A current-sharing copper bar structure and IGBT power module

Abstract

The application discloses a current-sharing copper bar structure and an IGBT power module, which comprises a first copper bar layer, a second copper bar layer and a third copper bar layer stacked in sequence from top to bottom in a vertical direction, and the extension direction of each copper bar layer is parallel to a horizontal direction; the first copper bar layer comprises a first copper bar and a second copper bar arranged left and right in a horizontal direction of a copper bar plane, the second copper bar layer comprises a third copper bar and a fourth copper bar arranged left and right in the horizontal direction of the copper bar plane, and the third copper bar layer comprises a fifth copper bar and a sixth copper bar arranged left and right in the horizontal direction of the copper bar plane; the second copper bar, the third copper bar, the fifth copper bar and the sixth copper bar are non-linear bending structures with the same plane shape and plane size, and the first copper bar and the fourth copper bar are one-word long strip structures with the same plane shape and plane size. The application can greatly reduce the current-sharing deviation of parallel modules and adapt to the power balance demand of a three-level ANPC architecture in photovoltaic, wind power and other scenes.

Description

Technical Field

[0001] This application relates to the field of semiconductor device assembly technology, and in particular to a current sharing copper bus structure and an IGBT power module. Background Technology

[0002] In the three-level ANPC (Active Neutral Point Clamped) architecture of photovoltaic, wind power and other fields, the parallel connection of half-bridge IGBT modules is widely used because it can effectively balance cost and power requirements. However, the current sharing problem between modules has always been a key technical challenge that restricts the improvement of system performance.

[0003] The single-phase circuit of this architecture needs to be composed of six half-bridge modules in a specific layout. The corresponding conduction requirements of multiple sets of emitters and collectors between modules need to be electrically connected through a copper busbar locking structure. However, the existing copper busbar design can only meet the basic circuit conduction function and does not fully consider the impact of the copper busbar's own resistance and stray inductance parameters on the current sharing performance. This has obvious design flaws. This flaw directly leads to uneven current distribution of parallel modules in actual applications, which not only affects the stability of system operation but also shortens the service life of the modules.

[0004] To address the current sharing problem in parallel modules caused by differences in copper busbar structural parameters, it is urgent to optimize the copper busbar connection structure design to reduce its adverse impact on current sharing performance. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a current-sharing copper busbar structure and an IGBT power module.

[0006] Firstly, this application provides a current-equalizing copper busbar structure, which adopts the following technical solution:

[0007] A current-equalizing copper busbar structure includes a first copper busbar layer, a second copper busbar layer, and a third copper busbar layer stacked vertically from top to bottom, with each copper busbar layer extending parallel to the horizontal direction. The first copper busbar layer includes a first copper busbar and a second copper busbar arranged horizontally along the copper busbar plane. The second copper busbar layer includes a third copper busbar and a fourth copper busbar arranged horizontally along the copper busbar plane. The third copper busbar layer includes a fifth copper busbar and a sixth copper busbar arranged horizontally along the copper busbar plane. The second, third, fifth, and sixth copper busbars are non-linear bent structures with the same planar shape and dimensions. The third and fifth copper busbars are arranged in the same horizontal direction, as are the second and sixth copper busbars. The third and second copper busbars are mirror images of each other in the horizontal direction. The non-linear bent structure has two signal terminals, each positioned horizontally. At both ends of the non-linear bending structure, the signal end closer to the left side of the copper busbar layer is the first signal end, and the signal end closer to the right side of the copper busbar layer is the second signal end. The first copper busbar and the fourth copper busbar are linear elongated structures with the same planar shape and planar dimensions. The linear elongated structures have signal ends at both ends, with the signal end closer to the left side of the copper busbar layer along the horizontal direction being the first end and the signal end closer to the right side of the copper busbar layer being the second end. The first end of the first copper busbar is electrically connected to the first signal end of the fifth copper busbar in the vertical direction, and the second end of the first copper busbar is electrically connected to the first signal end of the third copper busbar in the vertical direction. The fourth copper busbar is vertically sandwiched between the second copper busbar and the sixth copper busbar, and the first end of the fourth copper busbar is electrically connected to the second signal end of the second copper busbar in the vertical direction, and the second end of the fourth copper busbar is electrically connected to the second signal end of the sixth copper busbar in the vertical direction.

[0008] By adopting the above technical solution, a current sharing solution is constructed using a three-layer copper busbar stack and a symmetrical structural design: On the one hand, the non-linear bending structure (the second, third, fifth, and sixth copper busbars) adopts the same shape and size, and the third copper busbar is a horizontal mirror image of the second copper busbar. Combined with the symmetrical design of the straight strip structure (the first and fourth copper busbars), the consistency of copper busbar resistance and inductance parameters is ensured. On the other hand, through precise electrical connections in the vertical direction, such as the first copper busbar connecting the fifth and third copper busbars respectively, and the fourth copper busbar sandwiching and connecting the second and sixth copper busbars, the impedance of the key current path is made approximately equal. This eliminates the impact of copper busbar parameter differences on current sharing from the structural level, significantly reducing the current sharing deviation of parallel modules. At the same time, the three-layer stack design ensures the reliability of electrical connections without the need for additional complex structures, adapting to the power and cost balance requirements of the three-level ANPC architecture in photovoltaic, wind power generation, and other scenarios.

[0009] Optionally, the non-linear bending structure is a Z shape, including a first horizontal segment, an inclined segment, and a second horizontal segment connected in sequence. The first signal terminal is located at the free end of the first horizontal segment, and the second signal terminal is located at the free end of the second horizontal segment.

[0010] By adopting the above technical solution, the Z-shaped structure has the advantages of controllable path length and spatial adaptability. The first horizontal segment and the second horizontal segment can accurately connect to the signal terminals of different copper busbar layers, and the inclined segment can optimize the layout of the copper busbars in the horizontal space, reducing the interference problem during the stacking of multiple copper busbars. At the same time, the unified Z-shaped size design can ensure that the resistance and stray inductance parameters of each non-linear copper busbar are consistent, further ensuring the balance of the current path impedance, providing structural support for the current sharing effect, and the Z-shaped structure has low processing difficulty and is easy to be mass-produced by stamping process, adapting to engineering applications.

[0011] Optionally, the second copper busbar and the third copper busbar are vertically layered and crossed. The inclined segment of the third copper busbar extends from the first horizontal segment to the second horizontal segment diagonally downward to the right along the copper busbar plane, and the inclined segment of the second copper busbar extends from the first horizontal segment to the second horizontal segment diagonally upward to the right along the copper busbar plane.

[0012] By adopting the above technical solution, the vertical layered and crossed design of the second copper busbar and the third copper busbar, combined with the reverse extension of the inclined segment, can not only achieve a dense layout of the copper busbars in a limited horizontal space, but also ensure that the current paths of the two layers of copper busbars do not interfere with each other. At the same time, the reverse extended inclined segment makes the path lengths and bending angles of the two copper busbars completely symmetrical, further ensuring the consistency of the resistance and stray inductance parameters, preventing impedance deviation caused by structural asymmetry, and thus strengthening the current sharing effect, especially adapting to the connection requirements of the "pin" layout IGBT module in the three-level ANPC architecture.

[0013] Optionally, the non-linear bending structure is a diagonal structure. The diagonal structure extends in a single inclined shape. The two ends of the diagonal structure are the first signal terminal and the second signal terminal respectively, and the included angle between the diagonal structure and the horizontal direction in the copper busbar plane is 15° - 75°.

[0014] By adopting the above technical solution, the single inclined extension design simplifies the copper busbar processing process and reduces the impedance fluctuation caused by the bending nodes. The included angle range of 15° - 75° can prevent both the too small included angle from resulting in an overly long path (increasing resistance) and the too large included angle from occupying too much space (affecting the module layout), achieving a balance between impedance control and spatial adaptability. At the same time, the diagonal structures with the same shape and size can ensure that the parameters of each copper busbar are consistent, and can also meet the current sharing requirements, adapting to scenarios with lower requirements for the complexity of copper busbar processing.

[0015] Optionally, the second copper busbar and the third copper busbar intersect in layers in the vertical direction, and the intersection point of the diagonal structure is located at the midpoint of the length direction of the diagonal structure of the second copper busbar and the third copper busbar.

[0016] By adopting the above technical solution, the design of the intersection point located at the midpoint of the diagonal structure ensures that the intersection area of ​​the second and third copper busbars is completely symmetrically distributed, ensuring that the path length from the intersection point to the two signal terminals is completely equal, thereby ensuring that the resistance and inductance parameters are consistent. The vertical layered intersection prevents the two copper busbars from directly contacting and short-circuiting, while maximizing the use of vertical space and reducing the horizontal layout area, adapting to the connection scenarios of high-density IGBT modules, and further improving the practicality and current sharing stability of the structure.

[0017] Optionally, the thickness of the first copper busbar, the second copper busbar, the third copper busbar, the fourth copper busbar, the fifth copper busbar, and the sixth copper busbar is 0.5 mm to 3 mm.

[0018] By adopting the above technical solution, the thickness range of 0.5mm to 3mm balances conductivity and structural strength. The lower limit of 0.5mm ensures that the copper busbar has sufficient current carrying capacity, preventing excessive resistance due to excessive thickness, which would affect current sharing and heat dissipation. The upper limit of 3mm ensures the structural rigidity of the copper busbar, preventing deformation during latching and assembly, which could lead to connection deviations. At the same time, it is compatible with the terminal spacing and latching process requirements of mainstream IGBT modules, without the need for additional adjustments to the module design, thus improving the process compatibility of the copper busbar structure.

[0019] Optionally, the first signal terminal, the second signal terminal, the first end, and the second end are all provided with connection holes that penetrate the thickness direction of the copper busbar. The connection holes are configured to enable detachable electrical connections between different copper busbar layers or between the copper busbar and an external module through fasteners.

[0020] By adopting the above technical solution, the connection hole and fasteners work together to achieve a detachable and reliable electrical connection. On the one hand, the detachable design facilitates the installation, commissioning and subsequent maintenance of the copper busbar, such as replacing damaged copper busbars, reducing maintenance costs. On the other hand, fasteners, such as bolts and nuts, can ensure tight contact between different copper busbar layers and between the copper busbar and the IGBT module, reducing contact resistance and preventing contact resistance differences from affecting the current. At the same time, it ensures the stability of the electrical connection and meets the long-term use requirements of complex outdoor working conditions such as photovoltaic and wind power.

[0021] Optionally, the diameter of the connecting hole is 3mm to 8mm, and the edge of the connecting hole is provided with an annular chamfer with a radius of 0.3mm to 0.8mm.

[0022] By adopting the above technical solution, the connection hole diameter of 3mm to 8mm adapts to the specifications of mainstream fasteners, such as M3-M8 bolts, ensuring connection versatility; the annular chamfer design can prevent the sharp edges at the edge of the connection hole from scratching the surface of the fastener or the copper bar, reducing the risk of poor contact, and at the same time facilitating the alignment and installation of the fastener, improving the assembly efficiency; the chamfer radius of 0.3mm to 0.8mm ensures the chamfer effect while preventing the reduction of the strength of the copper bar connection area due to excessive chamfer, taking into account both practicality and structural reliability.

[0023] Optionally, the lengths of the first copper bar and the fourth copper bar are 70mm to 90mm, which is greater than the length of the non-linear bending structure in the horizontal direction.

[0024] By adopting the above technical solution, the length design of the first and fourth copper bars (70mm to 90mm) is greater than the horizontal length of the non-linear bending structure, which can not only provide sufficient space for the electrical connection in the vertical direction, such as ensuring that the two ends of the first copper bar can be respectively docked with the signal ends of the fifth copper bar and the third copper bar, but also prevent the connection stress concentration caused by too short length, prolonging the service life of the copper bar; at the same time, this length range adapts to the "pin" type layout spacing of the 62mm half-bridge IGBT module, without adjusting the module installation position, improving the compatibility of the copper bar structure with the existing architecture.

[0025] In the second aspect, an IGBT power module provided by the present application adopts the following technical solution:

[0026] An IGBT power module includes a current-sharing copper bar structure as described in any one of the above first aspects.

[0027] By adopting the above technical solution, the IGBT power module precisely matches the current-sharing copper bar structure with the half-bridge IGBT module, and realizes the path impedance symmetry for the module connection requirements of the three-level ANPC architecture. On the one hand, the impedance of the key parallel paths is ensured to be equal through the corresponding connection of the copper bar and the module; on the other hand, through the collaborative connection of multiple copper bars such as the first copper bar + the third copper bar, the first copper bar + the fifth copper bar, etc., the impedance balance of the cross paths is achieved, solving the current-sharing problem of parallel modules from the system level, reducing the current-sharing deviation to less than 8%, adapting to scenarios with high requirements for power output and operation stability such as photovoltaic and wind power generation, and the current-sharing copper bar structure is simple and easy to assemble, without an additional complex control unit, taking into account both the reliability and cost-effectiveness of the module.

[0028] In summary, the present application includes at least one of the following beneficial technical effects:

[0029] 1. A current sharing solution is constructed using a three-layer copper busbar stack and a symmetrical structural design: On the one hand, the non-linear bending structure (copper busbars 2, 3, 5, and 6) adopts the same shape and size, and the third copper busbar is a horizontal mirror image of the second copper busbar. Combined with the symmetrical design of the straight strip structure (copper busbars 1 and 4), the copper busbar resistance and inductance parameters are kept consistent. On the other hand, through precise electrical connections in the vertical direction, such as the first copper busbar connecting to the fifth and third copper busbars respectively, and the fourth copper busbar sandwiching and connecting to the second and sixth copper busbars, the impedance of the key current path is made approximately equal. This eliminates the impact of copper busbar parameter differences on current sharing from the structural level, significantly reducing the current sharing deviation of parallel modules. At the same time, the three-layer stack design ensures the reliability of electrical connections without the need for additional complex structures, adapting to the power and cost balance requirements of the three-level ANPC architecture in photovoltaic, wind power and other scenarios.

[0030] 2. The non-linear bending structure adopts a Z-shaped structure, which has the advantages of controllable path length and spatial adaptability. The first and second horizontal sections can accurately connect to the signal terminals of different copper busbar layers, while the inclined section can optimize the copper busbar layout in the horizontal space and reduce interference problems when multiple copper busbars are stacked. At the same time, the uniform Z-shaped size design can ensure that the resistance and inductance parameters of each non-linear copper busbar are consistent, further ensuring the impedance balance of the current path and providing structural support for the current sharing effect. Moreover, the Z-shaped structure is easy to process and can be mass-produced through stamping process, making it suitable for engineering applications.

[0031] 3. The IGBT power module precisely adapts the current-sharing copper busbar structure to the half-bridge IGBT module, achieving path impedance symmetry for the module connection requirements of the three-level ANPC architecture. On the one hand, the corresponding connection between the copper busbar and the module ensures that the impedance of the key parallel path is equal; on the other hand, through the collaborative connection of multiple copper busbars, such as the first copper busbar + the third copper busbar, the impedance balance of the cross path is achieved, solving the current sharing problem of parallel modules at the system level, reducing the current sharing deviation to below 8%, which is suitable for scenarios with high requirements for power output and operational stability, such as photovoltaic and wind power generation. Moreover, the current-sharing copper busbar structure is simple and easy to assemble, without the need for additional complex control units, thus balancing the reliability and cost-effectiveness of the module. Attached Figure Description

[0032] Figure 1 This is a diagram of a single-phase circuit structure based on a three-level ANPC architecture;

[0033] Figure 2 This is a physical diagram of the single-phase module layout of a three-level ANPC architecture in engineering applications;

[0034] Figure 3 This is a structural diagram of an existing copper busbar structure;

[0035] Figure 4 yes Figure 3An exploded view of the existing copper busbar structure;

[0036] Figure 5 This is a schematic diagram of the current sharing copper bus structure provided in the embodiments of this application;

[0037] Figure 6 yes Figure 5 Schematic diagram of the current equalization copper busbar structure (exploded or disassembled);

[0038] Figure 7 This is a schematic diagram of another current-sharing copper busbar structure provided in an embodiment of this application;

[0039] Figure 8 This is a schematic diagram of the current equalization copper busbar structure with respect to the oblique bending structure.

[0040] Explanation of reference numerals in the attached figures:

[0041] 10. First copper busbar layer; 11. First copper busbar; 12. Second copper busbar; 20. Second copper busbar layer; 21. Third copper busbar; 22. Fourth copper busbar; 30. Third copper busbar layer; 31. Fifth copper busbar; 32. Sixth copper busbar; 41. First signal terminal; 42. Second signal terminal; 51. First terminal; 52. Second terminal; 70. Connecting hole. Detailed Implementation

[0042] The following is in conjunction with the appendix Figure 1 - Appendix Figure 8 This application will be described in further detail.

[0043] The three-level ANPC architecture (active neutral point clamping architecture) is a core topology in the field of medium- and high-voltage high-power power conversion. Its "three-level" characteristic can realize three output levels: positive bus voltage, neutral point voltage, and negative bus voltage, which can significantly reduce the voltage stress on IGBT devices (only bearing 1 / 2 of the bus voltage). At the same time, the active clamping design stabilizes the DC bus neutral point potential and reduces output harmonics. It is widely used in scenarios such as new energy charging piles and energy storage converters. The single-phase circuit is a specific form of this architecture for single-phase power conversion. Through the coordinated switching of multiple IGBT half-bridge modules, bidirectional conversion between DC and single-phase AC is achieved. To improve current carrying capacity, parallel design of half-bridge modules is often used in engineering. This places high demands on the copper busbar structure of the electrical connection between modules. The impedance consistency of the copper busbar directly determines the current sharing effect of the parallel modules. If the copper busbar design is not reasonable, it can easily lead to problems such as uneven current distribution and local overheating damage.

[0044] Figure 1The figure shows the single-phase circuit structure diagram of a three-level ANPC architecture in the prior art targeted by this embodiment. This circuit includes six groups of parallel IGBT chip groups, T1.1 and T1.2, T2.1 and T2.2, T3.1 and T3.2, T4.1 and T4.2, T5.1 and T5.2, T6.1 and T6.2. Each group correspondingly realizes the switching and clamping functions of the architecture. The bold branches in the figure mark the key electrical connection relationships between modules (including the connection nodes of IGBT emitters E and collectors C); Figure 2 Then it is the physical diagram of the "pin" layout of the single-phase module in engineering applications. A total of six half-bridge modules with a specification of 62mm are integrated (marked as T1, T2, T3, T4, T5, and T6 respectively), and the modules and Figure 1 the chip groups correspond one by one, that is, the T1 module integrates the T1.1 and T1.2 chips, the T2 module integrates the T2.1 and T2.2 chips, the T3 module integrates the T3.1 and T3.2 chips, the T4 module integrates the T4.1 and T4.2 chips, the T5 module integrates the T5.1 and T5.2 chips, the T6 module integrates the T6.1 and T6.2 chips. At the same time, Figure 2 the physical connection paths are marked with solid and dashed lines respectively, corresponding to Figure 1 the electrical connection relationships of the bold branches in

[0045] In the engineering implementation of the single-phase circuit of the three-level ANPC architecture, Figure 2 the electrical connection between the half-bridge modules in the "pin" layout shown needs to be connected through a copper bar structure. The mainstream connection scheme in the prior art is Figure 3 the two-layer copper bar stacking structure shown. This structure realizes the connection requirements of the solid and dashed lines respectively through the staggered arrangement of the upper and lower two-layer copper bars, as Figure 2 shown in Figure 4 which specifically shows the plane structure diagram of the first-layer copper bar (top layer) and the plane structure diagram of the second-layer copper bar (bottom layer). Functionally, this two-layer stacking design can achieve the basic electrical conduction between the T1-T6 modules and meet the basic operation requirements of the circuit. However, there are obvious defects in the performance index "module current sharing". It only focuses on the conductivity of the connection, but does not consider the influence of the resistance parameters and stray inductance parameters of the copper bar itself on the current distribution of parallel modules, resulting in a significant current sharing deviation between modules during actual operation.

[0046] Taking Figure 1Taking the current sharing effect between T1.1 and T2.1 as an example, the formula for calculating the current sharing deviation is usually defined in the industry as follows: T1.1 current sharing deviation = |T1.1 current - (T1.1 current + T2.1 current) / 2| ÷ (T1.1 current + T2.1 current) / 2. After actual measurement, when using Figure 3 the two-layer copper busbar structure shown, the current sharing deviation can reach more than 20%, far exceeding the reliability requirement of "current sharing deviation ≤ 5%" in engineering applications. Long-term operation is likely to cause the modules with current concentration to age rapidly due to overheating, and even lead to device burnout failures.

[0047] Further analyze the root cause of the current sharing problem from the correlation between the circuit principle and the copper busbar structure: In the scenario where T1.1 and T2.1 operate in parallel, the ideal design goal of the three-level ANPC architecture is that "currents of the same magnitude flow from T1.1 to T5.1 and from T2.1 to T6.1 respectively". On the premise of ignoring the parameter differences of the half-bridge modules themselves, the realization of this goal depends on the strict symmetry of the copper busbar path impedance, which specifically needs to meet two core requirements. One is the symmetry of the main path impedance, that is, the copper busbar path impedance (including resistance and stray inductance) from T1.1 to T5.1 must be equal to that from T2.1 to T6.1; the other is the symmetry of the cross path impedance, that is, the copper busbar path impedance from T1.1 to T6.1 must be equal to that from T2.1 to T5.1. However, from Figure 4 the structure of the first-layer copper busbar of the existing technology shown, it can only meet the first symmetry requirement, and there are obvious defects in the second requirement: The path from T2.1 to T5.1 corresponds to Figure 4 the short straight section of the copper busbar in the figure. Since the T2 and T5 modules are adjacent and unobstructed in the "pin" layout, the copper busbars can be directly connected, with a short path length and no detours, and the impedance value is small; while the path from T1.1 to T6.1 corresponds to Figure 4 the long bent section of the copper busbar in the figure. Since the T1 and T6 modules are diagonally distributed in the layout, the copper busbar needs to bypass the terminals of the middle T2 and T5 modules, forming a detour path with two bends (it can be visually observed from Figure 4 that the physical length of this path is significantly longer than the former), resulting in its impedance value being significantly greater than that of the path from T2.1 to T5.1. According to circuit theory, the current distribution in parallel branches is inversely proportional to the impedance. The cross path impedance from T2.1 to T5.1 is smaller, resulting in more current being shunted from T​​To address the issue of uneven current distribution in parallel modules caused by differences in resistance and inductance parameters in existing copper busbar structures, this application discloses a current-sharing copper busbar structure. By optimizing the number of layers, bending shape, and inter-layer connection node layout of the copper busbar, the path impedance difference is eliminated from the structural design level, significantly reducing the negative impact of copper busbar parameters on the current-sharing effect and improving the operational reliability of the three-level ANPC architecture.

[0049] Reference Figure 5 and Figure 6 This application discloses a current-equalizing copper busbar structure, including a first copper busbar layer 10, a second copper busbar layer 20, and a third copper busbar layer 30 stacked vertically from top to bottom, with the extension direction of each copper busbar layer parallel to the horizontal direction; the first copper busbar layer 10 includes a first copper busbar 11 and a second copper busbar 12 arranged horizontally (X direction) along the copper busbar plane (XY plane); the second copper busbar layer 20 includes a third copper busbar 21 and a fourth copper busbar 22 arranged horizontally (X direction) along the copper busbar plane; the third copper busbar layer 30 includes a first copper busbar 11 and a second copper busbar 12 arranged horizontally (X direction) along the copper busbar plane (XY plane); the second copper busbar layer 20 includes a third copper busbar 21 and a fourth copper busbar 22 arranged horizontally (X direction) along the copper busbar plane (XY plane); and the third copper busbar layer 30 includes a third copper busbar 21 and a fourth copper busbar 22 arranged horizontally (X direction) along the copper busbar plane (XY plane). The copper busbars are arranged horizontally on the left and right sides, with a fifth copper busbar 31 and a sixth copper busbar 32. The second copper busbar 12, third copper busbar 21, fifth copper busbar 31, and sixth copper busbar 32 are non-linear bent structures with the same planar shape and dimensions. The third copper busbar 21 and the fifth copper busbar 31 are arranged in the same horizontal direction, as are the second copper busbar 12 and the sixth copper busbar 32. The third copper busbar 21 and the second copper busbar 12 are mirror images of each other in the horizontal direction. Each non-linear bent structure has two signal terminals. The signal terminals located at both ends of the non-linear bending structure along the horizontal direction, with the first signal terminal 41 being closer to the left side of the copper busbar layer and the second signal terminal 42 being closer to the right side of the copper busbar layer; the first copper busbar 11 and the fourth copper busbar 22 are linear strip structures with the same planar shape and dimensions, and signal terminals are provided at both ends of the linear strip structure, with the first terminal 51 being closer to the left side of the copper busbar layer along the horizontal direction and the second terminal 52 being closer to the right side of the copper busbar layer; the first terminal 51 of the first copper busbar 11 and the first signal terminal 41 of the fifth copper busbar 31 are electrically connected in the vertical direction, and the second terminal 52 of the first copper busbar 11 and the first signal terminal 41 of the third copper busbar 21 are electrically connected in the vertical direction; the fourth copper busbar 22 is sandwiched between the second copper busbar 12 and the sixth copper busbar 32 along the vertical direction, and the first terminal 51 of the fourth copper busbar 22 and the second signal terminal 42 of the second copper busbar 12 are electrically connected in the vertical direction, and the second terminal 52 of the fourth copper busbar 22 and the second signal terminal 42 of the sixth copper busbar 32 are electrically connected in the vertical direction.

[0050] Understandable Figure 5As a schematic diagram of the overall structure, it shows a three-layer design in which the first copper busbar layer 10, the second copper busbar layer 20, and the third copper busbar layer 30 are stacked vertically (Z) from top to bottom in sequence. Each layer of copper busbars extends horizontally (X), and its overall layout is precisely adapted to the terminal positions of the "pin" type half-bridge module, ensuring that all key connection requirements of modules T1 to T6 can be covered; as Figure 6 shown, the fifth copper busbar 31 for connecting T1 and T5, the third copper busbar 21 for connecting T2 and T6, the second copper busbar 12 for connecting T3 and T5, and the sixth copper busbar 32 for connecting T4 and T6 all adopt a non-linear bending structure similar to the Z shape. Except for the local thickness differences at their respective terminal locking parts, the overall planar structure dimensions are exactly the same; among them, the local thickness differences at the terminal locking parts are for adapting to the mechanical installation requirements of the half-bridge module terminals. This part needs to be locked and fixed with module terminals through fasteners such as bolts and nuts. The local thickening can improve the locking strength and prevent the copper busbar from deforming during locking. Except for this part, the planar structure parameters such as the horizontal segment length, inclined segment angle, and bending radius of the Z-shaped copper busbar are kept unified, ensuring that the resistance and stray inductance parameters of each Z-shaped copper busbar are the same from the design source; at the same time, the first copper busbar 11 and the fourth copper busbar 22 are both designed as straight long strip structures. The two ends of this structure are signal ends respectively, and are defined horizontally. The signal end near the left side of the copper busbar layer is the first end 51, and the signal end near the right side of the copper busbar layer is the second end 52; among them, the first end 51 of the first copper busbar 11 and the first signal end 41 of the fifth copper busbar 31 form a laminated electrical connection in the vertical direction (Z direction). This connection is achieved through copper column welding or bolt fastening, ensuring reliable current conduction between the two layers of copper busbars; the second end 52 of the first copper busbar 11 forms a laminated electrical connection with the first signal end 41 of the third copper busbar 21 in the vertical direction, and the connection method is the same as above. In addition, the fourth copper busbar 22 is sandwiched between the second copper busbar 12 (the first copper busbar layer) and the sixth copper busbar 32 (the third copper busbar layer 30) in the vertical direction, and the first end 51 of the fourth copper busbar 22 forms an electrical connection with the second signal end 42 of the second copper busbar 12 in the vertical direction, and the second end 52 of the fourth copper busbar 22 forms an electrical connection with the second signal end 42 of the sixth copper busbar 32 in the vertical direction. The setting of the above vertical connection nodes enables the three-layer copper busbars to form a complete current conduction path, and the contact area and connection method of each connection node are kept the same, further ensuring the symmetry of the path impedance.

[0051] In an embodiment, combined with the current sharing scenario of T1.1 and T2.1, further analysis is carried out from Figure 6The copper busbar paths are clearly defined. This application achieves precise impedance matching for critical current paths through a three-layer symmetrical design. On one hand, the copper busbar paths from T1.1 to T5.1 and from T2.1 to T6.1 use Z-shaped copper busbars of the same size and have the same path length, resulting in approximately equal resistance and stray inductance parameters. On the other hand, the copper busbar path parameters from T1.1 to T6.1 are actually composed of "the parameters of the straight copper busbar from T1.1 to T2.1" and "the parameters of the Z-shaped copper busbar from T2.1 to T6.1", while the copper busbar path parameters from T2.1 to T5.1 are composed of "the parameters of the straight copper busbar from T2.1 to T1.1" and "the parameters of the Z-shaped copper busbar from T1.1 to T5.1". Since the parameters of the straight copper busbar and the Z-shaped copper busbar are consistent, the copper busbar parameters of these two intersecting paths are also approximately equal. This symmetrical path design can minimize the impact of the copper busbar structure on the current sharing of parallel modules. According to actual calculations, after adopting the current sharing copper busbar structure of this application, the current sharing deviation of the modules can be controlled below 8%, which is significantly better than the current sharing effect of the two-layer copper busbar structure.

[0052] Similarly, it can be seen that, for Figure 2 The connection relationship between T3.2C, T4.2C, T5.2E, and T6.2E, marked with a dashed line, is also achieved through a symmetrical design in the three-layer copper busbar structure of this application to achieve current sharing: the copper busbars used to connect T3 and T5, T4 and T6, and T4 and T5 (which are the coordinated operation of the second copper busbar 12, the sixth copper busbar 32, and the fourth copper busbar 22) adopt the same design logic as the copper busbars connecting the aforementioned T1 and T2 modules. Among them, the Z-shaped copper busbars (the second copper busbar 12 and the sixth copper busbar 32) connecting T3 and T5 and T4 and T6, except for the terminals... Except for local thickness differences in the locking parts due to installation requirements, the overall planar structural dimensions (horizontal section length, inclined section angle, bending radius) are completely consistent with the Z-shaped copper busbars connecting T1 and T2, ensuring consistent resistance and inductance parameters. The paths connecting T3 and T6, and T4 and T5 rely on the vertical connection between the fourth copper busbar 22 (a long strip structure) and the second copper busbar 12 and the sixth copper busbar 32. Furthermore, the copper busbar combination method, connection node contact area, and vertical conduction length of this path are completely symmetrical with the aforementioned cross paths from T1.1 to T6.1 and from T2.1 to T5.1.

[0053] Specifically, the copper busbar path impedance from T3.2 to T5.2 is approximately equal to that from T4.2 to T6.2 because they use Z-shaped copper busbars of the same size and have the same path length. The copper busbar path parameters from T3.2 to T6.2 (composed of the "straight copper busbar parameters from T3.2 to T4.2" and the "Z-shaped copper busbar parameters from T4.2 to T6.2") are also approximately equal to those from T4.2 to T5.2 (composed of the "straight copper busbar parameters from T4.2 to T3.2" ​​and the "Z-shaped copper busbar parameters from T3.2 to T5.2") due to the symmetry of the copper busbar parameters. Therefore, connecting the corresponding T3.2 and T4.2 parallel modules with the dashed line can also achieve the effect of current sharing deviation of less than 8%, ensuring that the current distribution of all parallel half-bridge modules in the entire three-level ANPC architecture single-phase circuit remains balanced, preventing local modules from overheating and being damaged due to current concentration, and further improving the reliability and stability of circuit operation.

[0054] It should be noted that the copper busbar layers in this application are not simply stacked vertically from top to bottom. An insulating layer (not shown in the figure) is provided between adjacent copper busbar layers to prevent short circuits caused by non-targeted conduction between layers. At the same time, the thickness of the insulating layer must meet the electrical safety distance requirements to ensure the insulation reliability under high voltage conditions. In addition, although the "non-linear bending structure" of the second, third, fifth and sixth copper busbars has the same planar shape and planar dimensions, its bending direction is complementary to that of the adjacent copper busbars because they are located in different copper busbar layers (such as the horizontal mirror image of the third copper busbar 21 and the second copper busbar 12). This design is not only to adapt to the spatial position of the module terminals, but also to cancel out the difference in stray inductance through symmetrical current paths. For example, when the current flows through the second copper busbar 12 and the third copper busbar 21, the magnetic field generated can be partially canceled because the bending directions are opposite, further reducing the impact of stray inductance on current sharing. This is a detail that has not been considered in the existing two-layer copper busbar structure.

[0055] By adopting the above technical solution, a current sharing solution is constructed using a three-layer copper busbar stack and a symmetrical structural design: On the one hand, the non-linear bending structure (the second, third, fifth, and sixth copper busbars) adopts the same shape and size, and the third copper busbar 21 and the second copper busbar 12 are horizontally mirrored. Combined with the symmetrical design of the straight strip structure (the first and fourth copper busbars), the copper busbar resistance and inductance parameters are kept consistent. On the other hand, through precise electrical connections in the vertical direction, such as the first copper busbar 11 connecting the fifth copper busbar 31 and the third copper busbar 21 respectively, and the fourth copper busbar 22 clamping and connecting the second copper busbar 12 and the sixth copper busbar 32, the impedance of the key current path is made approximately equal. This eliminates the impact of copper busbar parameter differences on current sharing from the structural level, significantly reducing the current sharing deviation of parallel modules. At the same time, the three-layer stack design ensures the reliability of electrical connections without the need for additional complex structures, adapting to the power and cost balance requirements of the three-level ANPC architecture in photovoltaic, wind power generation, and other scenarios.

[0056] Reference Figure 5 and Figure 7 As shown, in one embodiment, the non-linear bending structure is Z-shaped, including a first horizontal segment, an inclined segment and a second horizontal segment connected in sequence, with the first signal terminal 41 located at the free end of the first horizontal segment and the second signal terminal 42 located at the free end of the second horizontal segment.

[0057] It is understandable that the Z-shaped design used in the non-linear bending structure of this application is not only to meet spatial layout requirements, but also to achieve technical optimization from three dimensions: impedance consistency, processing feasibility, and interlayer compatibility. Specifically, the Z-shaped structure includes a first horizontal segment (corresponding to the location of the first signal terminal 41), an inclined segment (located in the area between the first signal terminal 41 and the second signal terminal 42), and a second horizontal segment (corresponding to the location of the second signal terminal 42), all integrally formed sequentially. The free end of the first horizontal segment is the first signal terminal 41, and the free end of the second horizontal segment is the second signal terminal 42. The core advantage of this segmented structure is that the first and second horizontal segments can be customized according to the signal terminals of different copper busbar layers. The precise length setting of the position (such as the terminal spacing between the first copper busbar layer 10 and the second copper busbar layer 20, and the height difference between the third copper busbar layer 30 and the second copper busbar layer 20) ensures that the signal terminals / ends of other copper busbars in the vertical direction can achieve surface contact docking, preventing increased contact resistance due to connection misalignment; while the inclined section can flexibly adjust the extension angle (such as 30°, 40°, 45°, 60°, 90°, 120°, etc.) in the horizontal space, avoiding the terminal locking parts of adjacent copper busbars, and without increasing the overall length of the copper busbars, effectively solving the spatial interference problem when multiple copper busbars are stacked. For example, the inclined sections of the third copper busbar 21 and the second copper busbar 12 can be extended in opposite directions to achieve non-contact intersection in the same vertical projection plane.

[0058] By adopting the above technical solution, the Z-shaped structure has the advantages of controllable path length and spatial adaptability. The first horizontal segment and the second horizontal segment can accurately connect to the signal terminals of different copper busbar layers (such as the first horizontal segment of the third copper busbar 21 connecting to the second end 52 of the first copper busbar 11, and the second horizontal segment connecting to the module terminal). The inclined segment can optimize the copper busbar layout in the horizontal space, reduce the interference problem when multiple copper busbars are stacked (such as the first copper busbar layer 10, the second copper busbar layer 20, and the third copper busbar layer 30 are stacked along the Z direction), and prevent installation difficulties caused by mutual obstruction of copper busbars.

[0059] In one embodiment, all non-linear copper busbars (the second, third, fifth, and sixth copper busbars) adopt a uniform Z-shaped size design, with the total length (X direction) of the Z-shape being completely consistent, including the length of the first horizontal segment, the length of the second horizontal segment, and the length of the inclined segment. Preferably, the length of the first horizontal segment is 15-25 mm, the length of the second horizontal segment is 15-25 mm, and the length of the inclined segment is 30-40 mm. In one embodiment, the inclined angle is a vertical 90°. Figure 5 As shown; in another embodiment, the tilt angle is 30°, as... Figure 7 As shown, this standardized design ensures that the cross-sectional area and current flow path length of each non-linear copper busbar are exactly the same, thereby maintaining a high degree of consistency in the resistance (determined by material, cross-sectional area, and length) and inductance (determined by shape and spatial layout) parameters of each copper busbar, providing a fundamental guarantee for balanced current path impedance. In addition, compared with other complex bending shapes (such as wavy or multi-segment broken lines), the Z-shaped structure is significantly easier to process. It can be formed in one step through conventional stamping processes without the need for subsequent secondary bending. This not only ensures dimensional accuracy (error can be controlled within ±0.1mm) but also enables mass production, greatly reducing the cost of engineering applications and adapting to the large-scale production needs of three-level ANPC architecture in the new energy field.

[0060] Reference Figure 7 In one embodiment, the second copper busbar 12 and the third copper busbar 21 are intersected in a vertical direction, and the inclined segment of the third copper busbar 21 extends from the first horizontal segment to the lower right along the copper busbar plane to the second horizontal segment, and the inclined segment of the second copper busbar 12 extends from the first horizontal segment to the upper right along the copper busbar plane to the second horizontal segment.

[0061] It is understandable that the vertical layered intersection of the second copper busbar 12 and the third copper busbar 21 refers to the fact that they are located in different copper busbar layers (the second copper busbar 12 is located in the first copper busbar layer 10, and the third copper busbar 21 is located in the second copper busbar layer 20), and they appear to intersect on the vertical projection plane. This intersection is not a physical contact, but rather an electrical isolation achieved through interlayer insulation, forming an intersection layout only in spatial position. Specifically, the inclined section of the third copper busbar 21 adopts a design that extends downward to the right, starting from the end of its first horizontal section (near the left side of the copper busbar layer), and tilting downward to the right (+X, -Y direction) along its own copper busbar plane (XY plane) until it connects to the second horizontal section (near the right side of the copper busbar layer); while the inclined section of the second copper busbar 12 adopts a design that extends upward to the right, starting from the end of its first horizontal section, and tilting upward to the right (+X, +Y direction) along its own copper busbar plane, and finally connecting to the second horizontal section. The two inclined directions are opposite but the angles are the same (e.g., the angle θ is 30° for both), so that the inclined sections form an intersection point on the vertical projection plane, ensuring that the overall structure presents a mirror image.

[0062] By adopting the above technical solution, the vertical hierarchical cross design of the second copper bar 12 and the third copper bar 21, combined with the reverse extension of the inclined section, can not only achieve the intensive layout of copper bars within a limited horizontal space, but also ensure that the current paths of the two layers of copper bars do not interfere with each other; at the same time, the reverse-extended inclined section makes the path lengths and bending angles of the two copper bars completely symmetrical, further ensuring that the resistance and stray inductance parameters are consistent, preventing impedance deviation caused by structural asymmetry, thereby strengthening the current sharing effect, and especially adapting to the connection requirements of the IGBT module with a "pin" shape layout in the three-level ANPC architecture.

[0063] As Figure 8 所示, 在一实施例中, 非直线型弯折结构为斜线型结构, 斜线型结构呈单一倾斜延伸状, 斜线型结构两端分别为第一信号端41和第二信号端42, 且斜线型结构在铜排平面内(XY平面)与水平方向的夹角θ为15°-75°。 shown, in an embodiment, the non-linear bending structure is a diagonal structure, the diagonal structure is in a single inclined extension shape, the two ends of the diagonal structure are the first signal end 41 and the second signal end 42 respectively, and the angle θ between the diagonal structure and the horizontal direction in the copper bar plane (XY plane) is 15° - 75°.

[0064] It can be understood that the non-linear bending structure in this embodiment adopts a diagonal design, which is more simplified than the Z-shaped structure. Its whole is in a continuous single inclined extension shape, without an additional horizontal section or bending section, and only directly connects the first signal end 41 and the second signal end 42 at both ends through a section of inclined copper bar. Among them, the angle θ (i.e., the inclination angle) formed by the diagonal structure and the horizontal direction in its own copper bar plane is limited within the range of 15° - 75°. This angle can adapt to the terminal pitch, copper bar layer spacing and current path length requirements of the "pin" type module. For example, when the misalignment distance of the module terminals in the horizontal direction is small, a large angle of 60° - 75° can be selected to shorten the diagonal length; when the misalignment distance is large, a small angle of 15° - 30° can be selected to reduce the space interference caused by excessive inclination of the copper bar.

[0065] By adopting the above technical solution, the single inclined extension diagonal design eliminates the bending nodes of the Z-shaped structure, which not only simplifies the stamping process of the copper busbar (reducing mold complexity) but also prevents local impedance fluctuations caused by stress concentration at the bending point (bending may cause a slight change in the cross-sectional area of ​​the copper busbar). The included angle range of 15°-75° achieves a balance between impedance control and spatial adaptation. If the included angle is less than 15°, the diagonal line is close to horizontal, which will significantly increase the copper busbar path length (X direction), leading to increased resistance; if the included angle is greater than 75°, the diagonal line connection... A near-vertical orientation would excessively occupy space in the width direction (Y direction), causing interference with adjacent copper busbar layers and affecting the overall layout compactness. Meanwhile, all diagonal copper busbars (the second, third, fifth, and sixth copper busbars) adopt the same tilt angle, length, and cross-sectional area to ensure that the resistance and inductance parameters of each copper busbar are consistent. This also meets the path impedance symmetry requirements for current sharing. This design is particularly suitable for scenarios with lower requirements for copper busbar processing complexity and production cost. While ensuring the current sharing effect (the deviation can still be controlled below 8%), it improves the feasibility of the process.

[0066] Reference Figure 8 In one embodiment, the second copper busbar 12 and the third copper busbar 21 are intersected in a vertical direction, and the intersection of the diagonal structure is located at the midpoint of the length direction of the diagonal structure of the second copper busbar 12 and the third copper busbar 21.

[0067] It is understood that the vertical layering intersection of the second copper busbar 12 and the third copper busbar 21 refers to the fact that the two are located in different copper busbar layers and the diagonal structure forms an intersection on the vertical projection plane. In one embodiment, the intersection point is exactly located at the midpoint of the length direction of their respective diagonal structures. That is, the distance from the intersection point to the first signal end 41 and the second signal end 42 of the second copper busbar 12 is equal, and the distance from the intersection point to the first signal end 41 and the second signal end 42 of the third copper busbar 21 is also equal, and the total length of the diagonal lines of the two copper busbars is completely consistent.

[0068] By adopting the above technical solution, the design of the intersection point located at the midpoint of the diagonal structure ensures that the intersection area of ​​the second copper busbar 12 and the third copper busbar 21 is completely symmetrically distributed, ensuring that the path length from the intersection point to the two signal terminals of the two copper busbars is completely equal, thereby ensuring that the resistance and inductance parameters are consistent; the vertical layered intersection prevents the two copper busbars from directly contacting and short-circuiting, while maximizing the use of vertical space and reducing the horizontal layout area, adapting to the connection scenarios of high-density IGBT modules, and further improving the practicality and current sharing stability of the structure.

[0069] In one embodiment, the thickness of the first copper busbar 11, the second copper busbar 12, the third copper busbar 21, the fourth copper busbar 22, the fifth copper busbar 31 and the sixth copper busbar 32 is 0.5 mm to 3 mm.

[0070] Understandably, this application limits the thickness of all copper busbars (first to sixth copper busbars) to 0.5mm to 3mm. This is to accommodate the current requirements of the three-level ANPC architecture, the copper busbar processing technology, and the overall requirements of module installation space. On the one hand, this thickness range must meet the circuit current carrying requirements. For example, under a typical operating current of 200A to 500A, a thickness of 0.5mm can ensure that the current density is controlled within a safe range (preventing excessive heat generation) through a reasonable cross-sectional area (in conjunction with the copper busbar width). On the other hand, if the thickness is too thick (e.g., exceeding 3mm), the total height of the three layers of copper busbars will exceed the adaptation space of the module terminals, making locking difficult. If the thickness is too thin (e.g., less than 0.5mm), the copper busbar will lack rigidity and be prone to deformation during transportation or installation, affecting the connection accuracy.

[0071] By adopting the above technical solution, a thickness range of 0.5mm to 3mm achieves a balance between "performance, process, and space": the lower limit of 0.5mm ensures that the copper busbar has sufficient conductive cross-sectional area, preventing local heating or impedance deviation due to excessive resistance, and ensuring that the current sharing effect is not affected by the material thickness; the upper limit of 3mm maintains the structural rigidity of the copper busbar, making it less prone to warping or deformation when bolted, ensuring the contact stability of the connection node, and matching the terminal spacing of the mainstream 62mm half-bridge module (usually suitable for single-layer copper busbar thickness of less than 3mm), without the need to adjust the original design of the module, greatly improving the process compatibility and engineering adaptability of the copper busbar structure, and reducing the cost of replacing existing copper busbars.

[0072] Reference Figures 5 to 8 In one embodiment, the first signal terminal 41, the second signal terminal 42, the first terminal 51 and the second terminal 52 are all provided with a connecting hole 70 that penetrates the thickness direction of the copper busbar. The connecting hole 70 is configured to realize a detachable electrical connection between different copper busbar layers or between the copper busbar and an external module through fasteners.

[0073] It is understood that the connection holes 70 provided at the first signal end 41, the second signal end 42, the first end 51, and the second end 52 in this embodiment all penetrate completely along the thickness direction of the copper busbar. The size of the holes is precisely matched with the size of the suitable fasteners (for example, the hole diameter is 0.1mm to 0.2mm larger than the nominal diameter of the fastener, which facilitates insertion and prevents poor contact due to excessive gaps). The core function of these connection holes 70 is to provide a mechanical and electrical interface for the "vertical electrical connection between different copper busbar layers" and the "fixed connection between the copper busbar and the external IGBT module". When the connection between copper busbar layers is realized (such as the vertical connection between the first copper busbar 11 and the fifth copper busbar 31), the fastener can pass through the connection holes 70 of the two copper busbars in sequence to make the two copper busbars fit tightly together. When the connection between the copper busbar and the external module is realized (such as the terminal connection between the first copper busbar 11 and the T2 module), the fastener can pass through the copper busbar connection holes 70 and cooperate with the threaded holes of the module terminals to complete the fixation and conduction.

[0074] By adopting the above technical solution, the connection hole 70 and the fastener achieve a detachable and reliable electrical connection. On the one hand, the detachable design facilitates the installation, debugging and subsequent maintenance of the copper busbar, such as replacing damaged copper busbars, reducing maintenance costs. On the other hand, the fasteners adapted to the connection hole 70 (such as the combination of hexagonal head bolts and flat washers, and the combination of cross-head pan head self-tapping screws and spring washers) can ensure stable contact pressure between different copper busbar layers and between the copper busbar and the IGBT module through bolt tightening force or screw self-locking force, reducing contact resistance and preventing contact resistance differences from affecting current sharing. At the same time, it ensures the stability of the electrical connection and meets the long-term use requirements of complex outdoor working conditions such as photovoltaic and wind power.

[0075] In one embodiment, the diameter of the connecting hole 70 is 3mm to 8mm, and the edge of the connecting hole 70 is provided with an annular chamfer (not shown in the figure), the radius of the annular chamfer is 0.3mm to 0.8mm.

[0076] It is understandable that the design of the connection hole 70 in this embodiment is adapted to actual installation requirements in terms of both diameter and edge treatment. On the one hand, the diameter of the connection hole 70 is limited to 3mm to 8mm, a range that precisely matches the mainstream fastener specifications in the power electronics field (such as M3 to M8 series bolts and studs). For example, an M3 bolt corresponds to a 3.2mm hole diameter, and an M5 bolt corresponds to a 5.3mm hole diameter, which can cover the connection requirements of different power modules such as a 62mm half-bridge module, ensuring the universality and interchangeability of the connection between the copper busbar and external modules, and between copper busbar layers, without the need for customized fasteners of special specifications. On the other hand, the edge treatment of the connection hole 70... The edge is provided with an annular chamfer, and the chamfer radius is controlled between 0.3mm and 0.8mm. This chamfer is a rounded transition structure around the hole, which can eliminate the sharp edge of the hole and prevent scratches on the surface plating of the fastener or the copper busbar itself during installation (preventing increased contact resistance due to surface damage). It can also guide the fastener to pass smoothly into the hole, reducing the alignment difficulty and improving assembly efficiency. At the same time, the radius of 0.3mm to 0.8mm can prevent the effective cross-sectional area of ​​the copper busbar connection area from being weakened by an excessively large chamfer (especially suitable for copper busbar thickness of 0.5mm to 3mm), prevent the hole from deforming during fastening, and take into account both connection reliability and structural strength.

[0077] By adopting the above technical solutions, the diameter design of the connection hole 70 ensures compatibility with mainstream fasteners, while the chamfered design optimizes the ease of installation and contact stability. The combination of the two not only improves the engineering adaptability of the copper busbar structure, but also reduces the impact of contact resistance differences on current sharing, while ensuring connection reliability in long-term use, and adapts to the installation and operation requirements of complex working conditions such as photovoltaic and wind power.

[0078] In one embodiment, the lengths of the first copper busbar 11 and the fourth copper busbar 22 are 70mm to 90mm, which is greater than the length of the non-linear bending structure along the horizontal direction.

[0079] It can be understood that in this embodiment, the lengths of the first copper bar 11 and the fourth copper bar 22 are set to be 70 mm to 90 mm, and this length is greater than the projected length of the non-linear bending structure (the second, third, fifth, and sixth copper bars, which are mainly used to adapt to the short-distance connection within the module groups such as T1 and T5, T2 and T6) along the horizontal direction. This design is adapted to the module spacing of the "pin" layout in the three-level ANPC architecture. When the 62 mm specification half-bridge IGBT modules are arranged in a "pin" shape, sufficient space needs to be reserved for the horizontal spacing of the terminals of adjacent modules to prevent interference. The length of 70 mm to 90 mm can not only ensure reliable docking of the two ends of the first copper bar 11 with the signal ends of the fifth copper bar 31 and the third copper bar 21 in the vertical direction, but also ensure that the fourth copper bar 22 is stably clamped between the second copper bar 12 and the sixth copper bar 32 and is connected, while adapting to the installation positions of the existing modules without adjusting the module layout; in contrast, the horizontal length of the non-linear bending structure is relatively short, which is mainly used to adapt to the short-distance connection within the same module group. The differential design of the lengths of the two forms a complementarity and jointly constructs a complete current path.

[0080] By adopting the above technical solution, the length design of the first and fourth copper bars 22 provides sufficient space for the electrical connection in the vertical direction, preventing the misalignment of the connection points or the reduction of the contact area due to insufficient length, and at the same time preventing stress concentration in the connection part due to excessive stretching, thus prolonging the service life of the copper bar; the compatibility of this length range with the existing IGBT module architecture reduces the modification difficulty, and the traditional copper bar can be directly replaced, improving the engineering practicability of the solution.

[0081] This application also discloses an IGBT power module. The IGBT power module includes six sets of half-bridge IGBT modules and a current-sharing copper bus structure as described in any of the above embodiments. Each set of half-bridge IGBT modules includes at least two IGBT chips connected in parallel. The current-sharing copper bus structure is configured as follows: the first set of half-bridge IGBT modules and the fifth set of half-bridge IGBT modules are connected via a fifth copper bus 31; the first set of half-bridge IGBT modules and the sixth set of half-bridge IGBT modules are connected via a first copper bus 11 and a third copper bus 21; the second set of half-bridge IGBT modules and the fifth set of half-bridge IGBT modules are connected via a first copper bus 11 and a fifth copper bus 31; the second set of half-bridge IGBT modules and the sixth set of half-bridge IGBT modules are connected via a third copper bus 21; the third set of half-bridge IGBT modules and the fifth set of half-bridge IGBT modules are connected via a second copper bus 12; and the third set of half-bridge IGBT modules and the sixth set of half-bridge IGBT modules are connected via a fourth copper bus 22 and a sixth copper bus 32. The GBT module connects the fourth group of half-bridge IGBT modules to the fifth group of half-bridge IGBT modules via the second copper busbar 12 and the fourth copper busbar 22, and connects the fourth group of half-bridge IGBT modules to the sixth group of half-bridge IGBT modules via the sixth copper busbar 32. The copper busbar path impedances from the first group of half-bridge IGBT modules to the fifth group, the second group of half-bridge IGBT modules to the sixth group, the third group of half-bridge IGBT modules to the fifth group, and the fourth group of half-bridge IGBT modules to the sixth group are all equal.

[0082] Specifically, the IGBT power module includes six sets of half-bridge IGBT modules, such as... Figure 2 As shown, they are labeled T1, T2, T3, T4, T5, and T6 respectively. Each group of half-bridge IGBT modules contains at least two IGBT chips connected in parallel, namely T1.1 and T1.2 in group T1, T2.1 and T2.2 in group T2, T3.1 and T3.2 in group T3, T4.1 and T4.2 in group T4, T5.1 and T5.2 in group T5, and T6.1 and T6.2 in group T6 (e.g., T1.1 and T1.2 in group T6). Figure 1 As shown, the electrodes of each chip are defined as follows: the emitter of T1.1 is marked as T1.1E, the emitter of T2.1 is marked as T2.1E, the collector of T5.1 is marked as T5.1C, the collector of T6.1 is marked as T6.1C, the collector of T3.2 is marked as T3.2C, the collector of T4.2 is marked as T4.2C, the emitter of T5.2 is marked as T5.2E, and the emitter of T6.2 is marked as T6.2E.

[0083] The current-sharing copper busbar structure provided in this application embodiment achieves precise electrical connections between six groups of half-bridge IGBT modules through a specific combination of three layers of copper busbars. (Refer to...) Figure 5 (Schematic diagram of current equalization copper busbar structure) and Figure 6 (Exploded view of the current sharing copper busbar structure), and its specific connection relationship and matching method with the copper busbar are shown in the table below:

[0084] Serial Number Connection group The copper busbar assembly used 1 Group 1 half-bridge IGBT modules - Group 5 half-bridge IGBT modules Fifth copper busbar (used alone) 2 Group 1 half-bridge IGBT modules - Group 6 half-bridge IGBT modules First Bronze Bar + Third Bronze Bar 3 Second group of half-bridge IGBT modules - Fifth group of half-bridge IGBT modules First Bronze Row + Fifth Bronze Row 4 Second group of half-bridge IGBT modules - Sixth group of half-bridge IGBT modules Third copper busbar (used alone) 5 Third group of half-bridge IGBT modules - Fifth group of half-bridge IGBT modules Second copper busbar (used alone) 6 Group 3 half-bridge IGBT modules - Group 6 half-bridge IGBT modules Fourth Bronze Bar + Sixth Bronze Bar 7 Group 4 half-bridge IGBT modules - Group 5 half-bridge IGBT modules Second Bronze Bar + Fourth Bronze Bar 8 Group 4 half-bridge IGBT modules - Group 6 half-bridge IGBT modules Sixth copper busbar (used alone)

[0085] The table presents eight core connection relationships between six groups of half-bridge IGBT modules, along with the corresponding copper busbar combinations for each connection. Some group connections (e.g., numbers 1, 4, 5, and 8) require only a single non-linear copper busbar, while others (e.g., numbers 2, 3, 6, and 7) require a combination of a straight copper busbar and a non-linear copper busbar. All combinations are based on the aforementioned three-layer stacked design of the current-sharing copper busbar structure, and ultimately must meet two major impedance balancing objectives: one is T1.1E to... The copper busbar path impedance of T5.1C is equal to that of the copper busbar path impedances from T2.1E to T6.1C, T3.2C to T5.2E, and T4.2C to T6.2E; secondly, the copper busbar path impedances from T1.1E to T6.1C are equal to those of the copper busbar path impedances from T2.1E to T5.1C, T3.2C to T6.2E, and T4.2C to T5.2E, thus achieving current sharing.

[0086] By adopting the above technical solution, the IGBT power module precisely adapts the current sharing copper busbar structure to the six groups of half-bridge IGBT modules, achieving path impedance symmetry for the module connection requirements of the three-level ANPC architecture. On the one hand, through the corresponding connection between the copper busbars and the modules, such as the fifth copper busbar 31 connecting the first and fifth groups of modules, and the third copper busbar 21 connecting the second and sixth groups of modules, the impedance of key parallel paths, such as the impedance from the first group to the fifth group and the impedance from the second group to the sixth group, are equal. On the other hand, through the collaborative connection of multiple copper busbars, such as the first copper busbar 11 combined with the third copper busbar 21 and the first copper busbar 11 combined with the fifth copper busbar 31, the impedance of cross paths, such as the impedance balance from the first group to the sixth group and the impedance balance from the second group to the fifth group, is achieved, solving the current sharing problem of parallel modules at the system level and reducing the current sharing deviation to below 8%. Meanwhile, each half-bridge IGBT module contains at least two parallel chips. Combined with the current sharing effect of the copper busbar, the overall power density of the module can be further improved, making it suitable for scenarios with high requirements for power output and operational stability, such as photovoltaic and wind power generation. Moreover, the current sharing copper busbar structure is simple and easy to assemble, without the need for additional complex control units, thus balancing the reliability and cost-effectiveness of the module.

[0087] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A current-sharing copper busbar structure for IGBT power modules, characterized in that, It includes a first copper busbar layer (10), a second copper busbar layer (20) and a third copper busbar layer (30) stacked vertically from top to bottom, with the extension direction of each copper busbar layer parallel to the horizontal direction; The first copper busbar layer (10) includes a first copper busbar (11) and a second copper busbar (12) arranged horizontally along the copper busbar plane. The second copper busbar layer (20) includes a third copper busbar (21) and a fourth copper busbar (22) arranged horizontally along the copper busbar plane. The third copper busbar layer (30) includes a fifth copper busbar (31) and a sixth copper busbar (32) arranged horizontally along the copper busbar plane. Among them, the second copper busbar (12), the third copper busbar (21), the fifth copper busbar (31) and the sixth copper busbar (32) are non-linear bent structures with the same planar shape and planar size. The third copper busbar (21) and the fifth copper busbar (31) are arranged in the same direction in the horizontal direction. The second copper busbar (12) and the sixth copper busbar (32) are arranged in the same direction in the horizontal direction. The third copper busbar (21) and the second copper busbar (12) are mirror images of each other in the horizontal direction. The non-linear bent structure is provided with two signal terminals. The two signal terminals are located at both ends of the non-linear bent structure in the horizontal direction. The signal terminal closer to the left side of the copper busbar layer is the first signal terminal (41), and the signal terminal closer to the right side of the copper busbar layer is the second signal terminal (42). The first copper busbar (11) and the fourth copper busbar (22) are linear strip structures with the same planar shape and planar size. The linear strip structure has signal terminals at both ends, and the signal terminal closer to the left side of the copper busbar layer along the horizontal direction is the first terminal (51), and the signal terminal closer to the right side of the copper busbar layer is the second terminal (52). The first end (51) of the first copper busbar (11) is electrically connected to the first signal end (41) of the fifth copper busbar (31) in the vertical direction, and the second end (52) of the first copper busbar (11) is electrically connected to the first signal end (41) of the third copper busbar (21) in the vertical direction. The fourth copper busbar (22) is sandwiched between the second copper busbar (12) and the sixth copper busbar (32) in a vertical direction, and the first end (51) of the fourth copper busbar (22) and the second signal end (42) of the second copper busbar (12) are electrically connected in a vertical direction, and the second end (52) of the fourth copper busbar (22) and the second signal end (42) of the sixth copper busbar (32) are electrically connected in a vertical direction; the non-linear bending structure is Z-shaped, including a first horizontal segment, an inclined segment and a second horizontal segment connected in sequence, the first signal end (41) is located at the free end of the first horizontal segment, and the second signal end (42) is located at the free end of the second horizontal segment; the second copper busbar (12) and the third copper busbar (21) are intersected in layers in a vertical direction, the inclined segment of the third copper busbar (21) extends from the first horizontal segment to the lower right along the copper busbar plane to the second horizontal segment, and the inclined segment of the second copper busbar (12) extends from the first horizontal segment to the upper right along the copper busbar plane to the second horizontal segment.

2. A current-sharing copper busbar structure for IGBT power modules, characterized in that, It includes a first copper busbar layer (10), a second copper busbar layer (20) and a third copper busbar layer (30) stacked vertically from top to bottom, with the extension direction of each copper busbar layer parallel to the horizontal direction; The first copper busbar layer (10) includes a first copper busbar (11) and a second copper busbar (12) arranged horizontally along the copper busbar plane. The second copper busbar layer (20) includes a third copper busbar (21) and a fourth copper busbar (22) arranged horizontally along the copper busbar plane. The third copper busbar layer (30) includes a fifth copper busbar (31) and a sixth copper busbar (32) arranged horizontally along the copper busbar plane. Among them, the second copper busbar (12), the third copper busbar (21), the fifth copper busbar (31) and the sixth copper busbar (32) are non-linear bent structures with the same planar shape and planar size. The third copper busbar (21) and the fifth copper busbar (31) are arranged in the same direction in the horizontal direction. The second copper busbar (12) and the sixth copper busbar (32) are arranged in the same direction in the horizontal direction. The third copper busbar (21) and the second copper busbar (12) are mirror images of each other in the horizontal direction. The non-linear bent structure is provided with two signal terminals. The two signal terminals are located at both ends of the non-linear bent structure in the horizontal direction. The signal terminal closer to the left side of the copper busbar layer is the first signal terminal (41), and the signal terminal closer to the right side of the copper busbar layer is the second signal terminal (42). The first copper busbar (11) and the fourth copper busbar (22) are linear strip structures with the same planar shape and planar size. The linear strip structure has signal terminals at both ends, and the signal terminal closer to the left side of the copper busbar layer along the horizontal direction is the first terminal (51), and the signal terminal closer to the right side of the copper busbar layer is the second terminal (52). The first end (51) of the first copper busbar (11) is electrically connected to the first signal end (41) of the fifth copper busbar (31) in the vertical direction, and the second end (52) of the first copper busbar (11) is electrically connected to the first signal end (41) of the third copper busbar (21) in the vertical direction. The fourth copper busbar (22) is sandwiched between the second copper busbar (12) and the sixth copper busbar (32) in a vertical direction, and the first end (51) of the fourth copper busbar (22) and the second signal end (42) of the second copper busbar (12) are electrically connected in a vertical direction, and the second end (52) of the fourth copper busbar (22) and the second signal end (42) of the sixth copper busbar (32) are electrically connected in a vertical direction; the non-linear bending structure is a diagonal structure, the diagonal structure is a single inclined extension, the two ends of the diagonal structure are the first signal end (41) and the second signal end (42) respectively, and the angle between the diagonal structure and the horizontal direction in the plane of the copper busbar is 15° to 75°.

3. The current-equalizing copper busbar structure according to claim 2, characterized in that, The second copper busbar (12) and the third copper busbar (21) intersect in a vertical direction, and the intersection point of the oblique structure is located at the midpoint of the length direction of the oblique structure of the second copper busbar (12) and the third copper busbar (21).

4. The current-equalizing copper busbar structure according to any one of claims 1-3, characterized in that, The thickness of the first copper busbar (11), the second copper busbar (12), the third copper busbar (21), the fourth copper busbar (22), the fifth copper busbar (31), and the sixth copper busbar (32) is 0.5 mm to 3 mm.

5. The current-equalizing copper busbar structure according to any one of claims 1-3, characterized in that, The first signal terminal (41), the second signal terminal (42), the first terminal (51) and the second terminal (52) are all provided with a connecting hole (70) that penetrates the thickness direction of the copper busbar. The connecting hole (70) is configured to realize a detachable electrical connection between different copper busbar layers or between the copper busbar and an external module through fasteners.

6. The current-equalizing copper busbar structure according to claim 5, characterized in that, The diameter of the connecting hole (70) is 3mm to 8mm, and the edge of the connecting hole (70) is provided with an annular chamfer with a radius of 0.3mm to 0.8mm.

7. The current-equalizing copper busbar structure according to any one of claims 1-3, characterized in that, The lengths of the first copper busbar (11) and the fourth copper busbar (22) are 70mm to 90mm, which is greater than the length of the non-linear bending structure along the horizontal direction.

8. An IGBT power module, characterized in that, Includes the current-equalizing copper busbar structure as described in any one of claims 1-7.

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