Current detection device for copper bar

Abstract

The utility model relates to a current detection device used for a copper bar, the current detection device is installed on the copper bar, one side or two sides of the copper bar are provided with gaps, the current detection device comprises a current detection chip and a shielding case, the shielding case covers the copper bar, and the current detection chip is parallel to the copper bar and is installed on the surface of the copper bar or above the surface of the copper bar. Compared with the prior art, one side or two sides of the copper bar are provided with the gaps, so that an internal magnetic field of the shielding cover translates in the horizontal direction when the alternating current changes, and the influence of the skin effect on the induction magnetic field intensity of the current detection chip is reduced; the current in the copper bar can be detected without an additional communication wire harness or a shell, so that the size is greatly reduced, and the cost is reduced; current detection can be carried out by arranging the current detection chip on the surface of the copper bar, the installation position can be flexibly adjusted according to the internal space requirement of the product, and the application range is wide.

Description

Technical Field

[0001] The utility model relates to current detection, in particular to a current detection device for copper busbars. Background Art

[0002] Common current detection devices include Hall effect sensors, Rogowski coils, current transformers, photocurrent sensors, fluxgates, and shunt resistors. Current transformers and Rogowski coils are only used for AC current detection. Different measurement methods use different measurement principles, have different measurement objects, and have different measurement accuracy.

[0003] For example, the accuracy of the current detection module used in an inverter directly impacts the overall control performance of the inverter. Inverter products have the following different current detection requirements: three-phase AC current detection, boost output current detection, and DC-DC output current detection. Three-phase AC current detection collects the AC current flowing through the three-phase copper busbar, inputs it into the MCU, and uses an SVPWM closed-loop control strategy to drive the motor. Existing technical solutions generally use C-type Hall sensors, whose magnetic ring and copper busbar are integrally formed using an injection molding process. However, this solution is costly and difficult to flexibly arrange within the inverter.

[0004] In summary, how to design a current detection device with low cost and flexible layout is a technical problem that needs to be solved. Utility Model Content

[0005] The purpose of the present utility model is to provide a current detection device for a copper busbar in order to overcome the defects of the prior art such as high cost and inflexible layout.

[0006] The purpose of the utility model can be achieved through the following technical solutions:

[0007] According to one aspect of the present utility model, a current detection device for a copper busbar is provided, which is installed on the copper busbar, and a notch is provided on one or both sides of the copper busbar. The current detection device includes a current detection chip and a shielding cover, and the shielding cover is provided on the copper busbar. The current detection chip is parallel to the copper busbar and is installed on the surface of the copper busbar or above the surface of the copper busbar.

[0008] As a preferred technical solution, a notch is provided on one side of the copper busbar, and the shape of the notch is rectangular.

[0009] As a preferred technical solution, notches are provided on both sides of the copper busbar, and the shape of the notches is rectangular.

[0010] As a preferred technical solution, the projection of the current detection chip on the copper busbar is the first projection; the projection of the shielding cover on the copper busbar is the second projection; and the first projection is located within the second projection.

[0011] As a preferred technical solution, the shielding cover is U-shaped, including a bottom plate and two side plates perpendicular to the bottom plate and respectively connected to one side of the bottom plate; the two side plates are respectively located on both sides of the copper busbar in the width direction.

[0012] As a preferred technical solution, the width of the shielding cover is less than 15 mm.

[0013] As a preferred technical solution, the shielding cover and the copper busbar are an integrally formed structure.

[0014] As a preferred technical solution, the shielding cover is a shielding cover made of nickel iron or a shielding cover made of ferrosilicon and annealed.

[0015] As a preferred technical solution, the shielding cover is a laminated structure, including multiple layers of shielding sheets, and an insulating layer is provided on the surface of the shielding sheets.

[0016] As a preferred technical solution, the thickness of the shielding sheet is between 0.2 mm and 0.5 mm.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1) By providing notches on one or both sides of the copper busbar, the present invention causes the magnetic field inside the shield to shift horizontally when the AC current changes, thereby reducing the influence of the skin effect on the induced magnetic field strength of the current detection chip. This allows detection of the current inside the copper busbar without the need for additional communication wiring harnesses or housings, significantly saving volume and reducing costs. The current detection chip can be placed on the surface of the copper busbar to perform current detection, and the installation position can be flexibly adjusted according to the internal space requirements of the product, thus having a wide range of applications.

[0019] 2) The utility model sets a notch on one side of the copper busbar, which reduces the width of the copper busbar less and has better heat dissipation performance;

[0020] 3) The current detection chip of the utility model is located within the shielding range of the shielding cover and is less susceptible to external noise interference;

[0021] 4) The laminated structure of the shielding cover of the present invention can reduce eddy current loss and also reduce the phase delay caused by frequency change; the thickness of the shielding sheet is between 0.2mm and 0.5mm, which can ensure small eddy current loss and facilitate processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of the utility model installed on a copper busbar;

[0023] Figure 2 This is an exploded view of the utility model installed on a copper busbar;

[0024] Figure 3 The first structure schematic diagram of the copper bar of the utility model;

[0025] Figure 4 The second structure schematic diagram of the copper bar of the utility model;

[0026] Figure 5 The top view of the utility model installed on the inverter board;

[0027] Figure 6 The bottom view of the utility model installed on the inverter board;

[0028] Figure 7 The structure schematic diagram of the utility model installed on the inverter board and installed on the inverter shell;

[0029] The figure mark shows:

[0030] 1, copper bar, 11, notch, 2, current detection chip, 3, shield cover, 31, bottom sheet, 32, side sheet. Specific implementation

[0031] The technical scheme in the embodiments of the utility model will be described clearly and completely in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the utility model.

[0032] As shown in Figure 1 and Figure 2 The utility model provides a kind of current detection device for copper bar, including current detection chip 2 and shield cover 3.

[0033] In actual three-phase alternating current detection, skin effect caused by magnetic field attenuation will be encountered. Necking treatment is carried out on copper bar 1, and notch 11 is formed on one side or both sides of copper bar 1, so that the internal magnetic field of shield cover 3 produces translation in horizontal direction when alternating current changes, and the influence of skin effect on the magnetic field intensity sensed by current detection chip 2 is reduced. As shown in Figure 3 Rectangular notch 11 is formed on one side of copper bar 1; as shown in Figure 4As shown, rectangular notches 11 are provided on both sides of the copper busbar 1. Experiments have shown that, to achieve the same reduction in AC attenuation and magnetic field shift, a 4mm-wide notch 11 can be provided on one side of the copper busbar 1, or a 3mm-wide notch 11 can be provided on both sides. Actual testing has shown that a 5mm-wide notch on one side exhibits lower AC attenuation and magnetic field shift than those with 2.5mm and 3mm-wide notches on both sides. The maximum AC attenuation for a notch on one side is 1.2%, while for both sides it is 2.2%. The maximum magnetic field shift for a notch on one side is 3.2°, while for both sides it is 3.7°.

[0034] Introducing notches 11 on one side of the copper busbar 1 results in relatively low AC attenuation, but can lead to significant accuracy variations with assembly tolerances. Introducing notches 11 on both sides of the copper busbar 1 results in relatively high AC attenuation, but is relatively stable and less affected by assembly tolerances. Since notches 11 on both sides of the copper busbar 1 make it narrower, hindering heat dissipation and requiring more stamping cycles, introducing notches 11 on one side is generally preferred to minimize skin effect.

[0035] Current sensing chip 2 is parallel to copper busbar 1 and attached to or above the surface of copper busbar 1. It is located within the shielding cover 3. Current sensing chip 2 utilizes IMC (Integrated Magnetic Concentrator) technology to convert horizontal magnetic fields into vertical components, generating a Hall potential difference for detection. IMC enables current sensing chip 2 to simultaneously detect magnetic fields in the X, Y, and Z directions within the same plane. The current sensing chip 2 can be selected based on the actual product testing requirements, primarily focusing on two aspects:

[0036] 1) The magnetic field generated by the measured current multiplied by the gain factor cannot exceed the maximum limit of the current detection chip 2;

[0037] 2) While meeting the limit, the output voltage range of the current detection chip 2 can be increased as much as possible to improve the current detection resolution.

[0038] The shielding cover 3 is U-shaped and includes a bottom piece 31 and side pieces 32. There are two side pieces 32, which are connected to the two opposite sides of the bottom piece 31. The shielding cover 3 wraps the copper busbar 1 and the current detection chip 2, and concentrates the magnetic field generated by the current in the internal area. The concentrated magnetic points inside the current detection chip 2 make the magnetic lines of force "bend" and concentrate, which is convenient for detection. The shielding cover 3 is placed on the copper busbar 1, and the two side pieces 32 are located on both sides of the width direction of the copper busbar 1. The shielding cover 3 can be made of nickel-iron material, or it can be made of silicon iron and annealed.

[0039] The shielding cover 3 can be integrally formed with the copper busbar 1. The integrally formed structure has the following advantages:

[0040] 1. Enhanced mechanical strength: High-temperature one-piece injection molding makes the connection between the shielding cover 3 and the copper busbar 1 more secure and able to withstand greater mechanical stress.

[0041] 2. Improve heat resistance: The connection between the shielding cover 3 and the copper bus 1 can remain stable in a high temperature environment and is not easily deformed or damaged.

[0042] 3. Simplify the installation process: One-piece molding reduces installation steps and time, and improves production efficiency.

[0043] 4. Reduce costs: By eliminating additional fixings and processes, the overall cost can be reduced.

[0044] 5. Improve electrical performance: Tight connection helps reduce resistance and electromagnetic interference and improve electrical performance.

[0045] The main functions of the shield 3 are magnetic field concentration and interference rejection. Magnetic field concentration concentrates the magnetic field generated by the current in the area of ​​the current sensing chip 2, enhancing its magnetic field strength and enabling the current sensing chip 2 to output a voltage with appropriate resolution. Interference rejection reduces the interference of external stray magnetic fields on the internal effective magnetic field, reducing its proportion and improving the signal-to-noise ratio.

[0046] Based on this, the narrower the width and the higher the height of the shielding cover 3, the stronger its magnetic field collection and anti-interference capabilities are. The closer the current detection chip 2 is to the bottom film 31 of the shielding cover 3, the lower the external noise interference is.

[0047] As an important component of the current detection module, the shield 3 is made of magnetic material, so its material and manufacturing process will greatly affect the current detection accuracy.

[0048] The integrated shielding cover 3 (i.e., the shielding cover 3 that does not adopt the lamination process) will generate induced eddy currents under AC conditions, thereby reducing the concentrated magnetic field strength; under the same current size, the output voltage under AC conditions will be greatly attenuated relative to the DC conditions. The use of the lamination process can reduce eddy current losses and also reduce the phase delay caused by frequency changes.

[0049] The lamination process is a method of reducing eddy current losses by dividing the material into thin sheets and insulating them from each other, as follows:

[0050] Material selection: Silicon steel sheets or other high resistivity materials are usually used. Materials with higher resistivity help reduce eddy current losses.

[0051] Thin slice cutting: Cut the material into thin slices, the thickness is usually between 0.2mm and 0.5mm. The thinner the slice, the smaller the eddy current loss.

[0052] Insulation treatment: each sheet surface is coated with insulating paint or other insulating materials to ensure electrical insulation between the sheets. This can prevent eddy currents from flowing between the sheets.

[0053] Lamination assembly: the sheets after insulation treatment are stacked together in a specific order to form the required core or magnetic core structure. This structure can effectively limit the path of eddy currents, thereby reducing eddy current loss.

[0054] For the material selection of the shielding cover 3, experiments show that the response time and magnetic hysteresis of nickel-iron are better than that of silicon-iron, but the cost is higher; the cost of silicon-iron is low, and the annealing process can reduce the magnetic hysteresis problem after forming.

[0055] After adopting the lamination process and the annealing process for silicon-iron, the magnetic hysteresis and attenuation of the current detection device of the utility model are well solved.

[0056] As shown in Figures 5-7 The utility model can be used for inverter, detects the current of alternating current flowing in three-phase copper bar 1 of inverter, compared with traditional LEM's C type hall sensor, not only has great advantage in cost, and smaller size, need not set up area on inverter shell to place C type hall sensor, can decide the arrangement position according to the space limit inside product. Because motor is multipolar number, and the highest speed of application scene is less than or equal to 18000rpm, corresponding current flat is 1.2KHz. In actual operation process, the utility model 2kHz's current frequency band alternating current attenuation is 1.3%, and phase delay is 4.7%, the utility model has good performance and cost advantage.

[0057] The corresponding relationship between the detected current size and the output voltage size of the utility model is a first-order function.

[0058] The above is only a specific embodiment of the utility model, but the protection scope of the utility model is not limited to this, any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the utility model, and these modifications or replacements should be covered in the protection scope of the utility model. Therefore, the protection scope of the utility model should be subject to the protection scope of the claims.

Claims

1. A current detection device for a copper busbar, mounted on a copper busbar (1), characterized in that: The copper busbar (1) is provided with a notch (11) on one or both sides. The current detection device comprises a current detection chip (2) and a shielding cover (3). The shielding cover (3) is provided on the copper busbar (1). The current detection chip (2) is parallel to the copper busbar (1) and is installed on the surface of the copper busbar (1) or above the surface of the copper busbar (1).

2. A current detection device for copper busbar according to claim 1, characterized in that: A notch (11) is provided on one side of the copper busbar (1), and the notch (11) is in the shape of a rectangle.

3. The current detection device for copper busbar according to claim 1, characterized in that: Notches (11) are provided on both sides of the copper busbar (1), and the shape of the notches (11) is rectangular.

4. The current detection device for copper busbar according to claim 1, characterized in that: The projection of the current detection chip (2) on the copper busbar (1) is a first projection; the projection of the shielding cover (3) on the copper busbar (1) is a second projection; and the first projection is located within the second projection.

5. The current detection device for copper busbar according to claim 1, characterized in that: The shielding cover (3) is U-shaped and comprises a bottom plate (31) and two side plates (32) perpendicular to the bottom plate (31) and respectively connected to one side of the bottom plate (31); the two side plates (32) are respectively located on both sides of the copper busbar (1) in the width direction.

6. The current detection device for copper busbar according to claim 1, characterized in that: The width of the shielding cover is less than 15 mm.

7. The current detection device for copper busbar according to claim 1, characterized in that: The shielding cover (3) and the copper busbar (1) are an integrally formed structure.

8. The current detection device for copper busbar according to claim 1, characterized in that: The shielding cover (3) is a shielding cover (3) made of nickel iron or a shielding cover (3) made of silicon iron and subjected to annealing treatment.

9. The current detection device for copper busbar according to claim 1, characterized in that: The shielding cover (3) is a laminated structure, comprising multiple layers of shielding sheets, and an insulating layer is provided on the surface of the shielding sheets.

10. The current detection device for copper busbar according to claim 9, characterized in that: The thickness of the shielding sheet is between 0.2 mm and 0.5 mm.

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