A capacitor employing a double-sided metallized film winding

Abstract

This invention proposes a capacitor using double-sided metallized film winding, comprising a capacitor core, lead terminals, a double-sided metallized film winding layer, and protective support ribs; the capacitor core is formed by stacking and winding several layers of double-sided metallized film along the axial direction of the lead terminals; both sides of the double-sided metallized film winding layer are vapor-deposited with a composite structure metal coating, and an insulating layer is provided between adjacent double-sided metallized film winding layers; the internal cavity of the capacitor core is filled with a modified impregnating agent, and both ends of the capacitor core are provided with a gold-plated layer; the lead terminals are inserted through the winding center of the capacitor core, and the lead terminals are integrated conductive shafts, with conductive ribs evenly distributed along the axial direction on the surface of the lead terminals, the conductive ribs being connected to the inner metal coating layer of the double-sided metallized film winding layer; the gold-plated layer of the capacitor core is connected to the end of the lead terminals through a flexible conductive connector.

Description

Technical Field

[0001] This invention belongs to the field of capacitors, and particularly relates to a capacitor using double-sided metallized film winding. Background Technology

[0002] Currently, double-sided metallized film wound capacitors, as a type of passive component widely used in power electronics and new energy fields, are made by winding and encapsulating organic thin films with metal electrodes deposited on both sides, and are characterized by small size and high capacitance density. However, this technology has also shown some inherent drawbacks in its long-term development.

[0003] Because metallized thin films are used as electrodes, their thickness is extremely thin and their adhesion strength is limited. When subjected to high-frequency, high-amplitude pulse currents or frequent overvoltage impacts, the metal layer is prone to deterioration or even evaporation due to local overheating or electrical stress concentration, resulting in irreversible decay of capacitance and posing a challenge to long-term reliability.

[0004] The winding structure contains complex parasitic parameter distributions, especially a high equivalent series inductance, which limits its filtering and buffering performance in high-speed switching frequency applications. At the same time, there may be tiny gaps and dielectric inhomogeneities between the winding layers, which reduces the partial discharge initiation voltage and decreases the insulation reliability under high voltage conditions.

[0005] Factors such as thin film tension control, winding alignment accuracy, and end-face gold plating bonding quality in the production process can significantly affect the performance consistency of the final product. Small process fluctuations may lead to the dispersion of product characteristics between batches. Especially in harsh environments such as high temperature and high humidity, the difference in the coefficient of thermal expansion between the metal electrode and the thin film medium may cause poor electrode contact or internal stress accumulation, accelerating aging and failure.

[0006] Existing material systems face bottlenecks in their adaptability to extreme temperatures. At high temperatures, dielectric losses increase and self-healing properties weaken, while at low temperatures, decreased film flexibility may lead to an increased risk of mechanical damage. Overall, although this type of capacitor performs well under normal conditions, its performance in advanced applications requiring higher frequencies, higher voltages, and higher reliability is still limited by inherent defects in material properties, structural design, and process control. Technological breakthroughs are urgently needed through material innovation, structural optimization, and improvements in manufacturing processes. Summary of the Invention

[0007] This invention proposes a capacitor using double-sided metallized film winding. This technical solution mainly solves the problems of rapid capacitance decay, weak overload capacity, and short lifespan of traditional double-sided metallized film wound capacitors under high frequency and high current conditions, due to large internal parasitic parameters, uneven heat dissipation, and poor reliability of mechanical and electrical connections.

[0008] The technical solution of the present invention is implemented as follows: a capacitor using double-sided metallized film winding, comprising a capacitor core, lead terminals, a double-sided metallized film winding layer and protective support ribs; The capacitor core is formed by stacking and winding several layers of double-sided metallized film along the axial direction of the lead-out terminals; both sides of the double-sided metallized film winding layer are vapor-deposited with a composite metal coating, and an insulating isolation layer is provided between adjacent double-sided metallized film winding layers; the internal cavity of the capacitor core is filled with a modified impregnating agent, and both ends of the capacitor core are provided with a gold spray layer. The lead-out terminal is inserted through the winding center of the capacitor core. The lead-out terminal is an integrated conductive shaft. The surface of the lead-out terminal is provided with conductive ribs evenly distributed along the axial direction. The conductive ribs are connected to the inner metal plating layer of the double-sided metallized film winding layer. The gold-plated layer of the capacitor core is connected to the end of the lead-out terminal through a flexible conductive connector. One end of the lead-out terminal is provided with a threaded connection structure. The thread surface is provided with an anti-oxidation layer, and the root of the thread is provided with an anti-loosening structure mounting position. The protective support rib is fitted to the inner wall of the capacitor core. The protective support rib is an arc-shaped support rib, and a heat-conducting interface layer is provided on the surface of the support rib. The two ends of the protective support rib are provided with buckles, which are used to fix the shell cover of the lead-out terminal. The shell cover of the lead-out terminal cooperates to form an insulating and sealed structure inside the cavity of the capacitor core.

[0009] This technical solution systematically improves upon a series of inherent defects in traditional double-sided metallized film wound capacitors, specifically addressing the following technical challenges: At the level of electrical connection and internal structure, the connection between the metal plating of the traditional capacitor core and the lead-out terminals usually relies on welding or crimping after gold plating on the end face. This connection method has a large contact resistance and is prone to degradation of the connection point due to skin effect and heat generation under high frequency or pulse current. At the same time, the inherent spiral current path of the wound structure also leads to a high equivalent series inductance. This solution introduces an "integrated conductive shaft" as the lead-out terminal and sets conductive ribs evenly distributed along the axial direction on its surface, so that it is directly connected to the inner metal plating of each double-sided metallized film winding layer. This creates a radial current path that is approximately multi-channel and low impedance, which significantly reduces the length and resistance of the current transmission path, effectively suppresses parasitic inductance, and solves the core difficulties of impedance rise and local overheating at high frequencies.

[0010] To address the issues of localized evaporation and degradation of metallized films under electrical stress, as well as internal partial discharge, this proposed solution employs a "modified impregnating agent" to fill the internal cavities. This impregnating agent not only needs to possess excellent dielectric properties but also higher thermal conductivity and better gas absorption capacity to quickly dissipate heat generated by localized hot spots in the film and suppress the initiation and development of partial discharge. Its material formulation and potting process are key challenges in achieving stable heat dissipation and insulation self-healing.

[0011] In terms of mechanical structure and long-term reliability, the core of a traditional wound capacitor is hollow or simply supported. Under temperature cycling or mechanical vibration, the core is prone to slight deformation or loosening, leading to changes in internal stress and poor contact.

[0012] This design incorporates an arc-shaped protective support rib with a thermally conductive interface layer on the inner wall of the capacitor core. This design overcomes multiple challenges: the arc-shaped structure provides uniform radial support, preventing core collapse or deformation; the thermally conductive interface layer (such as insulating thermally conductive adhesive or ceramic coating) efficiently conducts heat from the core to the outer shell, optimizing overall thermal management; and the snap-fit ​​at both ends, working in conjunction with the shell cover, not only secures the capacitor but also forms a reliable insulating and sealing structure, effectively resisting the intrusion of external moisture and contaminants, thus solving the problem of poor long-term environmental tolerance. Finally, regarding the reliability of external electrical connections, the threaded connection structure at the end of the lead-out terminals features an anti-oxidation layer and an anti-loosening mounting position, directly addressing the common problem of connection point failure due to electrochemical corrosion or vibration loosening in outdoor or harsh industrial environments. The gold plating layer, connected to the end of the lead-out terminals via a flexible conductive connector, absorbs stress caused by differences in the thermal expansion coefficients of the materials, avoiding the risk of breakage that may result from rigid connections.

[0013] In summary, this solution systematically overcomes the complex technical challenges of traditional capacitors in low-inductance design, efficient heat dissipation, mechanical stability, environmental sealing, and stress release through innovative features such as integrated low-inductance terminal design, modified impregnating agent filling, internal support rib reinforcement structure, and multi-layer sealing connection, achieving a comprehensive improvement in performance and reliability.

[0014] In a preferred embodiment, the composite structure metal coating of the double-sided metallized film winding layer includes an inner layer and an outer layer that are directly bonded to the film body, wherein the thickness of the inner layer is 1 / 2 to 2 / 3 of the thickness of the outer layer.

[0015] In a preferred embodiment, the composite metal coating of the double-sided metallized film winding layer is a zinc-aluminum composite coating, wherein the inner layer is a zinc coating and the outer layer is an aluminum coating; the insulating isolation layer between adjacent double-sided metallized film winding layers is a biaxially oriented polypropylene film with a nano-scale silica insulating coating on its surface.

[0016] In a preferred embodiment, the number of protective support ribs is four, which are evenly distributed in a circle around the lead-out terminal. The protective support ribs protrude 0.2mm-0.5mm toward the lead-out terminal, and the protruding surface is coated with thermally conductive silicone.

[0017] In a preferred embodiment, the threaded connection structure at the end of the lead-out terminal is an M6 external thread, the anti-oxidation layer is a tin-plated layer, and the anti-loosening structure mounting position is an annular groove for installing a disc-shaped anti-loosening washer.

[0018] In a preferred embodiment, one end of the lead-out terminal is provided with a threaded connection structure, and the other end is provided with an insulating sealing assembly. The insulating sealing assembly includes an insulating sealing gasket, an elastic buffer ring, and an end cap. The insulating sealing gasket is fitted to the end face of the capacitor core, and the elastic buffer ring is sleeved on the shaft of the lead-out terminal and located between the insulating sealing gasket and the end cap. The end cap is fixedly connected to the end of the protective support rib through a snap-fit ​​structure.

[0019] In a preferred embodiment, the inner wall of the protective support rib is provided with a contact surface that matches the curvature of the outer surface of the capacitor core, and the thermal interface layer of the contact surface is a graphene thermal conductive film. The two ends of the protective support rib are provided with positioning bosses for cooperating with the slots of the end cap to achieve positioning and installation.

[0020] In a preferred embodiment, the double-sided metallized film winding layer adopts a gradient thickness winding structure: the inner winding unit near the lead-out terminal is set in a single-layer winding manner using a narrow double-sided metallized film, and its single-layer thickness is 1 / 3 of the single-layer thickness of the outer winding unit far from the lead-out terminal; the outer winding unit is set in a double-layer superimposed winding manner using a wide double-sided metallized film, and through the coordinated design of the winding width and the number of superimposed layers, a thickness gradient from the center to the outer periphery is formed.

[0021] In a preferred embodiment, the side of the narrow double-sided metallized film of the inner winding unit is flush with the side of the conductive rib of the lead-out terminal, and the end of the narrow double-sided metallized film is provided with an inwardly bent positioning flange, which is inserted into the groove between the conductive ribs to define the circumferential position of the inner winding unit.

[0022] In a preferred embodiment, when the wide double-sided metallized film of the outer winding unit is wound in double layers, a number of discrete positioning protrusions are provided between the two wide double-sided metallized films. The positioning protrusions are engaged with the positioning grooves at the corresponding positions of the adjacent insulating isolation layers to maintain the relative position of the double-layer superimposed structure. The edge of the wide double-sided metallized film extends beyond the edge of the inner winding unit to form a covering of the inner winding unit.

[0023] After adopting the above technical solution, the beneficial effects of the present invention are as follows: In terms of electrical performance, the integrated lead-out terminal and its axially distributed conductive rib structure constitute an extremely superior low-inductance current channel, which can significantly reduce the equivalent series inductance and equivalent series resistance of the product. This makes the capacitor exhibit lower self-loss and smaller voltage fluctuation when dealing with high-frequency switching operations and rapidly changing pulse currents, greatly improving its filtering, buffering and energy transfer efficiency in high-frequency power electronic circuits such as inverters and frequency converters, and effectively expanding its upper limit of operating frequency.

[0024] In terms of heat dissipation and thermal stability, the modified impregnating agent and the thermally conductive interface layer on the surface of the inner wall protective support ribs work synergistically to construct an efficient three-dimensional heat dissipation path from the metallized film hotspots to the capacitor casing. The modified impregnating agent directly contacts the film, rapidly absorbing and uniformly dispersing local temperature rises; the thermally conductive interface layer efficiently conducts heat away from the inner wall of the core. This dual heat dissipation mechanism significantly reduces the core operating temperature of the capacitor, slows down the aging rate of the dielectric material, and thus greatly enhances its ability to withstand high ripple currents and continuous overloads, thereby increasing power density.

[0025] In terms of mechanical reliability and long-term stability, the arc-shaped protective support ribs provide a robust internal framework for the entire capacitor core, ensuring structural stability under severe temperature cycling, mechanical vibration, or impact. This prevents the winding layers from loosening or misaligning, fundamentally avoiding electrical parameter drift or contact failure caused by mechanical deformation. Combined with the absorption of thermal stress by the flexible conductive connectors at the ends, and the insulating and sealing structure formed by the shell cover and snap-fit, the product achieves excellent vibration resistance, weather resistance, and moisture and dust resistance, enabling it to adapt to extremely demanding application environments with stringent reliability requirements, such as new energy vehicles, rail transportation, and outdoor power equipment.

[0026] In terms of lifespan and safety, the comprehensive improvements in electrical, thermal, and mechanical properties directly translate into a significant increase in product lifespan. Lower operating temperatures slow down the chemical aging of impregnating agents and film dielectrics; a more uniform electric field distribution and the ability to suppress partial discharge delay the decline in insulation strength; and robust connections and seals eliminate the causes of progressive failure.

[0027] The anti-oxidation and anti-loosening design of the lead-out terminal threads further ensures the long-term reliability of external electrical connections and reduces the risk of system failure. In summary, this solution, through a series of closely related integrated innovations, has enabled a leap forward in the overall performance of capacitors. It not only solves key bottlenecks in existing technologies but also endows products with strong competitiveness in high-performance, high-reliability, and long-life application scenarios, providing core component support for the development of next-generation high-end power electronic equipment. Attached Figure Description

[0028] 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 or the prior art 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.

[0029] Figure 1 This is a schematic diagram of the structure of a wound capacitor in an existing design; Figure 2 A comparison chart showing the performance of existing wound capacitors, conventional capacitors, and the capacitors described in this application. Figure 3 This is a schematic diagram of the overall structure of the present invention; Figure 4 This is an exploded view of the structure of the present invention.

[0030] In the diagram, 1-capacitor core; 2-lead terminal; 21-conductive rib; 22-insulating sealing gasket; 23-elastic buffer ring; 24-end cap; 3-double-sided metallized film winding layer; 4-protective support rib. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0032] like Figure 3 As shown, a capacitor using double-sided metallized film winding includes a capacitor core 1, lead terminals 2, double-sided metallized film winding layer 3, and protective support ribs 4. The capacitor core 1 is formed by stacking and winding several layers of double-sided metallized film winding layers 3 along the axial direction of the lead-out terminals 2; both sides of the double-sided metallized film winding layers 3 are vapor-deposited with a composite metal coating, and an insulating isolation layer is provided between adjacent double-sided metallized film winding layers 3; the internal cavity of the capacitor core 1 is filled with a modified impregnating agent, and both ends of the capacitor core 1 are provided with a gold sputtering layer. The lead-out terminal 2 is inserted through the winding center of the capacitor core 1. The lead-out terminal 2 is an integrated conductive shaft. The surface of the lead-out terminal 2 is provided with conductive ribs 21 that are evenly distributed along the axial direction. The conductive ribs 21 are connected to the inner metal plating layer of the double-sided metallized film winding layer 3. The gold-plated layer of the capacitor core 1 is connected to the end of the lead-out terminal 2 through a flexible conductive connector. One end of the lead-out terminal 2 is provided with a threaded connection structure. The thread surface is provided with an anti-oxidation layer, and the root of the thread is provided with an anti-loosening structure mounting position. The protective support rib 4 is fitted to the inner wall of the capacitor core 1. The protective support rib 4 is an arc-shaped support rib, and a heat-conducting interface layer is provided on the surface of the support rib. The two ends of the protective support rib 4 are provided with buckles, which fix the shell cover of the lead-out terminal 2. The shell cover of the lead-out terminal 2 cooperates to form an insulating and sealed structure inside the cavity of the capacitor core 1.

[0033] The capacitor described in this application, employing double-sided metallized film winding, can be integrated into the power module of a motor controller as a key DC support and filtering unit. Its working principle and implementation process in this specific scenario are explained in detail below.

[0034] First, a double-sided metallized polypropylene film with specific dielectric constant and high-temperature resistance is prepared as the dielectric substrate. A zinc-aluminum composite metal coating is formed on both sides of the film through a vacuum evaporation process, constituting the double-sided metallized film winding layer 3. The pre-processed integrated copper alloy lead-out terminal 2 is installed on the central shaft of the winding machine. The surface of the lead-out terminal has strip-shaped conductive ribs 21 that are evenly distributed along the axial direction.

[0035] During winding, the double-sided metallized film and the extremely thin polyester insulating layer are fed alternately, and precision layering and winding are performed with the lead-out terminal 2 as the axis. In this process, through precise tension control and alignment, reliable mechanical contact and electrical connection are ensured between the metal plating layer of the inner ring of each film layer and the conductive ribs 21 on the lead-out terminal, thereby gradually constructing the capacitor core 1.

[0036] After winding, the two ends of the core are subjected to high-speed gold spraying to form a robust gold-plated layer on the end electrodes. Then, a pre-formed arc-shaped protective support rib 4—made of glass fiber reinforced polymer coated with a ceramic thermally conductive layer—is inserted into the inner wall of the capacitor core 1. The metal clips at both ends of the support rib are temporarily unlocked. Next, the entire core assembly is placed in a vacuum infusion apparatus, and under high temperature and negative pressure, a composite impregnating agent with modified epoxy resin and nano-alumina filler as its core is injected, allowing it to fully penetrate and fill all interlayer and internal cavities of the thin film.

[0037] After the impregnating agent cures, the gold-plated layers at both ends of the capacitor core are welded to the corresponding ends of the lead-out terminals 2 using flexible metal braided straps. Finally, the cover with a sealing ring is fitted onto the lead-out terminals, and the snaps at both ends of the protective support ribs 4 are used to lock and fix it to the housing part of the lead-out terminals 2, forming a complete, internally insulated and sealed capacitor unit. The exposed threaded portion of the lead-out terminals 2 has been silver-plated for anti-oxidation treatment and has pre-cut grooves for installing anti-loosening gaskets.

[0038] In the actual operation of an electric vehicle, for example, when this capacitor is installed on the DC bus of the motor controller, its working principle and advantages are fully demonstrated under dynamic conditions. During vehicle acceleration or energy recovery, the power module in the controller performs high-frequency switching, causing severe pulse current and voltage spikes in the DC bus voltage. This capacitor, as an energy storage and buffer element on the DC side, responds immediately. The current enters the integrated lead-out terminal 2 through the threaded terminal with an anti-loosening structure. Because the current is directly introduced radially from the axial conductive shaft through multiple evenly distributed conductive ribs 21 to the inner layer of each metallized film in contact with it in near-synchronous manner, the current path is greatly shortened and multi-channel parallel distribution is achieved. This structure effectively cancels the parasitic inductance effect caused by the traditional spiral winding path, enabling the capacitor to quickly absorb and release charge with extremely low equivalent series inductance, thereby efficiently suppressing bus voltage fluctuations and peak overvoltages caused by switching operations, providing a stable operating environment for power switching devices.

[0039] During operation, the metallized thin film dielectric experiences dielectric loss due to the alternating electric field. This, combined with the Joule effect of the high-frequency ripple current, generates heat within the film. At this point, the internal modified impregnating agent, with its enhanced thermal conductivity, rapidly absorbs and evenly diffuses the locally generated heat. The heat is transferred to the inner wall of the capacitor core 1 and efficiently captured by the thermally conductive interface layer on the surface of the protective support rib 4, which is attached to the inner wall. This thermally conductive interface layer laterally conducts the heat to the entire support rib structure, and then, through its mechanical contact with the outer shell and the limited convection within the internal sealed space, the heat is ultimately dissipated to the capacitor's metal shell and external heat sink. This active heat dissipation mechanism, from the inside out and through multiple pathways, ensures that heat does not accumulate inside the core, thereby keeping the core temperature rise at a low level.

[0040] Continuous vibration and temperature cycling pose a severe test to the mechanical reliability of capacitors. The internal arc-shaped protective support rib 4 provides continuous radial restraint and support for the capacitor core 1, preventing the wound structure from loosening or deforming under vibration, and maintaining the stability of the contact pressure between the conductive rib 21 and the thin-film coating. Simultaneously, the flexible conductive connector between the gold-plated layer on the connecting end face and the lead-out terminals effectively buffers shear stress caused by differences in the thermal expansion coefficients of different materials, preventing the connection points from cracking due to fatigue. The insulating and sealed structure formed by the snap-fit ​​and support ribs completely isolates external moisture, salt spray, and contaminants, ensuring the long-term stable insulation performance of the internal dielectric and impregnating agent.

[0041] In summary, in this motor controller application scenario, this implementation scheme, through its unique low-inductance terminal design, internal reinforced heat dissipation structure, mechanical reinforcement and fully sealed packaging, achieves a complete and reliable workflow from high-speed charge throughput and efficient heat dissipation to long-term structural stability, significantly improving the overall performance and lifespan of the motor controller under harsh dynamic conditions.

[0042] The composite metal coating of the double-sided metallized film winding layer 3 includes an inner layer and an outer layer directly bonded to the film body. The thickness of the inner layer is 1 / 2 to 2 / 3 of the thickness of the outer layer. The composite metal coating of the double-sided metallized film winding layer adopts a differentiated thickness design. The inner layer coating directly bonded to the film body is set to a relatively thin thickness, while the outer layer coating has a greater thickness. Specifically, the thickness of the inner layer is about half to two-thirds of the thickness of the outer layer. In motor controller applications, this configuration aims to optimize the electrical performance and self-healing characteristics of the capacitor. The thinner inner layer is beneficial in the event of local dielectric breakdown, enabling the metal coating around the fault point to evaporate completely with lower energy and faster speed, thereby achieving rapid and effective electrical isolation (i.e., self-healing), minimizing capacitance loss and preventing fault expansion. At the same time, the thicker outer layer provides a low-resistance path for current transmission and enhances the overall mechanical strength and oxidation resistance of the coating, ensuring current carrying stability and long-term reliability under high-frequency, high-current-density conditions. The coordinated thickness of the inner and outer layers balances the two key requirements of rapid self-healing and robust conductivity.

[0043] The composite metal coating of the double-sided metallized film winding layer 3 is a zinc-aluminum composite coating, with the inner layer being a zinc coating and the outer layer being an aluminum coating. The insulating isolation layer between adjacent double-sided metallized film winding layers 3 is a biaxially oriented polypropylene film with a nano-scale silica insulating coating on its surface. Zinc has a relatively low melting point, which allows it to achieve vaporization isolation with lower energy during the aforementioned self-healing process when used as the inner layer, improving the sensitivity and effectiveness of self-healing. The aluminum layer provides excellent current carrying capacity and environmental stability due to its excellent conductivity and stable oxide film formed in air. The insulating isolation layer between adjacent film layers uses a biaxially oriented polypropylene film with a nano-scale silica insulating coating on its surface. In the high-voltage DC bus environment of the motor controller, this design has dual advantages: the polypropylene film itself has excellent dielectric strength and low loss characteristics; while the nano-scale silica coating on the surface can significantly improve the surface withstand voltage rating and partial discharge resistance of the film, and the microscopic roughness that the nanoparticles may form is beneficial for the wetting of the impregnating agent and heat dissipation. This combination enhances the reliability of interlayer insulation and effectively suppresses the risk of surface discharge or breakdown that may occur under high electric field stress.

[0044] The protective support ribs 4 are four in number, evenly distributed circumferentially around the lead-out terminal 2. Each rib 4 protrudes 0.2mm-0.5mm towards the lead-out terminal 2, and thermally conductive silicone is applied to the protruding surface. This embodiment specifies four protective support ribs evenly distributed circumferentially around the lead-out terminal. Their arc-shaped design is not completely concentric with the inner wall of the core, but rather designed with a slight protrusion towards the lead-out terminal. Thermally conductive silicone is pre-applied to the protruding surface of the support ribs facing the inner wall of the core. When specifically assembled into a motor controller, when the support ribs are placed inside the capacitor core cavity, their pre-designed protrusion structure will create a tighter fit with the inner wall of the core under assembly stress, and the applied thermally conductive silicone will fill all microscopic gaps, forming an excellent thermal interface. The four evenly distributed support ribs together constitute a stable and symmetrical radial support frame, effectively resisting centrifugal force or deformation force caused by multi-directional vibrations during vehicle operation, preventing the core from loosening. Meanwhile, this design efficiently conducts the heat generated by the core during operation to the support rib body through the tightly contacting thermally conductive silicone interface, and then dissipates it through the connection path between the support rib and the outer shell, significantly optimizing the heat dissipation efficiency of the core heat-generating area.

[0045] The threaded connection structure at the end of the lead-out terminal 2 is an M6 external thread, the anti-oxidation layer is a tin-plated layer, and the anti-loosening structure mounting position is an annular groove for installing a disc-shaped anti-loosening washer. The thread adopts a standard metric specification to ensure broad compatibility and ease of installation. A tin-plated layer is applied to the thread surface as an anti-oxidation layer. The tin layer remains stable in air, preventing the copper-based terminal from increasing contact resistance due to oxidation, ensuring the reliability of the long-term electrical connection. The annular groove machined at the root of the thread is specifically for installing the disc-shaped anti-loosening washer. In the harsh environment of continuous vehicle vibration, thread friction alone is insufficient to guarantee a permanent connection. During installation, the disc-shaped washer is placed between the groove and the nut. Its unique elastic deformation and cutout design provide continuous rebound force under vibration conditions, effectively counteracting the tendency of the nut to rotate and loosen. This detailed design fundamentally solves the potential faults of arcing, overheating, or even power failure caused by vibration-induced loosening of the electrical connection, greatly improving the electrical safety and connection durability of the system during dynamic operation.

[0046] like Figure 1 , 2 The table below shows the capacitance values ​​of a traditional capacitor, a capacitor from an existing technology, and the capacitor described in this application at different frequencies; their comparative characteristics are shown in Table 1 below:

[0047] Traditional and existing capacitors employ uniformly thick film winding, resulting in low capacitance density per unit axial length. The proposed solution in this application utilizes a gradient winding design with a narrow inner single layer and a wide outer double layer. The superposition of the wide outer film significantly increases the capacitance per unit length, resulting in a significantly higher base capacitance value compared to the former two. The helical winding structure of traditional and existing capacitors leads to long current paths and large parasitic inductance, which severely offsets the capacitance value at high frequencies. Furthermore, the single heat dissipation path causes film deformation and capacitance drift due to heat generation. In contrast, this solution employs an integrated conductive shaft with axial conductive ribs, enabling radial multi-channel parallel current transmission. This shortens the path, effectively cancels out parasitic inductance, and eliminates drastic capacitance fluctuations at high frequencies. Traditional capacitors have the lowest capacitance value and the most volatile capacitance, exhibiting extremely poor stability at high frequencies. While existing solutions have undergone preliminary optimization, significant capacitance fluctuations still exist. The capacitor in this application not only boasts the highest base capacitance value but also exhibits a fluctuation range of less than 5% across the entire frequency range, with the smoothest curve, directly reflecting its significant performance advantage under high-frequency conditions. Example 2

[0048] like Figure 4As shown, one end of the lead-out terminal 2 is provided with a threaded connection structure, and the other end is provided with an insulating sealing assembly. The insulating sealing assembly includes an insulating sealing gasket 22, an elastic buffer ring 23, and an end cap 24. The insulating sealing gasket 22 is fitted to the end face of the capacitor core 1. The elastic buffer ring 23 is sleeved on the shaft of the lead-out terminal 2 and located between the insulating sealing gasket 22 and the end cap 24. The end cap 24 is fixedly connected to the end of the protective support rib 4 through a snap-fit ​​structure.

[0049] This embodiment optimizes the structure of the non-threaded connection side of the lead-out terminal 2 by introducing a composite insulation and sealing assembly consisting of an insulating sealing gasket 22, an elastic buffer ring 23, and an end cap 24. In the high-vibration, wide-temperature-variation application scenario of new energy vehicle motor controllers, this assembly is crucial for ensuring the long-term internal sealing integrity and electrical safety of the capacitor.

[0050] Insulating sealing gasket 22: This component is typically made of a high-temperature resistant and electrolyte-corrosion-resistant elastomer material such as fluororubber, and it is directly attached to the gold-plated end face of the capacitor core 1. Its core function is to achieve a static primary seal: first, to prevent leakage of the internal modified impregnating agent due to thermal expansion at high temperatures or during long-term operation; second, as a critical barrier, to prevent moisture, salt spray, or contaminants from the external environment from penetrating into the capacitor core along the end face gaps, thereby protecting the metallized film and gold plating layer from corrosion and maintaining stable dielectric properties.

[0051] Elastic buffer ring 23: This annular element is sleeved on the shaft of the lead-out terminal 2 and located between the insulating gasket 22 and the end cap 24. It is typically made of silicone or a similar material with excellent resistance to compressive permanent deformation. Its core function is to provide dynamic stress compensation. Due to the significant difference in the coefficients of thermal expansion between the lead-out terminal and the capacitor core, axial relative displacement stress will be generated between them during the severe temperature cycling caused by vehicle operation. The elastic buffer ring actively absorbs and buffers this periodic thermal stress through its own compression and rebound, preventing stress from acting directly and continuously on the connection between the insulating gasket and the end cap, thereby preventing the sealing interface from failing due to fatigue or cracking.

[0052] End cap 24: This component is typically made of engineering plastic or metal and is mechanically locked to the end of the protective support rib 4 via its own snap-fit ​​structure. It serves multiple functions: First, it provides a rigid compression and load-bearing structure for the entire insulation and sealing assembly, ensuring the insulation sealing gasket 22 is evenly pressed onto the core end face through a well-designed structure; second, it connects with the end of the protective support rib, together completing the final sealing of the capacitor casing and forming part of the external mechanical protection; finally, its snap-fit ​​connection facilitates assembly and maintenance.

[0053] Installation and Workflow: During capacitor assembly, after the capacitor core is wound, impregnated, and connected with the flexible conductive connector, the insulating sealing gasket 22 is fitted onto the lead-out terminal 2 and pushed to a position close to the end face of the capacitor core. Next, the elastic buffer ring 23 is fitted onto the lead-out terminal and placed outside the sealing gasket. Finally, the end cap 24 is axially fitted and aligned and locked with the already positioned protective support rib 4 using its snap-fit ​​mechanism. During this process, the end cap 24 applies a pre-tightening force to the elastic buffer ring 23, placing it in a moderately compressed state, thereby providing a stable clamping force for the insulating sealing gasket 22 in advance and reserving elastic deformation space to cope with future thermal stress.

[0054] Throughout the motor controller's lifecycle, this component works in tandem: the insulating gasket acts as the primary sealing barrier; the elastic buffer ring functions like a "smart spring," continuously counteracting the destructive stress caused by thermal expansion and contraction; and the end cap ensures the overall structural stability. This design ensures that even under harsh automotive-grade temperature cycling and vibration environments, the capacitor's interior maintains a dry, clean, and stable insulating environment, thus guaranteeing long-term consistency in its electrical performance.

[0055] The inner wall of the protective support rib 4 is provided with a mating surface that matches the curvature of the outer surface of the capacitor core 1, and the thermally conductive interface layer of the mating surface is a graphene thermally conductive film. Positioning bosses are provided at both ends of the protective support rib 4 for positioning and installation by engaging with the slots of the end cap 24. The inner wall of the protective support rib 4 is precisely machined into a concave mating surface that perfectly matches the curvature of the outer cylindrical surface of the capacitor core 1. A further layer of graphene thermally conductive film is applied to this mating surface as a thermally conductive interface layer. The purpose of this design is twofold: First, to maximize the contact area. The perfect curvature match eliminates the line contact or point contact problems that may exist in traditional planar or simple curved surface supports, forming a large area of ​​surface contact and providing a broad channel for heat transfer. Second, to minimize contact thermal resistance. Graphene material has extremely high planar thermal conductivity; as a flexible pad, it can perfectly fill all microscopic uneven gaps between the outer wall of the core and the mating surface of the support rib, reducing the contact thermal resistance between the two to an extremely low level. This allows the heat generated during capacitor operation to be conducted laterally from the core body through this superconducting interface to the protective support skeleton made of metal or high thermal conductivity composite material in the most efficient way, and then transferred to the outer shell for heat dissipation.

[0056] In the assembly process, the protective support rib 4, coated with a graphene thermal conductive film, is first carefully inserted and attached to the predetermined position on the outer wall of the capacitor core 1 with its precise fitting surface. The positioning bosses at both ends of the support rib serve as the initial positioning reference. When installing the end cap 24, the slot designed on the inner side of the end cap must accurately align with the positioning bosses at the ends of the support ribs. This "boob-slot" fit ensures a unique and precise relative position between the end cap 24 and the support rib 4, and consequently, between the end cap 24 and the entire capacitor core 1. This not only makes the assembly process smoother and more repeatable, but more importantly, it ensures that the clamping force applied by the end cap is evenly and symmetrically distributed to the capacitor core through the support rib, avoiding localized stress concentration caused by misalignment. At the same time, precise positioning also ensures that the heat conduction path of the support rib itself and the external heat dissipation structure can achieve optimal alignment and contact.

[0057] During motor controller operation, heat is generated in the core and efficiently transferred to the support rib network through the low thermal resistance graphene interface. From there, it is conducted to the capacitor housing via a precisely positioned structure and finally dissipated into the controller assembly's cooling system. This entire heat dissipation path is extremely efficient and reliable due to the dual optimization of the interface and structure, a key guarantee for the stable operation of the capacitor in high-power-density motor controllers. Example 3

[0058] The double-sided metallized film winding layer 3 adopts a gradient thickness winding structure: the inner winding unit near the lead terminal 2 is set by using a narrow double-sided metallized film in a single-layer winding manner, and its single-layer thickness is 1 / 3 of the single-layer thickness of the outer winding unit away from the lead terminal 2; the outer winding unit is set by using a wide double-sided metallized film in a double-layer superimposed winding manner, and through the coordinated design of the winding width and the number of superimposed layers, a thickness gradient from the center to the outer periphery is formed.

[0059] This structure does not employ a uniform thin film and winding method, but rather a differentiated design based on the radial position within the core (i.e., distance from the lead-out terminals). Specifically, the inner layer region near the lead-out terminals uses a narrow double-sided metallized film for single-layer winding, and this single-layer film has a relatively thin physical thickness; while the outer layer region farther from the lead-out terminals uses a wide double-sided metallized film for double-layer superposition winding, and the thickness of the superimposed single layer is significantly greater than that of the inner layer. Through the coordinated design of the width of the winding film and the number of superimposed layers, the entire capacitor core forms a gradient transition from the central axis to the outer periphery, with increasing mechanical structural thickness and electrical load-bearing capacity. In the high-frequency, high-current application scenarios of new energy vehicle motor controllers, this gradient design has profound engineering considerations. The current injection point is located at the central lead-out terminal, and the inner winding region directly bears the highest current density and the most concentrated electrothermal stress. By employing thin, single-layer, narrow-width film winding, tighter and more precise winding can be achieved within a limited central space, reducing internal voids and optimizing the initial current transmission path from the terminals to the thin-film coating. This helps reduce parasitic inductance and contact resistance in this critical area. Simultaneously, the thin dielectric exhibits higher electric field strength withstand capability under high voltage. The outer region, which bears the primary energy storage capacity and mechanical support, utilizes thicker, double-layer, wide-width film winding. This not only significantly increases the capacitance density per unit axial length, but the thicker dielectric and wider structure also provide the core with greater mechanical strength and heat dissipation volume, better resisting external stress and maintaining a uniform internal temperature field. This gradient evolution from "refined and compact" to "robust and thick" achieves an optimized balance between electrical performance, mechanical stability, and space utilization.

[0060] The narrow double-sided metallized film of the inner winding unit has its side edge flush with the side edge of the conductive rib 21 of the lead-out terminal 2, and its end has an inwardly bent positioning flange. The positioning flange engages with the groove between the conductive ribs 21 to define the circumferential position of the inner winding unit. The narrow double-sided metallized film used in the inner winding unit must have its side edge flush with the side edge of the conductive rib on the lead-out terminal surface. More importantly, an inwardly bent metallized positioning flange is provided at the end of the narrow film (i.e., the starting winding end).

[0061] During assembly, this positioning flange is precisely engaged within the pre-machined axial grooves between the conductive protrusions of the lead terminals. This design is crucial in the operating scenarios of motor controller capacitors. First, the flush sides ensure that the metal plating of the thin film can achieve maximum overlap with the entire intended contact area of ​​the conductive protrusions, guaranteeing the effective area of ​​the current transmission interface.

[0062] The bent positioning flange and the engagement of the terminal groove provide absolute circumferential positioning. This prevents the inner film from rotating or shifting slightly around the central axis due to vibration or stress during the initial winding stage and throughout its entire service life. Such shifting would degrade the contact between the metal plating and the conductive ribs, introduce unstable contact resistance, and may even generate micro-sparks leading to localized damage. Through the mechanical locking of the flange groove, the inner winding unit and the lead-out terminal form a robust and fixed initial connection, establishing a precise center reference for all subsequent winding layers. This ensures extremely high repeatability and reliability of the current path from the terminal to the first electrode, improving the electrical consistency and stability of the product from the source.

[0063] When the wide double-sided metallized film of the outer layer winding unit is wound in double layers, several discrete positioning protrusions are provided between the two wide double-sided metallized films. These positioning protrusions engage with the corresponding positioning grooves of the adjacent insulating isolation layers to maintain the relative position of the double-layer superimposed structure. The edge of the wide double-sided metallized film extends beyond the edge of the inner layer winding unit, thus covering the inner layer winding unit. The outer layer winding uses wide double-sided metallized film for double-layer superimposed winding. To prevent relative sliding or misalignment between the two superimposed films under winding tension, impregnating agent shrinkage, or operational vibration, several discretely distributed micro-positioning protrusions are pre-set on the opposite surfaces of the two wide films.

[0064] During the winding process, these positioning protrusions engage with corresponding positioning grooves on adjacent insulating layers. This dot-matrix engagement structure acts like a miniature "positioning pin" system, effectively locking the relative positions of the two current-carrying films without affecting the overall penetration of the impregnating agent. This prevents them from shifting due to shear forces, ensuring that the double-layer structure works collaboratively as a whole, and that its electrical parameters (such as equivalent series resistance) remain consistent and stable as designed. Furthermore, this implementation explicitly requires that the edge of the wide double-sided metallized film must extend beyond the edge of the inner narrow winding unit. This ensures that, after final winding, the outer wide winding unit completely covers and encapsulates the inner narrow unit in the radial direction.

[0065] In the complex mechanical vibration environment experienced by new energy vehicles, this encapsulation structure offers dual benefits: First, it provides additional mechanical wrapping and support for the relatively delicate and fragile inner structure, enhancing the core's overall resistance to radial deformation; second, it optimizes the heat conduction path from the inner to the outer layer. Heat generated in the inner layer can be more easily transferred through its end faces and sides to the outer layer unit, which has a larger heat capacity and heat dissipation area, and then through the outer layer unit to the protective support ribs and outer shell, thus achieving more efficient gradient heat dissipation. The entire winding process therefore becomes a systematic engineering project characterized by tight structural interlocking, functional gradient transitions, and progressively enhanced stability from the inside out.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A capacitor employing double-sided metallized film winding, characterized in that, It includes a capacitor core (1), lead terminals (2), a double-sided metallized film winding layer (3), and protective support ribs (4). The capacitor core (1) is formed by stacking and winding several layers of double-sided metallized film winding layers (3) along the axial direction of the lead-out terminal (2); both sides of the double-sided metallized film winding layers (3) are vapor-deposited with a composite metal coating, and an insulating isolation layer is provided between adjacent double-sided metallized film winding layers (3); the internal cavity of the capacitor core (1) is filled with a modified impregnating agent, and both ends of the capacitor core (1) are provided with a gold sputtering layer; The lead-out terminal (2) is inserted through the winding center of the capacitor core (1). The lead-out terminal (2) is an integrated conductive shaft. The surface of the lead-out terminal (2) is provided with conductive ribs (21) evenly distributed along the axial direction. The conductive ribs (21) are connected to the inner metal plating layer of the double-sided metallized film winding layer (3). The gold spray layer of the capacitor core (1) is connected to the end of the lead-out terminal (2) through a flexible conductive connector. A threaded connection structure is provided on one end of the lead-out terminal (2). An anti-oxidation layer is provided on the thread surface, and an anti-loosening structure mounting position is provided at the root of the thread. The protective support rib (4) is fitted to the inner wall of the capacitor core (1). The protective support rib (4) is an arc-shaped support rib, and a heat-conducting interface layer is provided on the surface of the support rib. The two ends of the protective support rib (4) are provided with buckles, which fix the shell cover of the lead-out terminal (2) through the buckles. The shell cover of the lead-out terminal (2) cooperates to form an insulating and sealed structure inside the cavity of the capacitor core (1).

2. A capacitor employing a double-sided metallized film winding as defined in claim 1, wherein: The composite structure metal coating of the double-sided metallized film winding layer (3) includes an inner layer and an outer layer that are directly bonded to the film body. The thickness of the inner layer is 1 / 2 to 2 / 3 of the thickness of the outer layer.

3. A capacitor employing a double-sided metallized film winding as defined in claim 2, wherein: The composite structure metal coating of the double-sided metallized film winding layer (3) is a zinc-aluminum composite coating, wherein the inner layer is a zinc coating and the outer layer is an aluminum coating; the insulating isolation layer between adjacent double-sided metallized film winding layers (3) is a biaxially oriented polypropylene film with a nano-scale silicon dioxide insulating coating on its surface.

4. A capacitor employing double-sided metallized film winding as described in claim 1, characterized in that: The number of the protective support ribs (4) is four, which are evenly distributed in a circle around the lead-out terminal (2). The protective support ribs (4) protrude 0.2mm-0.5mm toward the lead-out terminal (2), and thermally conductive silicone is applied to the protruding surface.

5. A capacitor employing a double-sided metalized film winding as defined in claim 1, wherein The threaded connection structure at the end of the lead-out terminal (2) is an M6 external thread, the anti-oxidation layer is a tin-plated layer, and the anti-loosening structure mounting position is an annular groove for installing a disc-shaped anti-loosening washer.

6. A capacitor employing a double-sided metalized film winding as defined in claim 1, wherein One end of the lead-out terminal (2) is provided with a threaded connection structure, and the other end is provided with an insulating sealing assembly. The insulating sealing assembly includes an insulating sealing gasket (22), an elastic buffer ring (23), and an end cap (24). The insulating sealing gasket (22) is fitted to the end face of the capacitor core (1). The elastic buffer ring (23) is sleeved on the shaft of the lead-out terminal (2) and located between the insulating sealing gasket (22) and the end cap (24). The end cap (24) is fixedly connected to the end of the protective support rib (4) through a snap-fit ​​structure.

7. A capacitor employing a double-sided metalized film winding as defined in claim 1, wherein The inner wall of the protective support rib (4) is provided with a fitting surface that matches the curvature of the outer surface of the capacitor core (1), and the thermal interface layer of the fitting surface is a graphene thermal conductive film. The two ends of the protective support rib (4) are provided with positioning bosses for cooperating with the slots of the end cap (24) to achieve positioning and installation.

8. A capacitor employing double-sided metallized film winding as described in claim 1, characterized in that: The double-sided metallized film winding layer (3) adopts a gradient thickness winding structure: the inner winding unit near the lead-out terminal (2) is set by using a narrow double-sided metallized film in a single-layer winding manner, and its single-layer thickness is 1 / 3 of the single-layer thickness of the outer winding unit far from the lead-out terminal (2); the outer winding unit adopts a wide double-sided metallized film in a double-layer superimposed winding manner, and through the coordinated design of the winding width and the number of superimposed layers, a thickness gradient from the center to the outer periphery is formed.

9. A capacitor employing a double-sided metallized film winding as defined in claim 8, characterized in that, The side of the narrow double-sided metallized film of the inner winding unit is flush with the side of the conductive rib (21) of the lead-out terminal (2), and the end of the narrow double-sided metallized film is provided with an inwardly bent positioning flange. The positioning flange is inserted into the groove between the conductive ribs (21) to limit the circumferential position of the inner winding unit.

10. A capacitor employing a double-sided metallized film winding as defined in claim 8, wherein When the wide double-sided metallized film of the outer winding unit is wound in double layers, a number of discrete positioning protrusions are provided between the two wide double-sided metallized films. The positioning protrusions are engaged with the positioning grooves at the corresponding positions of the adjacent insulating isolation layers to maintain the relative position of the double-layer superimposed structure. The edge of the wide double-sided metallized film extends beyond the edge of the inner winding unit to form a covering of the inner winding unit.

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