A dry film flexible DC capacitor

Abstract

The present invention discloses a dry-type thin-film flexible DC capacitor, which relates to the field of capacitors. The electrode layers and the base layers stacked in the capacitor core are optimized. A protective layer is provided at the edge of the base layer, and at the same time, the thickness of the edge of the electrode layer is greater than that of the middle part of the electrode layer to improve the connection stability of the capacitor core. For the capacitor core with an internal series structure, an insulating layer is provided between the internal series electrodes to improve the voltage withstand performance of the capacitor. A pressure sensor is also provided inside the capacitor, and a plurality of pressure relief valves are arranged in partitions inside the capacitor. The action threshold of the pressure relief valve is controlled by the pressure sensor to improve the response rate of the pressure relief valve and timely disperse the local high voltage generated inside the flexible DC capacitor. The capacitor core groups installed inside the flexible DC capacitor are sequentially connected to an external circuit through connectors, switch elements, and lead terminals, so that the capacitance of the flexible DC capacitor is adjustable.

Description

Technical Field

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

[0002] With the widespread application of domestic ionization electron technology in the fields of smart grid, flexible DC power transmission, high-voltage high-power frequency converters, rail transit, etc., flexible DC capacitors, as one of the core components of converters, have a wide market demand, and higher requirements are put forward for the stability and reliability of flexible DC capacitors. Most of the existing flexible DC capacitors are metallized film capacitors. Such capacitors do not use liquid electrolytes. The internal metallized film coating is used as the electrode. 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. The dry film flexible DC capacitor has been favored by the market for its 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 edges of the metal film used as the electrode material will be exposed on the two circular end faces of the capacitor core. By performing a metallizing treatment 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 basis for pin welding and external connection of the capacitor. Good metallizing treatment can not only improve the working stability of the capacitor, but also effectively reduce the contact resistance during the welding of the capacitor core, enhancing the overall performance of the flexible DC capacitor. However, in actual production, due to the limitation of the metallizing process accuracy, the metallized layer may incorrectly extend to the inner layer area of the capacitor core, resulting in accidental contact or conduction between the positive and negative electrodes of the flexible DC capacitor, forming a short circuit between the electrodes. Summary of the Invention

[0004] In order to avoid the metal spray coating in the metallizing process covering the inner layer area of the capacitor core, resulting in accidental contact or conduction between the positive and negative electrodes of the capacitor and forming a short circuit, the present invention provides a dry film flexible DC capacitor, including a housing, lead terminals, and a plurality of capacitor cores installed inside the housing. The capacitor cores are all 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 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 DC capacitor provided by the present invention, the capacitor core installed inside the housing 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. 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 electrodes of the capacitor, and the first base layer between the first electrode layer and the second electrode layer is the dielectric between the electrodes. The second base layer prevents the first electrode layer and the second electrode layer from conducting after winding. After winding, the two ends of the capacitor core are sprayed with gold to form a sprayed gold layer as the basis for the electrical connection between the capacitor core and the external circuit. The protective layers at the edges of the first electrode layer and the second base layer are exposed on a circular end face of the capacitor core, that is, the positive electrode of the capacitor; the protective layers at the edges of the second electrode layer and the first base layer are exposed on the other circular end face of the capacitor core, that is, the negative electrode of the capacitor. The setting of the protective layer prevents the sprayed gold layer from contacting the first electrode layer and the second electrode layer simultaneously during the gold spraying process, resulting in the short-circuit failure of the positive and negative electrodes of the capacitor core, and improves the working reliability of the dry film flexible DC capacitor.

[0006] Furthermore, in order to increase the contact area between the electrode layer of the capacitor core and the sprayed gold layer in the dry film flexible DC capacitor and ensure good electrical connection between the sprayed gold layer and 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 that of the other side. 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 the other circular end face of the capacitor core. The edge of the thicker electrode layer ensures a reliable electrical connection between the sprayed gold layer and the first electrode layer and / or the second electrode layer, reduces the contact resistance generated during the welding of the capacitor core, and effectively ensures the stable electrical connection between the capacitor core and the external circuit. At the same time, the thickness of the first electrode layer and / or the second electrode layer gradually decreases from the edge to the middle. It can be understood that the sheet resistance of the first electrode layer and / or the second electrode layer from the edge to the middle increases accordingly, enhancing the overall voltage withstand capacity of the dry film flexible DC capacitor.

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

[0008] Among them, d is the medium thickness, k is the dielectric constant, b is the effective width of the electrode layer, and n is the number of capacitors. To further improve the performance of the dry film flexible DC 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 electrode layer of the capacitor core 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 insulating 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 one 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 film flexible DC 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 does not participate in the formation of capacitance and there is no voltage acting on the corresponding interval area between the third electrode layer and the fourth electrode layer, and it is only used for the series connection of the internal capacitors of 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 center of the second electrode layer is greater than the thickness of 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, so as to avoid breakdown between the third electrode layer and the fourth electrode layer due to the passage of large current during the operation of the capacitor, resulting in capacitor failure, 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 operation. To ensure that the insulating layer can bear the electric field pressure first when the capacitor withstands large current or high voltage, the insulating layer should be made of a material with high breakdown strength and good heat resistance performance, and 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, and to ensure the safety of the dry film flexible DC capacitor under high load conditions.

[0011] Furthermore, in existing flexible DC capacitors, all the capacitor cores inside the capacitor are connected in parallel with each other through an integrated copper bar, and then wrapped with electromagnetic shielding material and installed inside the flexible DC capacitor housing, so that the capacitance of the flexible DC capacitor is fixed, and the specific value of its capacitance depends on the size and quantity of the capacitor cores installed inside. However, 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; also, 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 connecting piece is also provided inside the housing of the dry film flexible DC capacitor. The connecting piece is arranged inside the housing, and the capacitor cores are installed inside the housing of the dry film flexible DC capacitor. After being connected in parallel with each other through the connecting piece, they are electrically connected to the lead-out terminals, and finally electrically connected to the external circuit through the lead-out terminals. At the same time, a switch is provided between the connecting piece and the lead-out terminals. The switch is used to control the electrical connection between the capacitor cores and the external circuit, so as to meet the need of dynamically adjusting circuit parameters in applications such as circuit regulation, protection, testing, and fault handling.

[0012] Furthermore, there are multiple capacitor cores inside the housing of the dry film flexible DC capacitor. In order to effectively reduce the electrical interference between the capacitor cores and prevent the performance degradation of the capacitor caused by electric field coupling or electric breakdown, an isolation layer is provided inside the housing. The isolation layer is used to divide the capacitor cores into multiple independent capacitor core groups, thus effectively avoiding the mutual influence between the capacitor cores and reducing the potential risks brought by electric field coupling, and ensuring the working stability and performance reliability of each capacitor core group. In addition, in order to ensure the pressure balance between the capacitor core groups inside the capacitor and prevent the capacitor cores from being damaged due to excessive local pressure inside the capacitor, a check valve is also provided on the isolation layer. The setting 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 check valve.

[0013] Furthermore, in order to disperse the pressure inside the housing of the dry film capacitor and improve the pressure relief efficiency of the pressure relief valve, multiple pressure relief valves are provided on the housing, and the installation positions of the pressure relief valves on the housing correspond to the capacitor core groups.

[0014] Furthermore, during the operation of the dry film flexible DC capacitor, local heat may be generated due to reasons such as poor contact of some capacitor cores, which may further lead to uneven pressure distribution inside the housing. In order to monitor the pressure inside the housing and timely disperse the local high pressure inside the housing, a sensor is provided inside the housing. The installation position of the sensor corresponds to the capacitor core group, and the sensor is used to control the action threshold of the pressure relief valve.

[0015] Among them, the method for the sensor to control the action threshold of the pressure relief valve is as follows:

[0016] Obtain the pressure data corresponding to each capacitor core group inside the housing;

[0017] Judge whether the pressure data is greater than the first threshold. If so, set the first pressure relief valve corresponding to the pressure data as the first action threshold, and set the second pressure relief valve adjacent to the first pressure relief valve as the second action threshold;

[0018] If not, then judge whether the pressure data is greater than the second threshold. If so, set the third pressure relief valve corresponding to the pressure data as the third action threshold.

[0019] Furthermore, during the operation of the dry film flexible DC capacitor, especially in the case of high power, fast switching or high frequency, mechanical vibration may occur and affect its internal structure. In order to monitor the mechanical vibration of the dry film flexible DC 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.

[0020] One or more technical solutions provided by the present invention have at least the following technical effects or advantages:

[0021] (1) Through the optimized design of the electrode layer and the base layer structure in the capacitor core, the two ends of the wound capacitor core respectively correspond to the positive and negative electrodes of the capacitor, ensuring a reliable electrical connection between the metallized layer and the electrode layer and good electrode contact.

[0022] (2) A pressure sensor is provided inside the flexible DC capacitor, and multiple pressure relief valves are set in zones, which can effectively monitor the pressure inside the capacitor housing, and control the action threshold of the pressure relief valve through the pressure sensor, improve the response rate of the pressure relief valve, and timely disperse the local high pressure generated inside the flexible DC capacitor.

[0023] (3) An isolation layer is provided inside the flexible DC capacitor to divide the capacitor cores inside the flexible DC capacitor into multiple independent capacitor core groups, thereby effectively avoiding the mutual influence between the capacitor cores, reducing the potential risk brought by electric field coupling, and ensuring the working stability and performance reliability of the flexible DC capacitor.

[0024] (4) Multiple capacitor cores installed inside the flexible DC capacitor are connected in parallel with each other through connecting pieces, and finally connected to the external circuit through the switch piece and the lead terminal, 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. Description of the Drawings

[0025] The accompanying drawings described herein are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the present invention, but do not limit the embodiments of the present invention;

[0026] Figure 1 It is a schematic structural diagram of a dry film flexible DC capacitor in the present invention;

[0027] Figure 2 It is a schematic structural diagram of a capacitor core in the present invention;

[0028] Figure 3 It is a schematic structural diagram of an internally series-connected capacitor core in the present invention;

[0029] Among them, 1 - housing, 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 - isolation layer, 13 - one-way valve, 14 - pressure relief valve. Detailed implementation manners

[0030] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0031] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0032] Embodiment 1

[0033] Please refer to Figure 1-2 , Embodiment 1 of the present invention provides a dry film flexible DC capacitor, including a housing 1, a lead terminal 3, and a plurality of capacitor cores 2 installed inside the housing 1. The capacitor cores 2 are all electrically connected to an external circuit through the lead terminal 3. The capacitor core 2 includes a first electrode layer 4, a first base layer 5, a second electrode layer 6, and a second base layer 7 stacked together, and a protective layer 8 is provided at the edge of the first base layer 5 and / or the second base layer 7.

[0034] Specifically, the capacitor cores 2 installed inside the housing 1 are wrapped with polyester films with a thickness of more than 0.2 mm (single-layer breakdown voltage resistance ≥ 12 kVdc) for more than 2 layers, and epoxy resin with a thickness of more than 5 mm (breakdown voltage ≥ 20 kV / mm) is poured between the housing 1 and the wrapped capacitor cores 2. Both the polyester film and the epoxy resin layer are used to protect the capacitor cores 2 from being insulated from the outside.

[0035] Specifically, the dry film flexible DC capacitor is provided with 8 lead terminals, and M12 internal thread lead terminals are specifically selected. Taking 4 lead terminals as one pole, the dry film flexible DC capacitor is connected to an external circuit. 16 mounting terminals are provided on the side of the dry film flexible DC capacitor housing, fully ensuring the strength requirements during the installation and use of the dry film flexible DC capacitor. Among them, the specific quantities of the lead terminals and the mounting terminals can be adjusted according to the specific requirements of the working circuit and environment of the dry film flexible DC capacitor, and no specific limitation is made in this embodiment.

[0036] Specifically, please continue to refer to Figure 1 The housing 1 of the dry film flexible DC capacitor is preferably made of 304 non-magnetic stainless steel, with high strength, no rusting, and 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 pressure that the welding strength can withstand is greater than 40 kPA. The interior of 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 no specific limitation is made in this embodiment.

[0037] The first electrode layer 4 and / or the second electrode layer 6 can be any metal electrode layer capable of forming an electrode, such as titanium, aluminum, zinc, etc., or any non-metal electrode layer capable of forming 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 no specific limitation is made in this embodiment; the first base layer 5 and / or the second base layer 7 can be a polypropylene film, a polyester film, or a polyimide film. The first base layer 5 and / or the second base layer 7 are preferably high-insulation polypropylene films, with an electric strength of 800 V / μm, a dielectric loss of about 0.02%, and a temperature resistance performance of up to 125 °C. Preferably, the thickness of the first base layer 5 and / or the second base layer 7 is 3.4 - 10 μm, and the width of the first base layer 5 and / or the second base layer 7 is determined according to actual needs, and no specific limitation is made in this embodiment. 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 methods such as evaporation coating, sputtering, or spin coating. The specific method is determined according to the type of the electrode layer and actual needs, and no specific limitation is made in this embodiment.

[0038] 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. The second base layer 7 prevents the first electrode layer 4 and the second electrode layer 6 from being conducted after the winding operation. Please refer toFigure 2 After 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. The circular end face is subjected to gold spraying treatment so that the first gold-sprayed layer is electrically connected to the first electrode layer 4, and the first gold-sprayed layer is isolated from the second electrode layer 6 through the protective layer 8 at the edge of the second base layer 7, thereby obtaining a positive capacitor electrode. 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. The circular end face is subjected to gold spraying treatment so that the second gold-sprayed layer is electrically connected to the second electrode layer 6, and the second gold-sprayed layer is isolated from the first electrode layer 4 through the protective layer 8 at the edge of the first base layer 5, thereby obtaining a negative capacitor electrode. 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 setting of the protective layer 8 avoids the short-circuit failure of the positive and negative electrodes of the capacitor core 2 caused by the gold-sprayed layer contacting the first electrode layer 4 and the second electrode layer 6 simultaneously during the gold spraying process, and improves the working reliability of the dry film flexible DC capacitor.

[0039] Further, please continue to refer to Figure 2 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, that is, the thicker side of the first electrode layer 4 is opposite to the thicker side of the second electrode layer 6. In the wound capacitor core 2, the thicker side of the first electrode layer 4 is exposed on a circular end face of the capacitor core 2. The circular end face is subjected to gold spraying treatment so that the first gold-sprayed layer is electrically connected to the first electrode layer 4, and the contact area between the first gold-sprayed layer and the first electrode layer 4 is enlarged, thereby obtaining a positive capacitor electrode; the thicker side of the second electrode layer 6 is exposed on another circular end face of the capacitor core 2. The circular end face is subjected to gold spraying treatment so that the second gold-sprayed layer is electrically connected to the second electrode layer 6, and the contact area between the second gold-sprayed layer and the second electrode layer 6 is enlarged. The edges of the thicker first electrode layer 4 and / or the second electrode layer 6 ensure the reliability of the electrical connection between the gold-sprayed layer and the electrode, reduce the contact resistance between the gold-sprayed layer and the electrode layer, and thereby improve 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.

[0040] Embodiment 2

[0041] Please refer to Figure 3, Embodiment 2 of the present invention provides a dry film flexible DC capacitor. On the basis of 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.

[0042] Among them, the stacked part of the third electrode layer 9 and the second electrode layer 6 correspondingly forms a first capacitor, and the stacked part of the fourth electrode layer 10 and the second electrode layer 6 correspondingly forms a second capacitor. The first capacitor and the second capacitor are connected in series with each other through the center of the second electrode layer 6. For a flexible DC capacitor, the main way to improve the capacitor's tolerance to large discharge currents is to increase the effective length of the metallized film electrode.

[0043] According to the calculation formula of the electrode effective length L and the capacitance C: It can be known 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 separating the first electrode layer 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 electrode effective length increases to 2L, effectively improving the capacitor's tolerance to large discharge currents.

[0044] Specifically, 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. Gold spraying is performed on this circular end face 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 positive electrode of the first capacitor, to obtain the positive electrode of the series-connected capacitor; 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 the other circular end face of the capacitor core 2. Gold spraying is performed on this circular end face 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 negative electrode of the second capacitor, to obtain the negative electrode of the series-connected capacitor. The specific thickness of the third electrode layer 9 and / or the fourth electrode layer 10 is determined according to actual needs and is not specifically limited in this embodiment.

[0045] Furthermore, please continue to refer to Figure 3, the middle part of the second electrode layer 6 does not participate in the formation of the capacitance of the capacitor core 2 and has no voltage applied. It is only used to connect the first capacitor and the second capacitor inside the capacitor core 2 in series. To ensure the stable 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.

[0046] Further, please continue to refer to Figure 3 , to ensure good insulation performance between the third electrode layer 9 and the fourth electrode layer 10 and avoid breakdown between the third electrode layer 9 and the fourth electrode layer 10 during the operation of the capacitor due to the passage of a large current, resulting in capacitor failure, an insulating layer 11 is provided between the third electrode layer 9 and the fourth electrode layer 10. When the capacitor withstands a large current or 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 prevent the third electrode layer 9 and the fourth electrode layer 10 from being broken down prior to the first electrode layer 4 and the second electrode layer 6, improving the safety of the dry film flexible DC capacitor under high load conditions.

[0047] 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 serves as the dielectric between the first electrode layer 4 and the second electrode layer 6. Under high power and large 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 being broken down, improving the usability of the dry film flexible DC capacitor.

[0048] Further, please continue to refer to Figure 3 , the dry film flexible DC capacitor further includes a connecting member. The connecting member is arranged inside the housing 1. The capacitor cores 2 are all electrically connected to the lead terminals 3 through the connecting member, and a switching member is provided between the connecting member and the lead terminals 3.

[0049] Specifically, two connecting pieces and multiple capacitor cores 2 are provided inside the dry-film flexible DC capacitor. The positive electrodes of the multiple capacitor cores 2 are all electrically connected to the first connecting piece, and the positive electrodes of the multiple capacitor cores 2 are all electrically connected to the second connecting piece. At this time, the first connecting piece is the positive electrode of the dry-film flexible DC capacitor, and the second connecting piece is the negative electrode of the dry-film flexible DC capacitor. The lead terminals on the dry-film flexible DC capacitor are divided into two poles. After passing through the first switching element, the first connecting piece connects the positive electrodes of the capacitor cores 2 in parallel to the lead terminal of the corresponding polarity; after passing through the second switching element, the second connecting piece connects the negative electrodes of the capacitor cores 2 in parallel to the lead terminal of the corresponding polarity. When operations such as adjustment, protection, testing, and fault handling are required in the external circuit, the first switching element and the second switching element are disconnected, and the dry-film flexible DC capacitor is equivalent to an open circuit, meeting the needs of circuit dynamic adjustment.

[0050] Specifically, 2x connecting pieces and multiple capacitor cores are provided inside the dry-film flexible DC capacitor. The multiple capacitor cores are divided into x groups. For each group of capacitor cores, its positive electrode is electrically connected to the third connecting piece, and its negative electrode is electrically connected to the fourth connecting piece. At this time, for each group of capacitor cores, the third connecting piece is the positive electrode after the parallel connection of the capacitor cores in this group, and the fourth connecting piece is the negative electrode after the parallel connection of the capacitor cores in this group. It can be understood that the 2x connecting pieces are divided into x positive connecting pieces and x negative connecting pieces. After passing through x positive switching elements respectively, the x positive connecting pieces connect the positive electrodes of the capacitors in parallel to the lead terminal of the corresponding polarity; after passing through x negative switching elements respectively, the x negative connecting pieces connect the negative electrodes of the capacitors in parallel to the lead terminal of the corresponding polarity. When operations such as adjustment, protection, testing, and fault handling are required in the external circuit, the positive switching elements and negative switching elements corresponding to the same group or multiple groups of capacitor cores are disconnected, and the capacitance of the capacitor can be adjusted, meeting the needs of circuit dynamic adjustment.

[0051] Embodiment 3

[0052] Please refer to Figure 1 , Embodiment 3 of the present invention provides a dry-film flexible DC capacitor. On the basis of Embodiment 1 and / or Embodiment 2, an isolation layer 12 is provided inside the housing 1. The isolation layer 12 is used to divide the capacitor cores 2 into multiple capacitor core groups, and a one-way valve 13 is provided on the isolation layer 12.

[0053] Among them, the isolation layer 12 is used to provide electrical isolation. It should have good insulation performance, chemical stability, and heat resistance when set inside the flexible DC capacitor. 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 capacitance working conditions, and no specific limitation is made in this embodiment.

[0054] The isolation layer 12 divides the capacitor core 2 into multiple capacitor core groups. Each capacitor core group includes multiple capacitor cores 2. The number of capacitor core groups and the number of capacitor cores 2 included in each capacitor core group are determined according to actual needs, and no specific limitation is made in this embodiment. A check valve 13 is provided on the isolation layer. The check valve 13 is used to balance the pressure difference between adjacent capacitor core groups. The check valve 13 can be a diaphragm check valve, a spring check valve, or a disc check valve. Preferably, the check valve 13 is a diaphragm check valve. When a pressure difference appears between adjacent capacitor core groups, the pressure difference forces the diaphragm check valve to deform, thereby opening a small hole or channel to allow gas to pass between adjacent capacitor core groups. After the pressure difference between the capacitor core groups is eliminated, the diaphragm check valve returns to its original shape and separates different capacitor core groups again. The specific installation position and number of the check valve 13 are determined according to actual needs, and no specific limitation is made in this embodiment.

[0055] Specifically, there are 2y connectors and y capacitor core groups inside the dry film flexible direct current capacitor. 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 respectively, the connected-in-parallel capacitor positive electrodes are connected to the lead terminals of the corresponding polarities; after the y negative connectors pass through y negative switch components respectively, the connected-in-parallel capacitor negative electrodes are connected to the lead terminals of the corresponding polarities. When operations such as adjustment, protection, testing, and fault handling are required in the external circuit, disconnecting the positive switch components and negative switch components corresponding to the same group or multiple groups of capacitor cores can adjust the capacitance of the capacitor and meet the needs of dynamic circuit adjustment.

[0056] Furthermore, a plurality of pressure relief valves 14 are provided on the housing 1. The installation positions of the pressure relief valves 14 correspond to the capacitor core groups and are internally connected to the capacitor core groups, that is, the pressure relief valves 14 are connected to the internal area isolated by the isolation layer 12. The pressure relief valves 14 can be spring pressure regulating relief valves or pneumatic pressure regulating relief valves. Since the pneumatic pressure regulating relief valve can accurately adjust the action threshold by the control system, preferably the pressure relief valve 14 is a pneumatic pressure regulating relief valve.

[0057] A sensor is provided inside the housing 1. The sensor is used to control the action threshold of the pressure relief valve 14. The sensor can be a resistive pressure sensor, a piezoresistive pressure sensor, a piezoelectric pressure sensor, etc.

[0058] Specifically, the method for the sensor to control the action threshold of the pressure relief valve 14 is as follows:

[0059] Obtain the pressure data corresponding to each sub-region inside the housing 1;

[0060] Judge whether the pressure data is greater than the first threshold. If so, it is considered that the pressure in the sub-region corresponding to the pressure data is too high, which is a high-pressure region. It is necessary to reduce the action threshold of the pressure relief valve corresponding to this sub-region to quickly reduce the pressure in this sub-region to avoid the capacitor core 2 in the region being affected by high pressure and failing. Set the first pressure relief valve corresponding to the pressure data to the first action threshold. At the same time, since the internal sub-regions of the housing 1 are interconnected, set the second pressure relief valve adjacent to the first pressure relief valve to 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 influence time of high pressure on the capacitor core 2.

[0061] If the pressure data is less than the first threshold, continue to judge whether the pressure data is greater than the second threshold. If so, it is considered that the pressure in the sub-region corresponding to this pressure region is relatively large, which is a sub-high-pressure region. Set the third pressure relief valve corresponding to the pressure data to the third action threshold to further improve the response efficiency of the pressure relief valve.

[0062] 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, and the first threshold is greater than the second threshold. The specific values of the above variables are determined according to actual needs and are not specifically limited in this embodiment.

[0063] Further, a plurality of mounting terminals are provided on the housing 1. The mounting terminals are used to mount the dry film flexible DC capacitor to corresponding positions of an external circuit. The mounting terminals can be M12 internal thread terminals. 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. Wherein, a vibration sensor is provided at a position adjacent to the mounting terminals on the housing 1 of the dry film flexible DC capacitor. Installing the vibration sensor at a position adjacent to the mounting terminals can improve the recognition sensitivity of the vibration sensor and monitor the situation of the dry film flexible DC capacitor being affected by a mechanical vibrator during operation, so as to perform preventive maintenance on the dry film flexible DC capacitor in a timely manner. The vibration sensor can be a capacitive vibration sensor, a magnetoelectric vibration sensor, or any other existing sensor capable of recognizing device vibration, and the specific type is determined according to actual needs and is not limited in this embodiment.

[0064] Although the preferred embodiments of the present invention have been described in detail herein, those skilled in the art can, after understanding the basic creative concepts of the present invention, make other changes and modifications to these embodiments without departing from the technical concept and core idea of the present invention. Therefore, the appended claims should be construed as covering not only the preferred embodiments but also all changes and modifications that fall within the scope of the present invention.

[0065] Obviously, based on the technical principles and innovation points of the present invention, those skilled in the art can make various reasonable changes and variations during the implementation of the present invention, and these changes and variations do not exceed the spirit and scope of the present invention. In other words, any modification and variation within the scope of the claims of the present invention and its equivalent technologies should be regarded as an integral part of the present invention. Therefore, the protection scope of the present invention not only includes the specifically described embodiments but also 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 film flexible DC capacitor, comprising a housing (1), lead terminals (3), and a plurality of capacitor cores (2) and a plurality of connectors installed inside the housing (1). The capacitor cores (2) are all electrically connected to an external circuit through the lead terminals (3), and it is characterized in that, The capacitor core (2) includes 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); The connecting member is arranged inside the housing (1), and the capacitor cores (2) are all electrically connected to the lead terminals (3) through the connecting member, and a switching member is provided between the connecting member and the lead terminals (3); An isolation layer (12), a pressure relief valve (14), and a sensor are provided inside the housing (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). The installation positions of the pressure relief valve (14) and the sensor correspond to the capacitor core groups, and the sensor is used to control the action threshold of the pressure relief valve (14); The method for the sensor to control the action threshold of the pressure relief valve (14) is as follows: Obtain the pressure data corresponding to each capacitor core group inside the housing (1); Judge whether the pressure data is greater than the first threshold. If so, set the first pressure relief valve corresponding to the pressure data as the first action threshold, and set the second pressure relief valve adjacent to the first pressure relief valve as the second action threshold; If not, then judge whether the pressure data is greater than the second threshold. If so, set the third pressure relief valve corresponding to the pressure data as the third action threshold.

2. The dry film flexible DC 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 DC capacitor according to claim 1, characterized in that, 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).

4. The dry film flexible DC capacitor according to claim 3, wherein, 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. The dry film flexible DC 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 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).

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