Large-aspect-ratio all-solid-state large-current pulse capacitor and method for manufacturing the same

Abstract

The application discloses a preparation method of a large-length-ratio full solid-state large-current pulse capacitor, wherein polypropylene film is evaporated with a fixed square resistance, the evaporated polypropylene film is stacked in a staggered manner, and a capacitor core is wound by a stretching winding device; the capacitor core is heat-treated, a bayonet is integrally formed at the inner center position of the tube wall of a cylindrical tube body; a capacitor external connector is additionally arranged outside a threaded connector connecting port, the inner end of the capacitor external connector is connected with a high-voltage end of the capacitor core, and the outer end of the capacitor external connector penetrates through an insulation structure; an n-stage parallel structure with a high-voltage end and a low-voltage end formed by n proportional units is arranged in the cylindrical tube body, the high-voltage end is led out from the capacitor external connector, and the low-voltage end is connected with the bayonet through an inserted sheet to form a grounding loop in the inner side of the tube wall; a high-voltage electrode is located at the capacitor external connector at both ends, and a low-voltage electrode is located at the bayonet.

Description

Technical Field

[0001] This invention belongs to the field of high-power pulse capacitor technology, and in particular to a high aspect ratio all-solid-state high-current pulse capacitor and its preparation method. Background Technology

[0002] my country's shale oil resources are mainly continental shale, with deep burial, low brittleness index, and strong reservoir heterogeneity, making industrial development difficult. Currently, it is proposed to use controlled shock wave technology to fracture shale oil layers, forming a network of fractures, to achieve deep shale oil development. The generation of the controlled shock wave involves using a pulse capacitor to generate a large current in a short time, thus providing high energy to the fracturing end. However, in actual shale mining operations, considering the deep blasting depth and the difficulty of drilling blasting wells, the diameter of the blasting wells is limited. This operating environment restricts the design diameter of the shock wave generating capacitor.

[0003] The size, shape, and structural design of a capacitor are crucial factors influencing its energy storage capacity and current-carrying capacity. Currently used capacitors generally do not have stringent size and shape limitations, and high-current discharge can usually be achieved by increasing the capacitor volume, connecting multiple capacitors in series or parallel, or modifying the overall structural design. However, in shale mining operations, the size constraints limit the capacitor's shape, making it impossible to achieve high current-carrying capacity by increasing the capacitor volume or using external series-parallel structures. Furthermore, the size limitations dictate a compact internal structure, placing high demands on high-current-carrying capacity design within a small space, energy storage capacity design, and internal short-distance high-voltage insulation. During controlled shock wave blasting, the shock wave propagates upwards with the entire machine, requiring high shock resistance from the capacitor. The combined effects of electrothermal and mechanical forces also place high demands on the capacitor's structural stability. Because shale oil blasting requires multiple high-frequency releases of shock waves from pulse capacitors to fully fragment the rock formation, these pulse capacitors need a certain pulse lifespan. Existing capacitors are difficult to simultaneously achieve in terms of structural design, current carrying capacity, pulse life, and shock resistance, making it difficult to realize the required controllable shock wave.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain information that does not constitute prior art known to those skilled in the art in this country. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a high aspect ratio all-solid-state high-current pulse capacitor and its fabrication method, enabling the overall design of a capacitor that achieves high-current discharge under the constraints of a small-radius, high-voltage environment. By adjusting the tension process during capacitor core winding and the sheet resistance value of vapor deposition, the capacitor core achieves high voltage withstand performance. An internal series-parallel structure design realizes the current carrying capacity under a fixed radius. Port insulation is designed to ensure the safety of the capacitor under high voltage and high current. The coaxial electrode design allows the internal structure to achieve a series-parallel structure within a limited space.

[0006] The objective of this invention is achieved through the following technical solution: a method for fabricating a high aspect ratio all-solid-state high-current pulse capacitor includes:

[0007] Step 1: The polypropylene film is fixed by vapor deposition, and the vapor-deposited polypropylene film is stacked in a staggered manner and wound into a capacitor core using a stretching and winding device.

[0008] Step 2: Heat-treat the capacitor core by placing it in an oven and maintaining it at a first temperature for a first time, then adjusting the oven to a second temperature and maintaining it at a second time, and finally adjusting the oven to a third temperature and maintaining it at a third time.

[0009] Step 3: A straight steel pipe with a length of 2m-3m, an inner diameter of 66-76mm, and an outer diameter of 80-100mm is used as a cylindrical tube with a large length-to-diameter ratio. A bayonet is integrally formed at the center of the inner wall of the cylindrical tube. This capacitor is suitable for mining. Due to the environmental conditions of the geological layer, the drilling pressure at great depths limits the diameter of the borehole, thus constraining the inner diameter. In addition, the commonly used drilling diameter at present is about 120mm. An excessively long pipe structure will increase the difficulty of transportation and affect the structural stability during use. Therefore, the design pipe length is no more than 4m and the outer diameter is 80-100mm.

[0010] Step 4: Threaded connectors are installed at both ends of the cylindrical tube to connect the tube to the connector structure;

[0011] Step 5: Install an external capacitor connector on the outside of the threaded connector. The inner end of the external capacitor connector is connected to the high-voltage end of the capacitor core, and the outer end of the external capacitor connector passes through the insulation structure.

[0012] Step 6: The series connection structure of the capacitor cores of the m-level capacitors forms a proportional unit. Inside the cylindrical tube, an n-level parallel structure consisting of n proportional units with high-voltage and low-voltage ends is placed. The high-voltage end is led out from the external connector of the capacitor, and the low-voltage end is connected to the bayonet through the insert to form a grounding loop on the inner side of the tube wall. The connection and parallel structure between the proportional units adopt a chain connection structure. The terminals of the high and low voltage ends are fixed through the inner cavity of the core to form an inner cavity coaxiality, which not only ensures the inner core connection in the short radius space, but also realizes the coaxial loop of the high and low voltage ends.

[0013] Step 7: The high-voltage electrode is located at the external connector of the capacitor at both ends, and the low-voltage electrode is located at the bayonet. The high-voltage electrode and the low-voltage electrode are coaxial structures that are spatially coaxial and symmetrical.

[0014] In the method for preparing a high aspect ratio all-solid-state high-current pulse capacitor, in step 2, the first temperature is 50°C and the first time is 3 hours; the second temperature is 70°C and the second time is 3 hours; the third temperature is 90°C and the third time is 6 hours.

[0015] In the method for preparing a high aspect ratio all-solid-state high-current pulse capacitor, in step 5, the insulating structure is made of polytetrafluoroethylene, and the insulating structure surrounds the high-voltage end of the capacitor core.

[0016] A high aspect ratio all-solid-state high-current pulse capacitor is prepared according to the aforementioned method for preparing a high aspect ratio all-solid-state high-current pulse capacitor.

[0017] Compared with existing technologies, this invention has the following advantages: The method for fabricating a high-aspect-ratio all-solid-state high-current pulse capacitor according to this invention, under conditions of significant spatial constraints, utilizes a single-core chain arrangement structure and a coaxial series-parallel connection method within the cavity. This allows for a significant expansion of the effective portion of the capacitor core within a small radius constraint, while simultaneously satisfying the core's circuit design and structural stability design. Furthermore, it incorporates short-distance high-voltage insulation protection, enabling the output of large pulse currents even with a high aspect ratio structure. This invention features a novel structure, stability, reliability, and a long service life, and is primarily applied in pulse discharge applications operating in small-diameter environments. Attached Figure Description

[0018] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0019] In the attached diagram:

[0020] Figure 1 This is a cross-sectional schematic diagram of a high aspect ratio all-solid-state high-current pulse capacitor according to an embodiment of the present invention.

[0021] Figure 2 This is a cross-sectional schematic diagram of the capacitor connector structure of a high aspect ratio all-solid-state high-current pulse capacitor according to an embodiment of the present invention; wherein, 1 is the external electrode connector, 2 is the pressure spring, 3 is the polytetrafluoroethylene insulator, 4 is the connector holder spring, 5 is the connector gasket, 6 is the metal electrode, 7 is the metal wire, and 8 is the outer tube structure.

[0022] Figure 3 This is a schematic diagram of the discharge current waveform of a pulse capacitor wire burst test of a high aspect ratio all-solid-state high-current pulse capacitor according to an embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the short-circuit discharge current of a high aspect ratio all-solid-state high-current pulse capacitor according to an embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of the single-core chain arrangement of the capacitor core and the coaxial series-parallel connection structure of the inner cavity; where 9 is the high-voltage end electrode plate, 10 is the core connecting wire, 11 is the core unit, 12 is the inner cavity coaxial support, 13 is the low-voltage end electrode insert, and 14 is the support connecting column.

[0025] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0026] Specific embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0027] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0028] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0029] To better understand, such as Figures 1 to 5 As shown, the fabrication method of a high aspect ratio all-solid-state high-current pulse capacitor includes,

[0030] Step 1: The polypropylene film is fixed by vapor deposition, and the vapor-deposited polypropylene film is stacked in a staggered manner and wound into a capacitor core using a stretching and winding device.

[0031] Step 2: Heat-treat the capacitor core by placing it in an oven and maintaining it at a first temperature for a first time, then adjusting the oven to a second temperature and maintaining it at a second time, and finally adjusting the oven to a third temperature and maintaining it at a third time.

[0032] Step 3: A straight steel pipe with a length of 2m-3m, an inner diameter of 66-76mm, and an outer diameter of 80-100mm is used as a cylindrical pipe with a large length-to-diameter ratio. A bayonet is integrally formed at the center of the inner wall of the cylindrical pipe.

[0033] Step 4: Threaded connectors are added to both ends of the cylindrical tube to connect the capacitor tube to the connector structure;

[0034] Step 5: Install an external capacitor connector on the outside of the threaded connector. The inner end of the external capacitor connector is connected to the high-voltage end of the capacitor core, and the outer end of the external capacitor connector passes through the insulation structure.

[0035] Step 6: The series connection structure of the capacitor cores of the m-level capacitors forms a proportional unit. Inside the cylindrical tube, an n-level parallel structure consisting of n proportional units with high-voltage and low-voltage ends is placed. The high-voltage end is led out from the external connector of the capacitor, and the low-voltage end is connected to the bayonet through the insert to form a grounding loop on the inner side of the tube wall. The connection and parallel structure between the proportional units adopt a chain connection structure. The terminals of the high and low voltage ends are fixed through the inner cavity of the core to form an inner cavity coaxiality, ensuring the inner core connection in the short radius space and realizing the coaxial circuit of the high and low voltage ends.

[0036] Step 7: The high-voltage electrode is located at the external connector of the capacitor at both ends, and the low-voltage electrode is located at the bayonet. The high-voltage electrode and the low-voltage electrode are coaxial structures that are spatially coaxial and symmetrical.

[0037] In a preferred embodiment of the method for preparing a high aspect ratio all-solid-state high-current pulse capacitor, in step 2, the first temperature is 50°C and the first time is 3 hours; the second temperature is 70°C and the second time is 3 hours; the third temperature is 90°C and the third time is 6 hours.

[0038] In a preferred embodiment of the method for preparing a high aspect ratio all-solid-state high-current pulse capacitor, in step 5, the insulating structure is polytetrafluoroethylene, and the insulating structure surrounds the high-voltage end of the capacitor core.

[0039] In one implementation, the method includes,

[0040] Step 1, the membrane structure design of the capacitor core is achieved by using a polypropylene film with an Ω / m... 3 The sheet resistance is vapor-deposited, and the vapor-deposited polypropylene film is stacked in a staggered manner and wound into a capacitor core with a tensile tension of 750g±50g.

[0041] Step 2: Perform heat treatment on the capacitor core that was vapor-deposited and wound in Step 1. Place the polypropylene film capacitor in an oven, set the temperature inside the oven to 50°C, and keep it at that temperature for 3 hours. Then set the oven to 70°C and keep it at that temperature for 3 hours. Finally, set the oven to 90°C and keep it at that temperature for 6 hours.

[0042] Step 3: This capacitor is suitable for mining. Due to the environmental conditions of the geological layer, the drilling pressure at great depths limits the diameter of the borehole. At present, the commonly used drilling diameter is about 120mm. At the same time, an excessively long pipe structure will increase the difficulty of transportation and affect the structural stability during use. Usually, the design pipe length is no more than 4m. Therefore, a straight steel pipe with a length of 2m-3m, an inner diameter of 66-76mm, and an outer diameter of 80-100mm is designed as a cylindrical pipe with a large length-to-diameter ratio using CAD software. A bayonet is integrally formed at the center of the inner wall of the cylindrical pipe. The straight steel pipe is designed as a cylindrical pipe with a length of 2m-3m, an inner diameter of 66-76mm, and an outer diameter of 80-100mm. A bayonet design is added at the center of the inner wall of the pipe to form an integral structure with the pipe wall.

[0043] Step 4: Add threaded connectors with an inner diameter of 76-86mm and an outer diameter of 80-100mm to both ends of the pipe body designed in Step 3;

[0044] Step 5: Install an external capacitor connector on the threaded connection designed in Step 4. The inner end of the connector connects to the high-voltage end of the capacitor core structure, and the outer end of the connector passes through the external insulation structure to serve as the high-voltage input of the external power supply. The connector insulation material is polytetrafluoroethylene (PTFE), and the insulation structure surrounds the high-voltage connector.

[0045] Step 6: Inside the tube body design in Step 3, the polypropylene film core that has been heat-treated in Step 2 is designed as an m-level series structure to form a proportional unit. n proportional units are placed inside the tube body, and the high voltage end is led out from the capacitor external connector. The low voltage end is connected to the bayonet through the insert to form a grounding circuit on the inner side of the tube wall. The connection and parallel structure between the proportional units adopts a chain connection structure. The terminals of the high and low voltage ends are fixed through the inner cavity of the core to form an inner cavity coaxiality, and the high and low voltage ends form a coaxial circuit.

[0046] Step 7: Place the n proportional units from both ends of the pipe into the interior, set the proportional units as an n-level parallel structure, and lead out the high-voltage end from the connector. The low-voltage end of the parallel structure is connected to the bayonet in the center of the pipe through the plug, and connected to the inner side of the pipe wall to form a grounding loop.

[0047] Step 8: The electrode structure is designed as a coaxial structure, with the high-voltage electrode located at both ends of the connector and the low-voltage connector located at the center of the tube body. It is spatially coaxial and symmetrical, avoiding uneven electric field and uneven heat distribution.

[0048] A high aspect ratio all-solid-state high-current pulse capacitor is prepared according to the aforementioned method for preparing a high aspect ratio all-solid-state high-current pulse capacitor.

[0049] In one embodiment, a high aspect ratio all-solid-state high-current pulse capacitor includes a capacitor shell structure, a capacitor end connector structure, a capacitor connector insulation structure, an internal core series-parallel connection structure, a coaxial electrode structure, and a capacitor core film structure.

[0050] In one embodiment, such as Figure 2 As shown, the external electrode connector 1 is fixed to the tube structure by a pressure spring 2 and a connector gasket 5. The metal electrode 6 is fixed to the PTFE insulator 3 via the external electrode connector 1 and the pressure spring 2. The metal wire 7 passes through the pressure spring 2 and the connector gasket 5, connecting the external electrode connector 1 to the metal electrode 6, thus providing electrode conductivity. The PTFE insulator 3 and the metal electrode 6 are fixed to the outer tube wall structure by an integrated retaining spring 4.

[0051] In one embodiment, such as Figure 3 As shown, the various structures of the present invention are assembled, and a metal wire is installed at the end of the capacitor to simulate a wire burst test. One high-voltage terminal of the capacitor is connected to a DC high-voltage source, and the DC charging voltage is set to 30kV. The other end of the capacitor is connected to a metal wire with a resistance of 50mΩ. The internal core connection structure of the capacitor is an 8-stage series structure. The DC charging time in the experiment is 24s. The wire connecting the metal wire and the capacitor is lengthened, and a coil is added to the connecting wire to detect the pulse current at the moment of wire burst. The detected waveform is displayed on an oscilloscope. The pulse current of the wire burst experiment shows an initial current peak of 24.8kA and a pulse rise time of 4μs.

[0052] like Figure 4 As shown, after assembling the various structures of the present invention, a short-circuit discharge test was performed on the capacitor to evaluate its pulse life. One boost discharge cycle was used as a counting period, and the capacitor was continuously subjected to short-circuit discharge tests. The capacitance was measured every 500 cycles. The capacitor was considered to have failed when its capacitance decreased by 5%. The short-circuit test showed an initial peak discharge current of 22kA, and the capacitor's short-circuit test life was 7000 cycles.

[0053] Figure 5This is a schematic diagram of a capacitor core arranged in a chain, with a coaxial series-parallel connection within the cavity. The m-stage capacitor cores 11 are connected in series to form a proportional unit. Inside the cylindrical tube, an n-stage parallel structure consisting of n proportional units, with high-voltage and low-voltage ends, is placed. High-voltage electrode plates 9 are led out from the capacitor's external connector, and low-voltage electrode inserts 13 are connected to the bayonet via inserts to form a grounding loop inside the tube wall. The connection and parallel structure between the proportional units adopt a chain-like connection structure 10. The high and low voltage end terminals are fixed within the core cavity to form a coaxial support column 12, ensuring both the connection of the cores in a short radius space and achieving a coaxial loop between the high and low voltage ends. Furthermore, a supporting connection column 14 is provided at the low-voltage end.

[0054] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of the present invention, and all of these are within the scope of protection of the present invention.

Claims

1. A method for fabricating a high aspect ratio all-solid-state high-current pulse capacitor, characterized in that, It includes the following steps, Step 1: The polypropylene film is vapor-deposited with a fixed sheet resistance, and the vapor-deposited polypropylene film is stacked in a staggered manner and stretched and wound into a capacitor core by a film stretching device. Step 2: Heat-treat the capacitor core by placing it in an oven and maintaining it at a first temperature for a first time, then adjusting the oven to a second temperature and maintaining it at a second time, and finally adjusting the oven to a third temperature and maintaining it at a third time. Step 3: A straight steel pipe with a length of 2m-3m, an inner diameter of 66-76mm, and an outer diameter of 80-100mm is used as a cylindrical pipe with a large length-to-diameter ratio. A bayonet is integrally formed at the center of the inner wall of the cylindrical pipe. Step 4: Threaded connectors are added to both ends of the cylindrical tube to connect the tube to the capacitor connector structure; Step 5: Install an external capacitor connector on the outside of the threaded connector. The inner end of the external capacitor connector is connected to the high-voltage end of the capacitor core, and the outer end of the external capacitor connector passes through the insulation structure. Step 6: The series connection structure of the capacitor cores of the m-level forms a proportional unit. Inside the cylindrical tube, an n-level parallel structure consisting of n proportional units with high voltage and low voltage ends is placed. The high voltage end is led out from the external connector of the capacitor, and the low voltage end is connected to the bayonet through the insert to form a grounding loop on the inner side of the tube wall. Step 7: The high-voltage electrode is located at the external capacitor terminals at both ends, and the low-voltage electrode is located at the bayonet. The high-voltage electrode and the low-voltage electrode are coaxial structures that are spatially coaxially symmetrical. In step 2, the first temperature is 50°C and the first time is 3 hours; the second temperature is 70°C and the second time is 3 hours; the third temperature is 90°C and the third time is 6 hours.

2. The method for fabricating a high aspect ratio all-solid-state high-current pulse capacitor according to claim 1, wherein, In step 5, the insulating structure is made of polytetrafluoroethylene and surrounds the high-voltage end of the capacitor core.

3. A high aspect ratio all-solid-state high-current pulse capacitor, characterized in that, It is prepared according to any one of claims 1-2.

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