CN217214469U - Alternating current filter film capacitor - Google Patents

Abstract

The utility model relates to the technical field of film capacitors, in particular to an alternating current filter film capacitor, which can increase the over-current capability and improve the operation stability and reliability, comprises a shell, a capacitor core and a potting material are arranged in the shell, the capacitor core is connected with a leading-out electrode, the capacitor is characterized in that the capacitor core body is formed by winding a metalized film, the width of the metalized film is 25-50mm, the metalized film comprises at least two layers of film media, a metal coating is evaporated on the outer surface of each layer of film media to form a capacitor plate, the middle of the outermost layer of the capacitor plate is disconnected, the edges of two sides of the outermost layer of the capacitor plate are thickened layers, alloy metal spraying layers covering the thickened layers and the inner layer of film media are coated on the side surfaces of the two sides of the outermost layer of the capacitor plate, T-shaped insulating white strips which are arranged in parallel are arranged on the capacitor plate, and metal strip fuses are arranged between the end parts of the adjacent T-shaped insulating white strips.

Description

Alternating current filter film capacitor

Technical Field

The utility model relates to a film capacitor technical field specifically is an exchange filtering film capacitor.

Background

In recent years, technology is rapidly developed, a large number of rectifying, frequency conversion and large-scale power electronic equipment are adopted in a power system, the pollution of harmonic waves to a power grid is gradually serious, a common capacitor is easy to damage, and an alternating current filter is more and more required by various power electronic equipment in order to cope with the increasingly serious power grid environment. In a dc power transmission system, in order to filter harmonics generated by a dc control system to avoid adverse effects on the ac power transmission system and to compensate for reactive power consumed by the dc control system, a certain number of ac filters must be added during the operation of the dc system (the minimum number of ac filter sets must be satisfied). The alternating current filter is composed of a capacitor, a reactor and a resistor which are connected in series-parallel.

The AC filter capacitor is used as the most important component of AC filter, and is a capacitor with large current-resisting capacity, and can be used in power supply system with high harmonic content, such as current transformer and frequency converter, etc. and can be series-connected with reactor to produce resonance, and can utilize low-impedance channel to absorb higher harmonic to attain the goal of filtering harmonic and improving voltage quality of power network, and at the same time can be used as reactive compensation.

The most previous selection scheme of people is to adopt oil formula alternating current filter electric capacity, because oil formula electric capacity can set up pressure differential explosion-proof equipment, when certain component insulating degree of condenser descends, must produce the extraordinary heat, and the internal pressure increases, makes the capacitor case warp, and the inflation, mechanical displacement is the rupture disk (line). But the explosion-proof advantage of oil type electric capacity, its shortcoming is also obvious equally, because the power is connected with capacitor element through the rupture disk, and rupture disk disconnection equals that the power breaks off, so the explosion-proof effect depends on the design, the mounted position of rupture disk and the leakproofness of capacitor etc.. The size of the explosion-proof piece directly influences the explosion-proof effect, the larger the explosion-proof piece is, the larger the internal pressure to be broken is, and the lower the probability of explosion-proof action is, so that all capacitors cannot be guaranteed to have the explosion-proof effect; the smaller the explosion-proof piece is, the lower the overcurrent capacity of the capacitor is (the maximum can only reach 40-50A), and the capacitor is failed due to the fact that the capacitor is disconnected from a power supply by misjudgment of the explosion-proof piece. In addition, the oil leakage risk exists in the oil type capacitor, and the stable and reliable operation of equipment is not facilitated. From the experience of present use, oil type capacitors are not good choices, so dry type thin film capacitors are preferred, but ordinary conventional dry type thin film capacitors cannot completely meet the severe application requirements.

The common conventional dry film capacitor is formed by winding a metallized film, and has the advantages of high voltage resistance, stable temperature characteristic, small loss angle, small self-inductance, strong surge resistance, no acid pollution and long service life. However, as an ac filter film capacitor, it needs to bear a much larger high frequency harmonic current than that in general occasions, and the working environment is relatively severe, and the capacitance and loss change of a conventional dry film capacitor are affected under the condition of continuous heating, and the service life and reliability are not guaranteed. We conclude that most conventional thin film capacitors, when used in ac filtering applications, suffer from metallization loss and film degradation, mainly due to electrochemical effects and wet corrosion, resulting in capacitance decay, increased loss tangent, reduced insulation resistance, and ultimately failure.

SUMMERY OF THE UTILITY MODEL

In order to solve current dry-type film capacitor poor at AC filter occasion operating stability, the problem that the reliability is low, the utility model provides an AC filter film capacitor, it can increase the overcurrent ability, promotes operating stability and reliability.

The technical scheme is as follows: the utility model provides an alternating current filter film capacitor, its includes the casing, be provided with capacitor core and potting material in the casing, the extraction electrode is connected to the capacitor core, a serial communication port, the capacitor core is formed around the book by metallized film, metallized film width is 25-50mm, metallized film includes at least two-layer film medium, every layer metal coating formation capacitor plate has been evaporated to the film medium surface, and is outmost break in the middle of the capacitor plate, the edge of both sides scribble for the side of thickening layer, both sides and cover thickening layer and inboard one deck the alloy metal spraying layer of film medium, set up the insulating white strip of T shape of arranging side by side on the capacitor plate, it is adjacent be provided with the metal strip fuse between the insulating white strip tip of T shape.

The capacitor is further characterized in that the film medium is a polypropylene film medium, and the capacitor plate is a zinc-aluminum alloy metal coating;

the alloy gold-spraying layer is a zinc-tin alloy spinning layer, and a silicone oil protective layer is coated on the outer surface of the alloy gold-spraying layer;

the width of the metal strip fuse is 0.6-2.0 mm;

the shell is made of PPS (polyphenylene sulfide), and the potting material is anhydride epoxy resin;

the shell is a plastic square shell or a plastic round shell, and the leading-out electrode is a circuit board contact pin mounting structure;

the shell is a metal square shell or a metal round shell, and the extraction electrode is of a metal cylinder, square bolt or nut extraction structure.

Adopt the utility model discloses afterwards, improved the film structure of condenser core, the film width narrows, redesign fuse figure can increase the overcurrent ability to satisfy its heavy current requirement under the circumstances of guaranteeing electric capacity safety, promoted operating stability and reliability.

Drawings

FIG. 1 is an external schematic view of a single-phase plastic square-shell dry-type AC filter thin-film capacitor structure;

FIG. 2 is a schematic diagram of the interior of a single-phase plastic square-shell dry AC filter thin-film capacitor structure;

FIG. 3 is an external schematic view of a three-phase metal round-shell dry-type AC filter thin-film capacitor structure;

FIG. 4 is a schematic diagram of the interior of a three-phase metal round-shell dry-type AC filter thin-film capacitor structure;

FIG. 5 is a schematic diagram of a three-phase metal square-shell dry-type AC filter film capacitor;

FIG. 6 is a schematic view of the thin film structure of the present invention;

FIG. 7 is a schematic view of an explosion-proof structure of the rupture disk;

fig. 8 is a schematic view of wave splitting.

Detailed Description

Referring to fig. 1 to 8, an ac filter film capacitor comprises a casing 2, a capacitor core 1 and a potting material 3 are arranged in the casing, the capacitor core 1 is connected with a leading-out electrode 4, the capacitor core 1 is formed by winding a metalized film, the width of the metalized film is 25-50mm, the width of the metalized film is much narrower than that of the original 50-100mm, the metalized film comprises at least two layers of polypropylene film media 1-1, a zinc-aluminum alloy metal coating is evaporated on the outer surface of each layer of polypropylene film media 1-1 to form a capacitor plate 1-2, the middle of the outermost layer of the capacitor plate 1-2 is broken, the edges of the two sides are thickening layers, the side surfaces of the two sides are coated with a zinc-tin alloy spinning layer 1-3 covering the thickening layer and the inner layer of polypropylene film media 1-1, the outer surface of the zinc-tin alloy spinning layer 1-3 is coated with a silicone oil protective layer, further playing the purpose of preventing oxidation, resisting high temperature and high humidity, T-shaped insulating white strips arranged in parallel are arranged on the capacitor plate 1-2, metal strip fuses are arranged between the end parts of the adjacent T-shaped insulating white strips, the width of each metal strip fuse is 0.6-2.0mm, the metal strip fuse is more than two times wider than the original metal strip fuse, the overcurrent capacity of the capacitor is increased, the novel thin film structure is designed to meet the heavy current requirement of the capacitor under the condition of ensuring the safety of the capacitor, each square capacitor plate and other square capacitor plates are isolated and insulated into a single area by the T-shaped insulating white strips, fuses are arranged between the adjacent T-shaped insulating white strips, the fuses are metal strips, when a certain square capacitor plate is abnormally damaged, the fuse can be disconnected by large current, so that the square capacitor plate is isolated, the whole capacitor plate is protected, and the explosion-proof capacity is good.

The shell 2 is made of PPS material, and the potting material 3 is anhydride epoxy resin.

The utility model discloses a dry-type does not have the oiliness structural design, and the product does not have the oil leak risk, and the shape and the mounting means of product can be more nimble convenient, adapt to customer's different installation demands more, lists common several kinds of structures below, specifically can see figure 1 to figure 5:

the shell is a plastic square shell or a plastic round shell, and the leading-out electrode is a circuit board contact pin mounting structure;

the shell is a metal square shell or a metal round shell, and the extraction electrode is a metal cylinder, a square bolt or a nut extraction structure.

A production process of an alternating current filter film capacitor comprises the following steps:

(1) film evaporation: when the film is used as a light film, plasma treatment is adopted, so that moisture impurities on the surface of a base film coating layer can be effectively removed, two surfaces of the film are roughened, on one hand, the adhesive force of a metal coating layer is improved, the film layer is more tightly attached, air gaps and spaces between medium film layers are reduced, the metal coating layer is prevented from being oxidized, and on the other hand, the surface is subjected to damp-heat resistance through plasma treatment on a non-metal surface; vacuum evaporation is adopted to form a metal coating on the surface of a film medium to serve as a capacitor electrode plate, the metal coating is an aluminum-zinc alloy metal coating, the sheet resistance of the film is reduced, the thickness of the coating is increased by 40-50 nm, the risk of oxidation, falling and peeling of the coating is reduced, the metallized film has higher pressure resistance, ESR is reduced, great overcurrent capacity is achieved, the reliability of the capacitor is ensured, and the edges of two sides of the metal coating are increased;

(2) cutting the film: by adopting the wave cutting mode, the contact area of the end face of the core body and the metal spraying layer is increased by 30-40% when the core body of the capacitor is subjected to subsequent metal spraying, the adhesive force of the metal spraying layer is improved, the over-current capacity of the capacitor is effectively increased, and meanwhile, the loss value of the capacitor can be relatively reduced by 40%;

(3) winding the film: winding the metallized film into a capacitor core by using a winding machine, wherein in order to ensure that the core achieves stable performance, the temperature is 22-28 ℃ and the humidity is less than or equal to 45% RH during winding, water vapor impurities and the like on the film caused by temperature and humidity changes are prevented from being generated, the winding tension is Dx H a, D is the width of the film, H is the thickness of the film, a is the tension coefficient, and the value is 1-1.4;

(4) heat setting of a core: the capacitor core is compressed and fixed by using a tooling jig, so that the structural performance and the electrical performance of the capacitor core are stable, the capacitor core is subjected to heat setting treatment in a stepped heating mode, the heat treatment temperature is increased to 115-125 ℃, so that air gap layers among thin film layers are reduced, the thin film is fully shrunk, the whole process of the heat setting treatment is vacuumized, and inert gases such as nitrogen and the like are filled to isolate air in the heating and air breaking stages;

(5) and (3) a metal layer spraying process: the end of the capacitor core is sprayed with the alloy metal layer in an electric arc melting spraying mode, the film is cut in a wavy mode, the adhesive force of the sprayed gold layer is improved, and the alloy metal layer is made of zinc-tin alloy, so that subsequent welding is facilitated;

(6) electrode welding: the copper electrode and the end of the capacitor core are welded by adopting an automatic welding technology in a proper electrode structure;

(7) the encapsulating process comprises the following steps: placing the capacitor core into a shell, filling the capacitor core by using epoxy resin under vacuum, selecting a TG point of the epoxy resin to be more than 110 ℃, ensuring that the shell and the epoxy can not crack under the conditions of high temperature and high humidity, and the electrode and the epoxy can not crack, heating the assembled capacitor core and the shell together in a drying oven to remove moisture, encapsulating the epoxy resin in a vacuum box, curing at the high temperature of 120 ℃, and sealing the capacitor core in a proper shell;

(8) an electric aging process: applying voltage to the capacitor at high temperature to perform reliability screening, and removing early-stage failure products;

(9) the high-temperature impact screening process comprises the following steps: and eliminating the products with the electrical parameters not meeting the requirements under the high temperature limit temperature by simulating the temperature impact condition in the reflow soldering process, thereby improving the reliability of the products.

The utility model has simple structure, improved over-current capability, stronger safety performance and low cost; the film cutting adopts wave cutting, when the core body is sprayed with gold, the contact area of the end face of the core body and the gold spraying layer is increased by 30-40%, the adhesive force of the gold spraying layer is improved, the over-current capacity of the capacitor is effectively increased, and meanwhile, the loss value of the capacitor can be relatively reduced by 40%. The utility model is a full-dry structure without positive and negative polarity, and is suitable for any installation mode and environmental requirements.

Claims (7)

1. The utility model provides an alternating current filter film capacitor, its includes the casing, be provided with capacitor core and encapsulating material in the casing, the electrode is drawn forth in the connection of capacitor core, a serial communication port, the capacitor core is formed around rolling up by the metallized film, metallized film width is 25-50mm, the metallized film includes at least two-layer film medium, every layer the metal coating that has evaporated on the film medium surface forms the capacitor plate, and is outmost break in the middle of the capacitor plate, the edge of both sides scribble for the side of thickening layer, both sides and cover thickening layer and inboard one deck the alloy of film medium spouts the gold layer, set up the insulating white strip of T shape of arranging side by side on the capacitor plate, it is adjacent be provided with the metal strip fuse between the insulating white strip tip of T shape.

2. The ac filter film capacitor of claim 1, wherein said film dielectric is a polypropylene film dielectric and said capacitor plates are zinc-aluminum alloy metal plated.

3. The ac filter thin film capacitor of claim 1, wherein said alloy gold-sprayed layer is a zinc-tin alloy spinning layer, and a silicone oil protective layer is coated on an outer surface of said alloy gold-sprayed layer.

4. An ac filter film capacitor according to claim 1, wherein said metal strip fuse width is 0.6-2.0 mm.

5. The AC filter film capacitor of claim 1, wherein the case is made of PPS and the potting compound is anhydride epoxy.

6. The ac filter film capacitor of claim 1, wherein the case is a plastic square case or a plastic round case, and the lead-out electrode is a circuit board pin mounting structure.

7. The AC filter film capacitor of claim 1, wherein the case is a metal square case or a metal round case, and the lead-out electrode is a metal cylinder, a square bolt or a nut lead-out structure.

Images