Low-inductance low-resistance core-penetrating structure pulse capacitor

Abstract

The application provides a low-inductance and low-resistance core-penetrating structure pulse capacitor, and belongs to the technical field of pulse capacitors.The application comprises a metal shell, a center core-penetrating electrode and an energy storage capacitor core group.The metal shell is set as an integrated conductive cylinder and serves as a low-voltage backflow electrode.The center core-penetrating electrode is coaxially arranged in the metal shell, and is set as an integrated solid metal column, with one end of the center core-penetrating electrode serving as a high-voltage input terminal.The energy storage capacitor core group is coaxially arranged between the center core-penetrating electrode and the metal shell, with the high-voltage side of the energy storage capacitor core group being electrically connected with the center core-penetrating electrode, and the low-voltage side of the energy storage capacitor core group being electrically connected with the metal shell.The current in the center core-penetrating electrode flows along the axial direction in a straight line, and the current in the metal shell flows back along the axial direction of the cylinder wall, so that a coaxial reverse current loop is formed between the center core-penetrating electrode and the metal shell and the magnetic fields thereof are offset.The application can simultaneously realize low equivalent series inductance and low equivalent series resistance.

Description

Technical Field

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

[0002] Existing low-inductance, low-resistance through-core pulse capacitors typically employ a method where the positive and negative electrodes are led out in the same direction. After the current enters the capacitor core assembly from the high-voltage electrode through the internal connecting piece, it needs to be bent and bypassed by the copper lead plate or copper busbar to reach the low-voltage electrode output. The current path involves multiple bends and loops. At the same time, the low-voltage electrode is often led out by connecting thin leads or copper sheets with solder joints, resulting in multiple splicing solder joints at the connection points.

[0003] The aforementioned structure leads to the accumulation of parasitic inductance and contact resistance along the current path, resulting in an overall large equivalent series inductance (ESL) and equivalent series resistance (ESR) of the capacitor, making it difficult to meet the stringent requirements of low inductance and low resistance under high-frequency, high-current pulse conditions. Summary of the Invention

[0004] To address the technical problems in related technologies, this invention provides a low-inductance, low-resistance through-core pulse capacitor.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A low-inductance, low-resistance through-core pulse capacitor, comprising: The metal casing is configured as an integral conductive cylinder, and the metal casing serves as a low-pressure reflux electrode. A central through-core electrode is coaxially disposed inside the metal housing and extends through and out of both ends of the metal housing along the axial direction of the metal housing. The central through-core electrode is configured as an integral solid metal column, and one end of the central through-core electrode serves as a high-voltage input terminal. An energy storage capacitor core assembly is coaxially disposed between the central through-core electrode and the metal shell, and the high-voltage side of the energy storage capacitor core assembly is electrically connected to the central through-core electrode, while the low-voltage side of the energy storage capacitor core assembly is electrically connected to the metal shell. The current in the central through-core electrode flows linearly along the axial direction, while the current in the metal shell flows axially back along its cylindrical wall, so that the central through-core electrode and the metal shell form a coaxial reverse current loop and cancel each other out of the magnetic field.

[0006] Optionally, the energy storage capacitor core assembly adopts a coaxial annular non-inductive winding structure of a polypropylene metallized film. The two ends of the metallized film are axially offset and exposed on the two end faces of the energy storage capacitor core assembly. The two end faces of the energy storage capacitor core assembly are respectively provided with a gold sputtering layer. The gold sputtering layer serves as the high-voltage side lead-out terminal and the low-voltage side lead-out terminal of the energy storage capacitor core assembly, respectively. The current passes through the width direction of the metallized film along the axial direction of the energy storage capacitor core assembly.

[0007] Optionally, it also includes a high-voltage connecting piece and a low-voltage connecting piece, wherein the high-voltage connecting piece is connected between the high-voltage side end face of the energy storage capacitor core group and the outer peripheral surface of the central through-core electrode, and the low-voltage connecting piece is connected between the low-voltage side end face of the energy storage capacitor core group and the inner wall of the metal shell.

[0008] Optionally, it also includes a high-voltage side insulator and a low-voltage side insulator, the high-voltage side insulator and the low-voltage side insulator being respectively disposed at both ends of the axial direction of the metal shell, and the central through-core electrode passing through the high-voltage side insulator and the low-voltage side insulator.

[0009] Optionally, the two end faces of the energy storage capacitor core group have a gold spray layer, and the gold spray layer is partially embedded inside the end face of the energy storage capacitor core group. The high-voltage connecting piece and the low-voltage connecting piece respectively form surface contact with the outer surface of the gold spray layer of the corresponding end face.

[0010] Optionally, an annular current sharing busbar is provided between the end face of the energy storage capacitor core group and the high-voltage connecting piece and / or the low-voltage connecting piece. The annular current sharing busbar forms a surface contact with the end face of the energy storage capacitor core group in the circumferential direction, so as to make the current uniformly distributed in the circumferential direction of the end face of the energy storage capacitor core group.

[0011] Optionally, the central through-core electrode is a solid copper pillar.

[0012] Optionally, the outer wall of the metal casing forms a 360° circumferential grounding structure, and the metal casing also serves as the mounting flange for the low-inductance, low-resistance through-core pulse capacitor.

[0013] Beneficial effects

[0014] 1. First, the equivalent series inductance of this invention is extremely low. Specifically, in this invention, the central through-hole electrode penetrates along the axial direction of the outer shell and extends to both ends. After current is input from one end, it passes through the inside of the capacitor in a straight line along the electrode axis. There are no bends or loops in the entire current path. The shortest path directly reduces the area of ​​the loop formed by the current, and the parasitic inductance is reduced accordingly. At the same time, the central through-hole electrode is arranged coaxially with the metal outer shell. The current in the central through-hole electrode flows in one direction along the axial direction, while the return current in the outer shell wall flows in the opposite direction along the axial direction. The two form a coaxial and opposite current loop. According to the right-hand screw rule and Ampere's law, the magnetic field lines generated by the two opposite and coaxial current segments are in opposite directions and cancel each other out in the internal space of the capacitor. The magnetic field energy storage is greatly reduced, and the equivalent series inductance is significantly reduced accordingly. The above two inductance reduction mechanisms work synergistically within the same structural framework, enabling this invention to achieve ultra-low equivalent series inductance from both the geometric configuration of the current path and the physical distribution of the electromagnetic field without the need for external compensation or special materials.

[0015] Secondly, the equivalent series resistance of this invention is extremely low. Specifically, in this invention, the central through-core electrode is a one-piece solid metal column, without segmented splicing or intermediate solder joints. The entire column maintains a uniform conductive cross-sectional area along its entire length, and there is no cross-sectional area shrinkage or material interface in the current transmission path. The metal shell is a one-piece conductive cylinder, also without splicing solder joints or thin lead wire transitions. The cross-sectional area of ​​the shell wall is much larger than that of the thin leads or thin copper sheets in the prior art. Maximizing the conductive cross-sectional area minimizes the individual resistance values ​​of the central through-core electrode and the metal shell. At the same time, since all intermediate solder joints are eliminated, there is no cumulative effect of solder joint interface resistance in the path. The gold plating layer on the core assembly end face and the connecting piece adopt a surface contact method, resulting in a large contact area and low contact resistance. The combined effect of these structural features systematically reduces the equivalent series resistance along the entire current conduction path.

[0016] Third, this invention enables magnetic field cancellation, resulting in excellent high-frequency characteristics. Specifically, the coaxial reverse current loop between the central through-core electrode and the metal casing causes the magnetic fields generated by the two to cancel each other out inside the capacitor (this magnetic cancellation effect is frequency-dependent; that is, the higher the frequency, the greater the rate of current change, and the more significant the reduction in inductive reactance due to magnetic field cancellation). Therefore, this invention offers superior performance under high-frequency pulse conditions compared to existing technologies, effectively meeting the requirements of pulse power systems for high-frequency capacitor response characteristics.

[0017] Fourth, the present invention has high structural reliability and excellent resistance to current surges. Specifically, in this invention, the central through-core electrode penetrates the entire length of the capacitor and extends to both ends. Insulators are located at both ends of the outer shell, with the central through-core electrode passing through them. The insulators at both ends provide two-point support for the electrode, ensuring that the electrode and the outer shell remain coaxial along the entire axial length. The radial gaps between the core assembly and the outer shell, and between the core assembly and the electrode, are uniform. The gold-plated layer is partially embedded inside the end face of the energy storage capacitor core assembly, forming an interlocking interlocking structure with the end of the metallized film. This results in high bonding strength and makes it difficult to peel off under the electromagnetic force impact generated by pulsed high currents. The metallized film adopts a non-inductive winding method, where the current passes through the width of the film layer axially without circling the circumference. The film layer itself does not form a coil-like current loop, which can eliminate the circumferential inductance caused by the winding structure. The structural stability of the core assembly is ensured in a strong electromagnetic field environment.

[0018] Fifth, this invention enables 360° circumferential grounding, providing excellent electromagnetic compatibility. Specifically, the outer wall of the metal casing forms a 360° circumferential grounding structure. The entire outer circumference of the casing can serve as a grounding surface, forming an annular contact with the external grounding device. The grounding current flows out simultaneously and uniformly along the 360° circumferential direction, eliminating the need for any grounding leads and ensuring the inductance of the grounding path approaches zero. Furthermore, the metal casing itself serves as the mounting flange, allowing the capacitor's grounding and mechanical installation to be completed synchronously on the same structure, simplifying the system assembly process. 360° circumferential grounding ensures that the casing wall is a zero-potential equipotential body throughout the entire circumference, eliminating circumferential or axial potential gradients. This helps suppress electromagnetic radiation from the casing surface and reduces electromagnetic interference from the capacitor to other electronic devices in the system.

[0019] Sixth, the present invention features uniform current distribution at the end face, resulting in excellent thermal management performance. Specifically, the annular current sharing busbar forms a full-circumferential contact with the end face of the energy storage capacitor core along the circumferential direction, ensuring uniform current distribution along the 360° circumference of the core end face. This avoids localized overheating caused by excessively high local current density, and ensures uniform current load in each ring of the film layer within the core, extending the lifespan of the core. Simultaneously, the central through-core electrode is made of copper, whose thermal conductivity is among the highest of commonly used metals. The Joule heat generated by the pulsed current can be efficiently conducted along the electrode axis to the extended portions at both ends for heat dissipation. Combined with the natural heat dissipation from the large-area metal cylinder wall of the outer shell, the overall thermal management performance of the capacitor is guaranteed, which is beneficial for maintaining stable performance under repetitive frequency pulse conditions.

[0020] Seventh, the present invention features an integrated structure and function, exhibiting a high degree of system integration. Specifically, the metal casing simultaneously serves as the low-voltage return electrode, a 360° grounding conductor, and a mounting flange, with one structure fulfilling three functions, eliminating the need for additional grounding terminals, mounting brackets, or low-voltage leads. The central through-core electrode serves as both a high-voltage input terminal and an internal connecting conductor and structural support component of the core assembly, simultaneously providing both electrical conduction and mechanical support. The overall structure is compact, with few components, simplifying system assembly and facilitating miniaturization and high power density integration in pulse power devices.

[0021] 2. Other beneficial effects or advantages of the present invention will be described in detail in the specific embodiments. Attached Figure Description

[0022] 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.

[0023] in: Figure 1 This is a schematic diagram of the structure of a non-low inductance, low resistance through-core pulse capacitor in existing related technologies; Figure 2 This is a three-dimensional structural schematic diagram of a low-inductance, low-resistance through-core pulse capacitor provided in an exemplary embodiment of the present invention. Figure 3 This is a side view of a low-inductance, low-resistance through-core 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 AA direction; Figure 5 yes Figure 4 A magnified schematic diagram of the local structure at point B; Figure 6 yes Figure 4 A magnified schematic diagram of the structure at point C.

[0024] Explanation of the labels in the attached drawings: 100 - Low inductance, low resistance through-core structure pulse capacitor; 1 - Metal shell; 2 - Center through-core electrode; 3 - Energy storage capacitor core group; 4 - High voltage connecting piece; 5 - Low voltage connecting piece; 6 - High voltage side insulator; 7 - Low voltage side insulator; 8 - Gold spray layer; 9 - Ring current sharing busbar. Detailed Implementation

[0025] To facilitate understanding by relevant technical personnel, the following is an explanation of the existing related technologies and their technical problems.

[0026] Please see Figure 1 Existing non-low-inductance, low-resistance through-core pulse capacitors typically employ a cylindrical or square metal casing, with the capacitor core sealed inside. Both the positive (high-voltage) and negative (low-voltage) terminals are located on the same end face or side of the capacitor. Specifically, both ends of the capacitor core are coated with gold plating as electrode leads. One end's gold plating is connected to the positive terminal via one or more copper connecting tabs, and the other end's gold plating is similarly connected to the negative terminal via copper connecting tabs. The positive and negative terminals exit from the same end cap of the capacitor for connection to external circuitry.

[0027] When a pulsed current flows into the capacitor from the high-voltage input terminal, the current first enters the positive terminal connector through the positive terminal, and then is conducted from the connector to the gold plating layer at one end of the core assembly. The current then flows laterally across the width of the metallized film to the gold plating layer at the other end of the core assembly, and subsequently flows out through the negative terminal connector to the negative terminal. In this process, the current enters the core assembly from the high-voltage terminal and then returns from the core assembly to the low-voltage terminal. The high-voltage path and the low-voltage path run parallel in space and extend in the same direction, and are isolated from each other by an insulating material.

[0028] The reason for its relatively large equivalent series inductance is that in a non-through-core structure, the high-voltage current path and the low-voltage current path are arranged in the same direction and parallel. According to the right-hand screw rule, the magnetic field lines generated by the two currents in the same direction are in the same direction, and the magnetic field strengths are superimposed and enhanced rather than canceled out. In addition, the current needs to pass through multiple paths from the terminal to the end face of the core assembly, such as the bending of the connecting piece and the copper sheet transition. Each path contributes additional parasitic inductance. The longer the path and the more bends, the greater the cumulative parasitic inductance.

[0029] The high equivalent series resistance is due to several factors. First, in non-through-core structures, the low-voltage side typically uses thin leads or thin copper sheets soldered from the core assembly end face to the low-voltage terminal. The cross-sectional area of ​​these leads or copper sheets is much smaller than that of the outer casing or terminal, creating a significant conductor cross-sectional area contraction. When a pulse current passes through this contraction area, it generates significant localized Joule heating. Second, there are multiple solder joints in non-through-core structures. These include: solder joints between the connecting piece and the gold plating layer, solder joints between the connecting piece and the lead-out copper sheet, and solder joints between the lead-out copper sheet and the lead-out terminal. Each solder joint has an interface resistance, and when multiple solder joints are connected in series, the total contact resistance increases significantly. When a high-current pulse passes through, the heat generated at the solder joints due to contact resistance is particularly concentrated. Over long-term use, the solder joints may also develop micro-cracks due to thermal cycling fatigue, further increasing the contact resistance and creating positive feedback deterioration.

[0030] In summary, existing non-low-inductance, low-resistance through-core pulse capacitors suffer from several drawbacks. These include the magnetic field superposition effect caused by the positive and negative terminals being led out in the same direction, the additional parasitic inductance due to the bends and loops in the current path, and the localized current limiting and increased contact resistance caused by thin leads and multiple solder joints. Consequently, their equivalent series inductance and equivalent series resistance fail to meet the requirements of high-frequency, high-current pulse applications. These structural defects are inherent problems at the structural level of the pulse capacitor itself and cannot be fundamentally solved by simply improving materials or using external circuit compensation.

[0031] In view of this, the present invention provides a novel solution: a low-inductance, low-resistance through-core pulse capacitor. The technical concept of this invention lies in reconstructing the pulse capacitor from a discrete connection structure of "terminal leads and bent paths" into a coaxial, integrated structure of "through-core straight-through and shell current-carrying." Specifically, the present invention allows the central through-core electrode to pass through the capacitor axis in a straight line, enabling the current to flow straight through without bends. Simultaneously, the metal shell itself serves as a low-voltage return electrode, allowing the return current to flow axially along the shell wall, forming a coaxial current path with the central through-core electrode in the opposite direction (according to Ampere's law in electromagnetism, the magnetic fields generated by the reverse current cancel each other out, thus eliminating most of the parasitic inductance at the root of the path). Furthermore, the central through-core electrode is a one-piece solid cylinder, and the shell is a one-piece conductive cylinder, eliminating thin leads and intermediate solder joints, maximizing the conductive cross-sectional area and eliminating interface resistance accumulation, thereby simultaneously reducing the equivalent resistance along the current conduction path.

[0032] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] like Figures 2 to 6 As shown, the present invention provides a low-inductance, low-resistance through-core pulse capacitor 100, comprising a metal shell 1, a central through-core electrode 2, and an energy storage capacitor core assembly 3. The metal shell 1 is configured as an integral conductive cylinder and serves as the low-voltage return electrode. The central through-core electrode 2 is coaxially disposed inside the metal shell 1, extending through the axial direction of the metal shell 1 and extending to both ends of the metal shell 1. The central through-core electrode 2 is configured as an integral solid metal column, with one end serving as a high-voltage input terminal. The energy storage capacitor core assembly 3 is coaxially disposed between the central through-core electrode 2 and the metal shell 1, with the high-voltage side of the energy storage capacitor core assembly 3 electrically connected to the central through-core electrode 2 and the low-voltage side of the energy storage capacitor core assembly 3 electrically connected to the metal shell 1. In this process, the current in the central through-core electrode 2 flows in a straight line along the axial direction, while the current in the metal shell 1 flows back along the axial direction of its cylindrical wall, so that the central through-core electrode 2 and the metal shell 1 form a coaxial reverse current loop and cancel each other out of the magnetic field.

[0034] Through the above technical solution, firstly, the through-core straight-through structure of the present invention can eliminate the bending and looping paths of the current, thereby effectively reducing the equivalent series inductance. Specifically, in the current path of the prior art, after the current enters the core assembly from the high-voltage terminal through the connecting piece, it needs to bend and loop to the low-voltage terminal for output, and there are at least two to three large-angle bends and detours in the path. According to the basic definition of inductance, any current-carrying circuit has self-inductance, the value of which is directly related to the geometry of the circuit and the enclosed area. In the present invention, the central through-core electrode 2 passes through the outer shell axially and extends to both ends. After the current enters from one end, it passes straight through the inside of the capacitor along the electrode axis, enters from the high-voltage side of the core assembly, flows out from the low-voltage side, and then directly flows back axially through the outer shell wall to the grounding terminal. There are no bending or looping sections in the entire current path, and the current travels in a straight line along the axial direction, minimizing the path. The shortened path directly leads to a reduction in the area of ​​the loop enclosed by the current, thus effectively reducing the equivalent series inductance.

[0035] Secondly, the central through-core electrode 2 and the outer shell of this invention form a coaxial reverse current loop, and their magnetic fields cancel each other out, effectively eliminating parasitic inductance. Specifically, in the prior art, the high-voltage path and the low-voltage path run in the same direction, and the magnetic field lines generated by the two currents in the same direction are in the same direction, with the magnetic field strengths superimposed. In this solution, the central through-core electrode 2 serves as the high-voltage current carrier, and the metal outer shell 1 serves as the low-voltage return electrode, and the two are arranged coaxially. The current in the central through-core electrode 2 flows in one axial direction, while the return current in the outer shell flows in the opposite axial direction. According to Ampere's law, the magnetic field lines generated by the two reverse and coaxial currents are in opposite directions, and their magnetic fields in the internal space of the capacitor cancel each other out. The effective cancellation of the magnetic field directly leads to a significant reduction in the energy stored in the magnetic field, thereby significantly reducing the equivalent series inductance (this effect increases with increasing frequency, especially under high-frequency pulse conditions).

[0036] Third, this invention uses a one-piece solid metal column as the central through-core electrode 2, which eliminates current limiting at solder joints and maximizes the conductive cross-sectional area. Specifically, in existing technologies, the positive electrode path typically contains multiple splicing solder joints or segmented connection structures, each of which constitutes a bottleneck for current transmission. The actual conductive cross-sectional area at the solder joint is usually smaller than the cross-sectional area of ​​the base material, and the resistivity of the solder itself is higher than that of copper. In this invention, however, the central through-core electrode 2 is a one-piece solid metal column, without segmented splicing or intermediate solder joints. The entire column maintains a uniform conductive cross-sectional area along its entire length, and the current is directly transmitted to the high-voltage side of the core assembly after being input from one end along the axial direction of the column, without any cross-sectional area shrinkage or material interfaces along the path. Thus, the technical solution of this invention eliminates splicing solder joints and maintains a uniform cross-sectional area throughout, minimizing the equivalent resistance of the central through-core electrode 2 itself.

[0037] Fourth, the metal casing 1 of this invention serves as both an integral conductive cylinder and a low-voltage return electrode, eliminating the need for lead wire current limiting and solder joint interface resistance. Specifically, in existing technologies, the low-voltage side typically uses thin leads or thin copper sheets as connectors from the core assembly to the low-voltage terminal. The cross-sectional area of ​​the leads is usually much smaller than that of the casing or terminal, creating a significant current-limiting bottleneck. Furthermore, multiple solder joints exist between the leads and the gold-plated layer 8 of the core assembly, and between the leads and the low-voltage terminal, each contributing additional contact resistance. In this invention, the metal casing 1 itself serves as the low-voltage return electrode, and it is configured as a single, seamless conductive cylinder. The low-voltage side of the core assembly is directly electrically connected to the inner wall of the casing via a connecting piece. After the return current enters the casing wall, it flows axially back to the grounding terminal. The cross-sectional area of ​​the casing wall is much larger than any lead wire or copper sheet; thus, the large cross-sectional area directly results in extremely low resistance. Meanwhile, there are no splicing solder joints or thin lead connections on the casing, and no interface resistance accumulation in the current path, which allows the equivalent resistance of the low-voltage circuit to be reduced to a minimum.

[0038] Fifth, the synergistic optimization of the overall structure of this invention achieves a balance between low inductance and low resistance. Specifically, in this invention, the various structures form a synergistic effect through the overall layout of coaxial core-through. The straight core-through of the central core electrode 2 and the return current through the outer shell are geometrically complementary, forming a reverse current loop to achieve magnetic cancellation. The solid column of the central core electrode 2 and the integrated cylinder of the outer shell are simultaneously maximized in terms of conductive cross-section, jointly minimizing the resistance along the entire current path. Thus, through this structural reconstruction of "core-through + outer shell return current," inductance reduction and resistance reduction can be achieved simultaneously within the same structural framework, thereby achieving a dual reduction in equivalent series inductance and equivalent series resistance overall.

[0039] In this invention, it should be noted that in the field of pulse capacitor technology, "high voltage" and "low voltage" are relative concepts characterizing different potential reference points within the same current loop, and have clear and generally accepted technical meanings. Specifically, "high voltage" refers to the side of the capacitor connected to the positive terminal of the charging power supply or the high-voltage pulse input terminal, i.e., the end where current flows into the capacitor; "low voltage" refers to the side of the capacitor connected to system ground or the negative terminal of the power supply, i.e., the end where current flows out of the capacitor and back into ground. These terms are not limitations on absolute voltage values, but rather a functional distinction between two different potential terminals within the internal current path of the capacitor.

[0040] In one embodiment of the present invention, such as Figure 4 and Figure 5As shown, the energy storage capacitor core group 3 of the present invention adopts a coaxial ring-shaped non-inductive winding structure of polypropylene metallized film. The two ends of the metallized film are axially offset and exposed on the two end faces of the energy storage capacitor core group 3. The two end faces of the energy storage capacitor core group 3 are respectively provided with gold sputtering layer 8. The gold sputtering layer 8 serves as the high voltage side lead-out terminal and the low voltage side lead-out terminal of the energy storage capacitor core group 3, respectively. The current passes through the width direction of the metallized film along the axial direction of the energy storage capacitor core group 3.

[0041] In this embodiment, firstly, the metallized film is axially offset at both ends and exposed to the end face gold spraying layer 8, allowing the current to directly enter and exit the core assembly along the axial end face, minimizing the path. Specifically, existing non-through-core capacitor core assemblies often use gold spraying on both ends before axial lead-out, but the bonding method between the film ends and the gold spraying layer 8 differs. In this invention, the two ends of the metallized film are axially offset and exposed on the two end faces of the core assembly, so that the end of each metallized film layer is directly exposed at the end face, and the gold spraying layer 8 forms direct electrical contact with the end of each film layer after spraying. After the current enters the core assembly from the gold spraying layer 8, it directly passes through the width direction of the metallized film along the axial direction to reach the other end face, with a path only one film width (exemplarily, the film width is approximately 20mm to 50mm). Compared to structures that require bending through connecting pieces or radial detours, the current path is significantly shortened, and the shortened path directly leads to a reduction in parasitic inductance on this path.

[0042] Secondly, the non-inductive winding method of this invention prevents the current from circulating around the circumference of the thin film, thereby eliminating the circumferential inductance of the film itself. Specifically, some existing capacitor cores use an inductive winding method, where the metallized film forms a spiral electrode during winding, and the current travels around the circumference of the film. Each turn of the film is equivalent to one coil, and the entire core is equivalent to a multi-turn spiral inductor, with its inductance increasing significantly with the number of turns. In contrast, this invention uses a non-inductive winding method. The metallized film employs a staggered stacking process during winding, causing the current to pass axially through the width of the film, rather than circulating along its length. Since the current path does not circumferentially, the film does not form a coil-like current loop, thus fundamentally eliminating the circumferential inductance generated by the winding structure of the core itself.

[0043] Third, the gold-plated layer 8 on the end face serves as the lead-out terminals for both the high-voltage and low-voltage sides, enabling a surface contact transition between the core assembly end face and the external connecting piece. Specifically, the gold-plated layer 8 on the capacitor core assembly end face has a porous metal structure, possessing a certain degree of flexibility and compressibility. When the connecting piece is pressed or welded to the gold-plated layer 8, the gold-plated layer 8 can form a tight surface contact with the surface of the connecting piece, with a contact area much larger than that of point or line contact. According to the contact resistance theory, contact resistance is inversely proportional to the contact area. A large contact area effectively reduces the contact resistance between the gold-plated layer 8 and the connecting piece, thereby reducing Joule heating at the connection point.

[0044] Fourth, the coaxial annular winding structure ensures that the geometry of the core assembly matches the coaxial layout of the outer shell and the central through-core electrode 2. Specifically, the core assembly adopts a coaxial annular winding structure, which is itself a hollow annular body, with its inner and outer diameters corresponding to the radial dimensions of the central through-core electrode 2 and the outer shell. In this way, when the core assembly is installed, a uniform radial distance is maintained between its inner circumferential surface and the central through-core electrode 2, and between its outer circumferential surface and the inner wall of the outer shell. When the current flows from the central through-core electrode 2 into the inner circumferential surface of the core assembly, or from the outer circumferential surface of the core assembly into the outer shell, or flows in the opposite direction, the current distribution on the cross-section of the core assembly is uniform, without any locally excessively dense areas. This helps to reduce the additional resistance and localized heating caused by concentrated current density.

[0045] In one embodiment of the present invention, such as Figures 4 to 6 As shown, the present invention also includes a high-voltage connecting piece 4 and a low-voltage connecting piece 5. The high-voltage connecting piece 4 is connected between the high-voltage side end face of the energy storage capacitor core group 3 and the outer peripheral surface of the central through-core electrode 2, and the low-voltage connecting piece 5 is connected between the low-voltage side end face of the energy storage capacitor core group 3 and the inner wall of the metal shell 1.

[0046] In this embodiment, firstly, the connecting piece directly connects the core assembly end face to the outer peripheral surface of the central through-core electrode 2, enabling the shortest path transition of current from the core assembly to the electrode. Specifically, in the prior art, the gold-plated layer 8 on the core assembly end face typically needs to pass through an intermediate transition copper sheet or flexible braided wire to connect to the lead-out terminal, resulting in multiple bends and additional transition interfaces in the transition path. In this invention, one end of the high-voltage connecting piece 4 is directly connected to the high-voltage side end face of the core assembly (i.e., the surface of the gold-plated layer 8), and the other end is directly connected to the outer peripheral surface of the central through-core electrode 2. Thus, when current flows out from the core assembly end face, it only travels the length of one connecting piece (exemplarily, typically 10mm to 20mm) to reach the central through-core electrode 2, with no intermediate transition links in the path and minimal additional parasitic inductance.

[0047] Second, the low-voltage connecting piece 5 directly connects the low-voltage side end face of the core assembly to the inner wall of the outer casing, achieving the shortest path transition of current from the core assembly to the outer casing. Specifically, one end of the low-voltage connecting piece 5 is connected to the low-voltage side end face of the core assembly, and the other end is directly connected to the inner wall of the metal outer casing 1. After the current flows out from the low-voltage side end face of the core assembly, it directly flows into the outer casing wall via the low-voltage connecting piece 5. Compared to the long path in the prior art that requires a thin lead wire to be drawn from the end face of the core assembly to the low-voltage terminal (for example, typically requiring a detour of 30mm to 60mm), the path of the present invention is significantly shortened, and it does not need to pass through the sealing structure on the outer casing end cover, thus avoiding the conductor cross-sectional area shrinkage caused by sealing.

[0048] Third, the connecting pieces are respectively connected to the outer peripheral surface of the central through-core electrode 2 and the inner wall of the outer shell, which can conform to the radial current distribution of the coaxial structure in space. Specifically, the high-voltage connecting piece 4 is connected to the outer peripheral surface (i.e., the side of the cylinder) of the central through-core electrode 2, and the low-voltage connecting piece 5 is connected to the inner wall of the outer shell, both of which are radial connections. This connection method allows the current to flow radially from the central through-core electrode 2 into the inner peripheral surface of the core assembly, pass through the core assembly axially, and then flow radially from the outer peripheral surface of the core assembly into the outer shell. The radial component and the axial component of the current are perpendicular to each other, and no additional surrounding magnetic field component is generated, which helps to maintain the coaxiality of the reverse current loop and optimize the magnetic cancellation effect.

[0049] In one embodiment of the present invention, such as Figures 4 to 6 As shown, the present invention also includes a high-voltage side insulator 6 and a low-voltage side insulator 7, which are respectively disposed at both ends of the metal shell 1, and the central through-core electrode 2 passes through the high-voltage side insulator 6 and the low-voltage side insulator 7.

[0050] In this embodiment, firstly, insulators are disposed at both ends of the outer casing, with the central through-core electrode 2 passing through them, achieving electrical isolation between the central through-core electrode 2 and the outer casing. Specifically, the central through-core electrode 2 penetrates the entire capacitor and extends beyond both ends of the outer casing, with a high-voltage potential, while the metal outer casing 1 has a low-voltage potential; reliable electrical insulation must be maintained between the two. High-voltage side insulators 6 and low-voltage side insulators 7 are respectively disposed at both axial ends of the outer casing. The central through-core electrode 2 passes through the central hole of the insulator, physically isolating the central through-core electrode 2 from the outer casing at its ends, preventing high-voltage current from creeping or breaking down along the outer surface of the electrode or the inner wall of the outer casing. The insulators can be made of high-insulation-strength materials (such as ceramics or engineering plastics), and their surface creepage distance and withstand voltage can be designed according to the operating voltage to ensure safe operation under rated conditions.

[0051] Secondly, the insulators at both ends provide two-point support for the central through-core electrode 2, ensuring the coaxial positioning accuracy between the electrode and the outer shell. Specifically, the central through-core electrode 2 penetrates the entire length of the outer shell, resulting in a large axial length. If radial positioning relies solely on the inner ring of the core assembly, the electrode is prone to eccentric displacement during transportation vibrations or installation misalignment. The high-voltage side insulator 6 and the low-voltage side insulator 7 are respectively located at both ends of the outer shell, with their central holes coaxial with the outer shell. The central through-core electrode 2 passes through the central holes of both insulators. The insulators at both ends provide two-point support for the electrode, ensuring that the electrode axis precisely coincides with the outer shell axis at both ends, guaranteeing that the electrode remains coaxial with the outer shell along its entire axial length. Maintaining coaxiality ensures uniform radial clearance between the central through-core electrode 2 and the inner wall of the outer shell, uniform current distribution, and stable magnetic cancellation effect.

[0052] Furthermore, the high-voltage side insulator 6 and the low-voltage side insulator 7 are located at both ends of the outer casing, forming a closed internal cavity together with the outer casing wall. The energy storage capacitor core group 3 is sealed inside this cavity. Moisture, dust, or conductive particles from the external environment cannot enter the cavity, thus preventing insulation performance degradation or partial discharge caused by impurities. At the same time, the inner end faces of the insulators form axial limits at both ends of the core group, fixing the core group axially between the two insulators. Under transportation vibration or pulse impact, the core group does not experience axial movement, ensuring reliable contact between the connecting piece and the end face of the core group.

[0053] In one embodiment of the present invention, such as Figure 5 As shown, the two end faces of the energy storage capacitor core group 3 of the present invention have a gold spray layer 8, and the gold spray layer 8 is partially embedded inside the end face of the energy storage capacitor core group 3. The high voltage connecting piece 4 and the low voltage connecting piece 5 respectively form surface contact with the outer surface of the gold spray layer 8 of the corresponding end face.

[0054] In this embodiment, firstly, the gold-plated layer 8 is partially embedded inside the end face, enabling an embedded bond between the metallized film end and the gold-plated layer 8, enhancing the interfacial bonding strength. Specifically, during the spraying process, molten metal particles impact the end face of the core assembly at high speed. Some particles embed into the surface layer of the end face, forming an interlocking interlocking structure with the edge of the metallized film end, while other particles accumulate on the end face surface to form an outer surface layer. Compared to a structure that only adheres to the surface, the embedded bond creates a microscopic "anchoring" effect between the gold-plated layer 8 and the film end, significantly enhancing the bonding force between them. Under the electromagnetic force impact generated by a pulsed high current, the gold-plated layer 8 is less likely to peel off or fall off from the end face, improving the capacitor's resistance to current surges.

[0055] Secondly, the current is conducted from the end of the metallized film to the external connecting piece, requiring passage through three interfaces: the metallized film end, the gold sputtering layer 8, and the connecting piece. In this invention, the gold sputtering layer 8 is partially embedded in the end of the film layer, and the two are in direct contact at the embedding interface, resulting in a large contact area and a short path. The outer surface of the gold sputtering layer 8 forms a surface contact with the connecting piece, rather than a point or line contact. The interfaces between each layer in the three-layer structure are large-area contacts, eliminating narrow current contraction regions. The series resistance of the three-layer structure is controlled to a minimum, thereby effectively reducing the total transmission resistance from the film layer to the connecting piece.

[0056] Furthermore, the surface contact method ensures stable contact resistance between the connecting piece and the gold plating layer 8, preventing degradation under temperature changes and vibration conditions. Specifically, in the surface contact method, the contact interface between the connecting piece and the gold plating layer 8 is a planar area with a large surface area, and the contact pressure is evenly distributed along the entire surface. When a pulse current passes through, the temperature rise in the contact area is uniform, and there are no local hot spots. Under conditions of ambient temperature changes or mechanical vibration, the surface contact method, due to its large contact area, suffers from a much lower degree of contact degradation caused by local fretting wear compared to point or line contact methods. This allows the contact resistance to remain stable during long-term use, avoiding the problem of gradually increasing contact resistance due to thermal cycling fatigue in existing technologies.

[0057] In one embodiment of the present invention, such as Figure 5 As shown, an annular current sharing bus 9 is provided between the end face of the energy storage capacitor core group 3 and the high voltage connecting piece 4 and / or the low voltage connecting piece 5. The annular current sharing bus 9 forms a surface contact with the end face of the energy storage capacitor core group 3 in the circumferential direction, so as to make the current uniformly distributed in the circumferential direction of the end face of the energy storage capacitor core group 3.

[0058] In this embodiment, by setting such an annular current sharing busbar 9, not only can the current be evenly distributed along the circumference of the core assembly end face, avoiding excessive local current density, but also the annular current sharing busbar 9 itself is a complete circle conductor, without any cut-off or solder joints in the circumference, thus not introducing additional local impedance. In addition, as an intermediate transition component, the busbar can also transform multi-point discrete connections into annular continuous contacts, thereby reducing the total contact resistance at the connection.

[0059] In one embodiment of the present invention, the central through-core electrode 2 of the present invention can be configured as a solid copper pillar.

[0060] In this embodiment, firstly, copper has excellent electrical conductivity, with a resistivity much lower than other commonly used metallic conductors. For pulsed high-current applications, the reduced resistance of the central through-core electrode 2 directly reduces Joule heat generation along that path, thereby improving the capacitor's energy transfer efficiency. Secondly, copper has excellent thermal conductivity, which facilitates the axial conduction and diffusion of Joule heat generated by the pulsed current, preventing excessive local temperature rise and reducing the risk of electrode material performance degradation due to local overheating. Furthermore, the solid copper pillar possesses sufficient rigidity and strength to serve as the central support for the entire capacitor's internal structure. Thus, under transportation vibration and pulsed impact conditions, the structural rigidity of the solid copper pillar ensures the relative stability of the components, preventing core eccentricity or loosening of connecting pieces due to mechanical deformation.

[0061] In one embodiment of the present invention, such as Figure 2 As shown, the outer wall of the metal casing 1 of the present invention forms a 360° circumferential grounding structure (i.e. Figure 2 The metal casing 1 has ring-shaped structures at both ends, and the metal casing 1 also serves as the mounting flange for the low-inductance, low-resistance through-core pulse capacitor 100.

[0062] In this embodiment, firstly, the 360° circumferential grounding structure minimizes grounding impedance and eliminates the additional inductance of the grounding lead. Specifically, in the prior art, the capacitor casing is typically connected to the system ground via only one grounding terminal or a grounding copper busbar. The grounding path is single-point or unidirectional, and the inductance of the grounding lead itself is connected in series with the low-voltage circuit of the capacitor, increasing the total equivalent series inductance. In this invention, the outer wall of the metal casing 1 forms a 360° circumferential grounding structure, meaning that the entire outer circumference of the casing can serve as a grounding surface, forming an annular contact with an external grounding device (such as a mounting panel or grounding ring). The grounding current flows out simultaneously along the 360° circumferential direction, there are no grounding leads, the grounding point is the casing itself, and the inductance of the grounding path approaches zero. The 360° circumferential grounding also ensures that the return current on the casing wall is uniformly distributed along the entire circumference, exhibiting good symmetry with the coaxial reverse current loop of the central through-core electrode 2, and the magnetic cancellation effect is uniform and consistent throughout the entire circumference.

[0063] Secondly, the metal casing 1 also functions as a mounting flange, integrating electrical and mechanical functions and simplifying system assembly. Specifically, existing non-through-core capacitors typically require an external flange or mounting bracket, which may lead to insulation or poor contact issues between the flange and the casing. In this solution, the metal casing 1 itself serves as the mounting flange, allowing the external system to directly fix the capacitor to the system via mounting holes or clamping structures on the casing. This effectively reduces the number of intermediate connectors, minimizes accumulated assembly errors, and allows the capacitor's grounding and mechanical installation to be completed simultaneously on the same structure, simplifying the system assembly process.

[0064] Third, the 360° grounding combined with the integrated cylindrical structure of the outer shell ensures that there is no potential difference on the outer shell wall surface, making the entire outer shell an equipotential body. Specifically, the metal outer shell 1 is an integrated conductive cylindrical shell with continuous, uninterrupted wall material and uniform resistivity. 360° circumferential grounding distributes the grounding points across the entire circumference of the outer shell, rather than being limited to a specific angular direction. Under these conditions, any cross-section of the outer shell wall in the axial direction has zero potential (grounding potential) along its entire circumference, with no circumferential or axial potential gradient. This ensures that the contact interface between the inner wall of the outer shell and the low-voltage side end face of the core assembly (via the low-voltage connecting piece 5) is free from uneven current distribution caused by potential differences. Simultaneously, it helps suppress electromagnetic radiation from the outer shell surface, reducing electromagnetic interference from the capacitor to other electronic devices in the system.

[0065] 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 through-core pulse capacitor, characterized in that, include: Metal casing (1), the metal casing (1) is configured as an integral conductive cylinder, and the metal casing (1) serves as a low-pressure return electrode; The central through-core electrode (2) is coaxially disposed inside the metal shell (1) and extends through and out of both ends of the metal shell (1) along the axial direction of the metal shell (1). The central through-core electrode (2) is configured as an integral solid metal column, and one end of the central through-core electrode (2) serves as a high-voltage input terminal. Energy storage capacitor core group (3), the energy storage capacitor core group (3) is coaxially disposed between the central through-core electrode (2) and the metal shell (1), and the high voltage side of the energy storage capacitor core group (3) is electrically connected to the central through-core electrode (2), and the low voltage side of the energy storage capacitor core group (3) is electrically connected to the metal shell (1). The current in the central through-core electrode (2) flows in a straight line along the axial direction, and the current in the metal shell (1) flows back along its cylindrical wall in an axial direction, so that the central through-core electrode (2) and the metal shell (1) form a coaxial reverse current loop and cancel each other out magnetic field. The energy storage capacitor core group (3) adopts a coaxial ring-shaped non-inductive winding structure of polypropylene metallized film. The two ends of the metallized film are axially offset and exposed on the two end faces of the energy storage capacitor core group (3). The two end faces of the energy storage capacitor core group (3) are respectively provided with gold sputtering layer (8). The gold sputtering layer (8) serves as the high voltage side lead-out end and the low voltage side lead-out end of the energy storage capacitor core group (3). The current passes through the width direction of the metallized film along the axial direction of the energy storage capacitor core group (3). It also includes a high-voltage connecting piece (4) and a low-voltage connecting piece (5). The high-voltage connecting piece (4) is connected between the high-voltage side end face of the energy storage capacitor core group (3) and the outer peripheral surface of the central through-core electrode (2). The low-voltage connecting piece (5) is connected between the low-voltage side end face of the energy storage capacitor core group (3) and the inner wall of the metal shell (1). It also includes a high-voltage side insulator (6) and a low-voltage side insulator (7), the high-voltage side insulator (6) and the low-voltage side insulator (7) are respectively disposed at both ends of the axial direction of the metal shell (1), and the central through-core electrode (2) passes through the high-voltage side insulator (6) and the low-voltage side insulator (7). The central through-core electrode (2) is a solid copper pillar.

2. The low-inductance, low-resistance through-core pulse capacitor according to claim 1, characterized in that, The two end faces of the energy storage capacitor core group (3) have a gold spray layer (8), and the gold spray layer (8) is partially embedded inside the end face of the energy storage capacitor core group (3). The high voltage connecting piece (4) and the low voltage connecting piece (5) respectively form surface contact with the outer surface of the gold spray layer (8) of the corresponding end face.

3. The low-inductance, low-resistance through-core pulse capacitor according to claim 1, characterized in that, An annular current sharing bus (9) is provided between the end face of the energy storage capacitor core group (3) and the high voltage connecting piece (4) and / or the low voltage connecting piece (5). The annular current sharing bus (9) forms a surface contact with the end face of the energy storage capacitor core group (3) in the circumferential direction, so as to make the current uniformly distributed in the circumferential direction of the end face of the energy storage capacitor core group (3).

4. The low-inductance, low-resistance through-core pulse capacitor according to claim 1, characterized in that, The outer wall of the metal casing (1) forms a 360° circumferential grounding structure, and the metal casing (1) also serves as the mounting flange for the low-inductance, low-resistance through-core structure pulse capacitor.

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