A high current low self-inductance capacitor

Abstract

The utility model relates to electronic component technical field, concretely is a kind of high-current low self-induction capacitor, it has the characteristics of high overcurrent capacity and low self-induction, it is suitable for the high operating frequency of modern silicon carbide circuit, it includes shell, capacitor core and busbar, it is characterized in that, the busbar includes the upper busbar and lower busbar of laminated arrangement, two symmetrically arranged lead-out electrodes are arranged on the upper busbar and the lower busbar, the lower busbar is directly welded on the capacitor core upper end face, the two sides of the upper busbar are connected with the bottom of the capacitor core by connecting copper band, insulating paper is arranged between the upper busbar and the lower busbar, the insulating paper and the upper busbar are all provided with through hole for the lead-out electrode of the lower busbar.

Description

Technical Field

[0001] This utility model relates to the field of electronic component technology, specifically to a high-current, low-self-inductance capacitor. Background Technology

[0002] With the increasing demands for power density, efficiency, and high-temperature resistance of power electronic systems in fields such as new energy (e.g., photovoltaics, new energy vehicles), industrial control, and aerospace, power devices based on silicon carbide (SiC) materials (such as SiC MOSFETs and SiC Schottky diodes) have gradually replaced traditional silicon devices and become the core components for building high-frequency, high-efficiency power electronic circuits (such as high-frequency inverters, DC-DC converters, and power factor correction circuits) due to their significant advantages such as high switching frequency (up to 100kHz, which is 3-5 times that of traditional silicon devices), low conduction loss, and high temperature resistance (maximum operating temperature can reach over 200℃). In silicon carbide (SiC) high-frequency circuits, capacitors, as key passive components for energy storage, voltage filtering, signal coupling / decoupling, and surge suppression, directly determine the stability, efficiency, and reliability of the entire circuit. Specifically, the high switching frequency characteristics of SiC high-frequency circuits impose two core requirements on capacitors: first, excellent overcurrent capability to accommodate the high-frequency current ripple generated during high-frequency switching, preventing overheating, overload, shortened lifespan, or even burnout due to insufficient current carrying capacity; and second, extremely low equivalent series inductance (ESL, i.e., self-inductance). Under high-frequency conditions, the parasitic self-inductance of the capacitor resonates with the parasitic capacitance in the circuit, generating high-frequency voltage spikes. This not only exacerbates the voltage stress on SiC power devices (potentially exceeding the device's withstand voltage limit and causing damage) but also increases switching losses, severely restricting the full realization of the "high-frequency, high-efficiency" advantages of SiC devices. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a high-current, low-self-inductance capacitor, which features high overcurrent capability and low self-inductance, making it suitable for the high operating frequencies of modern silicon carbide circuits.

[0004] The technical solution is as follows: A high-current, low-self-inductance capacitor includes a shell, a capacitor core, and a busbar. The busbar comprises an upper busbar and a lower busbar arranged in a stacked configuration. Both the upper and lower busbars are provided with two symmetrically arranged lead-out electrodes. The lower busbar is directly welded to the upper end face of the capacitor core. The two sides of the upper busbar are connected to the bottom of the capacitor core via connecting copper strips. Insulating paper is provided between the upper and lower busbars. Both the insulating paper and the upper busbar have through holes for the lead-out electrodes of the lower busbar to pass through.

[0005] A further feature is that the insulating paper covers the side of the capacitor core; The housing is provided with a cross-shaped positioning plate, and the cross-shaped positioning plate has a through hole that matches the lead-out electrode.

[0006] With the adoption of this utility model, the stacked busbar structure has the positive and negative conductive layers tightly separated by the insulating layer, which greatly reduces the area of ​​the current loop and thus reduces the self-inductance. The four lead-out electrodes are set and integrated with the busbar, which increases the overcurrent capacity of the capacitor and can be directly integrated onto the circuit board. The two terminals are symmetrically led out to form a current path with a low loop area, forming a symmetrical low-inductance terminal, which is suitable for the high operating frequency of modern silicon carbide circuits. Attached Figure Description

[0007] Figure 1 This is a perspective view of the external structure of the capacitor of this utility model; Figure 2 This is a top view of the external structure of the capacitor of this utility model; Figure 3 This is a schematic diagram of the internal structure of the capacitor shell of this utility model; Figure 4 for Figure 3 Exploded view; Figure 5 This is a schematic diagram showing the connection status between the lower busbar and the capacitor core. Figure 6 This is a schematic diagram of a housing with a cross-shaped positioning plate. Detailed Implementation

[0008] See Figures 1 to 5 As shown, a high-current, low-self-inductance capacitor includes a housing 1, a capacitor core 2, and a busbar. The busbar includes an upper busbar 3 and a lower busbar 4 arranged in a stacked manner. Both the upper busbar 3 and the lower busbar 4 are provided with two symmetrically arranged lead electrodes 5. The integrated structure improves the capacitor's overcurrent capacity. The lower busbar 4 is directly welded to the upper end face of the capacitor core 2. The two sides of the upper busbar 3 are connected to the bottom of the capacitor core 2 through connecting copper strips 6, which saves copper strip usage, makes the structure more compact, saves space, improves welding efficiency, reduces labor costs, and reduces the error rate of electrode welding.

[0009] An insulating paper 7 is provided between the upper busbar 3 and the lower busbar 4. The positive and negative conductive layers are tightly separated by the insulating layer, which greatly reduces the area of ​​the current loop and thus reduces the self-inductance. In order to improve the direct insulation effect between the upper busbar 3 and the lower busbar 4, the insulating paper can cover the side of the capacitor core 2, similar to a cover covering the capacitor core 2. Both the insulating paper 7 and the upper busbar 3 are provided with through holes 8 for the lead-out electrodes of the lower busbar 4 to pass through. The size of the opening on the insulating paper 7 is the same as that of the lead-out electrode 5, and the opening on the upper busbar 3 is larger than the opening on the insulating paper 7.

[0010] To improve assembly consistency, a cross-shaped positioning piece 9 is added. The cross-shaped positioning piece 9 has a through hole 10 that mates with the lead electrode 5. After the busbar and capacitor core are assembled, the cross-shaped positioning piece 9 is then assembled with the lead electrode and finally installed into the housing 1. Encapsulation material is then injected into the housing 1 to complete the encapsulation.

Claims

1. A high-current, low-self-inductance capacitor, comprising a casing, a capacitor core, and a busbar, characterized in that, The busbar includes an upper busbar and a lower busbar arranged in a stacked manner. Each of the upper busbar and the lower busbar is provided with two symmetrically arranged lead-out electrodes. The lower busbar is directly welded to the upper end face of the capacitor core. The two sides of the upper busbar are connected to the bottom of the capacitor core through connecting copper strips. An insulating paper is provided between the upper busbar and the lower busbar. Both the insulating paper and the upper busbar have through holes for the lead-out electrodes of the lower busbar to pass through.

2. A high-current, low-self-inductance capacitor according to claim 1, characterized in that, The insulating paper covers the side of the capacitor core.

3. A high-current, low-self-inductance capacitor according to claim 1, characterized in that, The housing is provided with a cross-shaped positioning plate, and the cross-shaped positioning plate has a through hole that matches the lead-out electrode.

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