Explosion-proof reinforced low-stray-inductance laminated busbar assembly suitable for high-capacity power module

Abstract

The invention relates to the technical field of flexible direct-current transmission converter valves, in particular to an explosion-proof reinforced low-stray-inductance laminated busbar assembly suitable for a high-capacity power module, which comprises a capacitor laminated busbar and a power assembly laminated busbar, the capacitor laminated busbar and the power assembly laminated busbar are parallel to each other, and the capacitor laminated busbar and the power assembly laminated busbar are parallel to each other. The capacitor laminated busbar is fixedly connected with the capacitor unit, and the power assembly laminated busbar is fixedly connected with the power assembly water-cooling radiator. The capacitor laminated busbar has the advantages that the capacitor laminated busbar is of a two-pole two-layer structure, the capacitor positive busbar and the capacitor negative busbar are arranged to be of a large-area laminated parallel arrangement structure, and a current port of the capacitor positive busbar and a current port of the capacitor negative busbar are arranged in a cross input mode; according to the capacitor busbar, the current distributed in the capacitor anode busbar and the capacitor cathode busbar is crossed and overlapped as much as possible, and mutual inductance generated between the capacitor anode busbar and the capacitor cathode busbar counteracts self-inductance of the busbar to a certain extent, so that stray inductance of the capacitor busbar is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible direct current power transmission converter valves, and in particular to an explosion-proof reinforced low-inductance laminated busbar assembly suitable for a large-capacity power module. Background Art

[0002] Compared with the traditional mode, the flexible DC transmission mode has the technical advantages of no phase change failure, fast system response speed, flexible operation mode, strong support for the power grid, and easy construction of multi-terminal DC transmission system. It is an important equipment for building smart grids and will play an important role in the construction of new power systems with new energy as the main body in the future. In order to adapt to the construction of new power systems in the future, the flexible DC converter valve will develop in the following two aspects: 1. Further increase the capacity, and the capacity of a single valve set needs to reach ±800kV / 8000MW; 2. Improve the overload capacity.

[0003] The development of a converter valve with the above capabilities places higher demands on the development of power modules, and the main difficulties are as follows:

[0004] 1. Suppression of turn-off voltage spike

[0005] To suppress the turn-off spike, it is often necessary to reduce the stray inductance, but reducing the stray inductance will increase the destructiveness of energy release. It is necessary to comprehensively consider the balance between spike suppression and extreme barrier energy release.

[0006] 2. Protection technology for large-capacity energy release under extreme fault conditions

[0007] In the event of extreme faults (such as bypass switch failure to operate, device overvoltage short circuit, etc.), the large amount of energy stored in the capacitor will be released through the bridge arm, which is a great challenge to the explosion-proof capability of the power module.

[0008] The difficulties mentioned above restrict and influence each other, and need to be considered comprehensively to break through the technical limitations and complete the design of busbars suitable for the next generation of large-capacity and strong overload capacity power modules. Summary of the invention

[0009] The purpose of the present invention is to provide an explosion-proof reinforced low-noise laminated busbar assembly suitable for large-capacity power modules, adopting multi-level potential to adapt to complex connections, using multi-layer lamination to reduce noise, adopting power component laminated busbars with four layers of busbars arranged in one assembly, and using FR4 high-strength insulation material as the insulation layer of the busbar and packaging process to improve the explosion-proof performance of the busbar.

[0010] To achieve the above object, the present invention is implemented through the following technical solutions:

[0011] The invention relates to an explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules, comprising a capacitor laminated busbar and a power component laminated busbar, wherein the capacitor laminated busbar and the power component laminated busbar are parallel to each other, the capacitor laminated busbar is fixedly connected to the capacitor unit, and the power component laminated busbar is fixedly connected to the power component water-cooled radiator.

[0012] The capacitor laminated busbar is a two-pole structure, which includes a capacitor positive busbar and a capacitor negative busbar. The capacitor positive busbar and the capacitor negative busbar are stacked up and down. An intermediate insulating layer is provided between the capacitor positive busbar and the capacitor negative busbar. The capacitor positive busbar and the capacitor negative busbar are sealed together by an outer insulating layer.

[0013] The power component laminated busbar is a four-pole structure, which includes AC busbar 1, AC busbar 2, positive busbar and negative busbar. AC busbar 1, AC busbar 2, positive busbar and negative busbar are laminated from top to bottom. An intermediate insulating layer is provided between AC busbar 1, AC busbar 2, positive busbar and negative busbar. AC busbar 1, AC busbar 2, positive busbar and negative busbar are sealed together by an outer insulating layer.

[0014] The capacitor positive busbar is provided with a capacitor positive busbar current port, and the capacitor negative busbar is provided with a capacitor negative busbar current port. The capacitor positive busbar current port and the capacitor negative busbar current port are arranged as cross inputs, and the capacitor positive busbar current port and the capacitor negative busbar current port are respectively connected to the capacitor units.

[0015] The capacitor unit comprises a plurality of capacitors, the plurality of capacitors are connected in parallel, the positive busbar current port of the capacitor is connected to the positive electrode of the capacitor, and the negative busbar current port of the capacitor is connected to the negative electrode of the capacitor.

[0016] The outer insulation layer and the middle insulation layer are made of high-strength epoxy glass cloth laminate FR4.

[0017] The power component laminated busbar is fixedly connected to the power component water-cooled radiator through a high-strength metal pressure plate.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The capacitor stacked busbar is a two-pole two-layer structure. The capacitor positive busbar and the capacitor negative busbar are arranged in a large-area stacked parallel structure. The capacitor positive busbar current port and the capacitor negative busbar current port are arranged as cross inputs, so that the currents distributed in the capacitor positive busbar and the capacitor negative busbar are cross-overlapped as much as possible. The mutual inductance generated between the capacitor positive busbar and the capacitor negative busbar offsets the busbar self-inductance to a certain extent, thereby reducing the stray inductance of the capacitor busbar;

[0020] 2. The traditional power component busbar is designed as a discrete busbar structure, the positive busbar and the negative busbar are arranged alternately on one working surface, and the AC busbar 1 and the AC busbar 2 are arranged alternately on another working surface. The distance between the two working surfaces is large, and the current distributed on each busbar does not cross or overlap; the power component laminated busbar provided by the present invention is a four-pole four-layer structure, the positive busbar, the negative busbar, the AC busbar 1, and the AC busbar 2 are arranged as a large-area laminated parallel arrangement structure, the gap between the positive busbar, the negative busbar, the AC busbar 1, and the AC busbar 2 is small, and the current distributed in the positive busbar, the negative busbar, the AC busbar 1, and the AC busbar 2 crosses and overlaps, so that a large mutual inductance is generated between the positive busbar, the negative busbar, the AC busbar 1, and the AC busbar 2, which offsets the self-inductance of the positive busbar, the negative busbar, the AC busbar 1, and the AC busbar 2 to a certain extent, reduces the stray inductance of the power component busbar, thereby reducing the voltage spike during normal operation and improving the overvoltage operation capability of the converter valve;

[0021] 3. In order to improve the explosion-proof performance of the laminated busbar assembly, the insulation layer adopts an explosion-proof reinforced structure design. The outer insulation layer and the middle insulation layer of the capacitor laminated busbar and the power component laminated busbar are made of high-strength epoxy glass cloth laminate FR4. Compared with the conventional flexible insulation film, the high-strength epoxy glass cloth laminate FR4 is a hard material with better rigidity and stronger deformation resistance under extreme fault conditions; compared with the epoxy resin coated insulation layer of the discrete busbar, the laminated busbar insulation layer does not fall off or splash under extreme fault conditions, avoiding the external damage of the discrete busbar insulation layer fragments. The splashing has an adverse effect on the overall insulation performance of the converter valve; the plates and insulating layers of the capacitor laminated busbar and the power component laminated busbar are bonded with prepreg, which has stronger bonding performance than conventional insulating films, and the peel strength can reach several times that of conventional insulating films; the laminated busbar is filled with high-strength potting glue to encapsulate the plates and insulating layers into a whole, which can limit the local deformation of the busbar under extreme fault conditions and greatly improve the deformation resistance of the busbar plates; the explosion-proof design of the laminated busbar solves the problem that the busbar cannot withstand impact stress under extreme fault conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the installation diagram of the explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules.

[0023] Figure 2 It is a structural schematic diagram of an explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules.

[0024] Figure 3 It is a schematic diagram of the installation of capacitor laminated busbars.

[0025] Figure 4 It is a schematic diagram of the structure of a capacitor laminated busbar with an insulating layer.

[0026] Figure 5 It is a schematic diagram of the structure of a capacitor laminated busbar without an insulating layer.

[0027] Figure 6 It is a schematic diagram of the installation of the power component stacked busbar.

[0028] Figure 7 It is a schematic diagram of the structure of a laminated busbar of a power component with an insulating layer.

[0029] Figure 8 It is a schematic diagram of the structure of a laminated busbar of a power component without an insulation layer.

[0030] Fig. 9 This is the power module voltage spike test diagram.

[0031] Fig.10 This is a test diagram of the explosion-proof capability of the power module.

[0032] In the figure: 1-capacitor 2-laminated busbar assembly 3-power component water-cooled radiator 4-capacitor laminated busbar 5-power component laminated busbar 6-capacitor positive busbar 7-capacitor negative busbar 8-outer insulation layer 9-intermediate insulation layer 10-capacitor positive busbar current port 11-capacitor negative current busbar current port 12-semi-cured sheet 13-positive busbar 14-negative busbar 15-AC busbar one 16-AC busbar two 17-high-strength metal pressure plate 18-high-strength bolts. DETAILED DESCRIPTION

[0033] The present invention is described in detail below in conjunction with the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0034] The following examples are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0035] Example 1

[0036] Due to the complexity of the power module structure of the converter valve, the busbar structure and function that need to be designed are also relatively complex. For example, the ±800kV / 8000MW converter valve needs to use IGBT and Diode devices with a current level of 5kA, and the Diode device is a discrete crimping device that is not integrated inside the IGBT. At the same time, the full bridge needs to be considered, the number of devices is large, and the connection and layout are complex. The traditional laminated busbar design can reduce the stray inductance, but its strength is low and it cannot withstand the electric force generated by the release of extreme fault energy. The extreme fault is when the IGBT or diode has a short circuit fault, the capacitor is short-circuited, and at this time the capacitor instantly releases a large amount of energy to the busbar in the discharge circuit; the thickened discrete busbar has an advantage in explosion-proof characteristics, but its stray inductance is about 180nH, which will make the voltage spike during normal operation too high, affecting the overvoltage operation capability of the converter valve, see Table 1.

[0037] Table 1 Comparison of stray inductance and extreme fault electrical stress of different busbar structures

[0038]

[0039] Combining the strength of discrete busbars and the design concept of laminated busbars, a multi-level low-noise high-strength laminated busbar assembly is designed to reduce noise inductance, adapt to complex connections and meet explosion-proof performance. The explosion-proof reinforced low-noise laminated busbar assembly suitable for large-capacity power modules includes a capacitor laminated busbar 4 and a power component laminated busbar 5. The capacitor laminated busbar 4 and the power component laminated busbar 5 are parallel to each other. The capacitor laminated busbar 4 is fixedly connected to the capacitor 1 unit. The capacitor 1 unit includes three capacitors 1 connected in parallel. The power component laminated busbar 5 is fixedly connected to the power component water-cooled radiator 3 through a high-strength metal pressure plate 17 and a high-strength bolt 18.

[0040] The capacitor laminated busbar 4 is a two-pole structure, which includes a capacitor positive busbar 6 and a capacitor negative busbar 7. The capacitor positive busbar 6 and the capacitor negative busbar 7 are an upper and lower stacked structure. An intermediate insulating layer 9 is provided between the capacitor positive busbar 6 and the capacitor negative busbar 7. The capacitor positive busbar 6 and the capacitor negative busbar 7 are sealed together by an outer insulating layer 8; the capacitor positive busbar 6 is provided with a capacitor positive busbar 13 current port 10, and the capacitor negative busbar 7 is provided with a capacitor negative busbar current port 11. The capacitor positive busbar 13 current port 10 and the capacitor negative busbar current port 11 are arranged as cross inputs, and the capacitor positive busbar 13 current port 10 and the capacitor negative busbar current port 11 are respectively connected to the capacitor 1 unit; the capacitor positive busbar 13 current port 10 is connected to the positive pole of the capacitor 1, and the capacitor negative busbar current port 11 is connected to the negative pole of the capacitor 1.

[0041] The power component laminated busbar 5 is a four-pole structure, which includes an AC busbar 1 15, an AC busbar 2 16, a positive busbar 13, and a negative busbar 14. The AC busbar 1 15, the AC busbar 2 16, the positive busbar 13, and the negative busbar 14 are laminated structures from top to bottom. An intermediate insulating layer 9 is provided between the AC busbar 1 15, the AC busbar 2 16, the positive busbar 13, and the negative busbar 14. The AC busbar 1 15, the AC busbar 2 16, the positive busbar 13, and the negative busbar 14 are sealed together by an outer insulating layer 8; the AC busbar 1 15 is used to connect to a water-cooled radiator with a potential of AC1, the AC busbar 2 is used to connect to a water-cooled radiator with a potential of AC2, the positive busbar is used to connect to a water-cooled radiator with a positive potential and the positive terminal of the capacitor, and the negative busbar is used to connect to a water-cooled radiator with a negative potential and the negative terminal of the capacitor.

[0042] The outer insulating layer 8 and the middle insulating layer 9 are made of high-strength epoxy glass cloth laminate FR4. The capacitor laminated busbar 4, the power component laminated busbar 5, and the insulating layer are bonded with a prepreg 12, and the periphery is filled with a high-strength potting glue to encapsulate the capacitor laminated busbar 4, the power component laminated busbar 5, and the insulating layer into a high-strength laminated busbar assembly 2.

[0043] The laminated busbar assembly 2 provided by the present invention has been tested and the stray inductance is about 100nH. The voltage spike ΔU≈500V generated by the stray inductance during normal operation meets the requirement of controlling the voltage spike at 4100V when operating at 3600V. Fig. 9 , which is the optimization of the electrical parameters of the power module during extreme faults.

[0044] The optimization of busbar mechanical performance during extreme faults is as follows:

[0045] Compared with discrete busbars, although the peak current increases under extreme fault conditions, the laminated busbar has a larger area, more dispersed current distribution, and smaller local current density. Under extreme fault conditions, the local stress of the busbar electric force is smaller, and the local deformation is smaller, reducing the risk of busbar fracture at the stress concentration position under extreme fault conditions; at the same time, it also avoids excessive displacement of the water-cooled radiator due to excessive deformation of the busbar, and the laminated busbar structure plays a good limiting role for the water-cooled radiator; compared with discrete busbars, the laminated busbar plate has a smaller thickness, better toughness, and stronger resistance to hard impact, and is less likely to have a hard fracture under extreme fault conditions.

[0046] The laminated busbar assembly 2 provided by the present invention has been verified by explosion-proof tests. When the energy of the 24mF capacitor 1 and the voltage 4400V is released, the peak current reaches 1570kA. The designed laminated busbar assembly 2 has no tearing, no breaking, and no obvious deformation of various parts after the energy impact of the extreme fault state, and has good explosion-proof performance. Fig.10 。

Claims

1. Explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules, characterized by: It includes a capacitor stacked busbar and a power component stacked busbar, the capacitor stacked busbar and the power component stacked busbar are parallel to each other, the capacitor stacked busbar is fixedly connected to the capacitor unit, and the power component stacked busbar is fixedly connected to the power component water-cooled radiator.

2. The explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules according to claim 1 is characterized in that: The capacitor laminated busbar is a two-pole structure, which includes a capacitor positive busbar and a capacitor negative busbar. The capacitor positive busbar and the capacitor negative busbar are stacked up and down. An intermediate insulating layer is provided between the capacitor positive busbar and the capacitor negative busbar. The capacitor positive busbar and the capacitor negative busbar are sealed together by an outer insulating layer.

3. The explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules according to claim 1 is characterized in that: The power component laminated busbar is a four-pole structure, which includes AC busbar 1, AC busbar 2, positive busbar and negative busbar. AC busbar 1, AC busbar 2, positive busbar and negative busbar are laminated structures from top to bottom. An intermediate insulating layer is provided between AC busbar 1, AC busbar 2, positive busbar and negative busbar. AC busbar 1, AC busbar 2, positive busbar and negative busbar are sealed together by an outer insulating layer.

4. The explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules according to claim 2 is characterized in that: The capacitor positive busbar is provided with a capacitor positive busbar current port, and the capacitor negative busbar is provided with a capacitor negative busbar current port. The capacitor positive busbar current port and the capacitor negative busbar current port are arranged as cross inputs, and the capacitor positive busbar current port and the capacitor negative busbar current port are respectively connected to the capacitor unit.

5. The explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules according to claim 4 is characterized in that: The capacitor unit comprises a plurality of capacitors, which are connected in parallel, the positive busbar current port of the capacitor is connected to the positive electrode of the capacitor, and the negative busbar current port of the capacitor is connected to the negative electrode of the capacitor.

6. The explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules according to claim 2 or 3, characterized in that: The outer insulation layer and the middle insulation layer are made of high-strength epoxy glass cloth laminate FR4.

7. The explosion-proof reinforced low-inductance laminated busbar assembly suitable for large-capacity power modules according to claim 1 is characterized in that: The power component laminated busbar is fixedly connected to the power component water-cooling radiator via a high-strength metal pressing plate.

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