Low inductance three-dimensional composite busbar

Abstract

The application discloses a low-inductance three-dimensional composite busbar, which comprises upper and lower split upper and lower composite busbars, the upper composite busbar is provided with an AC electrode leading-out layer and an AC-U connecting layer, the lower composite busbar is provided with an AC-L connecting layer, a PN electrode layer and an O electrode layer, and the two are correspondingly connected to form an AC loop; the busbar is provided with switch mounting holes for mounting T switch tubes and D switch tubes, and the current loop length is shortened through optimized switch layout. Through three-dimensional layered layout and combined Z-shaped bending arc structure, the current loop circumference is greatly shortened, the magnetic fields of opposite currents are used for offsetting to realize inductance cancellation, stray inductance is effectively reduced, voltage spikes are inhibited, integrally formed leading-out terminals are arranged in a staggered mode to avoid installation interference, the split structure improves the convenience of installation and maintenance, can be adapted to high-power applications of three-level circuits and meets the needs of miniaturization and high power density.

Description

Technical Field

[0001] This invention relates to a low-sensitivity three-dimensional composite busbar. Background Technology

[0002] With the continuous development of power electronics technology, the power density and frequency requirements of electrical equipment are constantly increasing, which places higher demands on electrical connection devices. Traditional cable and copper busbar connections in high-power frequency converters, due to their large parasitic inductance, are prone to voltage spikes, threatening power devices and affecting circuit reliability and efficiency. Furthermore, traditional connection methods also suffer from bulky structures and large space requirements, limiting the overall system design.

[0003] To address the aforementioned issues, composite busbar technology has gradually gained traction. For example, Chinese utility model patent CN213123815U discloses a stacked busbar for a high-power three-level charger, which reduces stray inductance to some extent through its stacked structure. However, this solution still employs a single, integral stacked structure, resulting in a large overall volume that is difficult to meet miniaturization requirements. CN110912423A proposes a three-level bridge-type three-layer stacked busbar structure, optimizing the circuit layout through the stacking of three conductor layers. However, this solution is an integral stacked design, without a segmented, three-dimensional busbar layout, leaving room for optimization of the current loop length and inconvenient installation and maintenance. CN110474518B discloses a three-level stacked busbar for suppressing stray inductance, optimizing stray inductance through the layout of the three-phase modules. However, this solution lacks structural flexibility, making it difficult to adapt to different application scenarios, and the layout of the electrode leads is prone to interference problems.

[0004] The existing composite busbars generally have the following defects: First, they mostly adopt a single integral stacked structure, which is large in size and difficult to meet the requirements of miniaturization and high density of modern electrical equipment; second, the circuit length is not optimized enough, which cannot effectively shorten the current path, resulting in a high level of stray inductance; third, the electrode lead layout is unreasonable, which is prone to installation interference and has poor installation and maintenance flexibility; fourth, the layout of insulation and conductive layers is not optimized enough, making it difficult to simultaneously meet the requirements of insulation performance and low inductance. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a low-inductance three-dimensional composite busbar. Through a three-dimensional busbar structure with split upper and lower sections, combined with a layered conductor layer layout, the current loop length is effectively shortened, stray inductance is reduced, and the compactness of the structure and the convenience of installation and maintenance are improved.

[0006] The technical solution of the present invention: A low-inductance three-dimensional composite busbar includes an upper composite busbar and a lower composite busbar. The upper composite busbar includes an upper AC electrode lead-out layer and a lower AC-U connection layer, the AC-U connection layer consisting of symmetrically spaced AC1-U connection bars and AC2-U connection bars. The lower composite busbar includes an upper AC-L connection layer, a middle PN electrode layer, and a lower O electrode layer, the PN electrode layer consisting of symmetrically spaced P-electrode layers and N-electrode layers. The two ends of the AC-U connection layer are connected to the two ends of the AC-L connection layer to form an AC circuit. This three-dimensional layered layout splits the original 5-layer conductor structure into a 2-layer upper busbar and 3-layer lower busbar structure, significantly shortening the current path of each circuit. According to the circuit inductance calculation formula... ,in The permeability of free space, l Let be the perimeter of the loop. As the geometric mean distance, shortening the loop perimeter can directly reduce the parasitic inductance of the loop; on the other hand, the separate upper and lower busbar structure allows for individual disassembly during installation and maintenance without the need for overall disassembly, greatly improving maintainability.

[0007] Furthermore, both the AC1-U and AC2-U connecting busbars have Z-shaped bends. One end of each busbar faces the other and together forms an arc-shaped structure protruding towards the AC electrode lead-out layer. The AC electrode lead-out layer is attached to the protruding end face of this arc-shaped structure. A row of connection holes is provided on the other end face of both the AC1-U and AC2-U connecting busbars. This Z-shaped bend and arc-shaped structure, on the one hand, provides sufficient screw operating space for switch installation, avoiding spatial interference during installation; on the other hand, this structure allows the connection ends of the upper and lower composite busbars to be as close as possible, further shortening the current path of the AC circuit, reducing the circuit perimeter, and thus further reducing the stray inductance of the circuit.

[0008] Meanwhile, AC electrode lead-out terminals are provided on the outer side of the AC electrode lead-out layer. P-electrode lead-out terminals, N-electrode lead-out terminals, and O-electrode lead-out terminals are respectively provided on the outer sides of the P-electrode layer, N-electrode layer, and O-electrode layer. Each lead-out terminal is integrally formed with its corresponding electrode layer and is vertically bent onto the busbar body. The lead-out terminals of the upper and lower composite busbars are staggered. The integrally formed lead-out terminals avoid additional connecting components, reduce contact resistance, and improve conductivity reliability. The staggered lead-out terminals prevent interference between the lead-out ends of the upper and lower busbars during installation, making wiring operations more convenient and also making the overall structure more compact, reducing the overall space occupied by the busbar.

[0009] To accommodate different switch installation requirements, the switch mounting holes are formed by inserting nuts into the busbar body. The insert nuts are electrically connected to or separated from the conductor layers of the busbar by an insulating layer, depending on the installation requirements. This design allows the switch mounting holes to flexibly adjust their connection with the conductor layers according to different switch types and circuit connection requirements. It can achieve both electrical connection for current transmission and isolation through an insulating layer, improving the flexibility of the busbar structure and enabling it to adapt to different three-level circuit topologies.

[0010] In terms of switch layout, two sets of switch mounting holes are provided on the upper composite busbar, each with a T-switch tube mounted by screws, and four sets are provided on the lower composite busbar, each with two sets of T-switch tubes and two sets of D-switch tubes mounted by screws. Each set of switch mounting holes includes several pairs of positive and negative mounting holes. The positive terminals of the two T-switch tubes on the upper composite busbar are connected to the ends of the AC1-U and AC2-U connecting busbars respectively through the positive mounting holes, and the negative terminals of the two T-switch tubes are connected to the middle of the AC electrode lead-out layer through the negative mounting holes. The positive terminals of the two T-switch tubes on the lower composite busbar are connected to the ends of the P-electrode layer and N-electrode layer respectively through the positive mounting holes, and the negative terminals of the two T-switch tubes are connected to both ends of the AC-L connecting layer respectively through the negative mounting holes. The positive terminals of the two D-switch tubes are connected to the ends of the AC-L connecting layer near the middle through the positive mounting holes, and the negative terminals of the two D-switch tubes are connected to both ends of the central region of the O-electrode layer through the negative mounting holes. This switch layout allows all current loops to flow through the shortest possible path. Even the longest parasitic inductance test loop in the circuit has its path length compressed to a very small range. At the same time, in this longest loop, the currents in adjacent conductor layers are in opposite directions. According to the principle of electromagnetic induction, the magnetic fields generated by the currents in opposite directions can cancel each other out, achieving the effect of inductance cancellation. This further significantly reduces the stray inductance of the loop, effectively suppresses voltage spikes during switch operation, and improves the reliability of power devices.

[0011] Furthermore, the negative terminal mounting holes of the two T-switch tubes on the lower composite busbar are also assembled with the connection holes by bolts. This design allows the connection of the upper and lower busbars and the installation of the switches to share the same bolt structure, reducing the number of installation parts, simplifying the assembly process, and further shortening the connection path, thus reducing the inductance increment caused by additional connections.

[0012] Furthermore, an insulating layer is provided between each conductor layer of the upper and lower composite busbars. The insulating layer is made of NOM paper or PET. Both NOM paper and PET materials have excellent insulation properties and can be made extremely thin. This allows the distance between conductor layers to be minimized. According to the influence of geometric mean distance, reducing the spacing between conductor layers can further reduce the stray inductance of the circuit, while ensuring the insulation reliability between conductor layers and avoiding the risk of interlayer breakdown.

[0013] Correspondingly, the T switch is a transistor switch and the D switch is a diode switch. This switch type adaptation can perfectly match the topology requirements of the three-level circuit, realize the three-level output, and meet the needs of high-power frequency conversion, rectification and other applications.

[0014] The beneficial effects of this invention are: 1. By using a three-dimensional composite busbar structure with upper and lower splits, the overall 5-layer conductor layer is divided into a split structure with 2 upper busbar layers and 3 lower busbar layers, which effectively shortens the perimeter of each current loop. Based on the calculation principle of loop inductance, the parasitic inductance of the loop is directly reduced. At the same time, the split structure also improves the convenience of installation and maintenance, solving the problems of large volume and inconvenient maintenance of the overall stacked busbar in the existing technology.

[0015] 2. The Z-shaped bend and bow-shaped structure of the AC1-U and AC2-U connecting busbars not only provides operating space for switch installation, but also further shortens the connection path of the upper and lower busbars, further reducing the stray inductance of the AC circuit.

[0016] 3. The staggered, one-piece molded leads avoid installation interference, reduce contact resistance, improve conductivity reliability, and reduce overall space occupation.

[0017] 4. The switch mounting holes with insert nuts allow for flexible adjustment of the connection with the conductor layer, adapting to different switch and circuit requirements and improving structural flexibility.

[0018] 5. By optimizing the switch layout, the connection paths of all switches are compressed to the shortest possible length. At the same time, the magnetic fields of opposite currents cancel each other out, thus reducing the stray inductance of the longest loop, suppressing voltage spikes, and improving the reliability of power devices.

[0019] 6. By using a thin insulating layer made of Nomi paper or PET material, the spacing between conductor layers is reduced while ensuring insulation reliability, further reducing stray inductance.

[0020] 7. By adapting the switch type configuration to three-level circuits, it perfectly matches the requirements of three-level topologies and meets the needs of high-power applications. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the composite busbar structure of the present invention.

[0022] Figure 2 This is a schematic diagram of the cross-sectional structure of the composite busbar of the present invention.

[0023] Figure 3 This is a front view schematic diagram of the upper composite busbar structure of the present invention.

[0024] Figure 4 This is a top view of the upper composite busbar structure of the present invention.

[0025] Figure 5 This is a front view schematic diagram of the lower composite busbar structure of the present invention.

[0026] Figure 6 This is a top view of the lower composite busbar structure of the present invention.

[0027] Figure 7 This is a schematic diagram showing the current flow direction of the longest loop in the composite busbar according to the present invention.

[0028] Figure 8 This is a schematic diagram of a three-level circuit topology.

[0029] In the diagram: 1-Upper composite busbar, 2-Lower composite busbar, 3-Connection hole, 4a-AC1-U connection busbar, 4b-AC2-U connection busbar, 5-AC electrode lead-out layer, 6-Switch mounting hole, 7-AC lead-out terminal, 8-P pole lead-out terminal, 9-O pole lead-out terminal, 10-N pole lead-out terminal, 11-P pole electrode layer, 12-AC-L connection layer, 13-N pole electrode layer, 14-O pole electrode layer, 15-Upper and lower busbar fixing holes, 16-Insulation layer, 17-Connection via hole T1A-T1 switch positive terminal, T1B-T1 switch negative terminal, T2A-T2 switch positive terminal, T2B-T2 switch negative terminal, T3A-T3 switch positive terminal, T3B-T3 switch negative terminal, T4A-T4 switch positive terminal, T4B-T4 switch negative terminal, DAA-DA switch positive terminal, DAB-DA switch negative terminal, DBA-DB switch positive terminal, DBB-DB switch negative terminal. Detailed Implementation

[0030] The low-sensitivity three-dimensional composite busbar of the present invention is composed of an upper composite busbar 1 and a lower composite busbar 2 stacked on top of each other. The two are fixed by bolts at the connection hole 3. The conductor layers are insulated and isolated by an insulating layer 16. The insulating layer 16 is made of 0.1mm thick Nomi paper, which ensures insulation performance while compressing the interlayer distance.

[0031] like Figure 3 , Figure 4 As shown, the upper composite busbar 1 has a two-layer conductor structure: the upper layer is the AC electrode lead-out layer 5, and the lower layer is the AC-U connection layer, which is composed of symmetrical AC1-U connection busbars 4a and AC2-U connection busbars 4b. Both AC1-U connection busbars 4a and AC2-U connection busbars 4b are provided with Z-shaped bends, with one end of each facing each other, forming an upwardly convex arc-shaped structure. The AC electrode lead-out layer 5 is attached to the upper end face of this arc.

[0032] In the middle of the upper composite busbar 1, two sets of switch mounting holes 6 are provided, corresponding to the installation of two T-switch tubes respectively: The positive mounting hole T2A of switch T2 connects to the left end of AC1-U connecting busbar 4a, and the negative mounting hole T1B of switch T2 connects to the left end of AC electrode lead-out layer 5; the positive mounting hole T3A of switch T3 connects to the left end of AC2-U connecting busbar 4b, and the negative mounting hole T3B of switch T3 connects to the right end of AC electrode lead-out layer 5. At the other end of AC1-U connecting busbar 4a and AC2-U connecting busbar 4b, that is, at both ends of the arc-shaped structure, a row of connecting holes 3 is provided for connection to the lower composite busbar 2.

[0033] like Figure 5 , Figure 6As shown, the lower composite busbar 2 has a three-layer conductor structure: the upper layer is an AC-L connection layer 12, the middle layer is a PN electrode layer composed of symmetrical P-electrode layers 11 and N-electrode layers 13, and the lower layer is an O-electrode layer 14. In the middle of the lower composite busbar 2, four sets of switch mounting holes 6 are provided: two sets are mounting holes for T-type switches, and the other two sets are mounting holes for D-type switches. Specifically: The positive mounting hole T1A of switch T1 is connected to the left end of P electrode layer 11, and the negative mounting hole T1B is connected to the left end of AC-L connection layer 12. At the same time, the negative mounting hole is also aligned with the connection hole 3 of AC1-U connection row 4a of upper composite busbar 1. The connection between the upper and lower busbars and the fixation of switch T3 are completed by the same bolt. The positive mounting hole T4A of switch T4 is connected to the right end of N electrode layer 13, and the negative mounting hole T4B is connected to the right end of AC-L connection layer 12. Similarly, the negative mounting hole is also aligned with the connection hole 3 of AC2-U connection row 4b of upper composite busbar 1. The assembly is completed by the same bolt. The positive mounting hole DAA of the DA switch connects to the left end of the AC-L connection layer 12 near the center, while the negative mounting hole DAB connects to the left end of the central region of the O electrode layer 14. Similarly, the positive mounting hole DBA of the DB switch connects to the right end of the AC-L connection layer 12 near the center, while the negative mounting hole DBB connects to the right end of the central region of the O electrode layer 14. All switch mounting holes 6 are made using insert nuts embedded in the busbar body. The insert nuts are electrically connected to the corresponding conductor layer, but are separated from other conductor layers by an insulating layer 16, ensuring that the connection between the switches does not result in interlayer short circuits.

[0034] In terms of the layout of the lead-out terminals, the AC lead-out terminal 7 of the upper composite busbar 1 is bent vertically towards the front of the busbar, while the P-pole lead-out terminal 8, O-pole lead-out terminal 9, and N-pole lead-out terminal 10 of the lower composite busbar 2 are bent vertically towards the rear of the busbar. The staggered arrangement of the two avoids installation interference between the lead-out terminals and facilitates external wiring.

[0035] When this composite busbar is used in conjunction with a three-level circuit, the current will flow along different loops under different operating conditions. The longest current loop, which has the greatest impact on stray inductance, flows as follows: Figure 7As shown: Current is input from the P-terminal 8, enters the P-electrode layer 11, then flows into the T1 switch through the positive mounting hole T1A of the T1 switch, flows out from the negative mounting hole T1B of the T1 switch, and enters the left end of the AC-L connection layer 12; then the current flows to the middle of the AC-L connection layer 12, flows into the T2 switch through the positive mounting hole T2A of the T2 switch, flows out from the negative mounting hole T2B of the T2 switch, enters the AC electrode lead-out layer 5, enters the positive mounting hole T3A of the T3 switch and flows into the T3 switch, flows out from the negative mounting hole T3B of the T3 switch, enters the positive mounting hole T4A of the T4 switch and is thus transmitted to the N-electrode layer 13, after passing through the N-electrode layer 13, enters the DB switch through the positive mounting hole of the Db switch, then flows into the O-electrode layer 14 from the negative mounting hole of the DB switch, and enters the GND terminal through the O-electrode layer 14.

[0036] In this longest loop, the current path length is compressed to only 80mm, far less than the loop length of over 150mm for similar busbars in the prior art. According to the calculation formula for loop inductance, the perimeter of this loop is shortened by nearly 50%, directly reducing the parasitic inductance of the loop by more than 40%. Simultaneously, in this loop, the current direction in the P-electrode layer 11 is to the right, while the current direction in the O-electrode layer 14 is to the left, and the current direction in the AC-L connection layer 12 is to the right. The current directions in adjacent conductor layers are opposite, and the magnetic fields they generate cancel each other out, achieving an inductance cancellation effect. This further reduces the stray inductance of the loop by another 20%, ultimately resulting in a total stray inductance of only 7nH, far lower than the level of over 20nH in the prior art. During switching, the extremely low stray inductance effectively suppresses voltage spikes caused by di / dt, reducing the voltage spike of the switching transistor from 150V in the existing technology to below 50V, significantly improving the reliability of power devices, reducing switching losses, and improving the overall efficiency of the circuit. According to tests, the three-level circuit applied to this composite busbar has improved the overall efficiency by 1.2% and the power density by 30%, meeting the miniaturization requirements of modern electrical equipment.

Claims

1. A low-sensitivity three-dimensional composite busbar, characterized in that, include: Upper composite busbar (1) and lower composite busbar (2); The upper composite busbar (1) includes an upper AC electrode lead-out layer (5) and a lower AC-U connection layer. The AC-U connection layer is composed of AC1-U connection bars (4a) and AC2-U connection bars (4b) arranged symmetrically at intervals. The lower composite busbar (2) includes an upper AC-L connection layer (12), a middle PN electrode layer, and a lower O electrode layer (14). The PN electrode layer is composed of a symmetrically spaced P electrode layer (11) and an N electrode layer (13). The two ends of the AC-U connection layer are connected to the two ends of the AC-L connection layer respectively to form an AC circuit; Both the upper composite busbar (1) and the lower composite busbar (2) are provided with switch mounting holes (6), which are used to install T-switch tubes or D-switch tubes.

2. The low-sensitivity three-dimensional composite busbar according to claim 1, characterized in that, Both AC1-U connecting bar (4a) and AC2-U connecting bar (4b) have Z-shaped bends. One end of AC1-U connecting bar (4a) and AC2-U connecting bar (4b) are opposite to each other and together form an arc-shaped structure protruding toward the AC electrode lead-out layer (5). The AC electrode lead-out layer (5) is attached to the protruding end face of the arc-shaped structure. A row of connecting holes (3) is respectively provided on the other end face of AC1-U connecting bar (4a) and AC2-U connecting bar (4b).

3. The low-sensitivity three-dimensional composite busbar according to claim 1, characterized in that, The AC electrode lead-out layer (5) is provided with an AC electrode lead-out terminal (7) on its outer side, and the P electrode layer (11), N electrode layer (13), and O electrode layer (14) are respectively provided with a P electrode lead-out terminal (8), an N electrode lead-out terminal (10), and an O electrode lead-out terminal (9) on their outer sides.

4. The low-sensitivity three-dimensional composite busbar according to claim 3, characterized in that, Each lead-out terminal is integrally formed with the corresponding electrode layer and is bent vertically on the busbar body. The lead-out terminals of the upper composite busbar (1) and the lower composite busbar (2) are misaligned.

5. The low-sensitivity three-dimensional composite busbar according to claim 1, characterized in that, The switch mounting hole (6) is formed by inserting the insert nut into the busbar body. The insert nut and each conductor layer of the busbar are electrically connected or separated by an insulating layer (16) according to the installation requirements.

6. The low-sensitivity three-dimensional composite busbar according to claim 1, characterized in that, The switch mounting holes (6) are provided with two sets on the upper composite busbar (1), each with a T switch tube installed by screws, and four sets on the lower composite busbar (2), each with two sets of T switch tubes and two sets of D switch tubes installed by screws.

7. The low-sensitivity three-dimensional composite busbar according to claim 6, characterized in that, Each set of switch mounting holes (6) includes several pairs of positive and negative mounting holes; The positive terminals of the two T-switch transistors on the upper composite busbar (1) are connected to the ends of the AC1-U connecting busbar (4a) and AC2-U connecting busbar (4b) respectively through the positive terminal mounting holes, and the negative terminals of the two T-switch transistors are connected to the middle of the AC electrode lead-out layer (5) through the negative terminal mounting holes. The positive terminals of the two T-switch transistors on the lower composite busbar (2) are connected to the ends of the P-electrode layer (11) and the N-electrode layer (13) respectively through the positive terminal mounting holes. The negative terminals of the two T-switch transistors are connected to both ends of the AC-L connection layer (12) respectively through the negative terminal mounting holes. The positive terminals of the two D-switch transistors are connected to the ends of the AC-L connection layer (12) near the middle position respectively through the positive terminal mounting holes. The negative terminals of the two D-switch transistors are connected to both ends of the central region of the O-electrode layer (14) respectively through the negative terminal mounting holes.

8. The low-sensitivity three-dimensional composite busbar according to claim 7, characterized in that, The negative mounting holes of the two T-switch tubes on the 2 are also connected to the connecting hole (3) by bolts.

9. The low-sensitivity three-dimensional composite busbar according to claim 1, characterized in that, An insulating layer is provided between each conductor layer of the upper composite busbar (1) and the lower composite busbar (2), and the insulating layer is made of Nomi paper or PET.

10. The low-sensitivity three-dimensional composite busbar according to claim 1, characterized in that, The T switch is a transistor switch, and the D switch is a diode switch.

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