Low-inductance low-resistance coaxial structure pulse capacitor

Abstract

The application provides a low-inductance and low-resistance coaxial structure pulse capacitor, and belongs to the technical field of pulse capacitors.The application comprises a high-voltage electrode, a core group, a copper bar, at least three low-voltage electrodes and a lead-out copper sheet corresponding to each low-voltage electrode.The high-voltage electrode is arranged at the center of the pulse capacitor;each low-voltage electrode is arranged at intervals around the circumference of the high-voltage electrode with the high-voltage electrode as the center;the core group is arranged around the high-voltage electrode and is clamped between the high-voltage electrode and each low-voltage electrode;the copper bar is arranged at the bottom surface of the core group;each lead-out copper sheet is arranged at intervals around the circumference of the high-voltage electrode with the high-voltage electrode as the center, and the lead-out copper sheet is arranged in a sheet structure, and all the lead-out copper sheets are jointly enclosed to form a ring structure;the low-voltage electrode and the lead-out copper sheet are an integrated structure.The coaxial structure of the high-voltage electrode in the center and the integrated and annular arrangement of the low-voltage electrode and the lead-out copper sheet can simultaneously realize low ESL, low ESR and uniform current distribution.

Description

Technical Field

[0001] This invention relates to the field of pulse capacitor technology, and specifically to a low-inductance, low-resistance coaxial pulse capacitor. Background Technology

[0002] Currently, conventional pulse capacitors generally adopt a single-sided lead-out terminal structure. The charging and discharging current needs to be led out through a narrow foldback path, resulting in a large stray area in the circuit and high parasitic inductance and ohmic loss. At the same time, the low-voltage electrode and the external lead-out copper sheet are mostly made by separate welding or riveting processes. There is a natural interface contact resistance between the two. Under high current instantaneous discharge scenarios, problems such as widening of the discharge front, limited peak current, and local overheating are likely to occur, and the pulse cycle life decays relatively quickly.

[0003] In the above structure, the asymmetrical current path results in a very limited magnetic field cancellation effect, and the equivalent series inductance is difficult to reduce further, which cannot meet the application requirements of high-power narrow pulse scenarios. The split connection interface not only introduces additional equivalent series resistance, but also has reliability risks such as welding defects and thermal drift of contact resistance, making it difficult to guarantee the long-term stability of the device. Summary of the Invention

[0004] In order to solve the technical problems in related technologies, the present invention provides a low-inductance, low-resistance coaxial pulse capacitor.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A low-inductance, low-impedance coaxial pulse capacitor, comprising: A high-voltage electrode is positioned at the center of the pulse capacitor; At least three low-voltage electrodes are arranged circumferentially around the high-voltage electrode with the high-voltage electrode as the center. The core assembly is arranged around the high-voltage electrode and sandwiched between the high-voltage electrode and each low-voltage electrode to achieve capacitive coupling between the high-voltage electrode and the low-voltage electrode. A copper busbar is disposed on the bottom surface of the core assembly; Each of the lead-out copper sheets is arranged in a one-to-one correspondence with the low-voltage electrode. The lead-out copper sheets are arranged circumferentially around the high-voltage electrode with the high-voltage electrode as the center. Furthermore, the lead-out copper sheets are configured as sheet-like structures, and all the lead-out copper sheets together form a ring structure. Each of the low-voltage electrodes and the corresponding lead-out copper sheet are integrally formed; The current path of the low-inductance, low-resistance coaxial pulse capacitor is configured as follows: the current flows from the high-voltage electrode through the core group to the copper busbar, is guided through the copper busbar to each of the lead-out copper plates, and is finally led out from each of the low-voltage electrodes.

[0006] Optionally, four low-voltage electrodes and four lead-out copper sheets are provided. The four low-voltage electrodes are evenly distributed at 90° intervals along the circumference of the high-voltage electrode. The four lead-out copper sheets are arranged at intervals around the high-voltage electrode with the high-voltage electrode as the center and form a ring structure to jointly cover the high-voltage electrode.

[0007] Optionally, the high-voltage electrode includes an external portion and a mating portion coaxially connected. The mating portion is located close to the core assembly. The end of the mating portion away from the external portion is recessed inward to form a plurality of pressure equalization grooves arranged radially at intervals. The pressure equalization grooves are formed into annular structures. Each pressure equalization groove is provided with a pressure equalization protrusion. In the radial direction from the inside to the outside of the mating portion, the height of the plurality of pressure equalization protrusions gradually decreases. Each pressure equalization protrusion is used to abut against the core assembly.

[0008] Optionally, the pressure equalizing protrusion is formed as an arc-shaped protrusion on the side of the pressure equalizing protrusion away from the docking portion, and a docking plate is provided between the high-voltage electrode and the core assembly. The docking plate is provided with annular docking protrusions that match the arc-shaped protrusion and the pressure equalizing protrusion.

[0009] Optionally, the lead-out copper sheet is formed into a U-shaped structure. The lead-out copper sheet includes a first sheet and a second sheet disposed opposite to each other, and a third sheet connected between the first sheet and the second sheet. The side of the first sheet away from the second sheet is used to dock with the low-voltage electrode, and the second sheet and / or the third sheet is used to contact the copper busbar to conduct electricity. The second sheet has a strip-shaped groove formed on the side near the first sheet, and the copper busbar and / or the core assembly have strip-shaped protrusions corresponding to the strip-shaped groove. The strip-shaped groove is used for inserting the strip-shaped protrusions.

[0010] Optionally, the first sheet, the second sheet, and the third sheet have the same thickness, and the ratio of the thickness of the low-voltage electrode in the axial direction of the high-voltage electrode to the thickness of the first sheet is between 1.5 and 5.

[0011] Optionally, the low-inductance, low-resistance coaxial pulse capacitor further includes an insulator disposed between the high-voltage electrode and the low-voltage electrode to achieve electrical isolation between the high-voltage electrode and the low-voltage electrode.

[0012] Optionally, the outer edge of the insulator is provided with a surface creepage distance extension structure, which is an annular protrusion or an annular groove provided on the outer edge of the insulator.

[0013] Optionally, the low-inductance, low-resistance coaxial pulse capacitor further includes a housing, which covers the outside of the high-voltage electrode, the core assembly, the low-voltage electrode, the copper busbar, and the lead-out copper sheet, and the housing is filled with an insulating medium.

[0014] Beneficial effects

[0015] 1. First, this invention can significantly reduce the equivalent series inductance, making it suitable for high-power narrow-pulse scenarios. Specifically, this invention uses at least three sets of low-voltage electrodes and lead-out copper sheets arranged symmetrically around the high-voltage electrode. During charging and discharging, the self-inductance and mutual inductance magnetic field lines generated by the current in each branch are in opposite directions, and the magnetic fields cancel each other out, significantly reducing parasitic inductance from a physical structure perspective. Compared with conventional single-sided lead-out structures, the discharge front is significantly compressed, and the peak current output capability is improved, which can meet the stringent application requirements of high-power pulse systems; moreover, the radial annular voltage equalization structure of the high-voltage electrode does not disrupt the circumferential current symmetry and will not interfere with the magnetic field cancellation effect.

[0016] Secondly, this invention can effectively reduce the equivalent series resistance (ESR). Specifically, in this invention, the low-voltage electrode and the lead-out copper sheet adopt an integrated molding structure, which can completely eliminate the interface contact resistance and thermal drift hazards of the separate welding / riveting scheme; at the same time, the U-shaped cross-section of the lead-out copper sheet forms a dual-path current carrying path, which can effectively reduce the current density and ohmic loss, further improve the conductivity, and avoid local overheating under high current conditions.

[0017] Third, the uniform electric field distribution of this invention can effectively improve insulation reliability. Specifically, the high-voltage electrode docking part is provided with annular equalizing protrusions arranged radially at intervals and with a height that gradually decreases from the inside to the outside. This precisely matches the distribution law of the natural decay of the radial electric field intensity in the coaxial cylindrical structure, smooths out the electric field peaks in the near-axial region, increases the partial discharge initiation voltage, and reduces the risk of insulation breakdown from the root. At the same time, the annular structure does not interfere with the circumferential magnetic field cancellation effect.

[0018] Fourth, the present invention features a balanced current distribution and excellent pulse cycle life. Specifically, multiple sets of low-voltage electrodes and lead-out copper sheets form a parallel current path, ensuring a uniform circumferential current distribution within the core assembly. This avoids the problem of current concentration on one side caused by conventional single-sided lead-out structures. Combined with the uniform current-carrying characteristics of the U-shaped lead-out copper sheets, the probability of local hot spots is further reduced, delaying the aging of the insulating medium and effectively improving the pulse cycle life.

[0019] Fifth, this invention has excellent assembly precision and connection reliability. Specifically, the strip groove of the copper sheet and the strip protrusion of the copper busbar / core group adopt a plug-in fit, which can achieve self-positioning, eliminate lateral misalignment during the assembly process, and ensure the consistency of the contact area of ​​each group; at the same time, the plug-in structure can effectively resist the electromagnetic vibration generated by pulse discharge, avoid contact resistance drift caused by loose connection, eliminate the need for welding process, and avoid process defects such as poor soldering and cold soldering.

[0020] Sixth, the structure of this invention has high rigidity and good resistance to electromagnetic shock. Specifically, the radial multi-ring equalizing convex rings of the high-voltage electrode can form multi-point gradient abutment against the core assembly, adaptively absorbing assembly errors and suppressing the micro-displacement of the core assembly under the action of pulse discharge electromagnetic force, which is conducive to ensuring long-term reliable contact between the high-voltage electrode and the core assembly; the U-shaped lead-out copper sheet has higher bending stiffness than the traditional flat plate structure, which can reduce deformation under high current conditions and maintain long-term stable electrical performance.

[0021] Seventh, the structure of this invention can be effectively adapted to industrial mass production. Specifically, in this invention, the radial annular pressure equalizing convex ring is a rotating structure that can be formed by one clamping on a conventional lathe without the need for complex tooling; the U-shaped lead-out copper sheet can be prepared by standardized forging or stamping processes, the plug-in assembly process is simple, and product consistency can be easily guaranteed during mass production.

[0022] 2. Other beneficial effects or advantages of the present invention will be described in detail in the specific embodiments. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] in: Figure 1 This is a schematic diagram of the structure of a conventional pulse capacitor in existing related technologies; Figure 2 This is a three-dimensional structural schematic diagram of a low-inductance, low-resistance coaxial pulse capacitor provided in an exemplary embodiment of the present invention. Figure 3 This is a side view of a low-inductance, low-resistance coaxial pulse capacitor provided in an exemplary embodiment of the present invention. Figure 4 yes Figure 3 A schematic diagram of the cross-sectional structure along the middle AA line; Figure 5 yes Figure 4 Enlarged schematic diagram of the local structure at point B; Figure 6 This is a three-dimensional structural diagram of a copper strip provided in an exemplary embodiment of the present invention, wherein a low-voltage electrode is also shown; Figure 7 This is a schematic diagram of a partial cross-sectional structure of a high-voltage electrode provided in an exemplary embodiment of the present invention; Figure 8 and Figure 9 These are all three-dimensional structural diagrams of a low-inductance, low-resistance coaxial pulse capacitor provided by an exemplary embodiment of the present invention, wherein part of the outer shell is hidden to show the internal structure.

[0025] Explanation of the labels in the attached drawings: 100-Low inductance, low resistance coaxial pulse capacitor; 1-High voltage electrode; 11-External connection; 12-Matching part; 121-Equalizing groove; 122-Equalizing ring; 1221-Arc-shaped protrusion; 21-Low voltage electrode; 22-Lead copper sheet; 221-First sheet; 222-Second sheet; 2221-Strip groove; 223-Third sheet; 3-Core assembly; 4-Copper busbar; 5-Matching plate; 51-Annular mating protrusion; 6-Insulator; 7-Shell. Detailed Implementation

[0026] To facilitate understanding by relevant technical personnel, the following is an explanation of the existing related technologies and their technical problems.

[0027] In pulsed power systems, the pulse capacitor serves as the core energy storage and release component, and its performance directly determines the output characteristics of the entire system. For example... Figure 1 As shown, conventional pulse capacitors widely used in industry typically employ a design paradigm of "center-leaded" or "single-sided lead-out". In this conventional topology, current is input from the high-voltage electrode at the center of the capacitor, accumulates charge through the internal core (usually a metallized thin-film wound or laminated structure), and then, at the moment of discharge, the current needs to cross a relatively long physical distance, be collected by the conductive copper busbar at the bottom, and finally exit from the low-voltage electrode terminal located on one side or end face of the capacitor.

[0028] Taking a typical single-ended pulse capacitor as an example, when this capacitor undergoes a high-current pulse discharge, the instantaneous peak current (e.g., 100kA) originates from the high-voltage electrode, passes through the 200mm diameter core, then ascends along the 150mm high copper busbar, and after a 100mm horizontal offset, finally reaches the low-voltage terminal on the side. This current path forms a huge, elongated rectangular or even triangular loop in space. According to the principles of electromagnetism, any current loop generates a magnetic field, and the strength of this magnetic field is proportional to the area enclosed by the loop. In this non-coaxial, asymmetrical structure, the current loop encloses an extremely large cross-sectional area (theoretically reaching thousands of square millimeters), resulting in extremely high stray magnetic flux. This magnetic flux cannot be canceled out, thus exhibiting extremely high equivalent series inductance (ESL). Furthermore, the bottom copper busbar and the lead-out terminals are typically connected by bolts or welding. In actual operation, bolted connections have tiny contact gaps, while welding introduces microscopic lattice defects. Under the impact of a 100kA instantaneous pulse current, even if the contact resistance is only in the micro-ohm range, the heat generated instantaneously is enormous, which will cause the local temperature to rise sharply, thereby causing thermal drift of the contact resistance.

[0029] To reduce the uncertainty caused by this thermal drift, engineers often have to increase the cross-sectional area of ​​the copper busbars and connectors to reduce the initial resistance, but this further increases the physical volume of the conductor and the length of the current path, which may exacerbate the inductance problem.

[0030] Furthermore, this single-sided lead-out structure leads to a severe asymmetry in current distribution. During discharge, the current density distribution in the core assembly region far from the lead-out terminal is extremely uneven compared to that in the region near the lead-out terminal. Since current always preferentially flows along the path of least impedance, a large amount of current concentrates at the edge of the core assembly near the low-voltage terminal, while the current density in the region far from the terminal is relatively low. This uneven current distribution leads to two serious consequences: First, the formation of local magnetic field concentration inside the core aggravates the inductive effect in the local area, making it difficult to further reduce the equivalent series inductance (ESL) of the entire capacitor through structural optimization. Secondly, areas with concentrated current generate higher Joule heat, leading to uneven temperature distribution within the core assembly, accelerating the aging of local insulating media, and significantly reducing the capacitor's pulse cycle life and reliability.

[0031] In summary, existing conventional single-sided lead-out pulse capacitors, due to their inherent asymmetrical current path design, suffer from extremely large stray inductance, difficult-to-eliminate contact resistance thermal drift, and local overheating problems caused by uneven current distribution.

[0032] In view of this, the present invention provides a novel solution, namely, the low-inductance, low-resistance coaxial pulse capacitor of the present invention. The technical concept of the present invention is as follows: starting from the physical geometry of the current path, by placing the high-voltage electrode at the center of the capacitor, and arranging the low-voltage electrode and the lead copper plate around it circumferentially and integrally forming them, the charging and discharging current flows uniformly and symmetrically along the coaxial toroidal path. The forward path and the return path with opposite current directions are tightly coupled in space, and the magnetic field lines are opposite in direction, thus canceling each other out, fundamentally reducing parasitic inductance. At the same time, the integrated low-voltage electrode and lead copper plate can eliminate the connection nodes between the electrode and the lead structure. With the copper busbar guiding the current on the bottom surface of the core assembly, the current transmission path is compressed to the shortest length and maximized in cross-sectional area. In this way, ultra-low equivalent series inductance and ultra-low equivalent series resistance can be achieved simultaneously in the structure.

[0033] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0034] like Figures 2 to 9 As shown, the present invention provides a low-inductance, low-resistance coaxial pulse capacitor 100, including a high-voltage electrode 1, a core group 3, a copper busbar 4, at least three low-voltage electrodes 21, and lead-out copper sheets 22 arranged one-to-one with the low-voltage electrodes 21. A high-voltage electrode 1 is positioned at the center of the pulse capacitor; low-voltage electrodes 21 are arranged circumferentially around the high-voltage electrode 1 with the high-voltage electrode 1 as the center; a core assembly 3 is arranged around the high-voltage electrode 1 and sandwiched between the high-voltage electrode 1 and each low-voltage electrode 21 to achieve capacitive coupling between the high-voltage electrode 1 and the low-voltage electrodes 21; a copper busbar 4 is positioned on the bottom surface of the core assembly 3; each lead-out copper sheet 22 is arranged circumferentially around the high-voltage electrode 1 with the high-voltage electrode 1 as the center, and the lead-out copper sheets 22 are configured as sheet-like structures, with all lead-out copper sheets 22 forming a ring structure; wherein, each low-voltage electrode 21 and its corresponding lead-out copper sheet 22 are integrally formed; the current path of the low-inductance, low-resistance coaxial pulse capacitor 100 is configured as follows: the current flows from the high-voltage electrode 1 through the core assembly 3 to the copper busbar 4, is guided by the copper busbar 4 to each lead-out copper sheet 22, and finally leads out from each group of low-voltage electrodes 21.

[0035] Through the above technical solution, firstly, the present invention can effectively eliminate contact resistance. Specifically, in conventional pulse capacitors, the low-voltage electrode 21 and the lead-out structure (lead-out screw or lead-out copper sheet 22) are usually separate components, and electrical connection between them needs to be achieved by welding or crimping. Welding connections suffer from process defects such as internal porosity and incomplete welding, while crimping connections suffer from problems such as contact surface oxidation and contact pressure attenuation, inevitably forming contact resistance at the connection interface. Under high-current discharge conditions, contact resistance generates significant Joule heating, causing localized temperature concentration, accelerating insulation aging and connection fatigue. In the present invention, the low-voltage electrode 21 and the corresponding lead-out copper sheet 22 are integrally formed. In this way, there is no connection interface between the low-voltage electrode 21 and the lead-out copper sheet 22, and the current flows from the low-voltage electrode 21 to the lead-out copper sheet 22 without passing through the welding point or crimping surface, and is directly transmitted along the continuous conductor. As a result, the contact resistance that inevitably exists at the connection interface in the split structure is completely eliminated from the physical structure, the corresponding local heat source of high current is removed, the temperature rise of the capacitor under high current discharge conditions is effectively suppressed, and the pulse life is correspondingly improved.

[0036] Secondly, this invention effectively reduces parasitic inductance. Specifically, in a conventional single-sided lead-out structure, current flows in from one lead-out screw, is transmitted through the core assembly 3, and flows out from the other side or another lead-out screw on the same side. The forward path and the return path are spatially far apart, forming a large stray loop area. The larger the loop area, the greater the magnetic flux and the higher the parasitic inductance (ESL, Equivalent Series Inductance). High ESL limits the rate of current rise during pulse discharge, widens the discharge front, and prevents the peak current from being established within the required time. In this invention, the high-voltage electrode 1 is located at the center of the capacitor, and at least three low-voltage electrodes 21 are arranged circumferentially around the high-voltage electrode 1. The corresponding lead-out copper sheets 22 are also arranged circumferentially around the high-voltage electrode 1 and form a ring structure. In this way, the current can flow radially outward from the central high-voltage electrode 1 through the core assembly 3, be guided through the bottom copper busbar 4 to the surrounding lead-out copper sheets 22, and then be led out through the integrally formed low-voltage electrode 21. The forward current transmission (from the center outward) and the return current transmission (from the periphery) are spatially tightly coupled and in opposite directions (the magnetic field generated when the current flows radially outward and the magnetic field generated when the current flows circumferentially outward from the copper sheet 22 tend to cancel each other outward in space), thereby effectively reducing the equivalent series inductance ESL at the physical structure level, increasing the current rise rate of the pulse discharge, making the discharge front steeper, and shortening the peak current settling time.

[0037] Third, this invention effectively shortens the current transmission path and increases the conductive cross-sectional area. Specifically, in a conventional structure, the current from the end face of the core assembly 3 must cross laterally through the connecting copper busbar 4 to the lead-out screw position, and then be led out along the axial direction of the screw. The path includes multiple bends and lateral crossings, resulting in a long total path length. Simultaneously, the conductive cross-sectional area of ​​the lead-out screw is limited by the aperture of the insulating sleeve and cannot be effectively increased. The combination of a long path and a small cross-sectional area leads to a higher conductor ohmic resistance and a higher equivalent series resistance (ESR). In this invention, the lead-out copper sheet 22 is a sheet-like structure. Compared to a conventional circular cross-section lead-out screw, the sheet-like structure has a larger conductive cross-sectional area within the same space. Furthermore, the copper busbar 4 is located on the bottom surface of the core assembly 3. After the current flows out of the core assembly 3, it is directly guided to each lead-out copper sheet 22 via the bottom copper busbar 4, without needing to undergo axial bends and long lateral crossings, thus compressing the transmission path to its shortest possible length. The combined effect of increased cross-sectional area and shortened path significantly reduces the ohmic resistance of the current transmission path, and correspondingly reduces the equivalent series resistance (ESR), effectively suppressing conduction losses and heat generation during high-current discharge.

[0038] Fourth, this invention effectively improves the uniformity of current distribution. Specifically, in conventional structures, the number of leads is usually one or two sets, and the current flows out from a limited number of leads, resulting in a highly uneven current density distribution on the end face of the core assembly 3 (the current density of the core assembly 3 region near the lead position is high, and the current density of the core assembly 3 region far from the lead position is low). Excessive local current density not only increases local heating but also causes the core assembly 3 in that region to bear greater electrical stress, accelerating dielectric aging and lifespan decay. In this invention, the number of low-voltage electrodes 21 is at least three, arranged circumferentially around the high-voltage electrode 1, and the corresponding copper leads 22 are also arranged circumferentially at intervals. Multiple lead channels are evenly distributed circumferentially, allowing the current in the core assembly 3 to be simultaneously discharged from at least three directions, forming a multi-path current shunting effect inside the core assembly 3. Compared with single-sided or double-sided leads, the current distribution on the end face of the core assembly 3 is more uniform, thereby avoiding the problem of excessively high local current density. The electrical stress borne by the core assembly 3 in each region tends to be consistent, and the overall pulse life is correspondingly extended.

[0039] In one embodiment of the present invention, such as Figure 4 , Figure 8 and Figure 9 As shown, the low-voltage electrode 21 and the lead-out copper sheet 22 of the present invention are respectively configured as four. The four low-voltage electrodes 21 are evenly distributed at 90° intervals along the circumference of the high-voltage electrode 1. The four lead-out copper sheets 22 are arranged at intervals around the high-voltage electrode 1 with the high-voltage electrode 1 as the center and form a ring structure to jointly cover the outside of the high-voltage electrode 1.

[0040] In this embodiment, the four sets of electrode channels are uniformly distributed 90° circumferentially, allowing the current to flow outward from the center of the high-voltage electrode 1 and then be distributed along four symmetrical directions to each lead-out channel with equal path lengths. Compared to three or five channels, four channels achieve uniform current distribution while ensuring that the angle between adjacent channels is 90°. The corresponding lead-out copper sheets 22 can surround the high-voltage electrode 1 in a square ring shape, achieving optimal spatial symmetry and the best uniformity of magnetic field cancellation effect in all directions. The four lead-out copper sheets 22 collectively cover the high-voltage electrode 1, making the reverse current spatially as close as possible to the distribution area of ​​the forward current, maximizing the spatial coupling between the forward path and the return path, and further reducing parasitic inductance. In addition, the four lead-out channels also ensure a high degree of uniformity in the current distribution at the end face of the core assembly 3, avoiding local current density concentration.

[0041] In one embodiment of the present invention, such as Figure 5 and Figure 7 As shown, the high-voltage electrode 1 of the present invention includes an external portion 11 and a docking portion 12 coaxially connected. The docking portion 12 is disposed close to the core assembly 3. The end of the docking portion 12 away from the external portion 11 is recessed inward to form a plurality of pressure equalization grooves 121 arranged radially at intervals therein. The pressure equalization grooves 121 are formed into annular structures. Each pressure equalization groove 121 is provided with a pressure equalization protrusion ring 122. In the radial direction from the inside to the outside of the docking portion 12, the height of the plurality of pressure equalization protrusion rings 122 gradually decreases. Each pressure equalization protrusion ring 122 is used to abut against the core assembly 3.

[0042] By configuring the high-voltage electrode 1 in this way, firstly, it can match the radial electric field distribution law of the coaxial structure, fundamentally optimizing the electric field uniformity and reducing the risk of insulation failure. Specifically, in existing related technologies, the end face of the high-voltage electrode 1 of conventional pulse capacitors often adopts a flat surface or a single-stage stepped structure, which cannot adapt to the physical law of the natural attenuation of electric field intensity from the inside to the outside along the radial direction in the coaxial cylindrical structure (the electric field intensity in the near-axial region is much higher than that in the outer diameter region, and a flat end face will form a steep electric field peak in the near-axial region). The local field intensity is very likely to exceed the tolerance threshold of the insulating medium, inducing partial discharge or even dielectric breakdown, which is the primary cause of insulation failure of pulse capacitors.

[0043] In this embodiment, multiple annular equalizing grooves 121 are arranged radially at intervals, with corresponding annular equalizing protrusions 122 within each groove. The height of the protrusions gradually decreases radially from the inside to the outside. This structure is perfectly compatible with the radial electric field distribution of the coaxial structure (higher protrusions are configured in the near-axial high field strength region, increasing the creepage distance and providing sufficient buffer space for the strong electric field), while lower protrusions are configured in the far-axial low field strength region, avoiding ineffective structural redundancy. Simultaneously, the circumferentially continuous structure of the annular protrusions effectively preserves the circumferential current symmetry and does not interfere with the magnetic field cancellation effect of each branch. The gradient height of the protrusions transforms the electric field transition at the high-voltage electrode 1 end face from a "step-like" to a "gradual" transition, effectively smoothing out the electric field peaks in the near-axial region, thereby increasing the partial discharge initiation voltage, fundamentally reducing the probability of insulation failure, and extending the device's lifespan.

[0044] Secondly, a multi-ring gradient contact structure can be constructed to ensure long-term reliable contact between the high-voltage electrode 1 and the core assembly 3, maintaining the stability of capacitor performance. Specifically, in existing related technologies, conventional high-voltage electrode 1 and core assembly 3 often use planar contact or single-step contact, which has two inherent problems: First, assembly tolerances can easily lead to insufficient contact, with only localized contact, resulting in contact resistance fluctuating with operating conditions and unstable capacitor coupling efficiency; second, the single-ring contact structure has weak constraint on the core assembly 3, and the periodic radial electromagnetic force generated by pulse discharge can easily cause micro-displacement of the core assembly 3, further aggravating poor contact, and leading to prominent capacity decay and ESL drift problems after long-term operation.

[0045] In this invention, the radially spaced convex rings form a multi-ring gradient abutment system. Multiple convex rings are distributed along different radii, and the gradient height adaptively absorbs axial assembly errors, ensuring that at least two convex rings maintain reliable contact with the core assembly 3 at all times, effectively avoiding the instability of single-point contact. Simultaneously, the circumferentially continuous structure of the annular convex rings applies a uniform circumferential constraint force to the core assembly 3, effectively suppressing micro-displacements of the core assembly 3 in the radial and circumferential directions, thereby ensuring the long-term consistency of capacitive coupling between the high-voltage electrode 1 and the core assembly 3. Furthermore, the multi-ring abutment disperses the contact pressure to multiple radial positions, avoiding the problem of excessive local pressure damaging the internal insulating medium of the core assembly 3 when using a single-ring abutment.

[0046] Third, both the radially spaced annular grooves and the convex rings are rotating structures, which can be machined in one step on a conventional lathe without the need for complex tooling or multiple assembly processes. This makes the machining accuracy easy to control and reduces manufacturing costs. At the same time, the rotating structure naturally possesses circumferential symmetry and is not affected by the directionality of machining tolerances, which can effectively ensure the consistency of the product's electric field characteristics and structural performance during mass production.

[0047] In one embodiment of the present invention, such as Figure 5 and Figure 7As shown, the pressure equalizing protrusion 122 of the present invention is formed as an arc-shaped protrusion 1221 on the side near the docking portion 12. A docking plate 5 is provided between the high voltage electrode 1 and the core assembly 3. An annular docking protrusion 51 matching the arc-shaped protrusion 1221 and the pressure equalizing protrusion 122 is provided on the docking plate 5.

[0048] In this embodiment, the mating portion 12 of the high-voltage electrode 1 is matched and mated with the annular mating protrusion 51 of the mating plate 5 through the arc-shaped protrusion of the equalizing ring 122, so that the electrical contact between the high-voltage electrode 1 and the core assembly 3 is changed from conventional surface contact or point contact to multi-ring line contact. The line contact structure of the arc-shaped protrusion has higher contact reliability under the same clamping force, thereby avoiding poor contact caused by assembly tolerance or thermal expansion and contraction, and improving the assembly fault tolerance and long-term working reliability of the present invention.

[0049] In one embodiment of the present invention, such as Figure 4 and Figure 6 As shown, the copper lead-out sheet 22 of the present invention is formed into a U-shaped structure. The copper lead-out sheet 22 includes a first sheet 221 and a second sheet 222 disposed opposite to each other, and a third sheet 223 connected between the first sheet 221 and the second sheet 222. The side of the first sheet 221 away from the second sheet 222 is used to dock with the low-voltage electrode 21. The second sheet 222 and / or the third sheet 223 are used to contact the copper busbar 4 to conduct electricity. A strip-shaped groove 2221 is formed on the side of the second sheet 222 close to the first sheet 221. The copper busbar 4 and / or the core assembly 3 have strip-shaped protrusions corresponding to the strip-shaped groove 2221. The strip-shaped groove 2221 is used for the strip-shaped protrusions to be inserted.

[0050] By configuring the copper strip 22 in this way, firstly, dual-channel parallel conduction can be provided. Specifically, firstly, the second strip 222 and / or the third strip 223 can both contact the copper busbar 4 for conduction, which increases the effective conductive cross-sectional area and reduces the current density compared to a single-layer flat plate structure, thereby reducing ohmic losses; secondly, the U-shaped structure allows the current flowing from the copper busbar 4 to form a three-dimensional current-carrying path through the second strip 222, the third strip 223, and the first strip 221, resulting in a more uniform current distribution and avoiding the edge current concentration effect of the planar structure; finally, the U-shaped cross-section itself has high bending stiffness, and the deformation is small under the electromagnetic force of pulse discharge, which can ensure the long-term stability of the contact interface.

[0051] Secondly, it minimizes the current path. Specifically, the first piece 221 and the second piece 222 of the U-shaped structure are positioned opposite each other, with the third piece 223 connected between them, forming an open slot configuration. The low-voltage electrode 21 is abutted against the outer side of the first piece 221, and the copper busbar 4 is inserted from the open side of the U-shaped structure and contacts the second piece 222 and / or the third piece 223. In this way, the connection between the copper busbar 4 and the lead-out copper piece 22 does not require additional adapters or bending sections (the copper busbar 4 can be directly inserted into the opening of the U-shaped structure, and the second piece 222 and / or the third piece 223 can simultaneously contact the surface of the copper busbar 4), resulting in a short contact distance and a direct conduction path. In other words, the U-shaped structure can achieve the shortest transition path in terms of spatial geometry, reducing the additional resistance introduced by path bending.

[0052] Third, a strip-shaped groove 2221 is formed on the side of the second piece 222 near the first piece 221, and corresponding strip-shaped protrusions are provided on the copper busbar 4 and / or core assembly 3. During assembly, the strip-shaped protrusions are inserted into the strip-shaped groove 2221. This not only facilitates assembly positioning (the strip-shaped convex-concave fit provides precise circumferential and radial positioning for the U-shaped copper lead-out piece 22 relative to the copper busbar 4 and / or core group 3. After the strip protrusion is inserted into the strip groove 2221, the relative position between the U-shaped copper lead-out piece 22 and the copper busbar 4 / core group 3 is mechanically locked, which helps eliminate circumferential displacement and radial runout during assembly and ensures the alignment accuracy of each lead-out channel); but also effectively increases the contact area (the strip-shaped convex-concave fit makes the contact between the second piece 222 and the copper busbar 4 / core group 3 no longer a single planar contact, but increases the contact surface along the side wall of the strip protrusion. The increased contact area can reduce the contact resistance, which helps to reduce ESR); in addition, it can also achieve the effect of preventing loosening (after the strip protrusion is inserted into the groove, a mechanical interlock is formed. Even if subjected to electrodynamic impact, the relative position between the U-shaped copper lead-out piece 22 and the copper busbar 4 is constrained by the strip-shaped convex-concave fit, and the contact surface is not prone to slippage and misalignment, ensuring long-term contact reliability).

[0053] In one embodiment of the present invention, the first sheet 221, the second sheet 222 and the third sheet 223 of the present invention have the same thickness, and the ratio of the thickness of the low-voltage electrode 21 in the axial direction of the high-voltage electrode 1 to the thickness of the first sheet 221 is between 1.5 and 5.

[0054] In this embodiment, firstly, the uniform thickness of the first sheet 221, the second sheet 222, and the third sheet 223 ensures uniform deformation of all parts during the overall forming process of the U-shaped copper lead-out sheet 22, preventing localized stress concentration or forming defects caused by thickness differences. Secondly, the axial thickness of the low-voltage electrode 21 is 1.5 to 5 times the thickness of the copper lead-out sheet 22, allowing the conductive cross-sectional area of ​​the low-voltage electrode 21 to be significantly larger than the single cross-sectional area of ​​the copper lead-out sheet 22, ensuring sufficient current-carrying capacity at the current convergence point. The low-voltage electrode 21 is the convergence node where large currents flow from the core group 3 into the lead-out structure, and its cross-section needs to carry the large current from the core group 3. The copper lead-out sheet 22 only needs to transmit this current to the external circuit (the total current carried by the former is greater than that of the latter, therefore the low-voltage electrode 21 is configured with a larger cross-sectional area to match its resistance with that of the copper lead-out sheet 22), avoiding a bottleneck effect at the low-voltage electrode 21 and preventing it from becoming the main contributor to ESR.

[0055] Furthermore, the lower limit of the thickness ratio between the low-voltage electrode 21 and the first sheet 221 is set to 1.5 because: as the core component for achieving capacitive coupling, the axial thickness of the low-voltage electrode 21 directly determines the effective overlap area between the electrode and the dielectric layer, thus affecting the capacitance. If the ratio is lower than 1.5, i.e., the copper sheet 22 is relatively too thick or the electrode is relatively too thin, two problems will arise: first, insufficient axial thickness of the electrode will result in the capacitance not meeting the design requirements; second, the current density at the contact surface between the electrode and the core assembly 3 will be too high, which will easily cause local overheating under high current pulses and accelerate dielectric aging.

[0056] The reason for setting the upper limit of the thickness ratio of the low-voltage electrode 21 to the first sheet 221 to 5 is that the lead-out copper sheet 22 is responsible for carrying current from the copper busbar 4 to the low-voltage electrode 21, and its thickness directly determines the conductive cross-sectional area and equivalent series resistance (ESR) of this branch. If the ratio exceeds 5, that is, the electrode is too thick or the lead-out sheet is too thin, it will lead to: first, insufficient thickness of the lead-out copper sheet 22, too small current-carrying cross-sectional area, increased ESR, and the lead-out path becoming a bottleneck under high current; second, excessive axial thickness of the low-voltage electrode 21, reduced material utilization, unnecessary increase in volume and weight, and diminishing marginal benefits for capacity improvement.

[0057] In one embodiment of the present invention, such as Figures 2 to 4 , Figure 8 and Figure 9 As shown, the low-inductance, low-resistance coaxial pulse capacitor 100 of the present invention also includes an insulator 6, which is disposed between the high-voltage electrode 1 and the low-voltage electrode 21 to achieve electrical isolation between the high-voltage electrode 1 and the low-voltage electrode 21.

[0058] In this embodiment, in the coaxial structure with the high-voltage electrode 1 in the center and the low-voltage electrode 21 arranged around it, the spatial distance between the high-voltage electrode 1 and the low-voltage electrode 21 is limited by the overall size design, resulting in a relatively compact spacing. An insulator 6 is installed in this compact space to ensure that the high-voltage electrode 1 and the low-voltage electrode 21 do not experience breakdown or surface flashover under high-voltage conditions.

[0059] Furthermore, it is understandable that insulator 6, as an independently installed insulating component, can have its insulation distance and material selection designed independently without being limited by the processes of other components. This allows for flexible adjustment of the insulation margin for specific voltage levels, ensuring the safe operation of the product under high voltage.

[0060] In one embodiment of the present invention, such as Figure 8 and Figure 9 As shown, the outer edge of the insulator 6 of the present invention is provided with a surface creepage distance extension structure, which is an annular protrusion or an annular groove provided on the outer edge of the insulator 6.

[0061] In this embodiment, when the voltage difference between the high-voltage electrode 1 and the low-voltage electrode 21 is large, the outer surface of the insulator 6 may form a surface leakage path due to contamination or moisture. The annular protrusion or annular groove increases the actual path length required for the current to creep along the surface of the insulator 6 (the creepage distance is extended). A longer creepage distance means that the surface electric field strength is reduced at the same voltage, the surface leakage current is reduced, and the ability to resist surface flashover is enhanced, thereby improving the insulation reliability and safety margin of the capacitor in high-voltage and high-humidity environments.

[0062] In one embodiment of the present invention, such as Figures 2 to 4 As shown, the low-inductance, low-resistance coaxial pulse capacitor 100 of the present invention also includes a housing 7, which covers the outside of the high-voltage electrode 1, the core group 3, the low-voltage electrode 21, the copper busbar 4 and the lead copper sheet 22, and the housing 7 is filled with an insulating medium.

[0063] In this embodiment, the housing 7 provides mechanical protection for each internal component, preventing structural damage or electrode displacement caused by external impacts during installation, transportation, and use. Simultaneously, the insulating medium filling the housing 7 fills the gaps between the components, isolating the high-voltage electrode 1, core assembly 3, low-voltage electrode 21, and other energized components from the external environment, preventing air gap breakdown under high voltage.

[0064] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A low-inductance, low-resistance coaxial pulse capacitor, characterized in that, include: A high-voltage electrode (1) is disposed at the center of the pulse capacitor; At least three low-voltage electrodes (21) are arranged circumferentially around the high-voltage electrode (1) with the high-voltage electrode (1) as the center; The core assembly (3) is arranged around the high voltage electrode (1) and sandwiched between the high voltage electrode (1) and each low voltage electrode (21) to achieve capacitive coupling between the high voltage electrode (1) and the low voltage electrode (21); A copper busbar (4) is disposed on the bottom surface of the core assembly (3); The copper leads (22) are arranged in a one-to-one correspondence with the low-voltage electrode (21). Each copper lead (22) is arranged circumferentially around the high-voltage electrode (1) with the high-voltage electrode (1) as the center. The copper leads (22) are set as sheet-like structures. All the copper leads (22) together form a ring structure. Each of the low-voltage electrodes (21) and the corresponding lead-out copper sheet (22) are integrally formed; The current path of the low-inductance, low-resistance coaxial pulse capacitor is configured as follows: the current flows from the high-voltage electrode (1) through the core group (3) to the copper busbar (4), is guided through the copper busbar (4) to each of the lead-out copper pieces (22), and is finally led out from each of the low-voltage electrodes (21).

2. The low-inductance, low-resistance coaxial pulse capacitor according to claim 1, characterized in that, The low-voltage electrode (21) and the lead-out copper sheet (22) are respectively set to four. The four low-voltage electrodes (21) are evenly distributed at 90° intervals along the circumference of the high-voltage electrode (1). The four lead-out copper sheets (22) are arranged around the high-voltage electrode (1) with the high-voltage electrode (1) as the center and form a ring structure to jointly cover the high-voltage electrode (1).

3. The low-inductance, low-resistance coaxial pulse capacitor according to claim 1, characterized in that, The high-voltage electrode (1) includes an external part (11) and a docking part (12) connected coaxially. The docking part (12) is located close to the core assembly (3). The end of the docking part (12) away from the external part (11) is recessed inward to form a plurality of equalizing grooves (121) arranged radially. The equalizing grooves (121) are formed into annular structures. Each equalizing groove (121) is provided with an equalizing protrusion (122). In the radial direction from the inside to the outside of the docking part (12), the height of the plurality of equalizing protrusions (122) gradually decreases. Each equalizing protrusion (122) is used to abut against the core assembly (3).

4. The low-inductance, low-resistance coaxial pulse capacitor according to claim 3, characterized in that, The pressure equalizing ring (122) is formed as an arc-shaped protrusion (1221) on the side away from the docking part (12). A docking plate (5) is provided between the high voltage electrode (1) and the core group (3). The docking plate (5) is provided with an annular docking protrusion (51) that matches the arc-shaped protrusion (1221) and the pressure equalizing ring (122).

5. The low-inductance, low-resistance coaxial pulse capacitor according to claim 1, characterized in that, The lead-out copper sheet (22) is formed in a U-shape. The lead-out copper sheet (22) includes a first sheet (221) and a second sheet (222) disposed opposite to each other, and a third sheet (223) connected between the first sheet (221) and the second sheet (222). The side of the first sheet (221) away from the second sheet (222) is used to dock with the low-voltage electrode (21). The second sheet (222) and / or the third sheet (223) are used to contact the copper busbar (4) to conduct electricity. The second piece (222) has a strip groove (2221) formed on the side close to the first piece (221), and the copper busbar (4) and / or the core assembly (3) have strip protrusions corresponding to the strip groove (2221). The strip groove (2221) is used for the insertion of the strip protrusions.

6. The low-inductance, low-resistance coaxial pulse capacitor according to claim 5, characterized in that, The first sheet (221), the second sheet (222), and the third sheet (223) have the same thickness, and the ratio of the thickness of the low-voltage electrode (21) in the axial direction of the high-voltage electrode (1) to the thickness of the first sheet (221) is between 1.5 and 5.

7. The low-inductance, low-resistance coaxial pulse capacitor according to claim 1, characterized in that, The low-inductance, low-resistance coaxial pulse capacitor also includes an insulator (6), which is disposed between the high-voltage electrode (1) and the low-voltage electrode (21) to achieve electrical isolation between the high-voltage electrode (1) and the low-voltage electrode (21).

8. The low-inductance, low-resistance coaxial pulse capacitor according to claim 7, characterized in that, The outer edge of the insulator (6) is provided with a surface creepage distance extension structure, which is an annular protrusion or an annular groove provided on the outer edge of the insulator (6).

9. The low-inductance, low-resistance coaxial pulse capacitor according to any one of claims 1-8, characterized in that, The low-inductance, low-resistance coaxial pulse capacitor also includes a housing (7), which covers the outside of the high-voltage electrode (1), the core group (3), the low-voltage electrode (21), the copper busbar (4) and the lead copper sheet (22), and the housing (7) is filled with an insulating medium.

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