Low self-inductance film capacitor

Abstract

The utility model discloses a low self-inductance film capacitor which comprises a shell, an upper capacitor core and a lower capacitor core which are coaxially stacked up and down are arranged in the shell, the upper capacitor core is provided with a first upper end face and a first lower end face, the lower capacitor core is provided with a second upper end face and a second lower end face, the first upper end face is provided with a lower laminated busbar, and the second upper end face is provided with a lower laminated busbar. A first copper strip is connected in parallel between the lower laminated busbar and the second lower end face, and a second copper strip is connected in parallel between the first lower end face and the second upper end face. According to the utility model, the plurality of capacitor cores are stacked up and down, the capacity of the capacitor is improved, the selection range of the capacitor cores is enlarged, the upper and lower laminated busbars are used as electrodes, the self-inductance of the electrodes is offset, the laminated busbars are connected with the capacitor cores through the plurality of copper strips, and the copper strips with different polarities are connected in a staggered manner, so that the capacitor core selection range is enlarged. The current flowing paths of any two adjacent copper strips are opposite, the self-inductance of the connecting copper strips is offset, the self-inductance of the capacitor is reduced to below 13nH on the whole, and the use performance of the capacitor is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of capacitors, in particular to a low self-inductance film capacitor. Background Art

[0002] Metallized film capacitors are widely used in industrial control, new energy power generation, rail transportation, electric vehicles, smart grids and other fields. Existing large-capacity metallized film capacitors include a circular shell, an upper insulating cover, a capacitor lead terminal, a capacitor core arranged in the shell, a gold spray layer on the end surface of the capacitor core, a copper strip connecting the capacitor core and the lead terminal, and a sealant filled in the shell to protect the capacitor core.

[0003] In the prior art, in order to improve the power density of the equipment, when the current of the power device is limited, increasing the switching frequency of the equipment has become the industry's first choice, which requires the metallized film capacitor to have low self-inductance. Metallized film capacitors are wound without inductance, and the core inductance can be ignored. In order to meet the requirements of large capacity and small volume, the method of increasing the core height or vertically stacking the capacitor core is often adopted, which will increase the length of the lead copper strip, and also increase the current flow path, resulting in an increase in the inductance of the capacitor itself. Excessive self-inductance causes the capacitor to heat up when used at high frequencies, which ultimately leads to a decrease in the reliability of the capacitor in high-frequency applications, restricting the development of the power electronics industry.

[0004] CN202021342063.2 discloses a low self-inductance DC bus capacitor, comprising a first capacitor core and a second capacitor core arranged coaxially, an insulating diaphragm is arranged between the first capacitor core and the second capacitor core, the first capacitor core is provided with a first upper end face and a first lower end face, the second capacitor core is provided with a second upper end face and a second lower end face, the first upper end face and the second lower end face are connected in parallel through a first copper strip, the first lower end face and the second upper end face are connected in parallel through a second copper strip, and the upper and lower end faces of the core are staggered and connected by a copper strip, so that the current directions of the core are opposite, and the current directions of any two adjacent copper strips are also opposite, and the self-inductance of the core and the copper strip offset each other due to different polarities. In this technical solution, two capacitor cores are used to increase the capacity of the capacitor, and the upper and lower end faces of the core are staggered and connected by a copper strip, so that the self-inductance of the core and the copper strip offset each other due to different polarities to reduce the inductance of the capacitor. The inner and outer arrangement method limits the capacity selection of the capacitor core, and the insulating diaphragm also affects the assembly and use effect of the capacitor. Utility Model Content

[0005] The utility model aims to provide a low self-inductance film capacitor, which adopts two capacitor cores to be arranged inside and outside to increase the capacity of the capacitor, and adopts copper strips to connect the upper and lower end faces of the core in a staggered manner, so that the self-inductance of the core and the copper strip offset each other due to different polarities to reduce the inductance of the capacitor. The inner and outer arrangement method limits the capacity selection of the capacitor core, and the insulating diaphragm also affects the assembly and use effect of the capacitor, so as to overcome the shortcomings of the prior art.

[0006] The utility model provides a low self-inductance film capacitor through the following technical scheme, including a shell, wherein an upper capacitor core and a lower capacitor core coaxially stacked up and down are arranged in the shell, the upper capacitor core is provided with a first upper end face and a first lower end face, the lower capacitor core is provided with a second upper end face and a second lower end face, a lower laminated busbar is arranged on the first upper end face, a first copper strip is connected in parallel between the lower laminated busbar and the second lower end face, and a second copper strip is connected in parallel between the first lower end face and the second upper end face.

[0007] Furthermore, an upper stacking busbar is provided, the upper stacking busbar is located above the lower stacking busbar, and the upper stacking busbar is connected to the second copper strip.

[0008] Furthermore, an upper insulating sleeve is provided between the upper laminated busbar and the lower laminated busbar.

[0009] Furthermore, a first lead terminal is provided on the surface of the upper laminated busbar, and a second lead terminal is provided on the surface of the lower laminated busbar. The second lead terminal sequentially penetrates the upper insulating sleeve and the upper laminated busbar and is exposed from the upper laminated busbar.

[0010] Furthermore, the upper capacitor core and the lower capacitor core are sealed in the housing by sealant.

[0011] Furthermore, a lower insulating sleeve is also sleeved on the bottom of the lower capacitor core.

[0012] Furthermore, the bottom of the shell is integrally formed with mounting bolts.

[0013] The utility model has the following beneficial effects: a plurality of capacitor cores are stacked up and down, which increases the capacity of the capacitor while increasing the range of capacitor core selection; at the same time, the upper and lower laminated busbars are used as electrodes, so that the self-inductances of the electrodes cancel each other out; each laminated busbar is connected to the capacitor core through a plurality of copper strips; the copper strips of different polarities are staggered and connected, so that the current flow paths of any two adjacent copper strips are opposite, so that the self-inductances of the connected copper strips cancel each other out, and the self-inductance of the capacitor is reduced to below 13nH as a whole, thereby improving the performance of the capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1It is a three-dimensional schematic diagram of the upper and lower capacitor cores of a low self-inductance film capacitor described in the utility model.

[0015] Figure 2 The utility model is an exploded schematic diagram of the upper and lower capacitor cores of a low self-inductance film capacitor.

[0016] Figure 3 for Figure 1 Cross-sectional view in the AA direction.

[0017] Figure 4 for Figure 1 Cross-sectional view along the BB direction.

[0018] Figure 5 The figure is a schematic diagram of the overall appearance of a low self-inductance film capacitor described in the utility model.

[0019] in, Figures 1 to 5 The corresponding relationship between the reference numerals and component names in the figure is:

[0020] 1 housing, 2 upper capacitor core, 3 lower capacitor core, 4 first upper end face, 5 first lower end face, 6 second upper end face, 7 second lower end face, 8 lower laminated busbar, 9 first copper strip, 10 second copper strip, 11 upper laminated busbar, 12 upper insulating sleeve 12, 13 first lead terminal, 14 second lead terminal, 15 lower insulating sleeve, 16 mounting bolts. DETAILED DESCRIPTION

[0021] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0022] The components of the embodiments of the present application generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed, but merely represents the selected embodiments of the present application.

[0023] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0024] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0025] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] Refer to the following Figure 1-5 A low self-inductance film capacitor according to some embodiments of the present application is described.

[0027] A low self-inductance film capacitor comprises a shell 1, wherein an upper capacitor core 2 and a lower capacitor core 3 coaxially stacked up and down are arranged in the shell 1, wherein the upper capacitor core 2 is provided with a first upper end face 4 and a first lower end face 5, and the lower capacitor core 3 is provided with a second upper end face 6 and a second lower end face 7; a lower laminated busbar 8 is welded on the first upper end face 4, and the lower laminated busbar 8 is connected to the second lower end face 7 through a plurality of first copper strips 9 connected in parallel; the first lower end face 5 and the second upper end face 6 are connected through a plurality of second copper strips 10 connected in parallel, and the second copper strips 10 are also connected to an upper laminated busbar 11 located above the lower laminated busbar 8, and an insulating sleeve 12 is provided between the upper laminated busbar 11 and the lower laminated busbar 8.

[0028] The first copper strip 9 and the second copper strip 10 not only realize the corresponding electrical connection with the upper laminated busbar 11 and the lower laminated busbar 8, the upper capacitor core 2 and the lower capacitor core 3, but also fix the relative position of the upper capacitor core 2 and the lower capacitor core 3 through the upper laminated busbar 11 and the lower laminated busbar 8, so that an appropriate gap is formed between the first lower end surface 5 of the upper capacitor core 2 and the second upper end surface 6 of the lower capacitor core 3, thereby realizing effective insulation of the upper capacitor core 2 and the lower capacitor core 3 without adding additional insulating elements.

[0029] The upper laminated busbar 11 and the lower laminated busbar 8 have opposite polarities, so their inductances cancel each other out. In this embodiment, there are four first copper strips 9 and four second copper strips, and the first copper strips 9 and second copper strips of different polarities are staggered and connected, so that the current flow paths of any two adjacent copper strips are opposite, and their self-inductances cancel each other out. The total width of the four copper strips is four times that of ordinary capacitors. The wider the copper strips, the smaller the self-inductance. In addition, the wider the copper strips, the smaller the resistance, the lower the heat generation of the capacitor, the better the thermal conductivity, and the heat generation of the capacitor at high frequencies. Combining the above improvements, the self-inductance of the capacitor can be reduced to below 13nH, which improves the performance of the capacitor.

[0030] A first lead terminal 13 is provided on the surface of the upper laminated busbar 11 by welding, and a second lead terminal 14 is provided on the surface of the lower laminated busbar 8 by welding. The second lead terminal 14 passes through the upper insulating sleeve 12 and the upper laminated busbar 11 in sequence and is exposed from the upper laminated busbar 11. The first lead terminal 13 and the second lead terminal 14 are used to connect to an external circuit.

[0031] The upper capacitor core 2 and the lower capacitor core 3 are sealed in the housing 1 by means of sealant, and the sealant is preferably a polyurethane sealant with good high temperature and high humidity resistance.

[0032] A lower insulating sleeve 15 is also sleeved on the bottom of the lower capacitor core 3 to achieve mutual insulation between the lower capacitor core 3 and the housing 1 .

[0033] The bottom of the housing 1 is integrally formed with mounting bolts 16 for mounting the capacitor.

[0034] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low self-inductance film capacitor, comprising a housing, characterized in that: An upper capacitor core and a lower capacitor core coaxially stacked up and down are provided in the shell, the upper capacitor core is provided with a first upper end face and a first lower end face, the lower capacitor core is provided with a second upper end face and a second lower end face, a lower laminated busbar is provided on the first upper end face, a first copper strip is connected in parallel between the lower laminated busbar and the second lower end face, and a second copper strip is connected in parallel between the first lower end face and the second upper end face.

2. A low self-inductance film capacitor according to claim 1, characterized in that: An upper stacking busbar is also provided, the upper stacking busbar is located above the lower stacking busbar, and the upper stacking busbar is connected to the second copper strip.

3. A low self-inductance film capacitor according to claim 2, characterized in that: An upper insulating sleeve is arranged between the upper laminated busbar and the lower laminated busbar.

4. A low self-inductance film capacitor according to claim 3, characterized in that: A first lead terminal is provided on the surface of the upper laminated busbar, and a second lead terminal is provided on the surface of the lower laminated busbar. The second lead terminal sequentially penetrates the upper insulating sleeve and the upper laminated busbar and is exposed from the upper laminated busbar.

5. A low self-inductance film capacitor according to claim 4, characterized in that: The upper capacitor core and the lower capacitor core are sealed in the shell by sealant.

6. A low self-inductance film capacitor according to claim 5, characterized in that: The bottom of the lower capacitor core is also sleeved with a lower insulating sleeve.

7. A low self-inductance film capacitor according to any one of claims 1 to 6, characterized in that: The bottom of the housing is integrally formed with mounting bolts.

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