Metallized film for maintaining capacitance stability of capacitor and capacitor

Abstract

The invention discloses a metallized film used for maintaining the capacitance stability of a capacitor and the capacitor, and belongs to the technical field of metallized film capacitors, the metallized film is divided into a T-shaped region and a grid region by an isolation strip, the metallized film is divided into a metal thickening edge, the T-shaped region, the isolation strip, the grid region and an edge reserving region from left to right, the isolation strip is provided with an isolation strip fuse, and the isolation strip fuse is provided with an isolation strip fuse. The metallized film is adopted to prepare the capacitor, the capacitor is formed by sequentially stacking and winding a first metallized film, a dielectric layer and a second metallized film, the thickened edge of the first metallized film corresponds to the edge reserving area of the second metallized film, the two layers of metallized film structures are wound in a staggered mode, and the metallized film structure is formed. According to the invention, the capacitance loss caused by self-healing of the capacitance of the metallized film capacitor can be effectively reduced, and the capacitance stability of the self-healing capacitor is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallized film capacitors, and more specifically, relates to a metallized film and a capacitor for maintaining the stability of capacitor capacitance. Background Art

[0002] Metallized film capacitors have the advantages of low loss, high energy density, and high working reliability. They are widely used in the power industry, electric vehicles, and high-power pulse technology. Metallized film capacitors are made of two layers of metallized film. The electrodes of the metallized film are evaporated on the surface of the medium using vacuum evaporation technology, and the thickness is only nanometers. Due to lattice defects or mechanical damage in the medium, the metallized film has electrical weaknesses. When the external voltage is greater than the critical value, breakdown occurs. Under the action of the breakdown current, the metal electrodes around the breakdown point evaporate, thereby isolating the electrical weaknesses and the capacitor continues to work. The process of self-isolation of electrical weaknesses in metallized film capacitors is called self-healing.

[0003] The self-healing property of the metallized film enables the metallized film capacitor to operate under higher field strengths, improving the energy storage density of the capacitor. However, self-healing will cause the metallized film electrode to degrade, and the capacitance will gradually decrease with the increase in the number of self-healing cycles. At the same time, excessive self-healing current will cause breakdown damage to the multi-layer metallized film of the capacitor or even short-circuit breakdown.

[0004] The metallized safety film mainly divides the electrode based on the original metallized film structure. The original integral metallized electrode is divided into several micro-modules. The modules are directly divided by dielectric strips and connected by extremely narrow metallized electrode channels, which are called fuses. When the self-healing current is normal, the fuse will not operate and the capacitor will work normally. When the self-healing current is too large, the fuse will melt under the Joule heat of the current flowing through it, isolating the fault area, thereby avoiding large-area self-healing and short-circuit breakdown failures.

[0005] The existing safety film structures are mainly divided into T-type safety film, grid-shaped safety film, hexagonal safety film, and reinforced fuse-type safety film. Grid-shaped safety film, hexagonal safety film, and reinforced fuse-type safety film basically belong to the same category of grid-type installation. Their advantages are high sensitivity and small capacity loss. Their disadvantages are low effective utilization area of ​​the plate and high equivalent series resistance (ESR). The single module plate area of ​​the T-type metallized safety film is large. The advantages are low cost and higher effective utilization area of ​​the plate. The disadvantage is large capacity loss after the fuse is activated. The existing technology (publication number: CN 114334457 A) uses a T-type safety film and a grid-type safety film electrode alternating stacking structure. Due to the high ESR of the grid-type safety film, the temperature rise of this type of capacitor is high, which easily causes the capacitor to overheat and melt, resulting in excessive capacity loss. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides an electrode structure design method for a metallized film capacitor, the purpose of which is to solve the technical problem of how to reduce the capacitance loss of the metallized safety film capacitor during operation and improve the capacitance stability of the capacitor, so as to achieve the technical effect of small capacitance loss and high stability of the capacitor.

[0007] In order to achieve the above-mentioned purpose, the present invention provides a metallized film and a capacitor for maintaining the stability of the capacitance of a capacitor. According to a first aspect of the present invention, a metallized film for maintaining the stability of the capacitance of a capacitor is provided. The specific structure is that the metallized film comprises a metal thickened edge, a T-shaped area, an isolation zone, a grid area, and a margin area from left to right, and an isolation zone fuse is arranged on the isolation zone to connect the T-shaped area and the grid area.

[0008] Preferably, the sum of the widths of the T-shaped area and the area corresponding to the metal thickened edge is equal to the sum of the widths of the area corresponding to the mesh area and the edge-retaining area.

[0009] Preferably, the T-type zone includes a T-type zone main insulating zone, a T-type zone secondary insulating zone, a T-type zone main fuse, a T-type zone secondary fuse, and a T-type electrode zone, wherein a T-type zone main fuse is arranged on the T-type zone main insulating zone, the T-type zone main insulating zone and the T-type zone secondary insulating zone divide the T-type zone into T-type electrode zones, and each T-type electrode zone is connected through a T-type zone secondary fuse.

[0010] Preferably, the grid area comprises a grid area secondary fuse, a grid area secondary insulation tape, and a grid electrode area, wherein the grid area secondary insulation tape divides the grid area into grid electrode areas, and each grid electrode area is connected through the grid area secondary fuse.

[0011] Preferably, the ratio of the width of the secondary insulating tape in the T-shaped area to the width of the secondary insulating tape in the grid area is 10-50.

[0012] Preferably, the ratio of the area of ​​a single T-shaped electrode region to the area of ​​a single grid electrode region is 50-100.

[0013] According to another aspect of the present invention, a metallized film capacitor is provided, which specifically comprises a first metallized film, a dielectric layer, and a second metallized film which are stacked in sequence and then wound, and the first metallized film and the second metallized film are the above-mentioned metallized films.

[0014] Preferably, the thickened edge of the first metallized film corresponds to the margin area of ​​the second metallized film, the T-shaped area of ​​the first metallized film corresponds to the grid area of ​​the second metallized film, and the grid area of ​​the first metallized film corresponds to the T-shaped area of ​​the second metallized film, so that the two-layer metallized film structure is staggered and wound.

[0015] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0016] 1. The present invention uses a combination of a T-shaped area and a grid area as a metallized film. When a breakdown short circuit fault occurs in the metallized film, the current passing through the fuse will generate Joule heat. Since the bandwidth of the secondary insulation belt in the grid area is smaller than that of the secondary insulation belt in the T-shaped area, the secondary insulation belt in the grid area will be blown first, isolating the grid from other structures, thereby isolating the fault area. At this time, the loss of capacitance is a small area of ​​the grid area module, so that the loss of capacitance is minimized; when the self-healing current is extremely large, the grid module is blown and cannot prevent the breakdown fault from occurring. At this time, the main fuse in the T-shaped area will be blown, thereby isolating the fault area. The fault area is controlled within the electrode area of ​​a T-type area. At this time, the fuse in the T-type area is actuated to isolate the fault area over a large area, thereby avoiding multi-layer dielectric breakdown of the capacitor and causing greater electrode loss. Therefore, this structure can effectively prevent large-area loss of single-layer and multi-layer metallized electrodes. In addition, since the equivalent series resistance of the T-type area electrode is lower than that of the grid area, the T-type area is combined with the grid area as a metallized film. This structure can effectively overcome the disadvantage of the high equivalent series resistance of the grid-type safety film, effectively reduce the equivalent series resistance of the capacitor, and avoid overheating and melting of the capacitor.

[0017] 2. The capacitor stacking structure of the present invention is a staggered corresponding stack of T-type areas and grid areas. On the one hand, the smaller grid area module area makes the loss capacitance equal to the smaller grid area module area, and the isolation area is larger than the normal self-healing electrical breakdown area; on the other hand, the larger T-type area can isolate the fault area over a large area, thereby isolating the short-circuit fault and avoiding the sintering of the multi-layer film or even the damage of the capacitor. The designed grid area fuse and the T-type area fuse operate in an orderly manner, thereby effectively reducing the electrode area loss and improving the spatial isolation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the metallized film structure is provided for the present invention.

[0019] Figure 2 This is a schematic diagram of the thickness direction of the metallized film provided by the present invention.

[0020] In the figure, 1. metal thickened edge, 2. main fuse in T-type area, 3. T-type electrode area, 4. main insulating zone in T-type area, 5. secondary fuse in T-type area, 6. secondary insulating zone in T-type area, 7. isolation zone, 8. isolation zone fuse, 9. secondary fuse in grid area, 10. secondary insulating zone in grid area, 11. grid electrode area, 12. edge zone, 13. first metallized film, 14. second metallized film, 15. dielectric layer. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] In order to achieve the above object, the present invention provides a metallized film for maintaining the stability of capacitor capacitance, such as Figure 1 As shown, the specific structure is:

[0023] The metallized film is divided into a T-shaped area and a grid area by an isolation belt 7. From left to right, the metallized film is a metal thickened edge 1, a T-shaped electrode area 3, an isolation belt 7, a grid electrode area 11, and a margin area 12. An isolation belt fuse 8 is provided on the isolation belt 7 to connect the T-shaped electrode area and the grid electrode area. The area corresponding to the T-shaped area and the metal thickened edge 1 and the area corresponding to the grid area and the margin area 12 are symmetrically arranged about the isolation belt.

[0024] The T-type zone includes a T-type zone main insulating tape 4, a T-type zone secondary insulating tape 6, a T-type zone main fuse 2, a T-type zone secondary fuse 5, and a T-type electrode zone 3, wherein a T-type zone main fuse 2 is arranged on the T-type zone main insulating tape 4, the T-type zone main insulating tape 4 and the T-type zone secondary insulating tape 6 separate the metal electrode into T-type electrode zones 3, and each T-type electrode zone 3 is connected through the T-type zone secondary fuse 5.

[0025] The grid area includes a grid area secondary fuse 9 , a grid area secondary insulation band 10 , and a grid electrode area 11 , wherein the grid area secondary insulation band 10 separates the metal electrode into grid electrode areas 11 , and each grid electrode area is connected through the grid area secondary fuse 9 .

[0026] The widths of the main insulating tape, isolation tape, secondary insulating tape in the T-shaped area, and secondary insulating tape in the grid area are 2mm, 2mm, 0.4mm, and 0.1mm respectively, and the ratio of the area of ​​a single T-shaped electrode area to the area of ​​a single grid electrode area is 50.

[0027] The above-mentioned metallized film is used to prepare a metallized film capacitor. The capacitor is formed by stacking a first metallized film, a dielectric layer, and a second metallized film in sequence and then winding them. The thickened edge of the first metallized film corresponds to the margin area of ​​the second metallized film, the T-shaped area of ​​the first metallized film corresponds to the grid area of ​​the second metallized film, and the grid area of ​​the first metallized film corresponds to the T-shaped area of ​​the second metallized film. The two-layer metallized film structure is staggered and wound. Its structure is as follows Figure 2 shown.

[0028] When breakdown self-healing occurs, it can be divided into three situations according to the self-healing current and self-healing time.

[0029] 1. Normal self-healing: The square value of the self-healing current integrated by the self-healing time is extremely small, which is not enough to blow the fuse in the grid area. At this time, the loss of the metallized electrode area is only the self-healing area.

[0030] 2. Larger energy self-healing: The square value of the self-healing current is large enough to melt the secondary fuse of the grid area at the breakdown point. At this time, the loss area of ​​the metallized electrode is the module area of ​​the grid area.

[0031] 3. Breakdown short circuit fault: The square value of the self-healing current is extremely large compared to the integral of the self-healing time. The fuse in the grid area cannot prevent the breakdown fault, and the T-type area fuse corresponding to the breakdown point is blown.

[0032] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0033] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A metallized film for maintaining the stability of capacitor capacitance, characterized in that: The metallized film comprises, from left to right, a metal thickened edge (1), a T-shaped area, an isolation zone (7), a grid area, and a margin area (12). An isolation zone fuse (8) is arranged on the isolation zone (7) to connect the T-shaped area and the grid area.

2. A metallized film for maintaining the stability of capacitor capacitance as claimed in claim 1, characterized in that: The sum of the widths of the T-shaped area and the area corresponding to the metal thickened edge (1) is equal to the sum of the widths of the area corresponding to the mesh area and the edge-retaining area (12).

3. A metallized film for maintaining the stability of capacitor capacitance as claimed in claim 1, characterized in that: The T-type area comprises a T-type area main insulating band (4), a T-type area secondary insulating band (6), a T-type area main fuse (2), a T-type area secondary fuse (5), and a T-type electrode area (3), wherein the T-type area main fuse (2) is arranged on the T-type area main insulating band (4), the T-type area main insulating band (4) and the T-type area secondary insulating band (6) divide the T-type area into T-type electrode areas (3), and each T-type electrode area (3) is connected via the T-type area secondary fuse (5).

4. A metallized film for maintaining the stability of capacitor capacitance as claimed in claim 3, characterized in that: The grid area comprises a grid area secondary fuse (9), a grid area secondary insulation band (10), and a grid electrode area (11), wherein the grid area secondary insulation band (10) divides the grid area into grid electrode areas (11), and each grid electrode area (11) is connected via the grid area secondary fuse (9).

5. A metallized film for maintaining the stability of capacitor capacitance as claimed in claim 4, characterized in that: The ratio of the bandwidth of the secondary insulating tape (6) in the T-shaped area to the bandwidth of the secondary insulating tape (10) in the grid area is 10-50.

6. A metallized film for maintaining the stability of capacitor capacitance as claimed in claim 5, characterized in that: The ratio of the area of ​​a single T-shaped electrode area (3) to the area of ​​a single grid electrode area (11) is 50-100.

7. A metallized film capacitor, characterized in that: The capacitor is formed by stacking a first metallized film (13), a dielectric layer (15), and a second metallized film (14) in sequence and then winding them. The first metallized film (13) and the second metallized film (14) are the metallized films described in any one of claims 1 to 6.

8. The metallized film capacitor according to claim 7, wherein: Specifically, the stacking is to make the metal thickened edge (1) of the first metallized film correspond to the margin area (12) of the second metallized film, the T-shaped area of ​​the first metallized film correspond to the grid area of ​​the second metallized film, and the grid area of ​​the first metallized film correspond to the T-shaped area of ​​the second metallized film, so that the two-layer metallized film structure is staggered and wound.

Images