Hall current sensor magnetic core structure with high signal-to-noise ratio

Abstract

The invention provides a Hall current sensor magnetic core structure with a high signal-to-noise ratio. The Hall current sensor magnetic core structure comprises a magnetism gathering ring, a framework, an operational amplifier, a rivet, a Hall element, a PCB and a grounding copper column. The eight magnetic sheets are staggered and laminated left and right in the trapezoid groove of the framework for one-time forming, the wiring groove of the framework optimizes wiring of the secondary coils, extra electromagnetic signals caused by mutual coupling between the secondary coils are avoided, and accurate alignment of the framework and the PCB is achieved. The direct connection mode of precise rivet framework integration and copper column PCB spot welding replaces all heavy external shielding and unreliable mechanical contact, the contradiction of high signal-to-noise ratio, high reliability and miniaturization is fundamentally solved, the anti-interference capacity is built in the magnetic core body and achieved through extremely simple and reliable physical connection, and an external additional structure is not needed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of Hall current sensor, and particularly relates to a Hall current sensor magnetic core structure with high signal-to-noise ratio. BACKGROUND

[0002] The common current sensor types in the prior art include a Rogowski coil, a Hall, a fluxgate and a magnetoresistive current sensor, and the most widely used one is the Hall current sensor. The Hall current sensor has the advantages of wide working range and fast response speed, but also has some obvious defects, such as low sensitivity and large measurement error caused by the influence of the nonlinearity of the magnetic core and the magnetic hysteresis effect. In order to improve the output sensitivity, the Hall current sensor uses a magnetic concentrating ring structure to amplify the magnetic field, so the sensor also has the defects of large volume and weight, and the Hall element has large power consumption, poor linearity and temperature characteristics. Meanwhile, the magnetic concentrating ring is made of a material with high electromagnetic conductivity, and the electromagnetic field interference in the measurement environment will cause the output of the Hall sensor to be unstable.

[0003] With the increasing application scenarios of miniaturization, small signal and high-precision current detection, the research on improving the performance of the Hall current sensor is more urgent. At present, the schemes for improving the performance of the Hall current sensor at home and abroad generally have two major contradictions of "shielding and volume conflict" and "unreliable grounding": the patent

A shielding protection box for a Hall current sensor, CN221883731U, authorized

A current sensor with a copper foil shielding layer, CN209215468U, authorized

A magnetic core reliable grounding current sensor, CN222167107U, authorized

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, provide a Hall current sensor magnetic core structure with high signal-to-noise ratio, abandon the traditional anti-interference schemes of the Hall current sensor such as installing a shielding cover, winding a copper foil and clamping a spring sheet, and innovatively use a magnetic concentrating ring and a secondary coil-rivet-copper column-PCB structure to effectively solve the problems of large volume, large weight, unreliable grounding and secondary processing damage to the magnetic core in the traditional anti-interference schemes of the Hall current sensor in the prior art, and realize all-round improvement of the performance of the Hall current sensor.

[0005] This invention provides a Hall current sensor core structure with high signal-to-noise ratio, comprising: a magnetic ring, a frame, an operational amplifier, rivets, a Hall element, a PCB board, and a grounding copper pillar. Its manufacturing process mainly includes magnetic sheet stacking, integrated assembly of the magnetic ring and the frame, Hall element installation, secondary coil winding, PCB board installation, and grounding treatment of the magnetic ring.

[0006] The magnetic ring mounting frame has a hollow trapezoidal groove in the middle to accommodate the limiting interlocking magnetic ring.

[0007] Furthermore, the magnetic ring adopts a magnetic sheet structure with staggered left and right assembly, has an air gap, and can be directly formed after stacking without secondary processing, saving processing time and avoiding the problem that internal stress generated by secondary processing will affect the sensor output accuracy.

[0008] Furthermore, the frame consists of two rectangular cylinders. The square wire of the secondary coil is wound around the outside of these two long, straight rectangular cylinders. The two cylinders are connected by a raised outer frame. A rectangular slot is located at the bottom for quickly and accurately positioning the Hall element. A wiring groove is provided along the edge of the slot. After the secondary coil is wound from one side of the frame, it is routed through this groove to the other side for further winding, optimizing the signal transmission path, reducing winding difficulty, and improving winding efficiency. To facilitate heat dissipation, reduce weight, and maintain a certain level of rigidity, the top of the frame is designed as a symmetrical triangular boss structure, lower in the middle and higher on both sides. The outer sides of the two rectangular cylinders are bosses used to position the initial end of the secondary coil. Two small cylindrical positioning posts are located diagonally on both sides of the bottom, and two positioning holes are located on the other diagonal. The frame, with the magnetic core and secondary coil assembled, can be positioned and mounted on the printed circuit board via the positioning posts and holes, allowing the frame and the printed circuit board to be quickly integrated into a single unit.

[0009] A 2mm diameter, 0.2mm deep through-hole is drilled 1mm from the edge on one side of the frame. The hole diameter is 0.6mm. A rivet is installed in the through-hole. The rivet has a hole at its bottom. After the rivet is installed in the through-hole, the edge is pressed and then inspected under a microscope after flanging to ensure there are no cracks. The bottom of the magnetic ring in the frame overlaps with the secondary coil and the top of the rivet head.

[0010] The grounding copper post is pre-installed on the PCB circuit board. After aligning and positioning the grounding copper post with the hole at the bottom of the rivet, it is spot-soldered to ensure the reliability of the electrical connection between the grounding copper post and the rivet. This allows the magnetic ring and the secondary coil to be simultaneously grounded on the PCB, providing a stable reference potential for the sensor. This ensures that the sensor's output signal varies within a fixed reference level, thereby improving signal stability and consistency. Grounding also reduces the impact of power fluctuations on the sensor's measurement accuracy, improving the sensor's anti-interference capability. When the power supply voltage is unstable, grounding can act as a buffer, making the sensor's output signal more stable.

[0011] This invention achieves a paradigm shift in Hall current sensor anti-interference technology through two major innovations: "direct connection of the magnetic core body and secondary coil to PCB ground to suppress interference signals" and "highly integrated magnetic core structure that eliminates the need for secondary processing". It replaces all bulky external shielding and unreliable mechanical contact (spring sheet) with a direct connection mode of precision rivet skeleton integration and copper pillar PCB spot welding. It fundamentally solves the contradiction between high signal-to-noise ratio, high reliability and miniaturization, and integrates anti-interference capability into the magnetic core body and achieves it through a simple and reliable physical connection, rather than an external additional structure.

[0012] The beneficial effects of this invention are as follows:

[0013] 1. High signal-to-noise ratio and reliability: Compared with the traditional solution of attaching spring plates to the magnetic core and directly welding grounding wires, the rivet is physically connected to the magnetic core. There is no need to open complex slots on the magnetic core or apply assembly stress, which avoids damage to the surface of the magnetic core or the introduction of internal stress that affects the magnetic properties. This solves the problem of low sensitivity and poor linearity of the sensor caused by the nonlinearity and hysteresis effect of the magnetic core.

[0014] 2. Balancing high precision and miniaturization: Abandoning all external shielding layers and complex grounding components of traditional solutions, the magnetic core and secondary coil are connected to the PCB ground via the shortest path (copper pillars) to discharge to the PCB ground, resulting in extremely low contact resistance and extremely high efficiency, solving the problems of insufficient common-mode interference suppression and ground loops; without external wrapping, the frame adopts a boss design, significantly reducing the size and weight, and the temperature rise is greatly reduced compared to traditional shielding solutions, solving the problems of poor temperature characteristics and serious temperature drift;

[0015] 3. Excellent static characteristics: This invention uses eight magnetic sheets stacked alternately in a trapezoidal groove within the skeleton to form a single piece, avoiding damage from secondary processing. The magnetic permeability consistency is over 95%, significantly improving the yield rate and resulting in excellent core linearity. The skeleton wiring groove optimizes the wiring of the secondary coils, avoiding additional electromagnetic signals caused by mutual coupling between the secondary coils, which could interfere with the Hall element. The unshielded outer shell and the triangular boss top cover of the skeleton balance heat dissipation and rigidity, significantly reducing temperature drift. The positioning posts / holes achieve precise alignment between the skeleton and the PCB, optimizing sensor assembly and installation errors, ensuring that the sensitive area overlaps with the point of maximum magnetic flux density, and guaranteeing the uniformity of the air gap magnetic field. This improves linearity and zero-point drift, while simplifying the assembly process and significantly increasing production efficiency.

[0016] 4. Significantly Improved Dynamic Characteristics: This invention features countersunk holes along the edge of the frame, with specially designed rivets embedded inside, forming a mechanical connection through edge pressing and flanging; the grounding conduction of the magnetic ring is achieved by directly connecting the bottom of the magnetic ring to the top of the rivet head, and the copper pillar and rivet are directly connected by spot welding. The PCB is pre-installed with grounding copper pillars, which are inserted into the bottom hole of the rivet and then spot-soldered, forming a low-impedance path of magnetic ring → rivet → copper pillar → PCB ground, suppressing ground potential fluctuations, significantly improving the common-mode rejection ratio, and achieving full-band interference suppression. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 This is a diagram showing the assembly relationship of the magnetic core grounding.

[0019] Figure 2 This is a diagram of the magnetic core grounding structure of the present invention.

[0020] Wherein: 1-Magnetic ring, 2-Air gap, 3-Frame, 4-Operational amplifier, 5-Rivet, 6-Hall element, 7-PCB board, 8-Grounding copper pillar Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] This embodiment provides a Hall current sensor core structure with a high signal-to-noise ratio, and its schematic diagram is shown below. Figure 1As shown, it includes: a magnetic ring 1, a frame 3, an operational amplifier 4, a rivet 5, a Hall element 6, a PCB board 7, and a grounding copper pillar 8. Its manufacturing process mainly includes magnetic sheet stacking, integrated assembly of the magnetic ring and the frame, Hall element installation, secondary coil winding, PCB board installation, and grounding treatment of the magnetic ring.

[0023] The magnetic ring mounting frame 3 has a hollow trapezoidal groove in the middle to hold the limiting interlocking magnetic ring 1. The hollow trapezoidal groove is 3.3mm high, 2.35mm long on the short side, and 2.58mm long on the long side. The magnetic sheet is 0.4mm thick and 8 sheets are stacked together.

[0024] Furthermore, the magnetic ring 1 adopts a magnetic sheet structure with staggered left and right assembly, has an air gap 2, and is directly formed after stacking without secondary processing, saving processing time and avoiding the problem that internal stress generated by secondary processing will affect the sensor output accuracy.

[0025] Furthermore, the frame 3 consists of two rectangular tubes, each 11.4 mm long and 4.3 mm wide x 3.75 mm high. The square wire of the secondary coil is wound around the outside of these two long rectangular tubes. The two long rectangular tubes are connected by a raised outer frame of 8.15 mm x 7.3 mm x 2.6 mm. A rectangular slot of 1.7 mm x 4.5 mm x 6.58 mm is opened at the bottom for quick and precise positioning of the Hall element 6. A wiring groove with a width of 0.8 mm is opened on the edge of the groove. After the secondary coil is wound from one side of the frame, the wiring is led through this groove to the other side for further winding, optimizing the signal transmission path, reducing winding difficulty, and improving winding efficiency. To facilitate heat dissipation, reduce weight, and maintain a certain level of rigidity, the top of the frame is designed as a symmetrical triangular boss structure, lower in the middle and higher on both sides, with a boss height of 0.7 mm. The outer sides of the two rectangular tubes, each 11.4 mm long and 4.3 mm wide and 3.75 mm high, have bosses measuring 8.15 mm x 7.3 mm x 0.75 mm, used to position the initial end of the secondary coil. Two small cylindrical positioning posts are located diagonally on both sides of the bottom, and two positioning holes with a diameter of 0.5 mm are located on the other diagonal. The frame, with the magnetic core and secondary coil assembled, can be positioned and mounted on the printed circuit board via the positioning posts and holes, allowing the frame 3 to be quickly integrated with the printed circuit board as a single unit.

[0026] A through hole with a diameter of 2mm and a depth of 0.2mm is drilled 1mm from the edge on one side of the frame. The hole diameter is 0.6mm. Rivet 5, with a head diameter of 1.8mm and a height of 0.2mm, is installed inside the through hole. The rivet shaft has a diameter of 0.5mm and a length of 0.7mm. A hole with a diameter of 0.5mm and a depth of 0.5mm is drilled at the bottom of the rivet. After the rivet is installed in the through hole, the edge is pressed, and the outer diameter of the flange is 1mm. After flangeding, the flange is inspected under a 30x microscope and no cracks are found. The bottom of the magnetic ring in the frame overlaps with the secondary coil and the top of the rivet head.

[0027] like Figure 2 As shown, the grounding copper post 8 is pre-installed on the PCB circuit board 7. The grounding copper post 8 has an outer diameter of 0.5mm and a length of 4.5mm. After the grounding copper post is aligned and positioned in the 0.5mm diameter hole at the center of the bottom of the rivet, it is spot-soldered to ensure the reliability of the electrical connection between the grounding copper post 8 and the rivet 5. This allows the magnetic ring and the secondary coil to be simultaneously connected to the PCB ground, providing a stable reference potential for the sensor and ensuring that the sensor's output signal varies at a fixed reference level, thereby improving the stability and consistency of the signal. At the same time, grounding can also reduce the impact of power fluctuations on the sensor's measurement accuracy, improve the sensor's anti-interference capability, and provide a certain buffering effect when the power supply voltage is unstable, making the sensor's output signal more stable.

[0028] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A Hall current sensor core structure with high signal-to-noise ratio, characterized in that, include: Magnetic ring, bobbin, operational amplifier, rivet, Hall element, PCB board, grounding copper pillar; The magnetic ring is formed by directly stacking and pressing together eight magnetic sheets that are assembled in a staggered manner from left to right. The frame consists of two rectangular tubes, with square wires of the secondary coil wound around the outside of the two long straight rectangular tubes; The two rectangular tubes are connected in the middle by a raised outer frame; The frame has a hollow trapezoidal groove in the middle for placing a limiting interlocking magnetic ring; a rectangular groove at the bottom for positioning and placing a Hall element; the top of the frame is a symmetrical triangular boss structure with a lower middle and higher sides; a through hole is opened on one side of the frame, and a rivet is installed in the through hole, with a hole at the center of the bottom of the rivet. The assembled magnetic ring and secondary coil frame are positioned and mounted on the PCB board using positioning pins and positioning holes; The grounding copper pillar is pre-installed on the PCB board. After aligning and positioning it with the hole at the center of the bottom of the rivet, it is spot-soldered so that the magnetic ring and the secondary coil are simultaneously connected to the PCB ground.

2. The Hall current sensor core structure with high signal-to-noise ratio according to claim 1, characterized in that, The rectangular slot has a wiring groove on its side. After the secondary coil is wound from one side of the skeleton, it is routed through the wiring groove to the other side to continue winding.

3. The Hall current sensor core structure with high signal-to-noise ratio according to claim 1, characterized in that, The outer sides of the two rectangular tubes are protrusions used to locate the initial end position of the secondary coil.

4. The Hall current sensor core structure with high signal-to-noise ratio according to claim 1, characterized in that, The bottom of the magnetic ring overlaps with the secondary coil and the top of the rivet head.

5. The Hall current sensor core structure with high signal-to-noise ratio according to claim 1, characterized in that, The manufacturing process includes: magnetic sheet stacking, integrated assembly of the magnetic ring and the frame, Hall element installation, secondary coil winding, PCB board installation, and grounding treatment of the magnetic ring.

6. The Hall current sensor core structure with high signal-to-noise ratio according to claim 1, characterized in that, The magnetic sheet is 0.4 mm thick.

7. The Hall current sensor core structure with high signal-to-noise ratio according to claim 1, characterized in that, The hollow trapezoidal groove has a height of 3.3 mm, a short side length of 2.35 mm, and a long side length of 2.58 mm.

8. The Hall current sensor core structure with high signal-to-noise ratio according to claim 7, characterized in that, The rectangular tube is 11.4 mm long and 4.3 mm wide and 3.75 mm high.

9. The Hall current sensor core structure with high signal-to-noise ratio according to claim 1, characterized in that, In the triangular boss structure of the skeleton, the boss height is 0.7mm.

10. The Hall current sensor core structure with high signal-to-noise ratio according to claim 1, characterized in that, After installing the rivet into the through hole, press the edge, and the outer diameter of the flange is 1mm.

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