Dry-type thin film flexible straight capacitor

Abstract

The invention discloses a dry-type thin film flexible direct current capacitor, and relates to the field of capacitors, an electrode layer and a base layer which are laminated in a capacitor core are optimized, a protection layer is arranged at the edge of the base layer, and meanwhile, the edge thickness of the electrode layer is larger than the middle thickness of the electrode layer so as to improve the connection stability of the capacitor core. For a capacitor core with an inner string structure, an insulating layer is arranged between inner string electrodes so as to improve the voltage resistance of the capacitor. A pressure sensor is further arranged in the capacitor, a plurality of pressure release valves are arranged in the capacitor in a partitioned mode, action threshold values of the pressure release valves are controlled through the pressure sensor, the response rate of the pressure release valves is improved, and local high pressure generated in the flexible direct current capacitor is dispersed in time. The capacitor core group arranged in the flexible direct current capacitor is connected to an external circuit through the connecting piece, the switch piece and the leading-out terminal in sequence, so that the capacitance of the flexible direct current capacitor is adjustable.

Description

Technical Field

[0001] The present invention relates to the field of capacitors, and in particular to a dry-type thin-film flexible capacitor. Background Art

[0002] As domestic ionization electronic technology is widely used in smart grids and flexible DC transmission, high-voltage and high-power inverters, rail transit and other fields, flexible DC capacitors, as one of the core components of converters, have a wide market demand and put forward higher requirements for the stability and reliability of flexible DC capacitors. Most of the existing flexible DC capacitors are metallized film capacitors. This type of capacitor does not use liquid electrolytes. The metallized film coating is used as the electrode inside. The electrode material is made into a capacitor core by winding and installed in the capacitor housing. Therefore, it is also called a dry film flexible DC capacitor. Dry film flexible DC capacitors have been favored by the market for their advantages such as high stability, long life and high efficiency.

[0003] During the winding process of the capacitor core of the flexible DC capacitor, the edge of the metal film used as the electrode material will be exposed on the two circular end faces of the capacitor core. By spraying gold on the two circular end faces of the capacitor core, a uniform conductive metal layer can be formed on both end faces of the capacitor core, providing a good electrical connection foundation for pin welding and external connection of the capacitor. Good gold spraying treatment can not only improve the working stability of the capacitor, but also effectively reduce the contact resistance during welding of the capacitor core, and enhance the overall performance of the flexible DC capacitor. However, in actual production, due to the precision limitation of the gold spraying process, the gold spraying layer may incorrectly extend to the inner layer area of ​​the capacitor core, causing the positive and negative electrodes of the flexible DC capacitor to accidentally contact or conduct, forming a short circuit between the electrodes. Summary of the invention

[0004] In order to prevent the metal spray layer from covering the inner layer area of ​​the capacitor core during the gold spraying process, which may cause the positive and negative electrodes of the capacitor to accidentally contact or conduct and form a short circuit, the present invention provides a dry-type thin film flexible capacitor, including a shell, a lead terminal and a plurality of capacitor cores installed inside the shell, the capacitor cores are electrically connected to an external circuit through the lead terminals, the capacitor core includes a first electrode layer, a first base layer, a second electrode layer and a second base layer which are stacked, and a protective layer is provided at the edge of the first base layer and / or the second base layer.

[0005] In the dry film flexible capacitor provided by the present invention, the capacitor core installed inside the shell is wound by a first base layer, a second base layer, and a first electrode layer and a second electrode layer attached to the first base layer and the second base layer, and a protective layer is provided at the edge of the first base layer and / or the second base layer. Before winding, the first electrode layer, the first base layer, the second electrode layer and the second base layer are stacked, the first electrode layer and the second electrode layer are two plates of the capacitor, the first base layer between the first electrode layer and the second electrode layer is the dielectric between the plates, and the second base layer avoids the conduction between the first electrode layer and the second electrode layer after the winding operation. After the winding is completed, the two ends of the capacitor core are sprayed with gold to form a gold spray layer as the basis for the electrical connection between the capacitor core and the external circuit, the protective layer at the edge of the first electrode layer and the second base layer is exposed on one circular end face of the capacitor core, that is, the positive electrode of the capacitor; the protective layer at the edge of the second electrode layer and the first base layer is exposed on the other circular end face of the capacitor core, that is, the negative electrode of the capacitor. The provision of the protective layer prevents the gold spraying layer from contacting the first electrode layer and the second electrode layer at the same time during the gold spraying process, thereby causing the positive and negative electrodes of the capacitor core to short-circuit and fail, thereby improving the reliability of the dry-type film flexible capacitor.

[0006] Furthermore, in order to expand the contact area between the electrode layer of the capacitor core and the gold-sprayed layer in the dry-type thin-film flexible capacitor and ensure that the gold-sprayed layer is electrically well connected to the first electrode layer and / or the electrode layer, the thickness of one side of the first electrode layer and / or the second electrode layer is greater than the other side, and the first electrode layer and the second electrode layer are symmetrically arranged, that is, the side with the larger thickness of the first electrode layer is opposite to the side with the larger thickness of the second electrode layer. In the wound capacitor core, the side with the larger thickness of the first electrode layer is exposed on a circular end face of the capacitor core, and the side with the larger thickness of the second electrode layer is exposed on another circular end face of the capacitor core. The thicker electrode layer edge ensures a reliable electrical connection between the gold-sprayed layer and the first electrode layer and / or the second electrode layer, reduces the contact resistance generated when the capacitor core is welded, and effectively ensures that the capacitor core is electrically connected to the external circuit stably. At the same time, the thickness of the first electrode layer and / or the second electrode layer from the edge to the middle gradually decreases. It can be understood that the square resistance from the edge to the middle of the first electrode layer and / or the second electrode layer increases accordingly, which enhances the overall voltage resistance of the dry-type thin-film flexible capacitor.

[0007] Furthermore, for capacitors, the main way to increase the capacitance and withstand large discharge current is to increase the effective length of the metallized film electrode. The relationship between the effective length L of the electrode and the capacitance C can be expressed by the following formula:

[0008] Wherein, d is the dielectric thickness, k is the dielectric constant, b is the effective width of the electrode layer, and n is the number of capacitors. In order to further improve the performance of the dry film flexible capacitor in withstanding large discharge currents, the first electrode layer is separated into a third electrode layer and a fourth electrode layer. At this time, the third electrode layer and the fourth electrode layer respectively form two capacitors connected in series with the second electrode layer, and the effective width of the capacitor core electrode layer is reduced to , the number of capacitors increases to 2n, the capacitance increases to 2C, and the effective length of the electrode increases to 2L. Therefore, the first electrode layer includes an insulated third electrode layer and a fourth electrode layer, and the thickness of the third electrode layer and the fourth electrode layer near the edge of the first base layer is greater than the thickness of the third electrode layer and the fourth electrode layer near the center of the first base layer. In the wound capacitor core, the side with the larger thickness of the third electrode layer is exposed on a circular end face of the capacitor core, and the side with the larger thickness of the fourth electrode layer is exposed on the other circular end face of the capacitor core. The dry-type thin film flexible capacitor provided by the present invention improves the capacitance and stability of the capacitor, and at the same time, by optimizing the thickness of the electrode layer, the capacitor can maintain a relatively stable performance under different voltages and working environments.

[0009] Furthermore, since the first electrode layer is separated into a third electrode layer and a fourth electrode layer that are insulated from each other, the middle of the second electrode layer corresponding to the interval area between the third electrode layer and the fourth electrode layer does not participate in the formation of capacitance, has no voltage effect, and is only used for the series connection of the capacitor inside the capacitor core. Therefore, thickening the center of the second electrode layer can ensure the stability of the series connection inside the capacitor core, and the thickness of the second electrode layer at the center is greater than the thickness at the edge of the second electrode layer.

[0010] Furthermore, in order to ensure good insulation performance between the third electrode layer and the fourth electrode layer, thereby avoiding breakdown between the third electrode layer and the fourth electrode layer due to the passage of large current during the operation of the capacitor and causing the capacitor to fail, an insulating layer is provided between the third electrode layer and the fourth electrode layer. The insulating layer can effectively block the direct conduction of current between the third electrode layer and the fourth electrode layer, thereby maintaining the long-term stability of the capacitor. In order to ensure that the insulating layer can first withstand the electric field pressure when the capacitor is subjected to a large current or high voltage, the insulating layer should be made of a material with high node strength and good temperature resistance to ensure that the breakdown voltage of the insulating layer is greater than the breakdown voltage of the first base layer and / or the second base layer, to avoid the insulating layer being broken down before the first base layer and / or the second base layer, so as to ensure the safety of the dry film flexible capacitor under high load conditions.

[0011] Furthermore, in the existing flexible DC capacitor, all the capacitor cores inside the capacitor are connected in parallel through an integrated copper bar, and then wrapped with electromagnetic shielding material and installed in the flexible DC capacitor housing, so that the capacitance of the flexible DC capacitor is fixed, and the specific size of its capacitance depends on the size and number of the capacitor cores installed inside it. In some specific application scenarios, such as capacitance adjustment, filter adjustment and other application scenarios, it is necessary to change the capacitance of the flexible DC capacitor during operation; and when the circuit needs to be tested and diagnosed, it may be necessary to change the capacitance of the flexible DC capacitor or temporarily disconnect the flexible DC capacitor. Therefore, a connector is also provided inside the dry film flexible DC capacitor housing, and the connector is arranged inside the housing. The capacitor core is installed inside the dry film flexible DC capacitor housing, and is electrically connected to the lead-out terminal after being connected in parallel with each other through the connector, and finally electrically connected to the external circuit through the lead-out terminal. At the same time, a switch is provided between the connector and the lead-out terminal, and the switch is used to control the electrical connection between the capacitor core and the external circuit, so as to meet the needs of dynamically adjusting circuit parameters in applications such as circuit adjustment, protection, testing, and fault handling.

[0012] Furthermore, a plurality of capacitor cores are arranged inside the shell of the dry-type thin-film flexible capacitor. In order to effectively reduce the electrical interference between the capacitor cores and prevent the performance degradation of the capacitor due to electric field coupling or electrical breakdown, an isolation layer is arranged inside the shell. The isolation layer is used to divide the capacitor core into a plurality of independent capacitor core groups, thereby effectively avoiding the mutual influence between the capacitor cores and reducing the potential risks caused by electric field coupling, thereby ensuring the working stability and performance reliability of each capacitor core group. In addition, in order to ensure that the pressure between the capacitor core groups inside the capacitor is balanced and prevent the capacitor core from being damaged due to excessive local pressure inside the capacitor, a one-way valve is also arranged on the isolation layer. The provision of the isolation layer can prevent the failure of a single capacitor core from spreading to other capacitor cores, thereby protecting the overall function of the capacitor, and ensuring the pressure balance between the capacitor core groups through the one-way valve.

[0013] Furthermore, in order to disperse the internal pressure of the dry film capacitor shell and improve the pressure relief efficiency of the pressure relief valve, a plurality of pressure relief valves are provided on the shell, and the installation position of the pressure relief valve corresponds to the capacitor core group.

[0014] Furthermore, during operation, the dry-type thin-film flexible capacitor may generate local heat due to poor contact of some capacitor cores, thereby causing uneven pressure distribution in the shell. In order to monitor the pressure conditions in the shell and timely disperse the local high pressure in the shell, a sensor is provided inside the shell. The installation position of the sensor corresponds to the capacitor core group. The sensor is used to control the action threshold of the pressure relief valve.

[0015] Wherein, the method for the sensor to control the action threshold of the pressure relief valve is: Obtaining pressure data corresponding to each capacitor core group inside the housing; Determine whether the pressure data is greater than a first threshold value, and if so, set a first pressure relief valve corresponding to the pressure data as a first action threshold value, and set a second pressure relief valve adjacent to the first pressure relief valve as a second action threshold value; If not, it is determined whether the pressure data is greater than a second threshold value, and if so, the third pressure relief valve corresponding to the pressure data is set as a third action threshold value.

[0016] Furthermore, during operation, the dry film flexible capacitor may generate mechanical vibrations and affect its internal structure, especially in high power, fast switching or high frequency conditions. In order to monitor the mechanical vibration of the dry film flexible capacitor and perform preventive maintenance in a timely manner, a fixing device is provided on the housing, and the fixing device includes a vibration sensor.

[0017] One or more technical solutions provided by the present invention have at least the following technical effects or advantages: (1) By optimizing the design of the electrode layer and the base structure in the capacitor core, the two ends of the wound capacitor core correspond to the positive and negative electrodes of the capacitor respectively, ensuring reliable electrical connection between the gold spraying layer and the electrode layer, and ensuring good electrode contact.

[0018] (2) A pressure sensor is installed inside the flexible DC capacitor, and multiple pressure relief valves are installed in different zones. This can effectively monitor the pressure inside the capacitor shell, and control the action threshold of the pressure relief valve through the pressure sensor, thereby improving the response rate of the pressure relief valve and timely dispersing the local high pressure generated in the flexible DC capacitor.

[0019] (3) An isolation layer is set inside the flexible DC capacitor to divide the capacitor core inside the flexible DC capacitor into multiple independent capacitor core groups, thereby effectively avoiding mutual influence between the capacitor cores, reducing the potential wind direction caused by electric field coupling, and ensuring the working stability and performance reliability of the flexible DC capacitor.

[0020] (4) The multiple capacitor cores installed inside the flexible DC capacitor are connected in parallel through connectors, and finally connected to the external circuit through the lead-out terminals after passing through the switch, so that the capacitance of the flexible DC capacitor is adjustable, meeting the needs of dynamically adjusting circuit parameters in applications such as circuit regulation, protection, testing, and fault handling. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of the present invention, and do not constitute a limitation on the embodiments of the present invention; Figure 1 It is a schematic diagram of the structure of the dry-type thin-film flexible capacitor in the present invention; Figure 2 It is a schematic diagram of the capacitor core structure in the present invention; Figure 3 It is a schematic diagram of the structure of the inner series capacitor core in the present invention; Among them, 1-shell, 2-capacitor core, 3-lead terminal, 4-first electrode layer, 5-first base layer, 6-second electrode layer, 7-second base layer, 8-protective layer, 9-third electrode layer, 10-fourth electrode layer, 11-insulating layer, 12-isolating layer, 13-check valve, 14-pressure relief valve. DETAILED DESCRIPTION

[0022] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0023] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those within the scope of this description. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0024] Embodiment 1

[0025] Please refer to Figure 1-2 Embodiment 1 of the present invention provides a dry-type thin-film flexible capacitor, comprising a shell 1, a lead terminal 3 and a plurality of capacitor cores 2 installed inside the shell 1, wherein the capacitor cores 2 are electrically connected to an external circuit through the lead terminal 3, and the capacitor core 2 comprises a first electrode layer 4, a first base layer 5, a second electrode layer 6 and a second base layer 7 which are stacked, and a protective layer 8 is provided at the edge of the first base layer 5 and / or the second base layer 7.

[0026] Specifically, the capacitor core 2 installed inside the shell 1 is wrapped with more than two layers of 0.2mm thick polyester film (single-layer breakdown voltage ≥12kVdc), and more than 5mm thick epoxy resin (breakdown voltage ≥20kV / mm) is poured between the shell 1 and the wrapped capacitor core 2. The polyester film and the epoxy resin layer are used to protect the capacitor core 2 from external insulation.

[0027] Specifically, the dry film flexible DC capacitor is provided with 8 lead terminals, specifically M12 internal thread lead terminals are selected, and 4 lead terminals are used as one pole to connect the dry film flexible DC capacitor to the external circuit. The side of the dry film flexible DC capacitor housing is provided with 16 mounting terminals, which fully ensures the strength requirements of the dry film flexible DC capacitor during installation and use. Among them, the specific number of the lead terminal 3 and the mounting terminal can be adjusted according to the specific needs of the working circuit and environment of the dry film flexible DC capacitor, and this embodiment does not make specific limitations here.

[0028] For details, please continue to refer to Figure 1 The dry film flexible capacitor housing 1 is preferably made of 304 non-magnetic stainless steel, which has high strength, will not rust, and is not affected by the electric and magnetic fields of the surrounding environment. The housing 1 is welded by a shell body, a shell cover, and a shell bottom. The shell body, the shell cover, and the shell bottom are all welded by argon arc welding, and the welding strength can withstand a pressure greater than 40kPA. The housing 1 includes a plurality of capacitor cores 2, and the number of the capacitor cores 2 is determined according to actual needs, and this embodiment does not make specific restrictions here.

[0029] The first electrode layer 4 and / or the second electrode layer 6 can be any metal electrode layer that can form an electrode, such as titanium, aluminum, zinc, etc., or any non-metal electrode layer that can form an electrode, such as carbon nanotubes, conductive polymers, etc. The specific material of the first electrode layer 4 and / or the second electrode layer 6 is determined according to actual needs, and this embodiment does not make specific restrictions here; the first base layer 5 and / or the second base layer 7 can be a polypropylene film, a polyester film or a polyimide film, and the first base layer 5 and / or the second base layer 7 are preferably high-insulation polypropylene films, whose dielectric strength is 800V / μm, the dielectric loss is about 0.02%, and the temperature resistance reaches 125°C. Preferably, the thickness of the first base layer 5 and / or the second base layer is 3.4-10μm, and the width of the first base layer 5 and / or the second base layer 7 is determined according to actual needs, and this embodiment does not make specific restrictions here. The first electrode layer 4 and / or the second electrode layer 6 can be attached to the surface of the first base layer 5 and / or the second base layer 7 by evaporation, sputtering or spin coating. The specific method is determined according to the type of electrode layer and actual needs, and this embodiment does not make specific restrictions here.

[0030] Please continue to refer to Figure 1 Before winding, the first electrode layer 4, the first base layer 5, the second electrode layer 6 and the second base layer 7 are stacked, the first electrode layer 4 and the second electrode layer 6 are two plates of the capacitor, the first base layer 5 between the first electrode layer 4 and the second electrode layer 6 is the dielectric between the plates, and the second base layer 7 prevents the first electrode layer 4 and the second electrode layer 6 from being connected after the winding operation. Please refer to Figure 2 After the winding is completed, the first electrode layer 4, the first base layer 5, the second base layer 7 and the protective layer 8 at the edge of the second base layer 7 are exposed on a circular end face of the capacitor core 2, and the circular end face is sprayed with gold to make the first gold-sprayed layer electrically connected to the first electrode layer 4, and the first gold-sprayed layer is isolated from the second electrode layer 6 by the protective layer 8 at the edge of the second base layer 7 to obtain the positive electrode of the capacitor; the second electrode layer 6, the second base layer 7, the first base layer 5 and the protective layer 8 at the edge of the first base layer 5 are exposed on another circular end face of the capacitor core 2, and the circular end face is sprayed with gold to make the second gold-sprayed layer electrically connected to the second electrode layer 6, and the second gold-sprayed layer is isolated from the first electrode layer 4 by the protective layer 8 at the edge of the first base layer 5 to obtain the negative electrode of the capacitor. The protective layer 8 can be a polypropylene film, a polyester film or a polyimide film. Preferably, the material of the protective layer 8 is the same as that of the first base layer 5 and / or the second base layer 7, so that the protective layer 8 is integrally formed with the first base layer 5 and / or the second base layer 7. The provision of the protective layer 8 avoids the short circuit and failure of the positive and negative poles of the capacitor core 2 due to the simultaneous contact of the gold spraying layer with the first electrode layer 4 and the second electrode layer 6 during the gold spraying process, thereby improving the reliability of the operation of the dry film flexible capacitor.

[0031] For further information, please continue to refer to Figure 2 , the thickness of one side of the first electrode layer 4 and / or the second electrode layer 6 is greater than the other side, and the first electrode layer 4 and the second electrode layer 6 are symmetrically arranged, that is, the side of the first electrode layer 4 with a larger thickness is opposite to the side of the second electrode layer 6 with a larger thickness. In the wound capacitor core 2, the side of the first electrode layer 4 with a larger thickness is exposed on a circular end face of the capacitor core 2, and the circular end face is subjected to gold spraying treatment, so that the first gold spraying layer is electrically connected to the first electrode layer 4, and the contact area between the first gold spraying layer and the first electrode layer 4 is enlarged to obtain the positive electrode of the capacitor; the side of the second electrode layer 6 with a larger thickness is exposed on the other circular end face of the capacitor core 2, and the circular end face is subjected to gold spraying treatment, so that the second gold spraying layer is electrically connected to the second electrode layer 6, and the contact area between the second gold spraying layer and the second electrode layer 6 is enlarged. The thicker edge of the first electrode layer 4 and / or the second electrode layer 6 ensures the reliability of the electrical connection between the gold spraying layer and the electrode, reduces the contact resistance between the gold spraying layer and the electrode layer, and thus improves the working performance of the flexible DC capacitor. The thickness of the first electrode layer 4 and / or the second electrode layer 6 is determined according to actual needs and is not specifically limited in this embodiment.

[0032] Embodiment 2

[0033] Please refer to Figure 3Embodiment 2 of the present invention provides a dry-type thin-film flexible capacitor. Based on embodiment 1, the first electrode layer 4 includes a third electrode layer 9 and a fourth electrode layer 10 that are insulated from each other. The thickness of the third electrode layer 9 and the fourth electrode layer 10 near the center side of the first base layer 5 is less than the thickness of the third electrode layer 9 and the fourth electrode layer 10 near the edge side of the first base layer 5.

[0034] The third electrode layer 9 and the second electrode layer 6 stacked portion form a first capacitor, the fourth electrode layer 10 and the second electrode layer 6 stacked portion form a second capacitor, and the first capacitor and the second capacitor are connected in series through the center of the second electrode layer 6. For flexible DC capacitors, the main way to increase the capacitor's high discharge current resistance is to increase the effective length of the metallized film electrode.

[0035] According to the calculation formula of electrode effective length L and capacitance C: It can be seen that d is the dielectric thickness, k is the dielectric constant, b is the effective width of the electrode layer, and n is the number of capacitors. After the first electrode layer is separated into the third electrode layer 9 and the fourth electrode layer 10, the effective width of the electrode layer is reduced to , the number of capacitors increases to 2n, the capacitance increases to 2C, and the effective length of the electrode increases to 2L, which effectively improves the capacitor's ability to withstand large discharge currents.

[0036] For details, please continue to refer to Figure 3 In the wound capacitor core 2, the side with a larger thickness of the third electrode layer 9, the first base layer 5, the second base layer 7 and the protective layer 8 on the second base layer 7 are exposed on a circular end face of the capacitor core 2, and the circular end face is subjected to gold spraying, so that the first gold spraying layer is electrically connected to the side with a larger thickness of the third electrode layer 9, that is, electrically connected to the first capacitor positive electrode, to obtain the capacitor positive electrode after series connection; the side with a larger thickness of the fourth electrode layer 10, the first base layer 5, the second base layer 7 and the protective layer 8 on the second base layer 7 are exposed on another circular end face of the capacitor core 2, and the circular end face is subjected to gold spraying, so that the second gold spraying layer is electrically connected to the side with a larger thickness of the fourth electrode layer 10, that is, electrically connected to the second capacitor negative electrode, to obtain the capacitor negative electrode after series connection. The specific thickness of the third electrode layer 9 and / or the fourth electrode layer 10 is determined according to actual needs, and this embodiment does not make specific limitations here.

[0037] For further information, please continue to refer to Figure 3The middle part of the second electrode layer 6 does not participate in the formation of the capacitance of the capacitor core 2, has no voltage effect, and is only used to connect the first capacitor and the second capacitor in series inside the capacitor core 2. To ensure the stability of the series connection inside the capacitor core 2, the thickness at the center of the second electrode layer 6 is greater than the thickness at the edge of the second electrode layer 6. The specific thickness of the second electrode layer is determined according to actual needs and is not limited in this embodiment.

[0038] For further information, please continue to refer to Figure 3 In order to ensure good insulation performance between the third electrode layer 9 and the fourth electrode layer 10 and avoid failure of the capacitor due to breakdown between the third electrode layer 9 and the fourth electrode layer 10 caused by the passage of large current during the operation of the capacitor, an insulating layer 11 is provided between the third electrode layer 9 and the fourth electrode layer 10. When the capacitor is subjected to a large current or a high voltage, the insulating layer 11 first bears the electric field force. The breakdown voltage of the insulating layer 11 is greater than the breakdown voltage of the first base layer 5 and / or the second base layer 7, which can effectively avoid the third electrode layer 9 and the fourth electrode layer 10 from being broken down before the first electrode layer 4 and the second electrode layer 6, thereby improving the safety of the dry film flexible capacitor under high load conditions.

[0039] Among them, the breakdown voltage of the material selected for the insulating layer 11 is greater than the breakdown voltage of the material selected for the first base layer 5 and / or the second base layer 7. Specifically, the material of the insulating layer 11 can be selected as a polyimide (PI) film, and the material of the first base layer 5 and / or the second base layer 7 can be selected as a polypropylene (PP) film. During the operation of the capacitor core 2, the first base layer 5 and / or the second base layer 7 serve as the dielectric between the first electrode layer 4 and the second electrode layer 6. Under high power and high current conditions, the breakdown voltage of the insulating layer 11 is greater than the breakdown voltage of the first base layer 5 and / or the second base layer 7, which can effectively protect the third electrode layer 9 and the fourth electrode layer 10 from breakdown, thereby improving the availability of the dry film flexible capacitor.

[0040] For further information, please continue to refer to Figure 3 The dry film flexible DC capacitor also includes a connector, which is arranged inside the shell 1. The capacitor core 2 is electrically connected to the lead terminal 3 through the connector, and a switch is provided between the connector and the lead terminal 3.

[0041] Specifically, the dry film flexible DC capacitor is provided with two connectors and a plurality of capacitor cores 2, the positive electrodes of the plurality of capacitor cores 2 are all electrically connected to the first connector, and the positive electrodes of the plurality of capacitor cores 2 are all electrically connected to the second connector. At this time, the first connector is the positive electrode of the dry film flexible DC capacitor, and the second connector is the negative electrode of the dry film flexible DC capacitor. The lead-out terminals on the dry film flexible DC capacitor are divided into two poles. After the first connector passes through the first switch, the positive electrode of the capacitor core 2 connected in parallel is connected to the lead-out terminal of the corresponding polarity; after the second connector passes through the second switch, the negative electrode of the capacitor core 2 connected in parallel is connected to the lead-out terminal of the corresponding polarity. When the external circuit needs to be adjusted, protected, tested, fault-handled, etc., the first switch and the second switch are disconnected, and the dry film flexible DC capacitor is equivalent to an open circuit, which meets the needs of dynamic circuit adjustment.

[0042] Specifically, the dry-type thin-film flexible capacitor is internally provided with 2x connectors and a plurality of capacitor cores, and the plurality of capacitor cores are divided into x groups. For each group of capacitor cores, the positive electrode thereof is electrically connected to the third connector, and the negative electrode thereof is electrically connected to the fourth connector. At this time, for each group of capacitor cores, the third connector is the positive electrode of the group of capacitor cores after being connected in parallel, and the fourth connector is the negative electrode of the group of capacitor cores after being connected in parallel. It can be understood that the 2x connectors are divided into x positive connectors and x negative connectors. The x positive connectors respectively pass through x positive switch components to connect the positive electrodes of the capacitors connected in parallel to the lead-out terminals of the corresponding polarities; the x negative connectors respectively pass through x negative switch components to connect the negative electrodes of the capacitors connected in parallel to the lead-out terminals of the corresponding polarities. When the external circuit needs to be adjusted, protected, tested, fault-handled, etc., the positive and negative switch components corresponding to the same or multiple groups of capacitor cores are disconnected to adjust the capacitance of the capacitor, thus meeting the needs of dynamic circuit adjustment.

[0043] Embodiment 3

[0044] Please refer to Figure 1 Embodiment 3 of the present invention provides a dry-type thin-film flexible capacitor. Based on embodiment 1 and / or embodiment 2, an isolation layer 12 is provided inside the shell 1. The isolation layer 12 is used to divide the capacitor core 2 into multiple capacitor core groups. A one-way valve 13 is provided on the isolation layer 12.

[0045] Among them, the isolation layer 12 is used to provide electrical isolation. It is arranged inside the flexible DC capacitor and should have good insulation performance, good chemical stability and heat resistance. Therefore, the isolation layer 12 can be a polypropylene (PP) film, a polyester (PET) film, a polyimide (PI) film, etc. The specific selection of the isolation layer 12 should be determined according to the actual working conditions of the capacitor, and this embodiment does not make specific limitations here.

[0046] The isolation layer 12 divides the capacitor core 2 into a plurality of capacitor core groups, each of which includes a plurality of capacitor cores 2. The number of the capacitor core groups and the number of the capacitor cores 2 contained in the capacitor core groups are determined according to actual needs, and are not specifically limited in this embodiment. A one-way valve 13 is provided on the isolation layer, and the one-way valve 13 is used to balance the pressure difference between adjacent capacitor core groups. The one-way valve 13 can be a diaphragm one-way valve, a spring one-way valve, or a disc one-way valve. Preferably, the one-way valve 13 is a diaphragm one-way valve. When a pressure difference occurs between adjacent capacitor core groups, the pressure difference forces the diaphragm one-way valve to deform, thereby opening a small hole or channel to allow gas to pass between adjacent capacitor core groups. When the pressure difference between the capacitor core groups is eliminated, the diaphragm one-way valve returns to its original form and re-isolates different capacitor core groups. The specific location and number of the one-way valve 13 to be installed are determined according to actual needs, and are not specifically limited in this embodiment.

[0047] Specifically, the dry film flexible capacitor is provided with 2y connectors and y capacitor core groups. For each capacitor core group, its positive electrode is electrically connected to the fifth connector, and its negative electrode is electrically connected to the sixth connector. At this time, for each capacitor core group, the fifth connector is the positive electrode of the capacitor core group, and the sixth connector is the negative electrode of the capacitor core group. It can be understood that the 2y connectors are divided into y positive connectors and y negative connectors. After the y positive connectors pass through y positive switch components, the positive electrodes of the capacitors connected in parallel are connected to the lead-out terminals of the corresponding polarities; after the y negative connectors pass through y negative switch components, the negative electrodes of the capacitors connected in parallel are connected to the lead-out terminals of the corresponding polarities. When the external circuit needs to be adjusted, protected, tested, fault-handled, etc., the positive switch components and negative switch components corresponding to the same group or multiple groups of capacitor cores are disconnected, so as to realize the adjustment of the capacitor capacitance, and meet the needs of dynamic circuit adjustment.

[0048] Furthermore, the housing 1 is provided with a plurality of pressure relief valves 14, the installation positions of the pressure relief valves 14 correspond to the capacitor core group, and are in communication with the inside of the capacitor core group, that is, the pressure relief valves 14 are in communication with the internal area isolated by the isolation layer 12, and the pressure relief valves 14 can be spring pressure-regulating pressure relief valves or pneumatic pressure-regulating pressure relief valves. Since the pneumatic pressure-regulating pressure relief valve can accurately adjust the action threshold value by the control system, the pressure relief valves 14 are preferably pneumatic pressure-regulating pressure relief valves.

[0049] A sensor is disposed inside the housing 1 , and the sensor is used to control the action threshold of the pressure relief valve 14 . The sensor may be a resistive pressure sensor, a piezoresistive pressure sensor, or a piezoelectric pressure sensor.

[0050] Specifically, the method in which the sensor controls the action threshold of the pressure relief valve 14 is: Obtaining pressure data corresponding to each sub-area inside the housing 1; Determine whether the pressure data is greater than the first threshold value. If so, it is considered that the pressure in the sub-region corresponding to the pressure data is too high and is a high-pressure region. It is necessary to reduce the action threshold of the pressure relief valve corresponding to the sub-region, and quickly reduce the pressure in the sub-region to avoid the capacitor core 2 in the region from being affected by the high pressure and failing. The first pressure relief valve corresponding to the pressure data is set as the first action threshold. At the same time, since the sub-regions inside the housing 1 are interconnected, the second pressure relief valve adjacent to the first pressure relief valve is set as the second action threshold. By reducing the action threshold of the pressure relief valve corresponding to the sub-region adjacent to the high-pressure region, the adjacent sub-regions cooperate to complete the pressure relief action, further reducing the time of the high pressure affecting the capacitor core 2.

[0051] If the pressure data is less than the first threshold, it is further determined whether the pressure data is greater than the second threshold. If so, it is considered that the pressure in the sub-region corresponding to the pressure region is too high and is a sub-high pressure region. The third pressure relief valve corresponding to the pressure data is set to the third action threshold to further improve the response efficiency of the pressure relief valve.

[0052] Among them, the first action threshold is less than the second action threshold, the second action threshold is less than or equal to the third action threshold, the first threshold is greater than the second threshold, and the specific values ​​of the above variables are determined according to actual needs, and this embodiment does not make specific limitations here.

[0053] Furthermore, the housing 1 is provided with a plurality of mounting terminals, and the mounting terminals are used to install the dry-type thin-film flexible DC capacitor to the corresponding position of the external circuit. The mounting terminals can select M12 internal thread terminals, and the number of the mounting terminals and their specific positions on the housing 1 are determined according to actual needs, and are not specifically limited in this embodiment. Among them, a vibration sensor is provided at a position adjacent to the housing 1 of the dry-type thin-film flexible DC capacitor and the mounting terminal. Installing the vibration sensor adjacent to the mounting terminal can improve the recognition sensitivity of the vibration sensor and monitor the mechanical vibrator conditions of the dry-type thin-film flexible DC capacitor during operation, so as to perform preventive maintenance on the dry-type thin-film flexible DC capacitor in a timely manner. The vibration sensor can be a capacitive vibration sensor, or a magnetoelectric vibration sensor or any other existing sensor that can identify equipment vibration. The specific type is determined according to actual needs, and is not limited in this embodiment.

[0054] Although the preferred embodiments of the present invention have been described in detail herein, those skilled in the art, after understanding the basic creative concepts of the present invention, can make other changes and modifications to these embodiments without departing from the technical concept and core idea of ​​the present invention. Therefore, the attached claims should be interpreted as covering not only the preferred embodiments, but also all changes and modifications within the scope of the present invention.

[0055] Obviously, based on the technical principles and innovations of the present invention, those skilled in the art can make various reasonable changes and modifications to the present invention in the process of implementing the present invention, and these changes and modifications do not exceed the spirit and scope of the present invention. In other words, any modification and variation made within the scope of the claims of the present invention and their equivalents should be regarded as an integral part of the present invention. Therefore, the protection scope of the present invention is not limited to the specifically described embodiments, but should also include all technically feasible changes and adjustments, as long as these changes and adjustments do not deviate from the basic concept and technical solution of the present invention.

Claims

1. A dry-type thin-film flexible capacitor, comprising a housing (1), a lead terminal (3), and a plurality of capacitor cores (2) installed inside the housing (1), wherein the capacitor cores (2) are all electrically connected to an external circuit via the lead terminal (3), and characterized in that: The capacitor core (2) comprises a first electrode layer (4), a first base layer (5), a second electrode layer (6) and a second base layer (7) which are stacked, and a protective layer (8) is provided at the edge of the first base layer (5) and / or the second base layer (7).

2. A dry film flexible capacitor according to claim 1, characterized in that: One side of the first electrode layer (4) and / or the second electrode layer (6) is thicker than the other side, and the first electrode layer (4) and the second electrode layer (6) are symmetrically arranged.

3. A dry film flexible capacitor according to claim 1, characterized in that: The first electrode layer (4) comprises a third electrode layer (9) and a fourth electrode layer (10) which are insulated from each other, and the thickness of the third electrode layer (9) and the fourth electrode layer (10) close to the center side of the first base layer (5) is smaller than the thickness of the third electrode layer (9) and the fourth electrode layer (10) close to the edge side of the first base layer (5).

4. A dry film flexible capacitor according to claim 3, characterized in that: The thickness of the second electrode layer (6) at the center is greater than the thickness of the second electrode layer (6) at the edge.

5. A dry film flexible capacitor according to claim 3, characterized in that: An insulating layer (11) is provided between the third electrode layer (9) and the fourth electrode layer (10), and a breakdown voltage of the insulating layer (11) is greater than a breakdown voltage of the first base layer (5) and / or the second base layer (7).

6. A dry film flexible capacitor according to claim 1, characterized in that: The dry-type thin-film flexible capacitor further comprises a connecting piece, wherein the connecting piece is arranged inside the housing (1), the capacitor core (2) is electrically connected to the lead terminal (3) via the connecting piece, and a switch is arranged between the connecting piece and the lead terminal (3).

7. A dry film flexible capacitor according to claim 1, characterized in that: An isolation layer (12) is provided inside the housing (1), the isolation layer (12) is used to divide the capacitor core (2) into a plurality of capacitor core groups, and a one-way valve (13) is provided on the isolation layer (12).

8. A dry film flexible capacitor according to claim 7, characterized in that: The housing (1) is provided with a plurality of pressure relief valves (14), and the installation positions of the pressure relief valves (14) correspond to the capacitor core group.

9. A dry film flexible capacitor according to claim 8, characterized in that: A sensor is provided inside the housing (1), the installation position of the sensor corresponding to the capacitor core group, and the sensor is used to control the action threshold of the pressure relief valve (14).

10. A dry film flexible capacitor according to claim 9, characterized in that: The method in which the sensor controls the action threshold of the pressure relief valve (14) is: Obtaining pressure data corresponding to each capacitor core group inside the housing (1); Determine whether the pressure data is greater than a first threshold value, and if so, set a first pressure relief valve corresponding to the pressure data as a first action threshold value, and set a second pressure relief valve adjacent to the first pressure relief valve as a second action threshold value; If not, it is determined whether the pressure data is greater than a second threshold value, and if so, the third pressure relief valve corresponding to the pressure data is set as a third action threshold value.

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