferrite sheet structure of the Hall current sensor according to another embodiment of the present application.

[0039] Figure 12 shows the magnetic core and wedge-shaped ferrite sheet structure of the Hall current sensor according to yet another embodiment of the present application.

[0040] Figure 13 shows the magnetic core and complementary ferrite sheet structure of the Hall current sensor according to yet another embodiment of the present application.

[0041] Figure 14 shows the structure of the open-loop Hall current sensor according to an embodiment of the present application.

[0042] Figure 15 shows the structure of the closed-loop Hall current sensor according to an embodiment of the present application.

[0043] 10 element number explanation 11 magnetic core 12 air gap 13 Hall element 131 external soft plate 132 connecting soft plate 1321 land 1322 signal land 1323 fixed land 14 wedge-shaped ferrite sheet 141 first wedge-shaped ferrite sheet 142 second wedge-shaped ferrite sheet 15 conditioning chip 16 magnetic shield structure 161 first shield portion 162 second shield portion 163 notch 17 housing 18 coil 21, 31 operational amplifier 32 MOS device DETAILED DESCRIPTION

[0044] Other advantages and benefits of the present application will become apparent to those skilled in the art upon reading the following description in conjunction with the accompanying drawings. The present application can be carried out in practice without departing from the spirit and scope of the application, whereby the embodiments described herein are illustrative only.

[0045] It should be emphasized that the term comprising / comprises, when used in this specification, means that the features, integers, steps or components of which it refers are present, but do not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

[0046] Features described and / or illustrated with respect to one embodiment can be used in the same or similar manner in one or more other embodiments, in combination with or in place of features in other embodiments, or in place of other features in the same embodiment.

[0047] As illustrated in the detailed description of the embodiments of the present application, the cross-sectional view of the device structure is partially enlarged without the general proportion for the convenience of illustration, and the schematic view is only an example which should not limit the scope of protection of the present application herein. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in the actual manufacture.

[0048] For the convenience of description, spatial relationship words such as "under", "below", "lower than", "underneath", "above", "upper" and the like can be used herein to describe the relationship of one element or feature with other elements or features shown in the drawings. It will be understood that these spatial relationship words are intended to include other directions of the device in use or operation in addition to the directions depicted in the drawings. In addition, when a layer is referred to as "between" two layers, it can be the only layer between the two layers, or one or more intervening layers can also exist.

[0049] In the context of the present application, the structure in which the first feature is "above" the second feature can include an embodiment in which the first and second features are formed in direct contact, and can also include an embodiment in which another feature is formed between the first and second features, so that the first and second features can not be in direct contact.

[0050] It should be noted that the diagrams provided in the embodiments only schematically illustrate the basic concepts of the present application, and only the components related to the present application are shown in the diagrams, not the number, shape and size of the components when actually implemented. The actual implementation of each component can be a random change in shape, number and proportion, and the layout pattern of the components can also be more complex.

[0051] The open-loop Hall principle current sensor uses the Ampere loop law and the Hall effect for indirect current detection. That is, there is a magnetic field around the current-carrying wire, and the magnetic field strength is proportional to the current-carrying current. Using a Hall element or a Hall chip, the magnetic field can be detected, and the Hall output voltage is proportional to the magnetic field strength. This process completes the conversion of the current signal → the magnetic signal → the voltage signal. In this way, the current size can be represented according to the Hall element output voltage, and a conditioning circuit can be added at the back end to obtain the required output signal.

[0052] When testing a small current with an open-loop Hall current sensor, attention should be paid to the ratio of the measured current magnetic field size to the external interference magnetic field size, that is, the signal-to-noise ratio of the measured magnetic field. Leakage current detection requires high detection accuracy for small currents, such as a minimum resolution of 1 mA or less. The magnetic field around a small current is small and is easily overwhelmed by external interference magnetic fields, such as the geomagnetic field, interference from energized equipment, etc. To improve the signal-to-noise ratio, two approaches are needed. One is to increase the amount of magnetic field change brought about by the small current, that is, the magnetic field gain, and the other is to reduce the influence of the interference magnetic field.

[0053] To increase the magnetic field gain, two approaches can be taken. One is to wind the measured energized wire on the magnetic core for multiple turns to accumulate the magnetic field of small current, and the magnetic field at the air gap is the accumulated magnetic field of N turns of coil. This method can effectively increase the magnetic field gain, but in the leakage current detection, the wire is thick, and if it is wound into multiple turns of coil, the volume of the leakage current sensor will inevitably become very large, which is not suitable for the actual leakage current external detection scene. The second is to thin the air gap of the magnetic core. Under the same excitation current condition, the magnetic field at the air gap is approximately inversely proportional to the thickness of the air gap within a certain range. A thinner air gap can bring a higher magnetic induction intensity at the air gap. The traditional open-loop and closed-loop Hall current sensor uses a TO package or SOP package form of Hall element or Hall chip. Due to the physical limitations, the air gap cannot be made very thin, about 1 millimeter or more.

[0054] The application uses a thin film packaged magnetic sensing element, mainly through thinning the air gap to increase the magnetic field gain, and through a special-shaped magnetic core, such as making the air gap cross-sectional area smaller, and the cross-sectional length and width at the air gap are both less than 5 millimeters, to further enhance the magnetic field at the air gap. The use of a thin film packaged magnetic sensing element can significantly reduce the physical air gap and the InSb Hall COB packaged device for sensor design.

[0055] The application uses InSb material to manufacture a high-sensitivity thin film structure Hall element, and the COB packaged InSb Hall element has a thickness of less than 0.08 millimeters. The application of the Hall element can greatly reduce the air gap of the magnetic core to improve the magnetic field gain. The InSb Hall element itself has high magnetic sensitivity, higher Hall voltage under the same magnetic field, and high output signal-to-noise ratio. The Hall element of the application cooperates with the thin air gap magnetic core to effectively reduce the difficulty of the back-end conditioning circuit design. In the back-end signal processing, the amplification factor is small, which can effectively reduce the equivalent noise of the amplifier output and improve the system bandwidth and response time.

[0056] The application uses a COB packaged Hall element that can adapt to a thinner magnetic core air gap. The application uses a 0.5 millimeter nanocrystalline magnetic core for the air gap. The nanocrystalline magnetic core has many advantages such as small temperature drift, small residual magnetism, and high linearity. The use of a nanocrystalline magnetic core can improve the detection accuracy of the open-loop Hall leakage current sensor. Due to the manufacturing tolerance, the air gap is designed to be relatively thick, and a certain amount of margin is reserved. In the COB packaging and the air gap of the magnetic core, a complementary thickness of ferrite sheet is added to further reduce the air gap. The air gap after compensation is almost 0 millimeters, which makes the loop further closed and improves the overall performance of the current sensor. A modular magnetic core structure can also be used for design. The loop is closed by grinding. The application uses the ferrite sheet scheme to reduce the air gap.

[0057] The magnetic core of the traditional single magnetic ring or double magnetic ring open loop, closed loop magnetic flux gate leakage current sensor is not cut, the permeability in the magnetic circuit is uniform, and the position error of the wire has little influence. In the traditional scheme, the current sensor made by using the Hall principle, due to the large air gap of the magnetic core, the relative position error of the wire and the air gap has a great influence on the magnetic induction intensity at the air gap, the InSb thin film is used in the application, the magnetic circuit is almost closed, which can effectively weaken the influence and reduce the output change of the sensor caused by the position change.

[0058] The application adds a permalloy structure outside the magnetic core to shield the magnetic field. The shielding structure made of permalloy is placed outside the magnetic core, which can effectively attenuate the external stray magnetic field reaching the magnetic core and improve the anti-interference ability and output accuracy of the current sensor.

[0059] As shown in FIGS. 1-15, the embodiment provides a Hall current sensor, which comprises: a magnetic core 10, the magnetic core 10 is provided with an air gap 11 on one side; a Hall element 12, the Hall element 12 is arranged in the air gap 11; a ferrite structure, the ferrite structure is arranged in the air gap 11, the ferrite structure clamps the Hall element 12 in the air gap 11, reduces the air gap of the magnetic circuit, and makes the Hall element 12 perpendicular to the direction of magnetic induction lines in the air gap 11.

[0060] As shown in FIGS. 1 and 2, in one embodiment, the magnetic core 10 is a special-shaped nanocrystalline magnetic core, the width of the special-shaped nanocrystalline magnetic core gradually increases from both ends of the air gap 11 to the direction away from the air gap 11, so as to enhance the magnetic induction intensity at the air gap 11. The magnetic core 10 is provided with an air gap 11 on one side, the cross-sectional length of the air gap 11 is less than or equal to 5 mm, and the width is less than or equal to 5 mm, after the Hall element 12 and the ferrite structure are arranged in the air gap 11, the remaining air gap height is less than or equal to 0.2 mm, preferably, the remaining air gap height is 0 mm. The application improves the magnetic field gain by thinning the air gap 11, and further enhances the magnetic field at the air gap 11 by using the special-shaped magnetic core (the air gap 11 has a small cross-sectional area, and the cross-sectional length and width of the air gap 11 are both less than 5 mm). The magnetic sensing element packaged by the thin film can significantly reduce the physical air gap 11, and the InSb Hall COB packaged device is used for sensor design.

[0061] As shown in FIG. 3, the Hall element 12 includes a ferrite substrate, a patterned InSb thin film disposed on the ferrite substrate, and a protective layer disposed on the ferrite substrate and the InSb thin film. The InSb thin film of the Hall element 12 is connected to an external soft plate 13 disposed outside the air gap 11 to achieve circuit connection of the Hall element 12. The Hall element 12 is, for example, an InSb Hall element 12 packaged in a COB, which can be applied to the air gap 11 shown in FIGS. 1-2 due to its thin film structure, and is suitable for the detection circuit due to its high sensitivity and small noise. Specifically, the Hall element 12 is made of an InSb thin film on a ferrite sheet, which is used for preparation of a COB structure Hall element 12. Four pads of the Hall element 12 are respectively punched to the edge pins for circuit connection, and the Hall element 12 is packaged in a COB after adding a protective layer. The external soft plate 13 in FIG. 3 is circuit-connected to the COB packaged Hall element 12, and is led out to facilitate electrical connection of the conditioning chip 15. The external soft plate 13 can have six pads 132, four of which are signal pads 1321 for four pin signals of the Hall element 12, and the other two pads can be used as fixed pads 1322 for fixing the external soft plate 13. In an embodiment, the thickness of the Hall element 12 is less than or equal to 0.1 mm, for example, the thickness of the Hall element 12 can be 0.08 mm, etc.

[0062] In one embodiment, as shown in Fig. 4, the ferrite structure can include two ferrite pieces that are complementary in angle, the outer end faces of the two ferrite pieces are respectively connected with the magnetic core 10, and the inner end faces of the two ferrite pieces hold the Hall element 12, so that the Hall element 12 is perpendicular to the direction of magnetic induction lines in the air gap 11. For example, the ferrite pieces can be wedge-shaped ferrite pieces 14, the air gap 11 has an inclination angle θ between the two end faces and the perpendicular plane of the magnetic induction lines, the inclination angle is equal to the wedge angle of the wedge-shaped ferrite pieces 14, the right angle faces of the two wedge-shaped ferrite pieces 14 (a first wedge-shaped ferrite piece 141 and a second wedge-shaped ferrite piece 142) hold the Hall element 12, and the inclined faces of the two wedge-shaped ferrite pieces 14 are respectively connected with the two end faces of the air gap 11. The inclination angle between the two end faces of the air gap 11 and the perpendicular plane of the magnetic induction lines is between 5° and 20°, for example, 10°, and the wedge angle of the wedge-shaped ferrite pieces 14 is between 5° and 20°, for example, 10°. The wedge-shaped ferrite pieces 14 are used in the application, and are used in combination with the Hall element 12, which can effectively reduce the air gap 11 of the magnetic circuit, has higher tolerance for the position of the inner conductor of the through hole, has smaller residual magnetism, and can improve the output accuracy of the sensor. Compared with the ordinary structure, the magnetic field at the air gap 11 of the application can be enhanced by more than twice. Further, the air gap 11 of the magnetic core 10 is cut into an inclined plane, the angle of which is equal to the wedge angle of the wedge-shaped ferrite pieces 14, as shown in Fig. 5, the sensing core part of the Hall element 12 is first placed in the air gap 11, then the wedge-shaped ferrite pieces 14 are respectively aligned with the two sides of the inclined cut, and are pushed inward to complete the assembly at the air gap 11. After the assembly is completed, as shown in Figs. 6 and 7, further, adhesive can be arranged at the connection between the magnetic core 10 and the wedge-shaped ferrite pieces 14, and / or the connection between the wedge-shaped ferrite pieces 14 and the Hall element 12 to strengthen the fixation.

[0063] As shown in Fig. 8, the Hall current sensor further includes a conditioning chip 15 connected with the Hall element 12 through the external soft board 13, which is used for power supply and signal processing of the Hall element 12. The external soft board 13 includes a connection soft board 131 and a pad structure connected with the connection soft board 131. For example, AS851 can be used as the back-end conditioning chip 15 of the Hall element 12, which can supply power to the Hall element 12, amplify and filter the output signal of the Hall element 12, and process the Hall signal in a certain way to ensure the stability of the output of the sensor. The conditioning chip 15 can be burned and written to obtain the required voltage output, or a later-stage circuit can be arranged to convert the voltage signal into a current signal.

[0064] As shown in FIG. 9, the Hall current sensor further comprises a magnetic shielding structure 16, which is made of permalloy and comprises a first shielding part 161 and a second shielding part 162, and the first shielding part 161 and the second shielding part 162 are assembled into an integrated structure after being sleeved on the periphery of the magnetic core 10. The side of the magnetic shielding structure 16 is provided with a notch 163, and the external soft plate 13 extends to the outside of the magnetic shielding structure 16 through the notch 163. Specifically, after the Hall element 12, the wedge-shaped ferrite sheet 14 and the magnetic core 10 are assembled, the magnetic shielding structure 16 is used as an external electromagnetic shield. After assembly, the external soft plate 13 is exposed outside the magnetic shielding structure 16, and the side of the magnetic shielding structure 16 has a notch 163 for placing the external soft plate 13. During assembly, the assembly surfaces of the first shielding part 161 and the second shielding part 162 are aligned and fixed to ensure the fit of the cutting surfaces of the first shielding part 161 and the second shielding part 162, thereby improving the shielding effect.

[0065] As shown in FIG. 10, the Hall current sensor further comprises a shell 17, which covers the periphery of the magnetic shielding structure 16, the external soft plate 13 and the conditioning chip 15. The conditioning chip 15 can be arranged on a PCB, and the external soft plate 13 and the conditioning chip 15 are electrically connected through the PCB. Then, the above-mentioned magnetic core, magnetic shielding structure, PCB and the like are placed in the shell 17 to protect the above-mentioned components.

[0066] As shown in FIGS. 11 and 12, in some embodiments, the ferrite structure can also only comprise one wedge-shaped ferrite sheet 14, the first end surface of the air gap 11 has an inclination angle with the vertical plane of the magnetic induction line, and the second end surface is perpendicular to the magnetic induction line. The inclination angle is equal to the wedge angle of the wedge-shaped ferrite sheet 14. After the wedge-shaped ferrite sheet 14 and the Hall element 12 are embedded in the air gap 11, the Hall element 12 is clamped between a right angle surface of the wedge-shaped ferrite sheet 14 and the second end surface of the air gap 11, so that the Hall element 12 is perpendicular to the direction of the magnetic induction line in the air gap 11. As an example, the inclination angle between the first end surface of the air gap 11 and the vertical plane of the magnetic induction line is between 5° and 20°, for example, 10°, and the wedge angle of the wedge-shaped ferrite sheet 14 is between 5° and 20°, for example, 10°. The magnetic core 10 can also adopt a magnetic core with a constant width, as shown in FIG. 12. Of course, the magnetic core 10 can also be assembled by using two complementary arc-shaped magnetic cores, as shown in FIG. 13.

[0067] As shown in Figs. 14 and 15, the Hall current sensor can include one of an open-loop Hall leakage current sensor (as shown in Fig. 14) and a closed-loop Hall leakage current sensor (as shown in Fig. 15). As shown in Fig. 14, the open-loop Hall leakage current sensor includes an operational amplifier 21 connected to the Hall element 12. As shown in Fig. 15, the closed-loop Hall leakage current sensor includes an operational amplifier 31 connected to the Hall element 12, and two MOS devices 32 connected to the operational amplifier 31. The magnetic core 10 is also provided with multiple sets of coils 18.

[0068] As described above, the Hall current sensor of the present application has the following beneficial effects:

[0069] The present application provides a thin air gap magnetic concentration sensor, which is matched with a Hall sensor chip with a thin film structure. The magnetic field change caused by the initial current is increased by the magnetic concentration structure magnetic core with a thin air gap. The magnetic core can effectively shield and attenuate two axes of the external space magnetic field. For the third axis interference magnetic field, an external high magnetic permeability shielding structure is used to attenuate the magnetic field. At the same time, the magnetic shielding structure can also attenuate the magnetic field of the other two axes. The magnetic field gain and the signal-to-noise ratio of the measured magnetic field can be effectively improved. The influence of the stray magnetic field (including the geomagnetic field and the magnetic field generated by the external current with a distance of more than 5 cm) and the position error on the test accuracy of the sensor is within 0.5 mA. The output range can be programmed and adjusted. After the conditioning chip, a conditioning circuit can still be added to realize the preset output mode. The present application can significantly improve the detection accuracy, anti-interference ability, and anti-position error ability of the open-loop and closed-loop magnetic sensor in the weak magnetic field scene of leakage current and small current, and realize low-cost, high-precision, and fast-response current sensing.

[0070] The Hall leakage current sensor of the present application has high resolution for small current, strong anti-interference ability, and certain resistance to position error, so as to ensure the accuracy of small current detection and realize the leakage current detection effect. The open-loop current sensor scheme of the present application can ensure the detection accuracy in the detection of leakage current, small current, and other small magnetic fields, and realize low-cost and fast-response leakage current detection. Compared with the mutual inductor, the present application can be applied to direct current testing. Compared with the fluxgate current sensor, the present application can greatly reduce the manufacturing cost and achieve the same accuracy level. This scheme is suitable for open-loop and closed-loop Hall leakage current sensors and related magnetic sensing problems, reduces the design threshold of the leakage current sensor, and meets the leakage current detection requirements.

[0071] Therefore, the present application effectively overcomes the various shortcomings in the prior art and has high industrial utilization value.

[0072] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A Hall current sensor characterized by: The application relates to a magnetic core, a Hall element, a ferrite structure and a magnetic shielding structure. The Hall element comprises a ferrite base, a patterned InSb film arranged on the ferrite base and a protective layer arranged on the ferrite base and the InSb film, the InSb film of the Hall element is connected with an external soft plate, the external soft plate is arranged outside the air gap to realize circuit connection of the Hall element. The application further comprises a conditioning chip connected with the Hall element through the external soft plate, which is used for power supply and signal processing of the Hall element, the external soft plate comprises a connecting soft plate and a pad structure connected with the connecting soft plate. The magnetic shielding structure comprises a first shielding part and a second shielding part, the first shielding part and the second shielding part are sleeved on the periphery of the magnetic core and assembled into an integrated structure.

2. The Hall current sensor of claim 1, wherein: The side edge of the magnetic shielding structure is provided with a notch, and the external soft plate extends to the outside of the magnetic shielding structure through the notch.

3. The Hall current sensor of claim 2, wherein: The application further comprises an outer shell which covers the periphery of the magnetic shielding structure, the external soft plate and the conditioning chip.

4. The Hall current sensor of claim 3, wherein: The magnetic core is a special-shaped nanocrystalline magnetic core, the width of the special-shaped nanocrystalline magnetic core gradually increases from the two ends of the air gap to the direction away from the air gap, so as to enhance the magnetic induction intensity at the air gap.

5. The Hall current sensor of claim 4, wherein: The ferrite structure comprises two ferrite pieces with complementary angles, the outer end faces of the two ferrite pieces are connected with the magnetic core, and the inner end faces of the two ferrite pieces clamp the Hall element, so that the Hall element is kept perpendicular to the magnetic induction line direction in the air gap.

6. The Hall current sensor of claim 5, wherein: The ferrite piece is a wedge-shaped ferrite piece, the air gap has an inclination angle between the two end faces and the vertical plane of the magnetic induction line, the inclination angle is equal to the wedge angle of the wedge-shaped ferrite piece, the right angle faces of the two wedge-shaped ferrite pieces clamp the Hall element, and the inclined faces of the two wedge-shaped ferrite pieces are connected with the two end faces of the air gap.

7. The Hall current sensor of claim 1, wherein: The inclination angle between the two end faces of the air gap and the vertical plane of the magnetic induction line is between 5 DEG and 20 DEG, and the wedge angle of the wedge-shaped ferrite piece is between 5 DEG and 20 DEG.

8. The Hall current sensor of claim 1, wherein: The ferrite structure comprises a wedge-shaped ferrite piece, the first end face of the air gap has an inclination angle with the vertical plane of the magnetic induction line, and the second end face is perpendicular to the magnetic induction line, the inclination angle is equal to the wedge angle of the wedge-shaped ferrite piece, after the wedge-shaped ferrite piece and the Hall element are embedded in the air gap, the Hall element is clamped between the right angle face of the wedge-shaped ferrite piece and the second end face of the air gap, so that the Hall element is kept perpendicular to the magnetic induction line direction in the air gap.

9. The Hall current sensor of claim 8, wherein: The inclination angle between the first end face of the air gap and the vertical plane of the magnetic induction line is between 5 DEG and 20 DEG, and the wedge angle of the wedge-shaped ferrite piece is between 5 DEG and 20 DEG.

10. The Hall current sensor of claim 9, wherein: ​ 11. The Hall current sensor of claim 1, wherein: ​ 12. The Hall current sensor of claim 11, wherein: ​ 13. The Hall current sensor of claim 1, wherein: The cross-sectional length of the air gap is less than or equal to 5 mm, the width of the air gap is less than or equal to 5 mm, and the remaining height of the air gap after the Hall element and the ferrite structure are disposed in the air gap is less than or equal to 0.2 mm.

14. The Hall current sensor of claim 1, wherein: The thickness of the Hall element is less than or equal to 0.1 mm.

15. The Hall current sensor of claim 1, wherein: The Hall current sensor includes one of an open-loop Hall leakage current sensor and a closed-loop Hall leakage current sensor.

Images