High-temperature-resistant and high-ripple-current DC-link film capacitors and methods for use in new energy fields

Abstract

The present invention provides a high-temperature, high-ripple-current DC-link thin-film capacitor and method for use in the new energy sector. The capacitor comprises a flame-retardant plastic housing, an insulating epoxy resin adhesive layer, a capacitor core, and a metal connection layer disposed on corresponding positions on the side walls of the capacitor core. Two tinned lead wires are connected to corresponding positions on the walls on both sides of the metal connection layer. This capacitor effectively improves its thermal conductivity and heat dissipation capacity, enabling heat in the capacitor core to be quickly and effectively dissipated, achieving thermal equilibrium within the capacitor product. The capacitor exhibits high-temperature resistance and significantly shortens charging time, meeting the high-temperature, high-ripple-current capability requirements of capacitors in new energy sectors, such as those in the renewable energy sector. Furthermore, the capacitor has a simple preparation process and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitor product production, and in particular to high-temperature resistant and high-ripple current capacitors and methods for use in the new energy field, such as charging columns, that is, high-temperature resistant and high-ripple current DC-link film capacitors and methods for use in the new energy field. Background Art

[0002] With the continuous advancement of industrial science and technology, higher quality requirements are being placed on capacitors used in industrial applications and new energy vehicles, such as charging poles. Film capacitors, with their high reliability, excellent frequency characteristics, and low dielectric loss, have rapidly expanded from their original home appliance applications to new energy and other fields. DC-link film capacitors are widely used. Connected in parallel on the DC side of a rectifier bridge, they provide filtering and voltage stabilization. Due to the relatively high capacitance required for DC-link capacitors, electrolytic capacitors have long been the preferred choice due to their large individual capacitance and compact size. However, these advantages are countered by significant disadvantages, including low withstand voltage, poor heat resistance, unstable performance, and a short lifespan. The properties of the alumina dielectric and the conductivity of the electrolyte used in electrolytic capacitors limit their maximum withstand voltage and high-temperature resistance, leading to their widespread use.

[0003] At the same time, due to the high ripple frequency and large ripple current of DC-LINK film capacitors, the internal resistance requirements of film capacitors are very high, and the heat dissipation capacity of the product needs to be good. The temperature resistance of DC-link is also getting higher and higher. The ordinary DC-LINK on the market can no longer meet its requirements, and the volume pursued by customers is getting smaller and smaller. Therefore, without increasing the volume, DC-LINK capacitors with high temperature resistance and high ripple current resistance have strong market competitiveness. Ordinary DC-LINK film capacitors are usually made of Figure 5 The metal film structure generally has a maximum temperature resistance of around 85°C, and its ripple current capacity is about 0.4A per meter. However, the capacitor products used in the existing new energy field have high requirements for temperature and ripple current, generally around 100°C or above. At the same time, due to the space limitations of the needs of the new energy field, the volume of the capacitor cannot change significantly. In other words, it is required not only to meet the conditions of high temperature resistance and high ripple current, but also to not increase its volume, which can significantly shorten the charging time in the new energy field. The volume of DC-LINK film capacitors remains unchanged or even smaller.

[0004] For example, Chinese patent publication number CN 103151169 A) is titled "A film capacitor for use in DC-link applications." The present invention relates to the technical field of power electronic capacitors, and in particular to a capacitor for use as a DC support and DC-link capacitor on AC / inverter equipment. Specifically, the invention relates to a film capacitor for use in DC-link applications, which has the advantages of large capacity and filtering, small size, low cost, reliability and stability, and high safety performance. It can replace electrolytic capacitors on a large scale in DC-link applications in the field of power electronics. The film capacitor comprises a capacitor core, characterized in that the capacitor core is wound from a metallized polypropylene film, the metallized polypropylene film comprising a polypropylene film dielectric and a capacitor plate, and the capacitor plate is a metal coating evaporated on the polypropylene film dielectric.

[0005] It can be seen from the above-disclosed prior art solutions that none of the above-disclosed technical solutions discloses a DC-link film capacitor that can increase its high-temperature resistance and improve its high ripple current while not increasing its volume, so as to effectively meet the demand for DC-LINK film capacitors with high-temperature resistance and high ripple current capabilities in the 800V silicon carbide new energy field without increasing its volume.

[0006] Therefore, the goal is to provide a high-temperature, high-ripple current DC-link film capacitor and method for use in the new energy sector. This method can effectively improve the thermal conductivity and heat dissipation capacity of the capacitor, allowing the heat in the capacitor core to be quickly and effectively dissipated, achieving thermal balance within the capacitor product. This can also significantly shorten the charging time, meet the high-temperature, high-ripple current capability requirements of capacitors in the new energy sector, and thus ensure product reliability and provide a fast charging experience for the new energy sector. The prepared DC-link film capacitor has good quality stability and consistency, while reducing the production cost of the capacitor and improving the heat resistance and high ripple capability of the DC-link film capacitor. Summary of the Invention

[0007] The present invention discloses a high-temperature, high-ripple-current DC-link thin-film capacitor and method for use in the new energy field. The capacitor comprises a flame-retardant plastic housing 1, an insulating epoxy resin adhesive layer 2, a capacitor core 3, and a metal connection layer 301 disposed at corresponding positions on the side walls of the capacitor core 3. Two tinned lead wires 8 are connected to corresponding positions on the walls on both sides of the metal connection layer 301. The capacitor can effectively improve its thermal conductivity and the heat dissipation capacity of the capacitor, allowing heat in the capacitor core to be quickly and effectively dissipated, achieving thermal balance within the capacitor product. The capacitor has high-temperature resistance and can significantly shorten charging time, meeting the high-temperature, high-ripple-current capability requirements of capacitors in the new energy field, and has a simple preparation process and low cost.

[0008] The present invention provides a high-temperature resistant and high-ripple current DC-link film capacitor for use in the new energy field, comprising a flame-retardant plastic shell, an insulating epoxy resin adhesive layer, a capacitor core, and a metal connection layer and a tinned lead wire provided on corresponding positions on the winding side wall of the capacitor core. The flame-retardant plastic shell is configured as a groove inner cavity structure with an open end at one end and a closed end at the other end. The capacitor core is provided in the groove inner cavity formed by the flame-retardant plastic shell. One end of the tinned lead wire is fixedly electrically connected to the metal connecting layer on the winding side wall of the capacitor core. The connecting layer is positioned at a corresponding position and fixedly encapsulated at the open end of the inner cavity of the flame retardant plastic shell, with the other end extending out of the open end of the flame retardant plastic shell; the capacitor core located at the open end of the flame retardant plastic shell and the two tinned lead wires fixedly connected to the capacitor core are fixedly encapsulated by an insulating epoxy resin layer, and the outer wall surface of the capacitor core circumference between the closed end of the flame retardant plastic shell and the fixed encapsulation junction of the insulating epoxy resin layer and the corresponding side surface of the flame retardant plastic shell are fixedly encapsulated and connected as a whole by an insulating silicone layer.

[0009] The DC-link film capacitor with high temperature resistance and high ripple current used in the new energy field, wherein the capacitor winding core includes a metal film sheet, and the metal film sheet is composited by a film layer and a metal layer. The metal layer includes an aluminum-plated layer and a zinc-plated layer. The aluminum-plated layer is composited on one side wall of the film layer, and the zinc-plated layer is composited on the other side wall of the aluminum-plated layer corresponding to the contact with the film layer.

[0010] The high-temperature-resistant and high-ripple-current DC-link film capacitor for use in the new energy field is characterized in that the volume ratio of the insulating epoxy resin layer encapsulated in the open end of the inner cavity of the groove of the flame-retardant plastic shell and the insulating silicone layer located in the inner cavity of the groove of the flame-retardant plastic shell and located between the outer wall surface of the capacitor winding core and the side wall surface corresponding to the flame-retardant plastic shell is controlled to be 30-40:70-60.

[0011] The described high-temperature-resistant and high-ripple-current DC-link film capacitor for use in the new energy field has a metal film sheet that is divided into a thickened area, a transition area, and a normal area in a horizontal axial direction of a flat sheet. The thickened area and the transition area are sequentially provided with a thin film layer, an aluminum-plated layer, and a galvanized layer in a radial direction of the metal film sheet. The galvanized layer is in a trapezoidal structure and is composited with a corresponding position on a side wall of the aluminum-plated layer. The long side of the trapezoidal structure of the galvanized layer along the horizontal axial direction contacts the aluminum-plated layer. The hypotenuse of the trapezoidal structure of the galvanized layer intersects from high to low along the axial direction at a corresponding position on the side wall of the aluminum-plated layer that contacts the galvanized layer. The horizontal length of the hypotenuse of the trapezoidal structure galvanized layer is controlled to correspond to the length of the transition area. The normal area includes the thin film layer and the aluminum-plated layer.

[0012] The high-temperature-resistant and high-ripple-current DC-link thin-film capacitor for use in the new energy field has a capacitor core formed by winding two metal film sheets with their thickened region ends and common region ends offset and stacked; the thickened region end of one metal film sheet and the common region end of the other metal film sheet are controlled to be offset and stacked relative to each other before winding; and the length of the overlapping composite connection interval of the common region is controlled to be 10.5-11.8% of the sum of the lengths of the thickened region, transition region, and common region when the two metal film sheets are wound.

[0013] Preferably, the thermal conductivity of the insulating silicone layer is controlled to be much greater than the thermal conductivity of the insulating epoxy resin layer.

[0014] The high-temperature-resistant and high-ripple-current DC-link film capacitor used in the new energy field controls the length of the thickened area along the horizontal axial direction to be 10.5-11.8% of the sum of the lengths of the thickened area, the transition area, and the ordinary area along the axial horizontal direction.

[0015] Another object of the present invention is to provide a method for preparing a high-temperature-resistant, high-ripple-current DC-link thin-film capacitor for use in the new energy field, including preparing a capacitor core. The specific preparation method is as follows: 1) staggering and overlapping the thickened region end of one metal film sheet and the normal region end of another metal film sheet, and controlling the length of the overlapping portion of the normal regions of the two metal film sheets to account for 10.5-11.8% of the total length of the thickened region, transition region, and normal region of the metal layer located on the surface of the thin film layer; and simultaneously controlling the length of the thickened region located at the thickened region end of the metal film sheet to account for 10.5-11.8% of the total length of the thickened region, transition region, and normal region of the metal layer located on the surface of the thin film layer; winding the two metal film sheets overlapped according to the above specifications into the shape of a capacitor core, providing metal connecting layers on both side surfaces of the wound capacitor core, and fixing two tinned lead wires at corresponding positions of the metal connecting layers to form the capacitor core;

[0016] 2) Add insulating silicone into the inner cavity of the groove formed by the flame-retardant plastic shell, which has an open end and the other end corresponding to the open end as a closed end, and insert the capacitor core body with tinned lead wires fixedly connected to the two side walls into the inner cavity of the groove formed by the flame-retardant plastic shell with insulating silicone. The space between the outer wall of the capacitor core and the wall corresponding to the flame-retardant plastic shell in the inner cavity of the groove is filled with insulating silicone and formed into an insulating silicone layer after drying and curing; then use an insulating epoxy resin layer to encapsulate the capacitor core with two tinned lead wire ends at the open end in the inner cavity of the groove formed by the flame-retardant plastic shell, thereby preparing a DC-link film capacitor with high temperature resistance and high ripple current.

[0017] The method of the present invention controls the length of the short side of the galvanized layer arranged on the aluminum-plated layer in the top of the trapezoidal structure along the axial direction to be equal to the length of the thickened area; and simultaneously controls the thermal conductivity of the insulating epoxy resin adhesive layer to be 0.18-0.25 W / m·K.

[0018] The DC-link film capacitor and method for high-temperature-resistant and high-ripple-current DC-link used in the new energy field of the present invention are used to prepare a DC-link film capacitor having high-temperature-resistant and high-ripple-current characteristics, suitable for use in the new energy field, and having a small volume, i.e., without increasing the size of the film capacitor. Furthermore, the DC-link film capacitor prepared by the present invention has the following characteristics after actual testing and use:

[0019] First, the capacitors in the prior art usually reduce the equivalent series resistance (ESR) by increasing the volume, but the volume that customers are pursuing is getting smaller and smaller. This solution can no longer meet customer requirements. Therefore, without increasing the volume, the DC-LINK film capacitor with high temperature resistance and high ripple current prepared by the present invention can greatly meet market demand. This is because the overlapping length of the ordinary area on the metal film sheet 9 of the capacitor winding core 3 is increased, and the length of the thickened area, that is, the galvanized layer, is increased. For example, the thickened area of ​​the prior art is about 2.5mm, while the length of the thickened area of ​​the present invention is at least 3mm, which is an increase of more than 20%, thereby greatly reducing the internal resistance of the prepared DC-LINK film capacitor, and the corresponding ripple current capacity can be increased by about 20%; thereby greatly increasing the current flow capacity of the DC-LINK film capacitor;

[0020] Second, the existing common DC-LINK film capacitors use Figure 4 、 5 The metal film structure shown in the figure has a ripple current capacity of about 0.4A per meter after practical testing. The potting material used is as follows Figure 4 The potting of the insulating epoxy resin layer 2 shown in the figure has a thermal conductivity of about 0.18-0.25w / m·k. Its heat dissipation capacity is low. When the inner core of the product capacitor reaches 105°C, it is difficult to dissipate the heat. When thermal equilibrium cannot be achieved, the inner core temperature of the battery product will rise sharply, causing the DC-LINK film capacitor to fail. It cannot meet the requirements of the new energy field, such as charging piles, for capacitors with small size and large overcurrent, that is, high temperature resistance and high ripple current. The structure adopted by the present invention is as follows Figure 1 、 2The metal film structure shown in FIG3 reduces the equivalent series resistance (ESR) by increasing the length of its thickened and transition regions, i.e., the length along the horizontal axial direction. Specifically, the zinc coating 5 in the thickened region is configured as a trapezoidal structure. This reduces the internal resistance of the DC-LINK film capacitor, thereby lowering the equivalent series resistance (ESR) by approximately 40%, as shown in Table 1. Under the same load, the temperature rise can be reduced by up to 60%, as shown in Table 2. Furthermore, the potting compound used is a silicone potting compound with a thermal conductivity 15 times greater than that of the conventional insulating epoxy resin layer 2. This effectively reduces the internal resistance of the DC-LINK film capacitor core and facilitates the dissipation of internal heat. Even at 120°C, the core easily dissipates heat, allowing it to reach thermal equilibrium more quickly, thus ensuring product reliability. This significantly improves the DC-LINK film capacitor's high-temperature and high-ripple current resistance, enhancing the product's electrical performance.

[0021] The performance of the DC-link film capacitor core prepared using the high-temperature, high-ripple current DC-link film capacitor and method disclosed in this invention for use in the new energy field is shown in the following examples: its internal resistance change at a frequency of 100 kHz and its temperature rise comparison test at an ambient temperature of 70°C, 100 kHz, 900 Vdc, and 10 Arms: that is, a performance comparison with DC-link film capacitor products prepared using the prior art.

[0022] Product description: The experimental samples are from the same batch of experimental products, and the rest of the production materials and process conditions used are exactly the same;

[0023] Table 1 shows the internal resistance changes (mΩ) of DC-link film capacitors prepared by the method of the present invention and DC-link film capacitors prepared by the prior art at 1200V and 3μF at 100KHz.

[0024] Table 1, (Batch No.: R211129023-2)

[0025]

[0026] In Table 1, the DC-link film capacitor with a common structure, i.e., prepared by the existing technical method, takes 1200V 3μF as an example, and its internal resistance changes at a frequency of 100KHz. The DC-link film capacitor prepared by the method of the present invention in the embodiment of the present invention takes 1200V 3μF as an example, and its internal resistance changes at a frequency of 100KHz. The internal resistance of the DC-link film capacitor prepared by the present invention is nearly 40% lower than that of the existing technical solution, reaching 36.7%. The technical effect of excessive ripple electric waves is achieved. Disclosed in Table 1 above is a comparison of the internal resistance data of five DC-link film capacitors prepared by the method of the present invention. The preparation method and structure are as described in Example 1.

[0027] Table 2 shows the temperature rise comparison (°C) at 100KHz, 900Vdc, and 10Arms at an ambient temperature of 70°C. This is the temperature change when the capacitor is overcurrented.

[0028]

[0029] Table 1 shows the temperature rise (°C) of a conventional DC-link film capacitor (Comparative Example 1) prepared using the conventional method, 1200V, 3μF, at 70°C, 100kHz, 900Vdc, and 10Arms. This compares the temperature rise (°C) of a 1200V, 3μF DC-link film capacitor prepared using the inventive method at 70°C, 100kHz, 900Vdc, and 10Arms. This demonstrates that the temperature rise of the inventive DC-link film capacitor is over 40% lower than that of the prior art. The table above compares the temperature rise data of five DC-link film capacitors prepared using the inventive method. The preparation method and structure are as described in Example 1. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 , is a schematic diagram of the cross-sectional structure of a DC-LINK thin film capacitor prepared by an embodiment of the invention method,

[0031] Figure 2 , is a schematic diagram of the longitudinal cross-sectional structure of a DC-LINK thin film capacitor prepared by the inventive method according to an embodiment;

[0032] Figure 3 , is a schematic diagram of the structure of two metal film sheets for winding a capacitor core according to an embodiment of the present invention;

[0033] Figure 4 , is a schematic diagram of the cross-sectional structure of the existing DC-LINK film capacitor,

[0034] Figure 5 , is a schematic diagram of the structure of two metal film sheets used in winding capacitor cores;

[0035] In the figure, 1. flame-retardant plastic shell, 101. open end, 102. closed end, 103. groove inner cavity, 2. insulating epoxy resin layer, 3. capacitor core, 301. metal connection layer, 4. insulating silicone layer, 5. galvanized layer, 6. aluminum-plated layer, 7. polypropylene film layer or film layer, 8. tinned lead wire, 9. metal film sheet A, 901. metal film sheet B, 902. metal film sheet C, 903. metal film sheet D.

[0036] 902, metal film sheet C and 903, metal film sheet D, both are metal film sheets of the prior art, and both have the same material and structure; 9, metal film sheet A and 901, metal film sheet B, both are metal film sheets of the present invention, and both have the same material and structure.

[0037] L1 is the length of the thickened area of ​​the metal film sheet A9 and the ordinary area of ​​the metal film sheet B 901 of the present invention, after the ordinary areas of the two metal film sheets overlap and contact in the axial direction after the two metal film sheets overlap;

[0038] L2 is the length of the thickened area of ​​the metal layer on the metal membrane sheet of the present invention along the horizontal axial direction, that is, the short side length of the trapezoidal structure of the galvanized layer 5 on the metal membrane sheet A9 and the metal membrane sheet B901 in the horizontal axial direction, that is, the length of the thickened area on the membrane sheet A9 and the metal membrane sheet B901 along the horizontal axial direction;

[0039] L3 is the length of the overlapped ordinary areas of the two metal film sheets along the axial direction after the thickened area of ​​the metal film sheet C902 and the ordinary area of ​​the metal film sheet D903 are offset and overlapped;

[0040] L4 is the length of the thickened area of ​​the metal layer on the existing metal film sheet along the axial horizontal direction, which is the same as L2. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Terms such as "upper," "lower," "bottom," "top," "left," and "right" used in this application document refer to the accompanying drawings disclosed herein. The epoxy resin adhesive layer and the insulating epoxy resin adhesive layer herein have the same meaning, as do the film layer and the polypropylene film layer.

[0042] like Figure 1-3As shown, the DC-link film capacitor with high temperature resistance and high ripple current for use in the new energy field disclosed in the present invention includes a flame-retardant plastic shell 1, an insulating epoxy resin layer 2, a capacitor core 3, and a metal connection layer 301 provided on the corresponding position of the winding side wall of the capacitor core 3, two tinned lead wires 8 are connected to the corresponding parts of the wall on both sides of the metal connection layer 301, the flame-retardant plastic shell 1 is set as a groove cavity 103 structure with an open end 101 at one end and a closed end 102 at the other end, the capacitor core 3 is set in the groove cavity 103 formed by wrapping the flame-retardant plastic shell 1, and one end of the tinned lead wire 8 is fixedly electrically connected to the capacitor The core 3 is wound around the corresponding position of the metal connecting layer 301 on the side wall and is fixedly encapsulated in the open end 101 of the inner cavity of the flame-retardant plastic shell 1, and the other end extends out of the open end 101 of the flame-retardant plastic shell 1; the capacitor core 3 located at the open end 101 of the flame-retardant plastic shell 1 and the two tinned lead wires 8 fixedly connected to the capacitor core 3 are fixedly encapsulated by the insulating epoxy resin layer 2, and the outer wall of the capacitor core 3 located between the closed end 102 of the flame-retardant plastic shell 1 and the fixed encapsulation junction of the insulating epoxy resin layer 2 are fixedly connected to the corresponding side surface of the flame-retardant plastic shell 1 through the insulating silicone layer 4 as a whole.

[0043] The capacitor core 3 includes a metal film sheet, which is composed of a film layer 7 and a metal layer. The metal layer includes an aluminum layer 6 and a zinc layer 5. The aluminum layer 6 is compounded on one side wall of the film layer 7, and the zinc layer 5 is compounded on the other side wall of the aluminum layer 6 corresponding to the contact with the film layer 6.

[0044] The volume ratio of the insulating epoxy resin layer 2 encapsulated within the open end 101 of the recessed inner cavity of the flame-retardant plastic housing 1 and the insulating silicone layer 4 located within the recessed inner cavity 103 of the flame-retardant plastic housing 1, between the outer wall of the capacitor winding core 3 and the wall of the flame-retardant plastic housing 1, is controlled to be 30-40:70-60. The thermal conductivity of the insulating silicone layer 4 is controlled to be significantly greater than that of the insulating epoxy resin layer. Typically, the thermal conductivity of the insulating silicone layer 4 is controlled to be 15-30 times that of the insulating epoxy resin layer 2.

[0045] The metal film sheet is divided into a thickened area, a transition area and a common area in the horizontal axial direction of the flat spread; the thickened area and the transition area are divided into a thickened area, a transition area and a common area in the radial direction of the metal film sheet, that is, from the adjacent area to the adjacent area. Figure 3From bottom to top in the vertical direction, it is sequentially provided with a film layer 7, an aluminum-plated layer 6 and a galvanized layer 5. The galvanized layer 5 is in a trapezoidal structure and is compounded on the corresponding position of one side wall of the aluminum-plated layer 6. The horizontal side of the trapezoidal structure of the galvanized layer 5 along the axial direction is in contact with the aluminum-plated layer 6, that is, the long side of the trapezoidal structure of the galvanized layer 5. The hypotenuse of the trapezoidal structure of the galvanized layer 5 intersects from high to low along the axial direction at the corresponding position on the wall of the side in contact with the aluminum-plated layer 6, and the length of the hypotenuse of the trapezoidal structure galvanized layer 5 along the horizontal direction is controlled to correspond to the length of the transition zone; and the ordinary area includes the film layer 7 and the aluminum-plated layer 6.

[0046] The capacitor core 3 is formed by winding two metal film sheets with the thickened area ends and the ordinary area ends offset and superimposed; the thickened area end of one metal film sheet and the ordinary area end of the other metal film sheet are controlled to be offset and superimposed respectively before winding; when the two metal film sheets are wound, the length of the overlapping composite connection area of ​​the ordinary area is controlled to be 10.5-11.8% of the sum of the lengths of the thickened area, transition area and ordinary area.

[0047] The length of the thickened zone along the axial horizontal direction is controlled to be 10.5-11.8% of the sum of the lengths of the thickened zone, the transition zone and the ordinary zone along the axial horizontal direction.

[0048] The method for preparing a high-temperature resistant and high-ripple current DC-link film capacitor for use in the new energy field of the present invention includes preparing a capacitor core 3, and the specific method steps are as follows: 1) the thickened area end of one metal film sheet and the ordinary area end of another metal film sheet are staggered and overlapped, and the length of the overlapping portion of the ordinary areas of the two metal film sheets is controlled to account for 10.5-11.8% of the total length of the thickened area, transition area and ordinary area of ​​the metal layer provided on the surface of the film layer 7; at the same time, the thickened area on the metal film sheet is kept at 10.5-11.8%; The length of the thick zone is equal to or slightly less than the length of the thickened zone; the length of the thickened zone located at the end of the thickened zone of the metal film sheet 9 is controlled to be 10.5-11.8% of the total length of the thickened zone, transition zone, and ordinary zone of the metal layer located on the surface of the thin film layer 7; the two metal film sheets overlapped according to the above specifications are wound into the shape of a capacitor core, a metal connecting layer 301 is provided on both side surfaces of the wound capacitor core, and two tinned lead wires 8 are fixedly connected to corresponding positions of the metal connecting layer 301 to form the capacitor core 3;

[0049] 2) Insulating silicone is added to the groove cavity 103 formed by the flame-retardant plastic shell 1 and the other end corresponding to the open end 101 and the closed end 102, and the capacitor core 3 body with tinned lead wires 8 fixedly connected to the two side walls is inserted into the groove cavity 103 formed by the flame-retardant plastic shell 1 and provided with insulating silicone. The space between the outer wall of the capacitor core 3 and the side wall corresponding to the flame-retardant plastic shell 1 in the groove cavity 103 is filled with insulating silicone and formed into an insulating silicone layer 4 after drying and curing; then, an insulating epoxy resin layer 2 is used at the open end 101 to encapsulate the capacitor core 3 with two tinned lead wires 8 in the groove cavity 103 formed by the flame-retardant plastic shell 1, thereby preparing a DC-link film capacitor with high temperature resistance and high ripple current.

[0050] The galvanized layer 5 disposed on the aluminum-plated layer 6 is controlled to have a trapezoidal structure, forming a thickened area and a transition area; the length of the transition area is the length of the oblique line from the top edge of the thickened area to the connecting contact with the surface of the aluminum-plated layer 5; and the thermal conductivity of the insulating epoxy resin layer 2 is controlled to be 0.18-0.25 W / m·K.

[0051] Any matters not described in the following specific embodiments are the same as those described in this specific implementation manner and the specification. Example

[0052] The present invention discloses a high-temperature resistant and high-ripple current DC-link film capacitor for use in the new energy field and a preparation method thereof, such as Figure 1-3 As shown, in this embodiment, the two metal film sheets A 9 and B 901 used to prepare the capacitor core 3 have a horizontal or axial length of 26 mm. That is, the sum of the axial lengths of the thickened area, transition area, and normal area on the metal film sheet A 9 is 26 mm. Similarly, the sum of the axial lengths of the thickened area, transition area, and normal area on the metal film sheet B 901 is also 26 mm. The thickened area of ​​the metal film sheet A 9 and the normal area of ​​the metal film sheet B 901 are staggered and superimposed to form the capacitor core. Figure 3 shown.

[0053] like Figure 1-3As shown, the DC-link film capacitor with high temperature resistance and high ripple current for use in the new energy field disclosed in the present invention includes a flame-retardant plastic shell 1, an insulating epoxy resin layer 2, a capacitor core 3, and a metal connection layer 301 provided on the corresponding position of the winding side wall of the capacitor core 3, two tinned lead wires 8 are connected to the corresponding parts of the wall on both sides of the metal connection layer 301, the flame-retardant plastic shell 1 is set as a groove cavity 103 structure with an open end 101 at one end and a closed end 102 at the other end, the capacitor core 3 is set in the groove cavity 103 formed by wrapping the flame-retardant plastic shell 1, and one end of the tinned lead wire 8 is fixedly electrically connected to the capacitor The core 3 is wound around the corresponding position of the metal connecting layer 301 on the side wall and is fixedly encapsulated in the open end 101 of the inner cavity of the flame-retardant plastic shell 1, and the other end extends out of the open end 101 of the flame-retardant plastic shell 1; the capacitor core 3 located at the open end 101 of the flame-retardant plastic shell 1 and the two tinned lead wires 8 fixedly connected to the capacitor core 3 are fixedly encapsulated by the insulating epoxy resin layer 2, and the outer wall of the capacitor core 3 located between the closed end 102 of the flame-retardant plastic shell 1 and the fixed encapsulation junction of the insulating epoxy resin layer 2 are fixedly connected to the corresponding side surface of the flame-retardant plastic shell 1 through the insulating silicone layer 4 as a whole.

[0054] The capacitor core 3 is formed by winding two metal film sheets, namely, a thickened area of ​​a metal film sheet A 9 and a normal area of ​​another metal film sheet B901, which are staggered and corresponding. The metal film sheet A9 and the metal film sheet B901 are both composited by a thin film layer 7 and a metal layer, and the metal layer includes an aluminum-plated layer 6 and a galvanized layer 5. The aluminum-plated layer 6 is composited on one side wall of the thin film layer 7, and the galvanized layer 5 is composited on the other side wall of the aluminum-plated layer 6 corresponding to the contact with the thin film layer 6. The metal film sheet is divided into a thickening zone, a transition zone and a common zone in sequence along the horizontal axial direction of the flattened sheet; the thickening zone and the transition zone are sequentially set as a thin film layer 7, an aluminum-plated layer 6 and a galvanized layer 5 along the radial direction of the metal film sheet, the galvanized layer 5 is in a trapezoidal structure and is compounded on the corresponding position of the other side wall surface of the aluminum-plated layer 6 in contact with the thin film layer 7, the galvanized layer 5 is set as a trapezoidal structure with the horizontal side along the horizontal axial direction, that is, the long side of its trapezoidal structure is in contact with the aluminum-plated layer 6, the hypotenuse of the trapezoidal structure of the galvanized layer 5 intersects from high to low along the axial direction at the corresponding position on the wall surface of the aluminum-plated layer 6 on the side in contact with the galvanized layer 5, the length of the hypotenuse of the trapezoidal structure of the galvanized layer 5 is equal to the length of the transition zone; that is, the horizontal plane length of the hypotenuse of the trapezoidal structure galvanized layer 5 is controlled to correspond to the length of the transition zone; and the common zone includes the thin film layer 7 and the aluminum-plated layer 6. That is, the length of the common area on the metal film sheet is equivalent to the length of the aluminum layer 6 composited on the thin film layer 7; that is, the length of the aluminum layer 6 composited on the thin film layer 7 is equivalent to the length of the thin film layer 7, the aluminum layer 6 is composited on the thin film layer 7, the galvanized layer 5 is composited on the surface of the aluminum layer 6, the longest side of the trapezoidal galvanized layer 5 is compositely connected to the corresponding position on the surface of the aluminum layer 6, and the length of the shortest side in the axial direction, i.e., the thickened area, and the length of the trapezoidal oblique side, i.e., the transition zone, in the horizontal direction are equivalent to or equal to the longest side of the galvanized layer 5;

[0055] The capacitor core 3 is formed by staggering and overlapping the thickened end of a metal film sheet A9 and the normal end of a metal film sheet B901. The thickened end of the metal film sheet A9 and the normal end of another metal film sheet B901 are staggered and overlapped before winding. The length of the overlapping composite connection section of the normal area of ​​the two metal film sheets during winding is controlled to be 10.5-11.8% of the sum of the lengths of the thickened area, transition area, and normal area. In this embodiment, the lengths of L1 and L2 are both 3 mm. That is, the horizontal axial length of the trapezoidal structure of the thickened area of ​​the metal film sheet A9 is the length of the short side of the thickened area, L2, and L2 is controlled to be 3 mm.

[0056] The volume ratio of the insulating epoxy resin layer 2 encapsulated within the open end 101 of the recessed cavity of the flame-retardant plastic housing 1 and the insulating silicone layer 4 located within the recessed cavity 103 of the flame-retardant plastic housing 1, between the outer wall of the capacitor winding core 3 and the wall of the flame-retardant plastic housing 1, is controlled to be 30:70. The thermal conductivity of the insulating silicone layer 4 is controlled to be significantly greater than that of the insulating epoxy resin layer. In this embodiment, the thermal conductivity of the insulating silicone layer 4 is controlled to be approximately 16 times that of the insulating epoxy resin layer 2.

[0057] The specific preparation method is to prepare the capacitor winding core 3. The metal film sheet A9 and the metal film sheet B901 involved in the following are of the same material and structure. In order to clearly illustrate the present invention, the above-mentioned metal film sheets are numbered for illustration, and the following comparative examples are also the same; the specific method steps are as follows: 1) The thickened area end of the metal film sheet A9 and the ordinary area end of another metal film sheet B901 are staggered and overlapped, and the length of the overlapping portion of the ordinary area of ​​the metal film sheet A9 and the metal film sheet B901 is controlled to account for 10.5-11.8% of the total length of the thickened area, transition area and ordinary area of ​​the metal layer provided on the surface of the thin film layer 7, and the actual control L1 is 3mm; at the same time, the length L2 and L1 of the thickened area on the metal film sheet A9 are kept equal to each other, both 3mm; the metal film sheet A9 and the metal film sheet B901 overlapped according to the above specifications are stacked. 901 is wound into a capacitor core shape, and metal connection layers 301 are provided on both side surfaces of the wound capacitor core. Two tinned lead wires 8 are fixedly connected to corresponding positions of the metal connection layer 301 to form the capacitor core 3 body;

[0058] 2) Add insulating silicone with a thermal conductivity of 16 times that of the insulating epoxy resin layer 2 into the groove cavity 103 formed by the flame retardant plastic shell 1 and the other end corresponding to the open end 101 as the closed end 102, and insert the capacitor core 3 body with tinned lead wires 8 fixedly connected to the wall surfaces on both sides into the groove cavity 103 formed by the flame retardant plastic shell 1 provided with the insulating silicone. The outer wall surface of the capacitor core 3 and the wall surface corresponding to the side of the flame retardant plastic shell 1 in the groove cavity 103 will be filled with insulating silicone at the same time. At the same time, the upper open end of the capacitor core 3 with two tinned lead wires 8 at the open end 101 is encapsulated in the groove cavity 103 formed by the flame retardant plastic shell 1 using the insulating epoxy resin layer 2, and then dried. After drying and curing, the above-mentioned insulating silicone forms an insulating silicone layer 4; the volume ratio of the insulating epoxy resin layer 2 and the insulating silicone layer 4 is controlled to be 30:70; that is, the insulating silicone layer 4 located in the groove cavity 103 of the flame-retardant plastic shell 1 from the bottom of the outer wall of the capacitor core 3 to the contact with the insulating epoxy resin layer 2 accounts for 70% of the volume ratio, and the insulating epoxy resin layer 2 on the upper end surface of the capacitor core 3 and the related parts of the periphery encapsulated at the upper open end 101 of the flame-retardant plastic shell 1 accounts for 30% of the volume ratio; that is, the volume ratio of the insulating epoxy resin layer 2 used to encapsulate the upper end surface of the capacitor core 3 and the related parts of the periphery and the insulating silicone layer 4 located in the groove cavity 103 of the flame-retardant plastic shell 1 from the bottom of the outer wall of the capacitor core 3 to the contact with the insulating epoxy resin layer 2 is 30%:70%;

[0059] Due to the higher thermal conductivity of the insulating silicone layer 4, its heat dissipation efficiency is over 10 times greater than that of the insulating epoxy resin layer 2. This significantly improves the heat dissipation rate of the prepared DC-link film capacitor, allowing it to reach thermal equilibrium more quickly. This results in a high-temperature, high-ripple current DC-link film capacitor. The performance of the C-link film capacitor prepared using the method of the present invention is shown in Tables 1 and 2 above. The DC-link film capacitor of the present invention has a lower internal resistance than the prior art, resulting in faster heat dissipation.

[0060] Except for the following description, the remaining details in Comparative Example 1 are the same as those in Example 1.

[0061] like Figure 4-5As shown, in this comparative embodiment, a capacitor core 3 is prepared using existing metal film sheets C 902 and D 903. The length of the capacitor core 3 along the horizontal plane or in the axial direction is 26 mm. That is, the sum of the axial lengths of the thickened area, transition area, and normal area of ​​the metal film sheet C 902 is 26 mm. Similarly, the sum of the axial lengths of the thickened area, transition area, and normal area of ​​the metal film sheet D 903 is also 26 mm. The thickened area of ​​the metal film sheet C 902 and the normal area of ​​the metal film sheet D 903 are staggered and superimposed to form the capacitor core. Figure 5 As shown, Figure 5 The two metal film sheets C 902 and D 903 are wound to form a capacitor core 3, which is then encapsulated within the recessed cavity 103 formed by the flame-retardant plastic housing 1 using an insulating epoxy resin layer 2. The insulating epoxy resin layer 2 secures the capacitor core 3, while the outer wall of the capacitor core 3, located between the closed end 102 of the flame-retardant plastic housing 1 and the junction where the insulating epoxy resin layer 2 secures the capacitor core 3, is also securely connected to the corresponding side surface of the flame-retardant plastic housing 1 by the insulating epoxy resin layer 2, forming a single unit. Figure 4 shown.

[0062] like Figure 5 As shown, the capacitor core 3 is formed by winding the thickened area of ​​metal film sheet C 902 and the normal area of ​​metal film sheet D 903 in a staggered manner. In this comparative example, L3 is 5.6 mm, while L4 is 2.5 mm. The thermal conductivity of the insulating epoxy resin layer 2 is controlled to be 0.2 W / m·K. The DC-link film capacitor prepared using this comparative example exhibits insufficient high-temperature resistance and ripple current, as shown in Tables 1 and 2 above. These values ​​are over 40% lower than those of the present invention.

[0063] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents. All of which fall within the scope of this patent protection law.

Claims

1. A high-temperature, high-ripple-current DC-link film capacitor for use in the new energy sector, comprising a flame-retardant plastic housing, an insulating epoxy resin layer, a capacitor core, a metal connection layer disposed at corresponding positions on the sidewalls of the capacitor core, and tinned lead wires. The flame-retardant plastic housing is configured as a grooved inner cavity structure with an open end at one end and a closed end at the other end. The capacitor core is disposed within the grooved inner cavity formed by the flame-retardant plastic housing. One end of the tinned lead wire is fixedly and electrically connected to a corresponding position of the metal connection layer on the sidewalls of the capacitor core and is fixedly encapsulated in the open end of the flame-retardant plastic housing inner cavity, and the other end extends out of the open end of the flame-retardant plastic housing. The invention is characterized in that: The capacitor core at the open end of the flame-retardant plastic housing and the two tinned lead wires fixedly connected to the capacitor core are fixedly encapsulated by an insulating epoxy resin layer, and the outer wall of the capacitor core between the closed end of the flame-retardant plastic housing and the junction of the insulating epoxy resin layer and the fixed encapsulation are fixedly encapsulated and connected to the corresponding side surface of the flame-retardant plastic housing by an insulating silicone layer. The thermal conductivity of the insulating silicone layer is controlled to be much greater than that of the insulating epoxy resin layer.

2. A high temperature resistant and high ripple current DC-link film capacitor for use in the new energy field according to claim 1, characterized in that The capacitor winding core includes a metal film sheet, which is composed of a film layer and a metal layer. The metal layer includes an aluminum-plated layer and a zinc-plated layer. The aluminum-plated layer is compounded on one side wall of the film layer, and the zinc-plated layer is compounded on the other side wall of the aluminum-plated layer that contacts the film layer.

3. The high-temperature-resistant and high-ripple-current DC-link film capacitor for use in the new energy field according to claim 1 is characterized in that The volume ratio of the insulating epoxy resin layer encapsulated in the open end of the inner cavity of the flame-retardant plastic shell and the insulating silicone layer located in the inner cavity of the groove of the flame-retardant plastic shell and located between the outer wall surface of the capacitor winding core and the side wall surface corresponding to the flame-retardant plastic shell is controlled to be 30-40:70-60.

4. The high-temperature-resistant and high-ripple-current DC-link film capacitor for use in the new energy field according to claim 2 is characterized in that The metal film sheet is divided into a thickening zone, a transition zone and a common zone in sequence along the horizontal axial direction of the flattened sheet; the thickening zone and the transition zone are set as a thin film layer, an aluminum-plated layer and a galvanized layer in sequence along the radial direction of the metal film sheet, the galvanized layer is in a trapezoidal structure and is compounded on the corresponding position of one side wall of the aluminum-plated layer, the long side of the trapezoidal structure of the galvanized layer along the horizontal axial direction is in contact with the aluminum-plated layer, the hypotenuse of the trapezoidal structure of the galvanized layer intersects from high to low along the axial direction at the corresponding position on the wall of the aluminum-plated layer surface in contact with the galvanized layer, and the horizontal length of the hypotenuse of the trapezoidal structure galvanized layer is controlled to correspond to the length of the transition zone; and the common zone includes a thin film layer and an aluminum-plated layer.

5. The high-temperature-resistant and high-ripple-current DC-link film capacitor for use in the new energy field according to claim 2 is characterized in that The capacitor core is formed by winding two metal film sheets with the ends of the thickened areas and the ends of the ordinary areas offset and stacked; the thickened area end of one metal film sheet and the ordinary area end of the other metal film sheet are controlled to be offset and stacked respectively before winding; and when the two metal film sheets are wound, the length of the overlapping composite connection interval of the ordinary area is controlled to be 10.5-11.8% of the sum of the lengths of the thickened area, transition area and ordinary area.

6. A high-temperature-resistant and high-ripple-current DC-link film capacitor for use in the new energy field according to claim 4 or 5, characterized in that The length of the thickened zone along the horizontal axial direction is controlled to be 10.5-11.8% of the sum of the lengths of the thickened zone, the transition zone and the ordinary zone along the axial horizontal direction.

7. The method for preparing a high-temperature resistant and high-ripple current DC-link film capacitor for use in the new energy field according to any one of claims 1 to 6, comprising preparing a capacitor core, wherein: 1) The thickened region end of one metal film sheet and the common region end of another metal film sheet are staggered and overlapped, and the length of the overlapping portion of the common regions of the two metal film sheets is controlled to account for 10.5-11.8% of the total length of the thickened region, transition region, and common region of the metal layer located on the surface of the thin film layer; at the same time, the length of the thickened region located at the thickened region end of the metal film sheet is controlled to account for 10.5-11.8% of the total length of the thickened region, transition region, and common region of the metal layer located on the surface of the thin film layer; the two metal film sheets overlapped according to the above specifications are wound into the shape of a capacitor core, metal connecting layers are provided on both side surfaces of the wound capacitor core, and two tinned lead wires are fixedly connected at corresponding positions of the metal connecting layers to form the capacitor core; 2) Add insulating silicone into the inner cavity of the groove formed by the flame-retardant plastic shell, which has an open end and the other end corresponding to the open end as a closed end, and insert the capacitor core body with tinned lead wires fixedly connected to the two side walls into the inner cavity of the groove formed by the flame-retardant plastic shell with insulating silicone. The space between the outer wall of the capacitor core and the wall corresponding to the flame-retardant plastic shell in the inner cavity of the groove is filled with insulating silicone and formed into an insulating silicone layer after drying and curing; then use an insulating epoxy resin layer to encapsulate the capacitor core with two tinned lead wire ends at the open end in the inner cavity of the groove formed by the flame-retardant plastic shell, thereby preparing a DC-link film capacitor with high temperature resistance and high ripple current.

8. The method according to claim 7, wherein: The length of the short side of the galvanized layer on the aluminum layer in the top of the trapezoidal structure along the axial direction is controlled to be equal to the length of the thickened area; at the same time, the thermal conductivity of the insulating epoxy resin layer is controlled to be 0.18-0.25 W / m·K.

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