A low inductance pulse capacitor

Abstract

The utility model provides a low inductance pulse capacitor, including a plurality of capacitor core groups who set up in turn along first direction and connect in series, wherein each capacitor core group includes a plurality of capacitor core sub who set up in turn along second direction and parallel with each other, and adjacent capacitor core groups are connected in turn through metal connecting piece to form the snake type series connection structure. The pulse capacitor can reduce the parasitic inductance, avoid the problem that voltage rise rate is insufficient and peak current is small under the working condition of high voltage and large current.

Description

Technical Field

[0001] This utility model belongs to the field of electronic components, specifically, it relates to a low-inductance pulse capacitor. Background Technology

[0002] Capacitors are one of the commonly used electronic components in high-power pulse equipment. With the development of high-power pulse discharge technology, the operating voltage of capacitors is required to be higher and higher, the peak discharge current is required to be larger and larger, and the voltage rise rate is required to be higher and higher. In some cases, the operating voltage of capacitors is required to exceed 100kV, the peak current is required to reach 40kA, the parasitic inductance is less than 40nH, and the voltage rise time is on the order of hundreds of nanoseconds.

[0003] Real capacitors contain parasitic parameters (parasitic inductance, parasitic resistance, etc.), and their equivalent circuit can be simplified to a circuit consisting of equivalent inductance (ESL), ideal capacitance (C), and equivalent series resistance (ESR). In pulsed applications, the capacitor operates at high frequencies, and its impedance cannot be ignored. Because the pulse discharge voltage rise rate requirement is high, excessive impedance caused by parasitic inductance will prevent the pulse discharge peak value and voltage rise rate from meeting the requirements.

[0004] The formula for calculating capacitor impedance is as follows:

[0005]

[0006] Only when the equivalent series inductance (ESL) of a capacitor is very small, its impedance is also very small, thus meeting the performance requirements of the capacitor. In other words, the ESL of a capacitor determines the magnitude of its peak current and the upper limit of its voltage ramp-up rate. However, most existing pulse capacitors suffer from excessive parasitic inductance, insufficient voltage ramp-up rate, and small peak current.

[0007] On the other hand, high-voltage capacitors are usually large in size, and air bubbles are easily left inside during the capacitor manufacturing process, which can cause partial discharge under high voltage and lead to insulation failure. Utility Model Content

[0008] The purpose of this invention is to provide a pulse capacitor with a small parasitic inductance.

[0009] To achieve the above objectives, this utility model provides a low-inductance pulse capacitor, comprising a plurality of capacitor core groups arranged sequentially and connected in series along a first direction, wherein each capacitor core group comprises a plurality of capacitor cores arranged sequentially and connected in parallel along a second direction, and adjacent capacitor core groups are connected sequentially by metal connecting pieces to form a serpentine series structure, wherein the first direction is perpendicular to the second direction.

[0010] Preferably, the capacitor core is formed by winding a dielectric film and an electrode material layer. The dielectric film is made of at least one of polypropylene (PP), polyethylene terephthalate (PET), polyimide (PI), polyetheretherketone (PEEK), polyethylene naphthalate (PEN), polystyrene (PS), capacitor paper, and mica paper. The electrode material layer is aluminum foil or silver foil. The two ends of the capacitor core are formed into electrode leads by gold sputtering or tin dipping.

[0011] Preferably, the metal connecting piece is rectangular in shape, with its two opposite sides being comb-shaped, and each side is welded to the electrode lead of a capacitor core of a capacitor core assembly.

[0012] Preferably, the two capacitor cores at the beginning and end are respectively connected to a lead-out terminal via electrode lead-out plates. The electrode lead-out plates include mutually perpendicular comb-tooth portions and trapezoidal connecting portions. The comb-tooth portions are welded to the electrode lead-out portions of the capacitor cores, and the trapezoidal connecting portions are connected to the lead-out terminal.

[0013] Preferably, the lead-out terminal is oblong, with multiple threaded connection holes on one end face; the two lead-out terminals are respectively located on the outside of the two capacitor core groups at the beginning and end.

[0014] Preferably, an insulating plate is provided between adjacent capacitor core groups. The insulating plate is rectangular, and each end of one side is provided with a limiting protrusion. The metal connecting piece is located between a pair of limiting protrusions.

[0015] Preferably, the low-inductance pulse capacitor further includes a housing and a cover plate. The housing is used to accommodate the plurality of capacitor cores, and the housing is filled with insulating material. The cover plate is provided with reserved holes for filling the insulating material and relieving pressure.

[0016] The beneficial effects of this invention are as follows: By connecting multiple capacitor cores in series and parallel, the capacitance and voltage of the capacitor can be flexibly adjusted. Multiple capacitor core groups are connected sequentially by multiple metal connecting pieces to form a serpentine series structure. During operation, the current directions in adjacent capacitor core groups are always opposite, and the inductances generated by adjacent capacitor core groups can cancel each other out, thereby reducing parasitic inductance and avoiding problems such as insufficient voltage rise rate and small peak current under high voltage and high current operating conditions. Furthermore, compared to the U-shaped series connection scheme of capacitor cores, this connection method significantly reduces the potential difference across the insulating plate.

[0017] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] The above and other objects, features and advantages of the present invention will become more apparent from the accompanying drawings, in which like reference numerals generally represent like parts.

[0019] Figure 1 A schematic diagram of the capacitor core assembly of a low-inductance pulse capacitor according to an embodiment of the present invention is shown.

[0020] Figure 2 A schematic diagram showing the connection of adjacent capacitor cores of a low-inductance pulse capacitor according to an embodiment of the present invention is shown.

[0021] Figure 3 A schematic diagram of the structure of an insulating plate according to an embodiment of the present invention is shown.

[0022] Figure 4 A schematic diagram of the electrode lead sheet of a low-inductance pulse capacitor according to an embodiment of the present invention is shown.

[0023] Figure 5 A schematic diagram of the lead terminals of a low-inductance pulse capacitor according to an embodiment of the present invention is shown.

[0024] Figure 6 A schematic diagram of the external structure of a low-inductance pulse capacitor according to an embodiment of the present invention is shown.

[0025] Figure 7 A circuit diagram of a low-inductance pulse capacitor according to an embodiment of the present invention is shown.

[0026] Figure 8 The pulse discharge waveform of a low-inductance pulse capacitor according to an embodiment of the present invention is shown.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1-Capacitor core; 2-Metal connecting piece; 3-Electrode lead; 4-Electrode lead; 5-Comb tooth part; 6-Trapezoidal connecting part; 7-Lead terminal; 8-Threaded connecting hole; 9-Limiting protrusion; 10-Outer shell; 11-Insulating plate; 12-Cover plate. Detailed Implementation

[0029] Preferred embodiments of the present invention will now be described in more detail. While preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0030] like Figures 1 to 6As shown, the low-inductance pulse capacitor of this utility model includes a plurality of capacitor core groups arranged sequentially and connected in series along a first direction (i.e., the thickness direction of the capacitor core 1), wherein each capacitor core group includes a plurality of capacitor cores 1 arranged sequentially and connected in parallel along a second direction (i.e., the width direction of the capacitor core 1), and adjacent capacitor core groups are connected sequentially by metal connecting pieces 2 to form a serpentine series structure, wherein the first direction is perpendicular to the second direction.

[0031] Specifically, each end of a capacitor core group is connected to the capacitor core groups on both sides of it through a metal connecting piece, so that multiple capacitor core groups can be connected in sequence through multiple metal connecting pieces to form a serpentine series structure. Figure 7 The circuit diagram of a low-inductance pulse capacitor is shown. During operation, the current directions in adjacent capacitor cores are always opposite, and the inductance generated by adjacent capacitor cores can cancel each other out. This reduces parasitic inductance and avoids problems such as insufficient voltage ramp-up and small peak current under high voltage and high current operating conditions.

[0032] The capacitor core 1 is formed by winding a dielectric film and an electrode material layer. The dielectric film is made of at least one of PP, PET, PI, PEEK, PEN, PS, capacitor paper, and mica paper, and the electrode material layer is aluminum foil or silver foil. Alternatively, the capacitor core 1 can also be formed by winding a metallized film.

[0033] The two ends of the capacitor core 1 are formed into electrode leads 3 by gold sputtering or tin dipping, and the electrode leads 3 may include multiple layers of metal material.

[0034] like Figure 2 As shown, the metal connecting piece 2 is rectangular in shape, with two opposite sides being comb-shaped. Each side is welded to the electrode lead of a capacitor core 1 of a capacitor core assembly. The comb-shaped welding part increases the welding area with the electrode lead and improves the welding strength.

[0035] Furthermore, the two capacitor core groups at the beginning and end are each connected to a lead terminal 7 via electrode lead-out pieces 4, that is, connected to the positive lead terminal and the negative lead terminal respectively. (Reference) Figure 4 The electrode lead plate 4 includes mutually perpendicular comb-tooth portions 5 and trapezoidal connecting portions 6. The comb-tooth portions 5 are welded to the electrode lead portions 3 of the capacitor core. The comb-tooth portions 5 increase the welding area with the electrode lead portions 3, improving welding strength. The trapezoidal connecting portions 6 are connected to the lead terminals 7. The longer base of the trapezoidal connecting portion 6 connects to the comb-tooth portions 5, and the shorter base connects to the lead terminals 7, meaning the width gradually decreases from the comb-tooth portions 5 to the lead terminals 7. Current can gradually flow into the lead terminals 7 along the trapezoidal connecting portions 6, reducing electric field distortion and lowering the probability of partial discharge.

[0036] refer to Figure 5 The lead-out terminal 7 is oblong, with multiple threaded connection holes 8 on one end face. The threaded connection holes 8 are used for installation connections, allowing the capacitor core assembly to be fixedly connected inside the housing. The oblong lead-out terminal 7 has rounded ends, which helps reduce current density and avoids the probability of high-voltage arcing. Furthermore, the two lead-out terminals are respectively located on the outer sides of the two capacitor core assemblies at the beginning and end, effectively increasing the creepage distance and improving application reliability.

[0037] An insulating plate 11 is provided between adjacent capacitor core groups, and the insulating plate 11 can be disposed in close contact with the surface of the capacitor core group. (Reference) Figure 2 and Figure 3 As shown, the insulating plate 11 is rectangular, with limiting protrusions 9 at both ends of one side. A metal connecting piece 2 is positioned between the pair of limiting protrusions 9, which limit the metal connecting piece 2. Preferably, the length and width of the insulating plate 11 are greater than the length and width of the capacitor core assembly, for example, by at least 5mm, to achieve better insulation. Additionally, one side of the insulating plate 11 is at least 5mm higher than the capacitor core assembly to ensure sufficient distance between the end face of the capacitor core assembly and the inner surface of the outer casing, thus ensuring the casing's withstand voltage.

[0038] like Figure 6 As shown, the low-inductance pulse capacitor also includes a housing 10 and a cover plate 12. The housing 10 is used to accommodate multiple capacitor cores and is filled with insulating materials, such as perfluorocarbon, sulfur hexafluoride, nitrogen, or ultrapure air. The housing 10 can be made of insulating plastic to avoid the insulation problems of metal housings. Holes are provided at both ends of the housing 10 for lead-out terminals to pass through. The cover plate 12 has pre-drilled holes for filling with insulating material and for pressure relief. To ensure the bonding strength between the housing 10 and the cover plate 12, ultrasonic welding is used to melt the edges of the cover plate 12, which, after cooling, is tightly assembled with the housing 10 to form a seamless shell structure.

[0039] This utility model also provides a manufacturing method for manufacturing the aforementioned low-inductance pulse capacitor, comprising the following steps:

[0040] Multiple connected capacitor cores are placed inside the housing and connected with a cover plate to form a semi-finished pulse capacitor.

[0041] The semi-finished product is dried;

[0042] Preheat the semi-finished product;

[0043] Insulating material is poured into the casing in a vacuum environment and then left to stand.

[0044] The semi-finished product is subjected to cyclic pressurization to cure the insulating material.

[0045] Injecting insulating materials in a vacuum environment avoids residual air bubbles inside large capacitors, thus preventing partial discharge and insulation failure caused by these bubbles. Curing the insulating material using a cyclic pressurization method effectively reduces residual stress during the curing process, significantly improving the breakdown voltage of the pulse capacitor. Furthermore, compared to traditional continuous pressurization curing, cyclic pressurization curing greatly shortens the pressurization time, reduces the high-load operating time of the equipment, extends equipment lifespan, and significantly reduces process costs.

[0046] Specifically, the cyclic pressurization of the semi-finished product includes:

[0047] Return the pressure to normal atmospheric pressure and raise the temperature to 85℃~105℃;

[0048] Repeat the following process 3 to 5 times: increase the pressure to above 0.4 MPa and maintain it for the first preset time; then restore the pressure to normal pressure and maintain it for the second preset time.

[0049] Both the first and second preset times are 5 to 10 minutes, with 5 minutes being the preferred setting.

[0050] As a preferred option, the semi-finished product is dried using a forced-air drying oven at a temperature of 80℃~100℃ for 4~12 hours.

[0051] The preheating temperature is 85℃, and the time is 30 minutes;

[0052] After the insulating material is poured in, it is left to stand in a vacuum for 0.3 to 72 hours.

[0053] After the grouting process is completed, the reserved hole is sealed by hot melt welding.

[0054] Example 1

[0055] In this embodiment, the low-inductance pulse capacitor uses two layers of metallized polypropylene film material wound into a capacitor core 1. Three capacitor cores are arranged in the width direction to form a capacitor core group, and ten capacitor core groups are arranged in the thickness direction of the capacitor cores. Adjacent capacitor core groups are connected in sequence by metal connecting pieces to form a serpentine series structure. Other details of this embodiment are as described above.

[0056] Table 1 below compares the performance parameters of this embodiment with those of existing pulse capacitors. Figure 8 The pulse discharge waveform of the pulse capacitor in this embodiment is shown. (See Table 1 and...) Figure 8 As can be seen, the low-inductance pulse capacitor in this embodiment has a lower parasitic inductance, a larger pulse peak current, and a longer pulse discharge life.

[0057] Table 1

[0058] Parasitic inductance 60nH 35nH Pulse peak current 27kA 45kA parasitic resistance 45mΩ 45mΩ Pulse discharge lifetime 30,000 times 1 million times

[0059] Example 2

[0060] This embodiment provides a manufacturing method for producing a low-inductance pulse capacitor, comprising the following steps:

[0061] Obtaining semi-finished products: Place multiple connected capacitor core groups inside the housing and connect the cover plate to form a pulse capacitor semi-finished product;

[0062] Drying: The semi-finished product is dried in a forced-air drying oven at a temperature of 85℃ for 4 hours.

[0063] Preheating: The preheating temperature is 85℃, and the time is 30 minutes;

[0064] Vacuum infusion: Evacuate to a vacuum level of 100Pa, infuse epoxy resin under vacuum, and then let stand for 30 minutes;

[0065] Cyclic pressurization curing: Slowly restore the air pressure to normal pressure, raise the temperature to 95℃; gradually increase the air pressure to 0.4MPa, hold the pressure for 5 minutes, restore to normal pressure for 5 minutes, and repeat 3 times.

[0066] The low-inductance pulse capacitor produced in this embodiment has a breakdown voltage of 150kV, which is much higher than that of pulse capacitors produced by other conventional methods, and it also has fewer residual bubbles and lower manufacturing costs.

[0067] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A low-inductance pulse capacitor, characterized in that, It includes multiple capacitor core groups arranged in sequence and connected in series along a first direction, wherein each capacitor core group includes multiple capacitor cores (1) arranged in sequence and connected in parallel along a second direction, and adjacent capacitor core groups are connected in sequence by metal connecting pieces (2) to form a serpentine series structure, and the first direction is perpendicular to the second direction.

2. The low-inductance pulse capacitor according to claim 1, characterized in that, The capacitor core (1) is formed by winding a dielectric film and an electrode material layer, wherein the electrode material layer is aluminum foil or silver foil; the two ends of the capacitor core (1) are formed by sputtering gold or tinning to form electrode leads (3).

3. The low-inductance pulse capacitor according to claim 2, characterized in that, The metal connecting piece (2) is rectangular in shape, with two opposite sides being comb-shaped. Each side is welded to the electrode lead of a capacitor core of a capacitor core group.

4. The low-inductance pulse capacitor according to claim 2, characterized in that, The two capacitor cores at the beginning and end are respectively connected to a lead-out terminal (7) through an electrode lead-out piece (4). The electrode lead-out piece (4) includes a comb tooth part (5) and a trapezoidal connecting part (6) that are perpendicular to each other. The comb tooth part (5) is welded to the electrode lead-out part (3) of the capacitor core, and the trapezoidal connecting part (6) is connected to the lead-out terminal (7).

5. The low-inductance pulse capacitor according to claim 4, characterized in that, The lead-out terminal (7) is oblong, and has multiple threaded connection holes (8) on one end face.

6. The low-inductance pulse capacitor according to claim 4, characterized in that, Two leads are located on the outside of the two capacitor core groups at the beginning and end, respectively.

7. The low-inductance pulse capacitor according to claim 1, characterized in that, An insulating plate (11) is provided between adjacent capacitor core groups. The insulating plate is rectangular and has a limiting protrusion (9) at both ends of one side. The metal connecting piece (2) is located between a pair of limiting protrusions (9).

8. The low-inductance pulse capacitor according to claim 1, characterized in that, It also includes a housing (10) and a cover plate (12), the housing (10) being used to accommodate the plurality of capacitor cores, the housing (10) being filled with insulating material, and the cover plate (12) having reserved holes for filling with insulating material and for relieving pressure.

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