Current sensor and processing method thereof

Abstract

The invention relates to the technical field of sensors, in particular to a current sensor and a processing method thereof. The current sensor provided by the invention comprises a shell with an accommodating cavity; the first iron core and the second iron core are arranged in the accommodating cavity, the first iron core and the second iron core define a first area for detecting that a conductor passes through, the first iron core comprises a first end face and a second end face located at the two ends, the second iron core comprises a third end face and a fourth end face located at the two ends, and a first air gap is formed between the first end face and the third end face; a second air gap is formed between the second end face and the fourth end face; the detection conductor passes through the first area, and two ends of the detection conductor extend out of the shell for the current of a detection object to flow; the circuit board is provided with a magnetic detection element, and the magnetic detection element is arranged in the first air gap and is used for detecting the magnetic field intensity generated by the current flowing in the detection conductor. According to the invention, the second air gap can optimize the symmetry and rationality of the magnetic circuit, and improves the reliability in a large-current scene.

Description

Technical Field

[0001] This disclosure relates to the field of sensor technology, and in particular to a current sensor and its fabrication method. Background Technology

[0002] Current sensors are widely used in monitoring and control scenarios of various electronic devices and systems, playing a crucial role in motor control systems, battery management systems, and industrial control systems of new energy vehicles. With the rapid development of technologies in these application areas, increasingly stringent requirements are being placed on the performance of current sensors, with cost reduction, size reduction, and weight reduction becoming particularly critical indicators.

[0003] Traditional current sensors are limited by design concepts and structural forms, and generally suffer from problems such as large size and complex construction. Summary of the Invention

[0004] This disclosure provides a current sensor and its fabrication method to at least solve the above-mentioned technical problems existing in the prior art.

[0005] The first aspect of this disclosure provides a current sensor, comprising: A housing having a receiving cavity inside; A first iron core and a second iron core are disposed in the accommodating cavity. The first iron core and the second iron core surround a first area for detecting the passage of a conductor. The first iron core includes a first end face and a second end face located at both ends. The second iron core includes a third end face and a fourth end face located at both ends. The first end face and the third end face are disposed opposite to each other, and a first air gap is formed between the first end face and the third end face. The second end face and the fourth end face are disposed opposite to each other, and a second air gap is formed between the second end face and the fourth end face. A detection conductor passes through the first region and extends from both ends of the housing for the flow of current to the object being detected; The circuit board is equipped with a magnetic detection element, which is disposed in the first air gap and is used to detect the magnetic field strength generated by the current flowing through the detection conductor.

[0006] Furthermore, the detection conductor is provided with a first groove and a second groove, with the first iron core disposed in the first groove and the second iron core disposed in the second groove.

[0007] Furthermore, the distance between the second end face and the fourth end face is greater than 0.

[0008] Furthermore, the circuit board is provided with a limiting hole, and the housing is provided with a limiting post, the limiting post being inserted into the limiting hole.

[0009] Furthermore, the circuit board is equipped with a temperature sensor.

[0010] Furthermore, the housing is formed with a first clearance hole for avoiding the first positioning member and a second clearance hole for avoiding the second positioning member. The first positioning member is used for positioning the first iron core, and the second positioning member is used for positioning the second iron core.

[0011] Furthermore, the circuit board is connected to a wire harness, and the housing has a through hole for the wire harness to pass through.

[0012] Furthermore, the cavity is provided with thermally conductive adhesive, which is disposed on the side of the circuit board away from the first iron core and the second iron core.

[0013] Furthermore, the circuit board is provided with a potting channel and a venting channel.

[0014] The second aspect of this disclosure provides a method for fabricating a current sensor as described in the first aspect, comprising: The first iron core, the second iron core, and the circuit board are respectively positioned in the injection mold of the housing; The housing is injection molded to form a cavity that encloses the first iron core, the second iron core, and the circuit board.

[0015] The technical solution provided in this disclosure has the following advantages compared with the prior art: The current sensor provided in this embodiment includes a housing, a first iron core, a second iron core, a detection conductor, and a circuit board. The housing has a receiving cavity; both the first and second iron cores are disposed within the receiving cavity, forming a first region for the detection conductor to pass through. The first iron core includes a first end face and a second end face located at both ends, and the second iron core includes a third end face and a fourth end face located at both ends. The first and third end faces are positioned opposite each other, forming a first air gap between them. The second and fourth end faces are positioned opposite each other, forming a second air gap between them. The detection conductor passes through the first region, with both ends extending out of the housing, for current flow of the detected object. The circuit board is provided with a magnetic detection element disposed in the first air gap, used to detect the magnetic field strength generated by the current flowing through the detection conductor. When current flows through the detection conductor, the generated magnetic field is concentrated by the closed magnetic circuit formed by the first and second iron cores. If only the first air gap is designed without a second air gap, the uneven distribution of air gaps in the magnetic circuit will lead to excessive concentration of magnetic flux in the first and second iron cores, especially under high-current conditions, making them prone to magnetic saturation. The introduction of a second air gap creates a dual-air gap voltage-dividing structure in the magnetic circuit, with the total magnetopotential difference shared by both air gaps, resulting in a more stable magnetic field strength in the first air gap. Simultaneously, the dual-air gap design reduces magnetic circuit asymmetry caused by manufacturing errors in the iron cores, further ensuring the uniformity of the magnetic field distribution in the first air gap. The second air gap optimizes the symmetry and rationality of the magnetic circuit, improving reliability under high-current conditions.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0017] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0018] Figure 1 A schematic diagram of the structure of the current sensor provided in an embodiment of this disclosure is shown; Figure 2 A cross-sectional structural schematic diagram of a current sensor provided in an embodiment of this disclosure is shown; Figure 3 An exploded view of a current sensor provided in an embodiment of this disclosure is shown; Figure 4 A cross-sectional view showing the first iron core, the second iron core, and the detection conductor in combination is shown; Figure 5 A schematic diagram of the detector conductor is shown.

[0019] The following are the labels in the diagram: 1. Housing; 11. Limiting post; 12. First clearance hole; 13. Second clearance hole; 14. Through hole; 2. First iron core; 21. First end face; 22. Second end face; 3. Second iron core; 31. Third end face; 32. Fourth end face; 4. First region; 51. First air gap; 52. Second air gap; 6. Detection conductor; 61. First groove; 62. Second groove; 7. Circuit board; 71. Magnetic detection element; 72. Limiting hole; 73. Temperature sensor; 74. Wiring harness; 8. Thermal conductive adhesive. Detailed Implementation

[0020] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0021] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, the current sensor provided in this embodiment includes a housing 1, a first iron core 2 and a second iron core 3, a detection conductor 6, and a circuit board 7. The detection conductor 6 can be a plate-shaped conductor made of good electrical conductors such as copper or aluminum, forming a current path for current flow. The housing 1 has a receiving cavity; a first iron core 2 and a second iron core 3 are both disposed in the receiving cavity, forming a first region 4 for detecting the passage of a conductor 6. The first iron core 2 includes a first end face 21 and a second end face 22 located at both ends, and the second iron core 3 includes a third end face 31 and a fourth end face 32 located at both ends. The first end face 21 and the third end face 31 are arranged opposite to each other, forming a first air gap 51 between them. The second end face 22 and the fourth end face 32 are arranged opposite to each other, forming a second air gap 52 between them. The detection conductor 6 passes through the first region 4, with both ends of the detection conductor 6 extending out of the housing 1 for current flow of the detected object. The circuit board 7 is provided with a magnetic detection element 71, which is disposed in the first air gap 51 and is used to detect the magnetic field strength generated by the current flowing through the detection conductor 6. When current flows through the detection conductor 6, the magnetic field it generates is concentrated by the closed magnetic circuit formed by the first iron core 2 and the second iron core 3. If only the first air gap 51 is designed without the second air gap 52, the uneven distribution of air gaps in the magnetic circuit will lead to excessive concentration of magnetic flux in the first iron core 2 and the second iron core 3, especially under high current conditions, where the first iron core 2 and the second iron core 3 are prone to magnetic saturation. The introduction of the second air gap 52 creates a dual-air gap voltage-dividing structure in the magnetic circuit, with the total magnetopotential difference shared by both air gaps, making the magnetic field strength of the first air gap 51 more stable. At the same time, the dual-air gap design can reduce the magnetic circuit asymmetry problem caused by the iron core's processing errors, further ensuring the uniformity of the magnetic field distribution in the first air gap 51. The second air gap 52 can optimize the symmetry and rationality of the magnetic circuit, improving reliability under high current conditions.

[0022] The magnetic detection element 71 can be a Hall element, a giant magnetoresistive effect element, or an anisotropic magnetoresistive element, etc. The magnetic detection element 71 can output a voltage signal corresponding to the magnetic field strength along the detection axis. In this embodiment, the detection axis of the magnetic detection element 71 is the width direction of the detection conductor 6.

[0023] The detection conductor 6 can be a busbar or a busbar.

[0024] Reference Figure 4 As shown, the second air gap 52 ≥ 0 mm. When the second air gap 52 > 0, the magnetization linear region of the iron core assembly can be significantly improved. W1 = 2Wcore + Wgap. With W1 unchanged, the adjustment of the current measurement linear range can be achieved by adjusting the size of Wgap. The larger Wgap is, the larger the current measurement linear range is.

[0025] In some specific embodiments, the detection conductor 6 is provided with a first groove 61 and a second groove 62. The first iron core 2 is disposed in the first groove 61, and the second iron core 3 is disposed in the second groove 62, so that the first iron core 2 and the second iron core 3 can be embedded in the detection conductor 6. The first groove 61 provides a mechanical positioning reference for the first iron core 2, and the second groove 62 provides a mechanical positioning reference for the second iron core 3. The grooves can serve as "guide grooves" for iron core installation, reducing the alignment difficulty during assembly and improving production efficiency. After the first iron core 2 is embedded in the first groove 61 and the second iron core 3 is embedded in the second groove 62, it can be further fixed by injection molding housing 1 or potting material, enhancing the overall structural reliability of the current sensor.

[0026] Combination Figure 4 and Figure 5 As shown, Wbusbar = W1 - 2W2, which completes the accurate positioning of the core assembly formed by the first core 2 and the second core 3 in the X and Y directions. The slot size of the first groove 61 and the second groove 62 can be 1mm-2mm, which retains a large current carrying capacity.

[0027] The first groove 61 and the second groove 62 can control the relative position of the first iron core 2 and the second iron core 3. Ensuring that the first region 4 (the space through which the conductor passes) enclosed by the first iron core 2 and the second iron core 3 has a regular shape can improve the reliability of the detection.

[0028] In some specific embodiments, the distance between the second end face 22 and the fourth end face 32 is greater than 0. If the second end face 22 and the fourth end face 32 are completely in contact, the total magnetic reluctance of the magnetic circuit is mainly determined by the first air gap 51, which may cause the magnetic circuit to enter saturation earlier under high current. The presence of the second air gap 52 can increase the total magnetic reluctance of the magnetic circuit, making the magnetic reluctance distribution more balanced and extending the linear operating range of the magnetic circuit. When the conductor current changes, the second air gap 52 can share part of the magnetic pressure, avoiding nonlinear distortion of the magnetic field strength of the first air gap 51 due to magnetic reluctance concentration. Especially when detecting currents with a large dynamic range, it can significantly improve the linearity index of the sensor.

[0029] In some specific embodiments, the circuit board 7 is provided with a limiting hole 72, and the housing 1 is provided with a limiting post 11. The limiting post 11 is inserted into the limiting hole 72 to provide a rigid positioning reference for the circuit board 7. This can strictly control the position of the circuit board 7 and the magnetic detection element 71 on the circuit board 7 relative to the first iron core 2, the second iron core 3 and the first air gap 51, reducing the possibility of magnetic field detection point offset due to assembly deviation, thereby reducing detection error.

[0030] In some specific embodiments, the circuit board 7 is equipped with a temperature sensor 73. The temperature sensor 73 monitors the temperature of the circuit board 7 and its surrounding environment in real time, and feeds the temperature data back to the processing circuit. The detection signal is dynamically corrected through a preset compensation algorithm. The system can automatically amplify the signal based on the data from the temperature sensor 73 to counteract the influence of temperature. The source of the temperature is the detection conductor 6, and the temperature sensor 73 is used to monitor the heating of the detection conductor 6.

[0031] In some specific embodiments, the housing 1 has a first clearance hole 12 for avoiding the first positioning member and a second clearance hole 13 for avoiding the second positioning member. The first positioning member is used for positioning the first iron core 2, and the second positioning member is used for positioning the second iron core 3. The first and second positioning members are used to fix the positions of the first iron core 2 and the second iron core 3, ensuring that the relative positions of the first iron core 2 and the second iron core 3 within the housing 1 are accurate. After the housing 1 is injection molded, the housing 1 can fix the first iron core 2 and the second iron core 3. The first and second positioning members are used to position the first iron core 2 and the second iron core 3 during the injection molding process of the housing 1. After the housing 1 is injection molded, the circuit board 7 is fixedly connected to the housing 1. The first clearance hole 12 and the second clearance hole 13 provide through or extended space for the first and second positioning members, avoiding obstruction or interference of the housing 1 structure on the first and second positioning members, allowing the first and second positioning members to directly act on the first iron core 2 and the second iron core 3, ensuring the reliable realization of the positioning function of the first and second positioning members. Both the first and second positioning components can be positioning pins, buckles, or positioning blocks, etc.

[0032] In some specific embodiments, the circuit board 7 is connected to a wire harness 74, and the housing 1 has a through hole 14 for the wire harness 74 to pass through. The position and size of the through hole 14 can be set according to the direction of the wire harness 74, guiding the wire harness 74 through the housing 1 along a preset path and preventing the wire harness 74 from getting tangled or squeezed with other components inside the housing 1. The wire harness 74 can be adjusted to different forms, such as a wire harness 74 with a connector, etc. In some specific embodiments, a thermally conductive adhesive 8 is provided inside the accommodating cavity, and the thermally conductive adhesive 8 is disposed on the side of the circuit board 7 opposite to the first iron core 2 and the second iron core 3. The temperature is generated by the detection conductor 6, and the temperature sensor 73 is used to monitor the heating of the detection conductor 6. The thermally conductive adhesive 8 is provided to improve the thermal conductivity so that the temperature can be monitored in a timely manner.

[0033] In other words, the function of temperature sensor 73 is to monitor the temperature of the conductor. The conductor will generate heat when energized, and thermal conductive adhesive 8 is used to better conduct heat so that temperature sensor 73 can detect the temperature in a timely manner.

[0034] In some specific embodiments, the circuit board 7 is provided with a potting channel and a venting channel. The potting channel can serve as a guide for the adhesive, allowing it to flow along a preset path during the potting process. For example, when potting adhesive into the accommodating cavity, the adhesive can first fill the gap below the circuit board 7 through the potting channel, and then gradually spread upwards to the area around the components, avoiding local areas that cannot be covered by the adhesive due to obstruction by components. During the flow of the adhesive, air will be trapped; if not expelled in time, air bubbles will form. These air bubbles can not only block the heat conduction path, but may also cause the adhesive to crack due to stress concentration during vibration. The venting channel can vent air in a directional manner, ensuring a dense filling of the adhesive.

[0035] The current sensor processing method provided in this embodiment includes: positioning the first iron core 2, the second iron core 3, and the circuit board 7 in the injection mold of the housing 1; and injection molding the housing 1 to form an accommodating cavity that encompasses the first iron core 2, the second iron core 3, and the circuit board 7. In this embodiment, each component is pre-positioned in the mold before injection molding, and then the housing 1 is injection molded. After the housing 1 is formed, it can be directly wrapped and fixed, so that the air gap size between the first iron core 2 and the second iron core 3, and the alignment accuracy between the circuit board 7 and the air gap are controlled within a certain range, ensuring that the magnetic detection element 71 is accurately aligned with the first air gap 51, and reducing detection errors. This embodiment integrates positioning, injection molding, and fixing into a single process, eliminating the need for fasteners such as clips and screws.

[0036] In some specific embodiments, the first iron core 2 and the second iron core 3 can be processed by stamping and riveting thin silicon steel sheets, and the first iron core 2 and the second iron core 3 can be designed as identical components; the detection conductor 6 can be formed by stamping and riveting; the overall packaging of the current sensor can be formed by molding, positioning the first iron core 2, the second iron core 3, and the detection conductor 6 in the mold, and then injection molding. The design of the split iron core can show its advantages in the assembly and packaging stages.

[0037] Traditionally, the busbar needs to be inserted into the C-shaped magnetic core before matching within the mold. The insertion process requires a large gap, often necessitating a narrower busbar design, which affects current carrying capacity. Alternatively, a larger air gap in the core can lead to a decrease in interference immunity.

[0038] After the first iron core 2 and the second iron core 3 are designed separately, they can be flexibly matched, and the limiting of the iron core assembly in the X / Y direction and the cooperation of the busbar can complete the accurate positioning.

[0039] For the fabrication of circuit board 7, such as PCBA, the SMT solution can be used to fix the magnetic sensor and temperature sensor 73 on the printed circuit board, and the wire harness 74 can be fixed on the printed circuit board by soldering.

[0040] The PCBA is installed into module housing 1, which is designed with riveting features to complete the initial positioning of the PCBA.

[0041] The thermally conductive adhesive 8 is potted through the adhesive flow channels designed into the printed circuit board, completing the potting of the bottom and top of the printed circuit board.

[0042] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this embodiment can be achieved, and this is not limited herein.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A current sensor, characterized in that, include: A housing (1) having a receiving cavity inside; A first iron core (2) and a second iron core (3) are disposed in the accommodating cavity. The first iron core (2) and the second iron core (3) surround a first area (4) for detecting the passage of the conductor (6). The first iron core (2) includes a first end face (21) and a second end face (22) located at both ends. The second iron core (3) includes a third end face (31) and a fourth end face (32) located at both ends. The first end face (21) and the third end face (31) are disposed opposite to each other. A first air gap (51) is formed between the first end face (21) and the third end face (31). The second end face (22) and the fourth end face (32) are disposed opposite to each other. A second air gap (52) is formed between the second end face (22) and the fourth end face (32). A detection conductor (6) passes through the first region (4) and both ends of the detection conductor (6) extend out of the housing (1) for the current flow of the object being detected; The circuit board (7) is provided with a magnetic detection element (71), which is disposed in the first air gap (51) and is used to detect the magnetic field strength generated by the current flowing in the detection conductor (6).

2. The current sensor according to claim 1, characterized in that, The detection conductor (6) is provided with a first groove (61) and a second groove (62), the first iron core (2) is disposed in the first groove (61), and the second iron core (3) is disposed in the second groove (62).

3. The current sensor according to claim 1, characterized in that, The distance between the second end face (22) and the fourth end face (32) is greater than 0.

4. The current sensor according to claim 1, characterized in that, The circuit board (7) is provided with a limiting hole (72), and the housing (1) is provided with a limiting post (11). The limiting post (11) is inserted into the limiting hole (72).

5. The current sensor according to claim 1, characterized in that, The circuit board (7) is equipped with a temperature sensor (73).

6. The current sensor according to claim 1, characterized in that, The housing (1) is formed with a first clearance hole (12) for avoiding the first positioning member and a second clearance hole (13) for avoiding the second positioning member. The first positioning member is used for positioning the first iron core (2), and the second positioning member is used for positioning the second iron core (3).

7. The current sensor according to claim 1, characterized in that, The circuit board (7) is connected to a wire harness (74), and the housing (1) has a through hole (14) for the wire harness (74) to pass through.

8. The current sensor according to claim 1, characterized in that, The cavity is provided with thermally conductive adhesive (8), which is disposed on the side of the circuit board (7) away from the first iron core (2) and the second iron core (3).

9. The current sensor according to claim 1, characterized in that, The circuit board (7) is provided with a potting channel and an exhaust channel.

10. A method for fabricating a current sensor as described in any one of claims 1 to 9, characterized in that, include: The first iron core (2), the second iron core (3) and the circuit board (7) are respectively positioned in the injection mold of the housing (1); The housing (1) is injection molded to form a cavity that includes the first iron core (2), the second iron core (3), and the circuit board (7).

Images