Low self-inductance capacitor for flexible HVDC converter valves

Abstract

The application relates to the technical field of flexible direct current power transmission, in particular to a low self-inductance capacitor for a flexible direct current converter valve. The application provides a low self-inductance capacitor which comprises a first element strip, a second element strip, a first busbar and a second busbar, the first element strip comprises a first conductive strip, a second conductive strip and a plurality of first elements, the second element strip comprises a third conductive strip, a fourth conductive strip and a plurality of second elements, the first busbar and the second busbar are arranged on the same side or different sides of the first element strip and the second element strip along a first direction; along the winding axis direction of the first element or the second element, the first conductive strip is closer to the third conductive strip than the fourth conductive strip, the first conductive strip and the third conductive strip have the same polarity and are connected with the first busbar, the second conductive strip and the fourth conductive strip have the same polarity and are connected with the second busbar, and the second busbar is provided with a first connecting end which is located between the second conductive strip and the fourth conductive strip.

Description

Technical Field

[0001] This application relates to the field of flexible DC transmission technology, and in particular to a low self-inductance capacitor for a flexible DC converter valve. Background Technology

[0002] Flexible DC transmission technology employs voltage source converters and fully controlled power electronic devices. This technology provides excellent dynamic reactive power support, exhibits superior grid connection performance, and eliminates synchronization stability issues. Flexible DC transmission is one of the best options for achieving large-scale clean energy generation, grid connection, and transmission using high-voltage DC grids in the future.

[0003] The converter valve is the core equipment of the flexible DC transmission project, and the capacitor used in the flexible DC converter valve is the core component of the converter valve. It is a key hub device and energy storage element for realizing energy interaction.

[0004] Capacitors possess parasitic inductance (hereinafter referred to as self-inductance), which generates a corresponding induced electromotive force when the switching device operates. As the input capacitance increases, the current of the switching device increases, leading to increased self-inductance and heat generation from the capacitor. Excessive self-inductance and heat generation from the capacitor can damage other electronic components within the converter valve, thus failing to meet requirements. Summary of the Invention

[0005] This application provides a low self-inductance capacitor for a flexible DC converter valve, which solves the technical problems of excessive self-inductance and excessive heat generated by the capacitor, and achieves the technical effect of reducing the self-inductance and heat generated by the capacitor.

[0006] To achieve the above objectives, the main technical solutions adopted in this application include:

[0007] In a first aspect, embodiments of this application provide a low-self-inductance capacitor for a flexible DC converter valve, comprising a first element strip, a second element strip, a first busbar, and a second busbar. The first element strip includes a first conductive strip, a second conductive strip, and a plurality of first elements. The plurality of first elements are arranged sequentially along a first direction, and both the first conductive strip and the second conductive strip extend along the first direction. The first direction is perpendicular to the winding axis direction of the first elements. Each first element is connected to the first conductive strip at one end along its winding axis direction, and each first element is connected to the second conductive strip at the other end along its winding axis direction. The second element strip includes a third conductive strip, a fourth conductive strip, and a plurality of second elements. The plurality of second elements are arranged sequentially along the first direction, and both the third conductive strip and the fourth conductive strip extend along the first direction. The winding axis direction of the second elements is perpendicular to the winding axis direction of the first element. The winding axis of each element is parallel, and each second element is connected to the third conductive strip at one end in the winding axis direction, and to the fourth conductive strip at the other end in the winding axis direction; along the first direction, the first busbar and the second busbar are disposed on the same side or opposite side of the first element strip and the second element strip; wherein, along the winding axis direction of the first element or the second element, the first conductive strip is closer to the third conductive strip than the fourth conductive strip, the first conductive strip and the third conductive strip have the same polarity and are both connected to the first busbar, the second conductive strip and the fourth conductive strip have the same polarity and are both connected to the second busbar, the second busbar is provided with a first connecting end, and along the winding axis direction of the first element or the second element, the first connecting end is located between the second conductive strip and the fourth conductive strip.

[0008] The low self-inductance capacitor proposed in this application embodiment has a first conductive strip and a second conductive strip connected to both ends of its winding axis, and a third conductive strip and a fourth conductive strip connected to both ends of its winding axis, respectively. Along the winding axis of the first or second element, the first conductive strip is close to the third conductive strip and is connected to the first busbar to form one pole of the capacitor. The second conductive strip is far from the third conductive strip, and both the second and fourth conductive strips are connected to the second busbar to form the other pole of the capacitor. That is, along the winding axis of the first or second element, the second conductive strip and the fourth conductive strip are connected to the third conductive strip to form the other pole of the capacitor. The conductive strips are connected to opposite sides of the second busbar. The second busbar has a first connection end located between the second conductive strip and the fourth conductive strip along the winding axis of the first or second element. When current is introduced into the second busbar from the first connection end, the current flows from the first connection end to the second conductive strip and the fourth conductive strip respectively. The current flowing to the second conductive strip and the current flowing to the fourth conductive strip on the second busbar are in opposite directions. Therefore, the inductance generated by the current loop flowing to the second conductive strip and the inductance generated by the current loop flowing to the fourth conductive strip will partially cancel each other out, thereby reducing the self-inductance of the capacitor.

[0009] Furthermore, the first and third conductive strips can conduct the heat generated by the first and second components to the first busbar; the second and fourth conductive strips can conduct the heat generated by the first and second components to the second busbar. The larger area of ​​the first and second busbars has good heat dissipation performance, which can assist the capacitor in heat dissipation, thereby reducing the thermal resistance of the capacitor and thus achieving the purpose of reducing the heat generated by the capacitor.

[0010] Optionally, the first bus and the second bus are disposed on the same side of the first element strip and the second element strip; along the first direction, at least a portion of the second bus is located on the side of the first bus away from the first element strip and the second element strip. The first bus and the second bus are disposed on the same side of the first element strip and the second element strip, and along the first direction, the projection of at least a portion of the second bus coincides with the first bus. When current flows through the first bus and the second bus, the inductance generated by the first bus and the inductance generated by the second bus will partially cancel each other out, further reducing the self-inductance of the capacitor. Furthermore, the fact that the first bus and the second bus are disposed on the same side of the first element strip and the second element strip effectively reduces the current path, thereby reducing the self-inductance and heat generated by the capacitor.

[0011] Optionally, the second bus includes a first body portion, a second body portion, and a raised portion. The first body portion is connected to the second conductive strip, and the second body portion is connected to the fourth conductive strip. Along the winding axis of the first element or the second element, both ends of the raised portion are connected to the first body portion and the second body portion, respectively. Along the first direction, at least a portion of the raised portion protrudes relative to the first body portion and the second body portion towards the side away from the first element strip and the second element strip, to form a receiving cavity for accommodating the first bus. The second bus has a raised portion, and the first bus is correspondingly disposed with the raised portion. The raised portion increases the spacing between the first bus and the second bus, thereby forming an insulating distance between the first bus and the raised portion and reducing the risk of short circuit in the capacitor.

[0012] Optionally, the raised portion is provided with a clearance hole, which extends through the raised portion along its thickness direction. The clearance hole in the raised portion facilitates the introduction or extraction of current on the first busbar.

[0013] Optionally, the raised portion includes a top wall, a first side wall, and a second side wall; along the first direction, the top wall is spaced apart from the first busbar, the first side wall is connected to one side of the top wall and the first body portion, and the second side wall is connected to the other side of the top wall and the second body portion. Along the winding axis of the first element or the second element, the first side wall is connected to opposite sides of the top wall to form a receiving cavity, the first busbar corresponds to the receiving cavity, and the first busbar is spaced apart from the top wall, the first side wall, and the second side wall, forming an insulating distance.

[0014] Optionally, along the first direction, the minimum distance between the top wall and the first busbar is 3-10 mm. Maintaining a distance of at least 3-10 mm between the top wall and the first busbar along the first direction reduces contact between the first and second busbars, thereby reducing the risk of short circuits caused by the connection between the first and second busbars.

[0015] Optionally, along the first direction, the same-side ends of the first conductive strip and the third conductive strip pass through the first busbar and overlap with the first busbar in the thickness direction; the same-side ends of the second conductive strip and the fourth conductive strip overlap with the second busbar in the thickness direction. The first and third conductive strips overlap with the first busbar to form one pole of the capacitor, and the second and third conductive strips overlap with the second busbar to form the other pole of the capacitor. Current is introduced through the first connection terminal of the second busbar and then flows to the second and fourth conductive strips respectively. The two currents on the second busbar are in opposite directions, and the inductances they generate partially cancel each other out. One current flows through the first element and then through the first conductive strip into the first busbar, and the other current flows through the second element and then through the third conductive strip into the first busbar, and then flows out from the first busbar. The currents on the first busbar and the currents at corresponding positions on the second busbar are in opposite directions, and the inductances they generate can also partially cancel each other out, thereby achieving the purpose of reducing the self-inductance of the capacitor.

[0016] Optionally, there are multiple first element strips and multiple second element strips, arranged opposite to each corresponding second element strip along the winding axis of the first or second element. The multiple first element strips are arranged sequentially along a second direction, and the multiple second element strips are arranged sequentially along the second direction, with the first direction, the second direction, and the winding axis of the first or second element being perpendicular to each other. Connecting multiple first element strips in parallel, then connecting multiple second element strips in parallel, and finally connecting the multiple first element strips and multiple second element strips in parallel as a whole reduces the equivalent series resistance of the capacitor, thereby reducing capacitor heat generation.

[0017] Optionally, the capacitor further includes a first connecting strip, a second connecting strip, a third connecting strip, and a fourth connecting strip. The first connecting strip is connected to a plurality of first conductive strips, the second connecting strip is connected to a plurality of second conductive strips, the third connecting strip is connected to a plurality of third conductive strips, and the fourth connecting strip is connected to a plurality of fourth conductive strips. The first and second connecting strips are used to connect a plurality of first element strips in parallel, and the third and fourth connecting strips are used to connect a plurality of second element strips in parallel. The parallel connection of multiple first element strips and multiple parallel second element strips reduces the equivalent series resistance of the capacitor, thereby reducing the heat generation of the capacitor.

[0018] Optionally, there are multiple first connecting strips, second connecting strips, third connecting strips, and fourth connecting strips. Multiple first connecting strips are spaced apart along the first direction, multiple second connecting strips are spaced apart along the first direction, multiple third connecting strips are spaced apart along the first direction, and multiple fourth connecting strips are spaced apart along the first direction. Multiple first and second connecting strips serve to connect multiple first component strips in parallel while also providing heat dissipation; multiple third and fourth connecting strips serve to connect multiple second component strips in parallel while also providing heat dissipation, thereby improving the heat dissipation efficiency of the capacitor.

[0019] Optionally, the capacitor further includes a housing, an end cap, a first terminal, and a second terminal. The housing has a receiving space for accommodating the first component strip, the second component strip, the first busbar, and the second busbar. Along the first direction, the housing has an opening. The end cap is connected to the housing to close the opening. The first terminal passes through the end cap to connect to the first busbar, and the second terminal passes through the end cap to connect to the second busbar. The first terminal connected to the first busbar forms one pole of the capacitor, and the second terminal connected to the second busbar forms the other pole of the capacitor. The housing and end cap enclose the first and second component strips within the housing, reducing damage to the first and second component strips.

[0020] Optionally, along the winding axis of the first element or the second element, the first connection end is located at the midpoint between the second conductive strip and the fourth conductive strip. When current is introduced into the second bus from the first connection end, the current flows from the first connection end to the second conductive strip and the fourth conductive strip respectively. The current flowing to the second conductive strip and the current flowing to the fourth conductive strip on the second bus are in opposite directions, and the paths through which the currents flow are equal. Therefore, the inductance generated by the current loop flowing to the second conductive strip and the inductance generated by the current loop flowing to the fourth conductive strip will cancel each other out, thereby reducing the self-inductance of the capacitor. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a partial structural schematic diagram of the low self-inductance capacitor of this application;

[0023] Figure 2This is a partial structural schematic diagram of the low self-inductance capacitor of this application;

[0024] Figure 3 This is a schematic diagram of the structure of the first element strip in this application;

[0025] Figure 4 This is a schematic diagram of the structure of the second element strip in this application;

[0026] Figure 5 This is a schematic diagram of the structure of the low self-inductance capacitor of this application;

[0027] Figure 6 for Figure 5 Side view of a medium-low self-inductance capacitor;

[0028] Figure 7 for Figure 5 Top view of a medium-low self-inductance capacitor.

[0029] [Explanation of Labels in the Attached Image]

[0030] 1: First element strip; 11: First element; 12: First conductive strip; 13: Second conductive strip;

[0031] 2: Second component strip; 21: Second component; 22: Third conductive strip; 23: Fourth conductive strip; 3: First busbar; 32: Second connecting end; 4: Second busbar; 41: First body part; 42: First connecting end; 43: Raised part; 431: Receiving cavity; 432: Clearance hole; 433: Top wall; 434: First side wall; 435: Second side wall; 44: Second body part; 5: First connecting strip; 6: Outer shell; 61: Insulating paper; 7: End cap; 8: First terminal; 9: Second terminal; A: First direction; B: Second direction. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0034] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0035] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0036] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0037] In this application, "multiple" refers to two or more (including two), and similarly, "multiple groups" refers to two or more (including two), and "multiple pieces" refers to two or more (including two).

[0038] Currently, dry-type capacitors are used in flexible DC transmission projects of ±420kV / 1.25GW and below. However, as the voltage of flexible DC transmission increases to ±500kV and ±800kV, and the transmission capacity increases to 8GW, the current in the switching devices increases, leading to increased self-inductance and heat generated by the capacitors, and a corresponding increase in induced electromotive force. This can damage the switching devices or other electronic components. As shown by the formula U=L×di / dt, reducing the self-inductance of the capacitor can reduce the induced electromotive force. Furthermore, reducing the self-inductance of the capacitor helps reduce the electrical stress on the switching devices and protects other electronic components within the converter valve. Therefore, a capacitor capable of reducing self-inductance is needed.

[0039] Furthermore, during the operation of the converter valve, ripple current flows through the capacitor, which can cause the capacitor to heat up. Excessive capacitor temperature can shorten its lifespan and even lead to thermal breakdown. The relationship between capacitor temperature rise and the effective value of ripple current Irms is ΔT = Irms / Irms. rm3 2 ×ESR×Rth reduces the equivalent series resistance (ESR) and thermal resistance (Rth), thus reducing the temperature rise of the capacitor. Reducing heat generation in capacitors extends their lifespan and improves their reliability.

[0040] Therefore, reducing capacitor self-inductance and heat generation is of great significance for ensuring the stable operation of flexible DC engineering.

[0041] Therefore, embodiments of this application provide a low self-inductance capacitor for a flexible DC converter valve, with reference to... Figures 1 to 4The low self-inductance capacitor includes a first element strip 1, a second element strip 2, a first busbar 3, and a second busbar 4. The first element strip 1 includes a first conductive strip 12, a second conductive strip 13, and a plurality of first elements 11. The plurality of first elements 11 are arranged sequentially along a first direction A. The first conductive strip 12 and the second conductive strip 13 both extend along the first direction A, which is perpendicular to the winding axis direction of the first elements 11. Each first element 11 is connected to the first conductive strip 12 at one end along its winding axis direction, and to the second conductive strip 13 at the other end along its winding axis direction. The second element strip 2 includes a third conductive strip 22, a fourth conductive strip 23, and a plurality of second elements 21. The plurality of second elements 21 are arranged sequentially along the first direction A. The third conductive strip 22 and the fourth conductive strip 23 both extend along the first direction A, and the winding axis direction of the second elements 21 is perpendicular to the winding axis direction of the first elements 11. In parallel directions, each second element 21 is connected to a third conductive strip 22 at one end in the direction of its winding axis, and to a fourth conductive strip 23 at the other end in the direction of its winding axis; a first busbar 3 and a second busbar 4 are disposed on the same side or opposite side of the first element strip 1 and the second element strip 2 along the first direction A; wherein, along the winding axis direction of the first element 11 or the second element 21, the first conductive strip 12 is closer to the third conductive strip 22 than the fourth conductive strip 23, the first conductive strip 12 and the third conductive strip 22 have the same polarity and are both connected to the first busbar 3, the second conductive strip 13 and the fourth conductive strip 23 have the same polarity and are both connected to the second busbar 4, the second busbar 4 is provided with a first connecting end 42, which is located between the second conductive strip 13 and the fourth conductive strip 23 along the winding axis direction of the first element 11 or the second element 21.

[0042] Specifically, along the first direction A, a plurality of first elements 11 are arranged sequentially. A first conductive strip 12 and a second conductive strip 13 both extend along the first direction A and are connected to each of the first elements 11 at both ends of the first element 11 along the winding axis. That is, the first conductive strip 12 and the second conductive strip 13 connect the plurality of first elements 11 in parallel to form a first element strip 1. Along the first direction A, a plurality of second elements 21 are arranged sequentially. A third conductive strip 22 and a fourth conductive strip 23 both extend along the first direction A and are connected to each of the second elements 21 at both ends of the second element 21 along the winding axis. That is, the third conductive strip 22 and the fourth conductive strip 23 connect the plurality of second elements 21 in parallel to form a second element strip 2. For example, the first element strip 1 and the second element strip 2 are arranged opposite to each other. The first element 11 can be arranged in a one-to-one correspondence with the second element 21, and the winding axis of the corresponding first element 11 coincides with the winding axis of the second element 21; or the number of first elements 11 and second elements 21 is different, and the winding axis of the first element 11 does not coincide with the winding axis of the second element 21; the first element 11 and the second element 21 can be arranged according to specific needs, and this application is not limited thereto. The first conductive strip 12 connected to the multiple first elements 11 and the third conductive strip 22 connected to the multiple second elements 21 are close to each other, the first conductive strip 12 connected to the multiple first elements 11 is far away from the fourth conductive strip 23 connected to the multiple second elements 21, and the second conductive strip 13 connected to the multiple first elements 11 and the fourth conductive strip 23 connected to the multiple second elements 21 are far away from each other. The first conductive strip 12 and the third conductive strip 22 are connected to the first busbar 3 by welding, and the second conductive strip 13 and the third conductive strip 22 are connected to the second busbar 4 by welding. It should be understood that, since the first conductive strip 12 is close to the third conductive strip 22, the connection positions of the first conductive strip 12 and the first busbar 3 are also close. Conversely, since the second conductive strip 13 and the fourth conductive strip 23 are far apart, the connection positions of the second conductive strip 13 and the second busbar 4 are also far apart. In other words, the second conductive strip 13 and the fourth conductive strip 23 are connected to both sides of the second busbar 4 along the winding axis of the first element 11 or the second element 21. The second busbar 4 has a first connecting end 42, located between the second conductive strip 13 and the fourth conductive strip 23 along the winding axis of the first element 11 or the second element 21. The first busbar 3 has a second connection end 32. Since the first conductive strip 12 and the third conductive strip 22 are close to each other, the second connection end 32 can be located between the first conductive strip 12 and the third conductive strip 22, or it can be located on the side closer to the first conductive strip 12 and away from the third conductive strip 22, or it can be located on the side closer to the third conductive strip 22 and away from the first conductive strip 12.

[0043] It should be understood that the first busbar 3 and the second busbar 4 can be simultaneously located on the same side of the first element bar 1 and the second element bar 2, or they can be located on different sides of the first element bar 1 and the second element bar 2, depending on the specific circumstances. This application is not limited to this.

[0044] The low self-inductance capacitor proposed in this application embodiment has a first conductive strip 12 and a second conductive strip 13 connected to both ends of its winding axis, and a third conductive strip 22 and a fourth conductive strip 23 connected to both ends of its winding axis, respectively. Along the winding axis direction of the first element 11 or the second element 21, the first conductive strip 12 is close to the third conductive strip 22 and both are connected to the first busbar 3 to form one pole of the capacitor. The second conductive strip 13 is far from the third conductive strip 22, and both the second conductive strip 13 and the fourth conductive strip 23 are connected to the second busbar 4 to form the other pole of the capacitor. That is, along the winding axis direction of the first element 11 or the second element 21, the second conductive strip 13 and the third conductive strip 22 are connected to the first busbar 4 to form the other pole of the capacitor. Four conductive strips 23 are connected to opposite sides of the second busbar 4. The second busbar 4 has a first connection end 42. Along the winding axis of the first element 11 or the second element 21, the first connection end 42 is located between the second conductive strip 13 and the fourth conductive strip 23. When current is introduced into the second busbar 4 from the first connection end 42, the current flows from the first connection end 42 to the second conductive strip 13 and the fourth conductive strip 23 respectively. The current flowing to the second conductive strip 13 and the current flowing to the fourth conductive strip 23 on the second busbar 4 are in opposite directions. Therefore, the inductance generated by the current loop flowing to the second conductive strip 13 and the inductance generated by the current loop flowing to the fourth conductive strip 23 will cancel each other out, thereby reducing the self-inductance of the capacitor.

[0045] Furthermore, the first conductive strip 12 and the third conductive strip 22 can conduct the heat generated by the first element 11 and the second element 21 to the first busbar 3; the second conductive strip 13 and the fourth conductive strip 23 can conduct the heat generated by the first element 11 and the second element 21 to the second busbar 4. The first busbar 3 and the second busbar 4, which have larger areas, have good heat dissipation performance and can assist the capacitor in heat dissipation, thereby reducing the thermal resistance of the capacitor and thus achieving the purpose of reducing the heat generated by the capacitor.

[0046] In an optional embodiment, along the winding axis of the first element 11 or the second element 21, the first connection terminal 42 may be located near the midpoint between the second conductive strip 13 and the fourth conductive strip 23. When current is introduced into the second busbar 4 from the first connection terminal 42, the current flows from the first connection terminal 42 to the second conductive strip 13 and the fourth conductive strip 23, respectively. The current flowing to the second conductive strip 13 and the current flowing to the fourth conductive strip 23 on the second busbar 4 are in opposite directions. Therefore, the inductance generated by the current loop flowing to the second conductive strip 13 and the inductance generated by the current loop flowing to the fourth conductive strip 23 will partially cancel each other out, thereby reducing the self-inductance of the capacitor.

[0047] Optionally, refer to Figure 1 Along the winding axis of the first element 11 or the second element 21, the first connection end 42 is located at the midpoint between the second conductive strip 13 and the fourth conductive strip 23. When current is introduced into the second busbar 4 from the first connection end 42, the current flows from the first connection end 42 to the second conductive strip 13 and the fourth conductive strip 23 respectively. The current flowing to the second conductive strip 13 and the current flowing to the fourth conductive strip 23 on the second busbar 4 are in opposite directions, and the paths through which the currents flow are equal. Therefore, the inductance generated by the current loop flowing to the second conductive strip 13 and the inductance generated by the current loop flowing to the fourth conductive strip 23 will cancel each other out, thereby reducing the self-inductance of the capacitor.

[0048] Optionally, refer to Figure 1 The first bus 3 and the second bus 4 are disposed on the same side of the first element strip 1 and the second element strip 2. Along the first direction A, at least a portion of the second bus 4 is located on the side of the first bus 3 away from the first element strip 1 and the second element strip 2. Because the first bus 3 and the second bus 4 are disposed on the same side of the first element strip 1 and the second element strip 2, and the projection of at least a portion of the second bus 4 coincides with the first bus 3 along the first direction A, when current flows through the first bus 3 and the second bus 4, the inductance generated by the first bus 3 and the inductance generated by the second bus 4 will cancel each other out, further reducing the self-inductance of the capacitor. Furthermore, the fact that the first bus 3 and the second bus 4 are disposed on the same side of the first element strip 1 and the second element strip 2 effectively reduces the current path, thereby reducing the self-inductance and heat generated by the capacitor.

[0049] It should be understood that the first busbar 3 may have a first side away from the first element bar 1 and the second element bar 2, and a second side close to the first element bar 1 and the second element bar 2, wherein the first side and the second side are arranged opposite to each other. The first busbar 3 may also have a third side and a fourth side connecting the first side and the second side. At least a portion of the second busbar 4 is disposed on the first side of the first busbar 3. This can be understood as the second busbar 4 being entirely disposed on the first side of the first busbar 3, or the second busbar 4 having a portion disposed on the first side of the first busbar 3, and also having portions disposed on the third side and / or the fourth side. Wherein, any portion of the second busbar 4 has a gap between it and the first busbar 3 to prevent the first busbar 3 and the second busbar 4 from contacting each other, thereby reducing the risk of short circuit in the capacitor.

[0050] Optionally, refer to Figure 1 The second busbar 4 includes a first body portion 41, a second body portion 44, and a raised portion 43. The first body portion 41 is connected to the second conductive strip 13, and the second body portion 44 is connected to the fourth conductive strip 23. Along the winding axis of the first element 11 or the second element 21, both ends of the raised portion 43 are connected to the first body portion 41 and the second body portion 44, respectively. Along the first direction A, at least a portion of the raised portion 43 protrudes relative to the first body portion 41 and the second body portion 44 towards the side away from the first element strip 1 and the second element strip 2, to form a receiving cavity 431 for accommodating the first busbar 3. The second busbar 4 has a raised portion 43, and the first busbar 3 is correspondingly provided with the raised portion 43. A portion or the entire raised portion 43 protrudes towards the first busbar 3, increasing the distance between the first busbar 3 and the second busbar 4, thus forming an insulating distance between the first busbar 3 and the raised portion 43, reducing the risk of short circuit in the capacitor. It should be understood that there is also an insulating distance between the body part 41 of the second busbar 4 and the first busbar 3.

[0051] Optionally, refer to Figure 1 The raised portion 43 is provided with a clearance hole 432, which extends through the raised portion 43 along its thickness direction. Specifically, the first busbar 3 has a second connection end 32, which protrudes from the first side of the first busbar 3 away from the first element 11 and the second element 21, and the second connection end 32 passes through the clearance hole 432 and connects to the first terminal 8 to facilitate the introduction or extraction of current on the first busbar 3.

[0052] Optionally, refer to Figure 1 The raised portion 43 includes a top wall 433, a first side wall 434, and a second side wall 435. Along the first direction A, the top wall 433 is spaced apart from the first busbar 3, the first side wall 434 is connected to one side of the top wall 433 and the first body portion 41, and the second side wall 435 is connected to the other side of the top wall 433 and the second body portion 44.

[0053] Specifically, the body portion 41 of the second busbar 4 has a first body portion 41 connected to the second conductive strip 13 and a second body portion 41 connected to the fourth conductive strip 23. Along the first direction A, a first sidewall 434 is connected between the top wall 433 near the second conductive strip 13 and the first body portion 41, and a second sidewall 435 is connected between the top wall 433 near the fourth conductive strip 23 and the second body portion 41. In other words, along the winding axis of the first element 11 or the second element 21, the first sidewall 434 is connected to opposite sides of the top wall 433, forming a receiving cavity 431. The first busbar 3 corresponds to the receiving cavity 431, and the first busbar 3 is spaced apart from the top wall 433, the first sidewall 434, and the second sidewall 435 to form an insulating distance.

[0054] Optionally, along the first direction A, the minimum distance between the top wall 433 and the first busbar 3 is 3-10 mm. By leaving a distance of at least 3-10 mm between the top wall 433 and the first busbar 3 along the first direction A, the contact between the first busbar 3 and the second busbar 4 is reduced, thereby reducing the risk of short circuit caused by the connection between the first busbar 3 and the second busbar 4.

[0055] Optionally, refer to Figure 1 and Figure 2 Along the first direction A, the ends of the first conductive strip 12 and the third conductive strip 22 on the same side are inserted through the first busbar 3 and overlap with the first busbar 3 on the side in the thickness direction; the ends of the second conductive strip 13 and the fourth conductive strip 23 on the same side overlap with the second busbar 4 on the side in the thickness direction. The first conductive strip 12 and the third conductive strip 22 are connected to the first busbar 3 to form one pole of the capacitor, and the second conductive strip 13 and the third conductive strip 22 are connected to the second busbar 4 to form the other pole of the capacitor. The current is introduced through the first connection terminal 42 of the second busbar 4 and then flows to the second conductive strip 13 and the fourth conductive strip 23 respectively. The two currents on the second busbar 4 are in opposite directions, and the inductances they generate cancel each other out. One current flows through the first element 11 and then through the first conductive strip 12 into the first busbar 3, and the other current flows through the second element 21 and then through the third conductive strip 22 into the first busbar 3 and then out of the first busbar 3. The current on the first busbar 3 is in opposite directions to the current at the corresponding position on the second busbar 4, and the inductances they generate can also cancel each other out, thereby reducing the self-inductance of the capacitor.

[0056] In one alternative embodiment, reference Figure 2The first busbar 3 has a through hole through which the first conductive strip 12, connected to the first element 11, and the third conductive strip 22, connected to the second element 21, both pass and overlap with the first busbar 3. The first busbar 3 has a second connection end 32, which is located near the through hole to reduce the current path on the first busbar 3, thereby reducing the inductance generated by the first busbar 3.

[0057] In another optional embodiment, the first bus 3 has two through holes. A first conductive strip 12 connected to the first element 11 passes through one through hole, and a third conductive strip 22 connected to the second element 21 passes through the other through hole. A second connection end 32 is located between the two through holes. Optionally, the second connection end 32 is positioned close to both through holes, that is, close to both the first conductive strip 12 and the third conductive strip 22, making the distance between the first conductive strip 12 and the third conductive strip 22 and the second connection end 32 negligible. This reduces the current path between the first conductive strip 12 and the third conductive strip 22 and the second connection end 32, thereby reducing the inductance generated by the first bus 3. Optionally, there is a gap between the first conductive strip 12 and the second connection end 32, and between the third conductive strip 22 and the second connection end 32. The current direction generated from the first conductive strip 12 to the second connection end 32 is opposite to the current direction generated from the third conductive strip 22 to the second connection end 32. The resulting inductances can cancel each other out, further reducing the inductance generated by the first bus 3.

[0058] Optionally, there are multiple first element strips 1 and multiple second element strips 2, arranged opposite to each corresponding second element strip 2 along the winding axis of the first element 11 or the second element 21. Multiple first element strips 1 and multiple second element strips 2 are arranged sequentially along the second direction B, with the first direction A, the second direction B, and the winding axis of the first element 11 or the second element 21 being perpendicular to each other. Connecting multiple first element strips 1 and multiple second element strips 2 in parallel forms a first element group, and multiple second element strips 2 form a second element group. Connecting the first element group and the second element group in parallel reduces the equivalent series resistance of the capacitor, thereby reducing capacitor heat generation. Furthermore, the first busbar 3 and the second busbar 4 have large flow areas and correspondingly low equivalent series resistances, thus reducing the overall equivalent series resistance of the capacitor.

[0059] It should be understood that each first element strip 1 is connected to a first conductive strip 12 and a second conductive strip 13, and each second element strip 2 is connected to a third conductive strip 22 and a fourth conductive strip 23.

[0060] Optionally, the capacitor further includes a first connecting strip 5, a second connecting strip, a third connecting strip, and a fourth connecting strip. The first connecting strip 5 is connected to a plurality of first conductive strips 12, the second connecting strip is connected to a plurality of second conductive strips 13, the third connecting strip is connected to a plurality of third conductive strips 22, and the fourth connecting strip is connected to a plurality of fourth conductive strips 23. The first connecting strip 5 and the second connecting strip are used to connect a plurality of first element strips 1 in parallel, and the third connecting strip and the fourth connecting strip are used to connect a plurality of second element strips 2 in parallel. The parallel connection of the plurality of first element strips 1 and the parallel connection of the plurality of second element strips 2 reduces the equivalent series resistance of the capacitor, thereby reducing the heat generation of the capacitor.

[0061] Optionally, refer to Figure 1 and Figure 2 There are multiple first connecting strips 5, second connecting strips, third connecting strips, and fourth connecting strips. Multiple first connecting strips 5 are spaced apart along a first direction A, multiple second connecting strips are spaced apart along a first direction A, multiple third connecting strips are spaced apart along a first direction A, and multiple fourth connecting strips are spaced apart along a first direction A. The second, third, and fourth connecting strips are not shown in the figure. Multiple first and second connecting strips, while connecting multiple first element strips 1 in parallel, also serve a heat dissipation function; multiple third and fourth connecting strips, while connecting multiple second element strips 2 in parallel, also serve a heat dissipation function, thereby improving the heat dissipation efficiency of the capacitor.

[0062] It should be understood that the first conductive strip 12 needs to be connected to all the first elements 11, and the first connecting strip 5 can be connected to all the first conductive strips 12, and there can be multiple layers of the first connecting strip 5, with each layer also having multiple first connecting strips 5; the first connecting strip 5 may also not be connected to all the first conductive strips 12, and the length of the first connecting strip 5 can also be determined according to specific circumstances. The second, third, and fourth connecting strips are similar, and will not be described in detail here.

[0063] Optionally, refer to Figures 5 to 7The capacitor also includes a housing 6, an end cap 7, a first terminal 8, and a second terminal 9. The housing 6 has a receiving space for accommodating a first element strip 1, a second element strip 2, a first busbar 3, and a second busbar 4. The housing 6 has an opening along a first direction A. The end cap 7 is connected to the housing 6 to close the opening. The first terminal 8 passes through the end cap 7 to connect with the first busbar 3, and the second terminal 9 passes through the end cap 7 to connect with the second busbar 4. The first element 11 and the second element 21 are formed by winding a metallized polypropylene film using a non-inductive winding method. The axial length of the first element 11 and the second element 21 is relatively short, resulting in a short current path and low self-inductance and equivalent series resistance of individual elements. Multiple first elements 11 are connected in parallel via a first conductive strip 12 and a second conductive strip 13 to form a first element strip 1. Multiple second elements 21 are connected in parallel via a third conductive strip 22 and a fourth conductive strip 23 to form a second element strip 2. The multiple first element strips 1 and multiple second element strips 2 are then connected in parallel, wrapped with insulating paper 61, and placed inside a housing 6. An end cap 7 encloses the multiple first element strips 1 and multiple second element strips 2 within the housing 6. The housing 6 protects the first element strips 1 and multiple second element strips 2, reducing damage to them. A first terminal 8 passes through the end cap 7 and connects to a first busbar 3 via a second connecting terminal 32. A second terminal 9 passes through the end cap 7 and connects to a second busbar 4 via a first connecting terminal 42. The connection between the first terminal 8 and the first busbar 3 forms one pole of a capacitor, and the connection between the second terminal 9 and the second busbar 4 forms the other pole of the capacitor.

[0064] Specifically, the first busbar 3 has multiple second connection terminals 32, the second busbar 4 has multiple first connection terminals 42, and the capacitor also has multiple first terminals 8 connected to the second connection terminals 32 and multiple second terminals 9 connected to the first connection terminals 42. The first connection terminals 42 protrude from the first busbar 3 and pass through the clearance hole 432 of the second busbar 4 to connect with the first terminals 8, forming one pole of the capacitor. The second connection terminals 32 protrude from the second busbar 4 and connect with the second terminals 9, forming the second pole of the capacitor. Providing multiple pairs of first terminals 8 and second terminals 9 can meet the requirements of high current and reduce the heat generated by a single pair of first terminals 8 and second terminals 9.

[0065] The low self-inductance capacitor of this application includes multiple first element strips 1 and multiple second element strips 2 arranged in parallel, a first busbar 3 and a second busbar 4 arranged along a first direction A, an end cap 7, a housing 6, a first terminal 8 and a second terminal 9, and potting material. The first conductive strip 12, the second conductive strip 13, the third conductive strip 22, and the fourth conductive strip 23, as well as the first connecting strip 5, the second connecting strip, the third connecting strip, and the fourth connecting strip in this application, are all copper strips. Along the winding axis of the first element 11, both ends of the first element 11 have core rods, which are insulating components. The first conductive strip 12 and the second conductive strip 13 both have through-hole structures and welding leads. The core rods at both ends of the first element 11 cooperate with the through-hole structures of the first conductive strip 12 and the second conductive strip 13 to position the first element 11. The two ends of the first element 11 are welded to the welding leads of the first conductive strip 12 and the second conductive strip, respectively, which can reduce welding stress and reduce the risk of desoldering. Along the winding axis of the second element 21, both ends of the second element 21 have core rods, which are insulating components. The third conductive strip 22 and the fourth conductive strip 23 both have through-hole structures and welding leads. The two ends of the second element 21 cooperate with the through-hole structures of the third conductive strip 22 and the fourth conductive strip 23, respectively, to position the second element 21. The two ends of the second element 21 are welded to the welding leads of the third conductive strip 22 and the fourth conductive strip 23, respectively, which can reduce welding stress and reduce the risk of desoldering.

[0066] Multiple first components 11 are arranged side by side. A first conductive strip 12 and a second conductive strip 13 cover the gold-plated surfaces at both ends of the first component 11, respectively. The soldering leads of the first conductive strip 12 and the second conductive strip 13 are connected to the gold-plated surfaces at both ends of the first component 11 by soldering or high-current soldering. The copper strip can be one or more layers. The first layer of copper strip must connect all components. The first layer of copper strip is the first conductive strip 12 and the second conductive strip 13, and the first conductive strip 12 and the second conductive strip 13 must connect all the first components 11. The length of the second and subsequent layers of copper strip can be shortened according to the actual working conditions. The second and subsequent layers of copper strip are the first connecting strip 5 and the second connecting strip. The copper strip is fixed to the gold-plated surfaces of the multiple first components 11 by soldering to form a first component strip 1. The two end faces of the first component strip 1 serve as two poles, respectively.

[0067] Multiple second elements 21 are arranged side by side. A third conductive strip 22 and a fourth conductive strip 23 cover the gold-plated surfaces at both ends of the second elements 21. The soldering leads of the third conductive strip 22 and the fourth conductive strip 23 are connected to the gold-plated surfaces at both ends of the second elements 21 by soldering or high-current soldering. The copper strip can be one or more layers. Except for the first layer of copper strip, which must connect all elements, the first layer consists of the third conductive strip 22 and the fourth conductive strip 23, and must connect all second elements 21. The length of the second and subsequent layers of copper strip can be shortened according to actual operating conditions. The second and subsequent layers of copper strip serve as the third and fourth connecting strips. The copper strip is fixed to the gold-plated surfaces of the multiple second elements 21 by soldering to form a second element strip 2. The two end faces of the second element strip 2 serve as poles. Multiple first element strips 1 are then connected by copper strip to form a first element group. The copper strip can be one or more layers, and the two end faces of the first element group serve as poles. Multiple second element strips 2 are then connected by copper strips to form a second element group, wherein the copper strip can be one layer or multiple layers, and the two end faces of the second element group serve as two poles respectively. The first element group and the second element group are placed side by side opposite each other. The first conductive strip 12 of the first element group and the third conductive strip 22 of the second element group are led out from the through holes reserved in the first busbar 3 and fixed to the surface of the first busbar 3 by welding to form one pole; then the second conductive strip 13 of the first element group and the fourth conductive strip 23 of the second element group are covered on the second busbar 4 to form the other pole. The second busbar 4 is located above the first busbar 3, with an insulating distance between them. It should be understood that, except for the differences caused by welding and insulation factors, the main areas of the first busbar 3 and the second busbar 4 basically overlap. Preferably, the first busbar 3 and the second busbar 4 partially overlap in the conductive area.

[0068] The first terminal 8 and the second terminal 9 are connected to the first busbar 3 and the second busbar 4, respectively, forming the two poles of the capacitor. When the capacitor is working, the current flows in from the second terminal 9. When it passes through the second busbar 4, the current is shunted from the middle of the second busbar 4 to the second conductive strip 13 and the fourth conductive strip 23 on both sides. The current directions are opposite, which cancels out part of the inductance. The current paths on the first busbar 3 and the second busbar 4, and the first element group and the second element group are all short, thereby reducing the self-inductance of the capacitor.

[0069] The first and second component groups utilize a larger number of components. The parallel connection of these numerous components reduces the equivalent series resistance of both groups. The first busbar 3 and the second busbar 4 have large current-carrying areas, resulting in lower equivalent series resistances. This leads to a lower overall equivalent series resistance for the capacitor when combined with the first and second component groups. The copper strips connecting to the first and second component groups conduct some of the self-heating from the components to the first and second busbars 3 and 4. The large area of ​​the first and second busbars provides excellent heat dissipation, thus optimizing the overall heat dissipation path and reducing thermal resistance. By reducing both the equivalent series resistance and thermal resistance, the capacitor achieves a low temperature rise.

[0070] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0071] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0072] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0073] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A low-self-inductance capacitor for a flexible DC converter valve, characterized in that, include: The first element strip includes a first conductive strip, a second conductive strip, and a plurality of first elements. The plurality of first elements are arranged sequentially along a first direction. Both the first conductive strip and the second conductive strip extend along the first direction. The first direction is perpendicular to the winding axis direction of the first element. Each first element is connected to the first conductive strip at one end in the winding axis direction, and each first element is connected to the second conductive strip at the other end in the winding axis direction. The second element strip includes a third conductive strip, a fourth conductive strip, and a plurality of second elements. The plurality of second elements are arranged sequentially along the first direction. The third conductive strip and the fourth conductive strip both extend along the first direction. The winding axis direction of the second element is parallel to the winding axis direction of the first element. Each second element is connected to the third conductive strip at one end in the winding axis direction and to the fourth conductive strip at the other end in the winding axis direction. The first busbar and the second busbar are disposed on the same side or opposite side of the first element bar and the second element bar along the first direction. Wherein, along the winding axis of the first element or the second element, the first conductive strip is closer to the third conductive strip than the fourth conductive strip. The first conductive strip and the third conductive strip have the same polarity and are both connected to the first busbar. The second conductive strip and the fourth conductive strip have the same polarity and are both connected to the second busbar. The second busbar is provided with a first connecting end, and along the winding axis of the first element or the second element, the first connecting end is located between the second conductive strip and the fourth conductive strip.

2. The low self-inductance capacitor according to claim 1, characterized in that, The first busbar and the second busbar are disposed on the same side of the first component strip and the second component strip; Along the first direction, at least a portion of the second busbar is located on the side of the first busbar away from the first element bar and the second element bar.

3. The low self-inductance capacitor according to claim 2, characterized in that, The second busbar includes a first body portion, a second body portion, and a raised portion. The first body portion is connected to the second conductive strip, and the second body portion is connected to the fourth conductive strip. Along the winding axis of the first element or the second element, the two ends of the raised portion are respectively connected to the first body portion and the second body portion. Along the first direction, at least a portion of the raised portion protrudes toward a side away from the first and second element bars relative to the first and second body portions, to form a receiving cavity for accommodating the first busbar.

4. The low self-inductance capacitor according to claim 3, characterized in that, The raised portion is provided with a clearance hole, which extends through the raised portion along its thickness direction.

5. The low self-inductance capacitor according to claim 4, characterized in that, The raised portion includes a top wall, a first side wall, and a second side wall; Along the first direction, the top wall is spaced apart from the first busbar, the first side wall is connected to the top wall and the first body portion respectively, and the second side wall is connected to the top wall and the second body portion respectively.

6. The low self-inductance capacitor according to claim 5, characterized in that, Along the first direction, the minimum distance between the top wall and the first busbar is 3-10 mm.

7. The low self-inductance capacitor according to claim 1, characterized in that, Along the first direction, the first conductive strip and the third conductive strip are inserted through the first busbar at the same side end and overlap the first busbar in the thickness direction. The ends of the second conductive strip and the fourth conductive strip on the same side overlap with the second busbar in the thickness direction.

8. The low self-inductance capacitor according to claim 1, characterized in that, There are multiple first element strips and multiple second element strips, and each first element strip is arranged opposite to the corresponding second element strip along the winding axis direction of the first element or the second element; Multiple first element strips are arranged sequentially along the second direction, and multiple second element strips are arranged sequentially along the second direction, with the first direction, the second direction, and the winding axis direction of the first element or the second element being perpendicular to each other.

9. The low self-inductance capacitor according to claim 8, characterized in that, The capacitor further includes a first connecting strip, a second connecting strip, a third connecting strip, and a fourth connecting strip. The first connecting strip is connected to a plurality of first conductive strips, the second connecting strip is connected to a plurality of second conductive strips, the third connecting strip is connected to a plurality of third conductive strips, and the fourth connecting strip is connected to a plurality of fourth conductive strips.

10. The low self-inductance capacitor according to claim 9, characterized in that, There are multiple first connecting strips, second connecting strips, third connecting strips and fourth connecting strips. Multiple first connecting strips are spaced apart along the first direction, multiple second connecting strips are spaced apart along the first direction, multiple third connecting strips are spaced apart along the first direction, and multiple fourth connecting strips are spaced apart along the first direction.

11. The low self-inductance capacitor according to claim 1, characterized in that, The capacitor also includes: The housing has a receiving space inside to accommodate the first component strip, the second component strip, the first busbar, and the second busbar, and has an opening along the first direction; An end cap, which is connected to the housing to close the opening; A first terminal and a second terminal, wherein the first terminal passes through the end cap to connect to the first busbar, and the second terminal passes through the end cap to connect to the second busbar.

12. The low self-inductance capacitor according to claim 1, characterized in that, Along the winding axis of the first element or the second element, the first connecting end is located at the midpoint between the second conductive strip and the fourth conductive strip.

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