Bus bar filter

Abstract

To solve the following problem: a bus bar filter design has to be corrected to improve insulation performance between components, increase space utilization and reduce a cost.SOLUTION: A bus bar filter includes: a core having a through-hole; two bus bars that extend through the through-hole; and a first overmolding part that is formed on the two bus bars between the two bus bars and a core. The first overmolding part fills a gap between the two bus bars and a remaining space within the through-hole.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates generally to busbar filters, and more particularly to busbar filters having overmolded components for electrically insulating the busbars, cores, and lead frames mounted thereon. [Background technology]

[0002] Busbar filters are commonly used in electrical and electronic systems to filter out unwanted frequencies, harmonics, or noise on power supply lines. Busbars are conductive materials that distribute power within a system, and when integrated with filters, busbars help ensure that the delivered power remains clean and stable.

[0003] In electrical and electronic equipment, insulation distance is important to ensure safe operation without posing a risk to the user or other devices. Isolation distance refers to the physical gap between components with different electrical potentials (for example, between a conductor and a grounded part or between a conductor and another electrical element). This gap must be large enough to prevent short circuits or electrical failures. Designers must calculate the appropriate insulation distance based on safety criteria, which are typically determined by the rated operating voltage, creepage distance, and clearance distance.

[0004] In traditional busbar filter designs, the filtering effect is achieved through the connection between the PCB and the capacitor. From a safety regulatory perspective, the insulation distance between the PCB and the busbar is calculated using the point-to-point (linear) distance along a plane. As the input voltage increases, the required insulation distance also increases. As a result, the safety distance between the busbar and the capacitor becomes larger, resulting in increased product size and higher manufacturing costs. Therefore, those skilled in the art need to modify busbar filter designs to improve the insulation performance between components, increase space utilization, and reduce costs. Summary of the Invention

[0005] In view of the above-mentioned drawbacks of the prior art, the present invention provides a novel busbar filter featuring an overmolding formed between the busbar, the core, and the lead frame mounted thereon, which improves insulation performance. In addition, the capacitor is connected using a flexible lead frame instead of a conventional PCB, resulting in improved space utilization. As a result, the required safety distance and product size are reduced, and manufacturing costs are reduced.

[0006] An object of the present invention is to provide a busbar filter including: a core having a through hole; two busbars extending along a first direction through the through hole, each of the two busbars including a first end and a second end; and a first overmolding portion formed on the two busbars between the two busbars and the core, the first overmolding portion filling gaps between the two busbars and the remaining space in the through hole.

[0007] These and other objects of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 illustrates an isometric view of a busbar filter according to a preferred embodiment of the present invention.

[0009] [Figure 2] 1 illustrates an exploded view of a busbar filter according to a preferred embodiment of the present invention;

[0010] [Figure 3] 3 presents a cross-sectional view of a busbar filter taken along section line A-A' of FIG. 2 according to a preferred embodiment of the present invention.

[0011] [Figure 4] 1 illustrates a top view of a busbar showing a first overmolding portion molded thereon, according to a preferred embodiment of the present invention;

[0012] [Figure 5] 1 illustrates a perspective view of a first lead frame showing an overmolded portion molded thereon and a capacitor mounted thereon, according to a preferred embodiment of the present invention;

[0013] [Figure 6] 1 illustrates a top view of a first lead frame showing an overmolding portion molded thereon, according to a preferred embodiment of the present invention;

[0014] [Figure 7] 1 illustrates a perspective view of a second lead frame according to a preferred embodiment of the present invention, showing a second overmolding portion molded thereon and a capacitor mounted thereon;

[0015] [Figure 8] 1 illustrates a top view of a second lead frame showing a second overmolding portion molded thereon, according to a preferred embodiment of the present invention;

[0016] [Figure 9] 1 presents a schematic diagram of a busbar filter according to a preferred embodiment of the present invention;

[0017] [Figure 10] 10 provides an expanded view of a second overmolded portion according to one embodiment of the present invention.

[0018] [Figure 11] 1 presents a close-up view of two bus bars with a first overmolding portion molded thereon according to one embodiment of the present invention.

[0019] [Figure 12] 1 presents a close-up view of two bus bars with a first overmolding portion molded thereon according to one embodiment of the present invention.

[0020] [Figure 13] 10 presents an exploded view of a second lead frame according to an alternative embodiment of the present invention with a second overmolding portion molded thereon and a capacitor mounted thereon.

[0021] [Figure 14] 10 presents an exploded view of a second lead frame according to an alternative embodiment of the present invention with a second overmolding portion molded thereon and a capacitor mounted thereon.

[0022] [Figure 15] 10 provides an exploded view of a bent busbar according to an alternative embodiment of the present invention.

[0023] [Figure 16] 10A-10C illustrate bus bars in various bent configurations according to alternative embodiments of the present invention.

[0024] For clarity and convenience in the drawings, the relative dimensions and proportions of parts in the drawings may be shown exaggerated or reduced in size, and the same reference symbols are generally used to refer to corresponding or similar features in modified and different embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0025] Reference will now be made in detail to exemplary embodiments of the present invention as illustrated in the accompanying drawings in order to understand and practice the present disclosure and to achieve the technical effects. It can be understood that the following description is for illustrative purposes only and is not intended to limit the present disclosure. Various configurations in the various embodiments and non-inconsistent embodiments of the present disclosure can be combined and reconfigured in various ways. Modifications, equivalents, or improvements to the present disclosure that do not depart from the spirit and scope of the present disclosure are understandable to those skilled in the art and are intended to be encompassed within the scope of the present disclosure.

[0026] It should be immediately understood that the meanings of "on," "above," and "over" in this disclosure should be interpreted in the broadest possible manner, such that "on" not only means "directly on" something, but also includes the meaning "on" of something with an intermediate structure or layer therebetween, and "above" or "over" not only means "above" or "over" something, but also includes the meaning "above" or "over" of something without an intermediate structure or layer therebetween (i.e., directly above something). Furthermore, spatially relative terms such as "beneath," "below," "lower," "above," "upper," etc. may be used herein to describe the relationship of one element or structure to another element or structure as illustrated in the figures for ease of explanation.

[0027] As used herein, the term "layer" refers to a portion of material that includes a region having a thickness. A layer can extend throughout an underlying or overlying structure, or it can have an extent that is less than the extent of the underlying or overlying structure. Furthermore, a layer can be a homogeneous or heterogeneous region of a continuous structure that has a thickness that is less than the thickness of the continuous structure. For example, a layer can be disposed between the top and bottom surfaces of a continuous structure or between any pair of horizontal planes at such top and bottom surfaces. A layer can extend horizontally, vertically, and / or along a tapered surface. A substrate can be a layer and / or can include one or more layers therein and / or have one or more layers on, above, and / or below it. A layer can include multiple layers. For example, an interconnect layer can include one or more conductor and contact layers (in which contacts, interconnect lines, and / or through-holes are formed) and one or more dielectric layers.

[0028] In general, terms may be understood, at least in part, from their usage in context. For example, the term "one or more" as used herein may be used in a singular sense to describe any configuration, structure, or feature, or in a plural sense to describe a combination of features, structures, or features, depending at least in part on the context. Similarly, terms such as "a," "an," or "the" may be understood to convey either a singular or plural meaning, again depending at least in part on the context. Additionally, the term "based on" may be understood as not necessarily intended to convey an exclusive set of factors, but may allow for the presence of other factors not necessarily explicitly recited, again depending at least in part on the context.

[0029] It will be further understood that the terms "includes," "including," "comprises," and / or "comprising," as used herein, specify the presence of stated structures, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other structures, integers, steps, operations, elements, components, and / or groups thereof.

[0030] First, refer to FIG. 1 , which shows an isometric view of a busbar filter 100 according to a preferred embodiment of the present invention. The busbar filter 100 primarily includes a core 102, two busbars 104, a first overmolding portion 106, a first lead frame 108, a second lead frame 110, and a second overmolding portion 112. Among these components, the core 102 is a magnetic core that houses an internal winding or coil, such as a common-mode choke, and functions as a passive electromagnetic component. The core material is typically a magnetic material, such as ferrite, iron powder, or a multilayer stack of nanocrystalline magnetic materials. It allows desired electrical signals to pass through power lines (e.g., from a switching power supply or motor) while filtering out undesirable high-frequency noise signals generated by external sources or other circuits in the system. By suppressing common-mode electromagnetic interference (EMI), the common-mode choke helps protect sensitive circuitry and maintain signal integrity during data transmission. In addition, it enhances the system's electromagnetic compatibility (EMC) and ensures compliance with international electromagnetic interference standards.

[0031] Still referring to FIG. 1 , the busbar 104 is a metallic conductor designed to efficiently distribute large amounts of electrical current within an electrical system. It is typically a solid strip or bar made from a highly conductive metal, such as copper, aluminum, or their alloys, chosen for their excellent electrical performance and mechanical durability. The busbar 104 enables current distribution to multiple circuits or components, resulting in lower resistance and reduced power loss compared to traditional wiring. This makes it ideal for high-current applications, including electric vehicles (EVs), power distribution units (PDUs), and industrial power systems. In filter applications, the busbar 104 not only functions as a current conductor but also interacts with the magnetic components (i.e., the core 102) to filter electromagnetic noise. This improves EMI filtering and EMC performance by allowing mains power or signals to pass through while suppressing unwanted noise.

[0032] Still referring to FIG. 1 , the first lead frame 108 and the second lead frame 110 in the present invention function as electrical interconnects, conducting signals or power directly between the bus bar 104 and the capacitors 114 mounted thereon. In addition to their electrical role, the lead frames also function as mechanical support structures, providing a stable mounting platform for the capacitors 114 on the bus bar filter 100. Furthermore, the lead frames aid in thermal management by helping to dissipate heat generated by the capacitors 114, thereby contributing to stable and reliable operation of the system. These lead frames are typically fabricated from copper, copper alloys, or nickel-plated steel, which are selected for their high electrical conductivity, mechanical flexibility, and long-term reliability. In this embodiment, the first lead frame 108 and the second lead frame 110 are attached to opposite ends of the bus bar 104, with their respective leads electrically connected to the left and right bus bars 104.

[0033] Still referring to FIG. 1 , it is important to note that in the present invention, the busbar filter 100 includes overmolded components, e.g., a first overmolded portion 106 and a second overmolded portion 112. As the name suggests, these overmolded portions are produced through an overmolding process. A layer of material (typically plastic) is molded over another component or assembly to create a single, integrated part. This technique combines multiple materials into a unified structure. Specifically, in a preferred embodiment, the first overmolded portion 106 is formed by molding a thermoplastic compound, such as a thermoplastic elastomer (TPE) or a thermoplastic polyurethane (TPU), around a base component (e.g., the core 102 and busbar 104). Similarly, the second overmolded portion 112 is formed by injection molding the overmolded compound around a base component, such as the second lead frame 110. In the design of the busbar filter 100, the first overmolding portion 106 and the second overmolding portion 112 serve multiple functions: they seal and secure the busbar 104 and the second lead frame 110, respectively; they insulate the electrical paths between the components; and they provide mechanical stability and environmental protection. Additionally, depending on product requirements, the first lead frame 108 may include a third overmolding portion 109 to enhance its functionality. The following embodiment focuses on the second overmolding portion 112 as an example to illustrate the application of overmolded components within the busbar filter 100 of the present invention.

[0034] 2, an exploded view of a bus bar filter 100 according to a preferred embodiment of the present invention is shown. In this embodiment, a first overmolding portion 106 and a second overmolding portion 112 are each molded around a bus bar 104 and a second lead frame 110, respectively. The first overmolding portion 106 encapsulates substantially the entire length of the bus bar 104, except for portions of the first and second ends 104a, 104b that are left exposed for electrical connection to inputs and outputs of a circuit system, and mounting holes 104c for securing the first and second lead frames 108, 110. The first overmolding portion 106 is essentially molded around the base components of the core 102 and the bus bar 104 and includes specific configurations such as two fixed stops 106 a, a middle portion 106 b positioned between the fixed stops 106 a, and two outer portions 106 c positioned outside either of the two fixed stops 106 a. After assembly, the bus bar 104, together with the first overmolding portion 106, extends through the central through-hole 102 a of the core 102, and the first and second ends 104 a, 104 b of the bus bar 104, together with the two outer portions 106 c of the first overmolding portion 106, are positioned on either side of the core 102 in the first direction D1 (i.e., the longitudinal direction of the bus bar 104). The core 102 is positioned between two fixed stops 106a of the first overmolding part 106, and the central portion 106b fills the through hole 102a of the core 102. The distance w1 between the two outer sides of the two bus bars in the second direction D2 is smaller than the hole width w2 of the through hole 102a of the core 102 in the second direction D2. The two fixed stops 106a effectively limit and fix the position of the core 102 relative to the bus bars 104.Specifically, the core 102 includes two side planes 102b defined by a normal vector in a first direction D1, and two fixed stops 106a extend along the two side planes 102b, respectively, in a second direction D2 perpendicular to the first direction D1 and do not extend beyond the boundaries of the two side planes 102b in the second direction D2.

[0035] Still referring to FIG. 2 , in a preferred embodiment, the mounting holes 104c of the bus bar 104 remain exposed from the two outer portions 106c of the first overmolding part 106. This ensures that the lead frames 108, 110 and the bus bar 104 are properly aligned within the filter assembly. The leads 108a, 110a of the first and second lead frames 108, 110 may pass through these mounting holes 104c and be soldered on the opposite side to establish both electrical connection and mechanical stability. Additionally, in this embodiment, the second overmolding part 112 and the outer portion 106c of the first overmolding part 106 include corresponding ground bushings 116 exposed from the overmolding material at the second end 104b of the bus bar 104. The second overmolding portion 112, together with the inner second lead frame 110, is firmly secured to the first overmolding portion 106 using set screws or bolts (not shown) that pass through two ground bushings 116. Additionally, for enhanced input / output filtering, at least one capacitor 114 is attached to both the first and second lead frames 108, 110, and the overmolding compound (e.g., the second overmolding portion 112) acts as an insulating barrier to improve the isolation performance between components. In the present invention, the capacitor 114, together with the first and second lead frames 108 and 110 and the first and second overmolding portions 109 and 112, respectively, form a first capacitor assembly and a second capacitor assembly. These capacitor assemblies are electrically and / or structurally symmetrical and, together with the core 102 and bus bar 104, form an LC-type common mode filter. In some embodiments, the filtering function can be achieved by a common mode inductor consisting only of the busbar 104 and the core 102, without including the two capacitor assemblies described above. The filtering requirements of the power system can be met by adjusting the size or material of the core 102.

[0036] See Figure 3, which presents a cross-sectional view of the busbar filter 100 taken along section line A-A' in Figure 2, according to a preferred embodiment of the present invention. Preferably, the first overmolding part 106 does not cover or only partially covers the outer surface (e.g., the flat side surface 102b) of the core 102. Preferably, the first overmolding part 106 fills the through-hole 102a of the core 102 and covers the opening of the through-hole 102a on both flat side surfaces 102b of the core 102, and two fixed stops 106a of the first overmolding part 106 limit and fix the position of the core 102 relative to the busbar 104.

[0037] Reference is now made to FIG. 4 , which illustrates a top view of a bus bar 104 and a first overmolding portion 106 molded thereon according to a preferred embodiment of the present invention. In this embodiment, the bus bar 104 is formed as a solid conductive strip or bar oriented parallel to and extending along the first direction D1. While only two bus bars 104 are shown in the figure, it should be readily understood by those skilled in the art that the number of bus bars 104 is not limited to two. In a basic design, each bus bar 104 includes a first end 104 a and a second end 104 b positioned opposite each other along the first direction D1, which serve as input and output terminals for the bus bar filter, respectively. Additionally, each bus bar 104 includes two mounting holes 104 c positioned near the first and second ends 104 a and 104 b, respectively. In a preferred embodiment, each mounting hole 104c on one bus bar 104 corresponds to a mounting hole 104c on the same end of the other bus bar 104, allowing for precise alignment and secure attachment of the lead frame. Importantly, in the present invention, the first overmolding portion 106 is molded around the bus bar 104. As illustrated in FIG. 4, the first overmolding portion 106 encapsulates substantially the entire length of the bus bar 104, except for the first and second ends 104a, 104b and the through-hole 104c, which are intentionally left exposed to allow for electrical connection and mechanical assembly.

[0038] Still referring to FIG. 4 , in a preferred embodiment, the first overmolding part 106 includes several defined structural features: two fixed stops 106 a, a middle portion 106 b positioned between the fixed stops 106 a, and two outer portions 106 c disposed outside either of the two fixed stops 106 a. As described above with reference to FIG. 2 , after assembly, the core 102 is firmly positioned between the two fixed stops 106 a, which function to precisely limit and stabilize the position of the core relative to the busbar 104. Additionally, in a preferred embodiment, the outer portion 106 c of the first overmolding part 106 near the second part 104 b includes two ear features 106 d. These ear features 106 d extend in a direction perpendicular to the first direction D1, and each ear feature is configured to receive a ground bushing 116 exposed from the overmolding material. These bushings are designed to receive fastening elements such as screws or bolts (not shown) to allow for secure grounding and mechanical attachment.

[0039] Reference is now made collectively to FIGS. 5 and 6, which present perspective and top views of a first lead frame 108 according to a preferred embodiment of the present invention. In this embodiment, the first lead frame 108 is comprised of two separated conductive portions 108b that are electrically insulated from one another. This insulation is provided by a third overmolding portion 109 that encapsulates the first lead frame 108, leaving two leads 108a exposed for electrical connection to the bus bar 104 through through-holes 104c (see FIG. 2). With respect to the separated conductive portions 108b, each of the separated conductive portions 108b includes at least one terminal portion 108c exposed from the third overmolding portion 109 to facilitate electrical connection to the capacitor 114. The capacitor 114 is attached to the first lead frame 108, with its two terminals 114a electrically connected to the respective terminal portions 108c on the two separated conductive portions 108b of the first lead frame 108. In this embodiment, the capacitor 114 may function as a battery-side capacitor in an electric vehicle (EV) power system. The two terminals 114a of the capacitor 114 and the two terminal portions 108c of the first lead frame 108 correspond to two bus bars 104 electrically connected to HV+ and HV- input terminals of a line impedance stabilization network (LISN) in a high-voltage power system based on an EV power architecture. In this embodiment, a gap exists between the two separated conductive portions 108b, with the shortest distance between them. In this design, the third overmolding portion 109 fills the gap 118 to enhance the insulation between the separated conductive portions 108b. This configuration helps to shorten the insulation distance in line with safety standards while also optimizing the overall product size. In this embodiment, the gap between the two bus bars 104 or the separated conductive portions 108b, 108c is within the range of 1.0 mm to 3.2 mm.

[0040] Reference is now made collectively to FIGS. 7 and 8, which present perspective and top views of a second lead frame 110 according to a preferred embodiment of the present invention. Similarly, in this embodiment, the second lead frame 110 is comprised of four isolated conductive portions 110b, 110c that are electrically isolated from one another. This isolation is provided by a second overmolding portion 112 that encapsulates the second lead frame 110, leaving two leads 110a on the conductive portion 110b exposed for electrical connection to the bus bar 104 through through-holes 104c (FIG. 2). With respect to the isolated conductive portions 110b, 110c, each of the isolated conductive portions 110b, 110c includes at least one terminal portion 110d exposed from the second overmolding portion 112 to facilitate electrical connection to the capacitors 114b, 114c. The capacitors 114b, 114c are attached to the second lead frame 110, and their two terminals 114a are electrically connected to respective terminal portions 110d on the two separated conductive portions 110b, 110c of the second lead frame 110. The capacitors 114b, 114c in this embodiment may function as inverter-side capacitors in an electric vehicle (EV) power system.

[0041] Unlike the conductive portion 108b of the first lead frame 108, the second lead frame 110 in the preferred embodiment includes two types of conductive portions 110b and 110c designed for output terminal connection and grounding, respectively. As shown in FIGS. 7 and 8, the two terminals 114a of the center capacitor 114b are connected to two terminal portions 110d belonging to the two conductive portions 110b. These conductive portions 110b are further electrically connected to two bus bars 104, which correspond to the HV+ and HV- output terminals connected to an inverter in a high-voltage power system based on an EV power architecture, for example. On the other hand, the two terminals 114a of the side capacitor 114c are connected to one terminal portion 110d of the conductive portion 110b and one terminal portion 110d of the conductive portion 110c, respectively, thereby forming a ground path for the capacitor 114c. The conductive portion 110c of the second lead frame 110 is grounded through a designated ground portion 110e, which, after assembly, is electrically connected to a ground bushing 116 on the first overmolding portion 106 (see FIG. 2) via a fastening screw or bolt (not shown). To ensure sufficient electrical insulation, a gap 118 exists between the separated conductive portions 110b and 110c, providing the shortest possible insulation distance. In this design, the second overmolding portion 112 fills the gap 118, effectively strengthening the insulation between the two conductive regions. This approach not only aids in compliance with electrical safety standards, but also contributes to optimizing the overall size of the product.

[0042] Referring now to FIG. 9 , which presents a schematic diagram of a busbar filter 100 according to a preferred embodiment of the present invention, this design illustrates the application of the busbar filter 100 as an automotive filter positioned between the battery and inverter in electric vehicles (EVs) and hybrid electric vehicles (HEVs). This key component facilitates the transfer of high-power DC (direct current) from the battery—through a line impedance stabilization network (LISN)—to the inverter, which subsequently converts the DC power to AC (alternating current) to drive an electric motor, such as a permanent magnet synchronous motor (PMSM). In this system, HV+ and HV− represent the high-voltage positive and negative busbars, respectively, that carry the high-power DC between the battery and the inverter. During the power conversion process, high-frequency noise and electromagnetic interference (EMI) are often generated, particularly due to switching operations in the inverter. The busbar filter 100 is strategically positioned between the HV+ and HV− lines to mitigate these high-frequency disturbances. By filtering out unwanted EMI, the busbar filter 100 ensures stable and clean power delivery, thereby meeting stringent electromagnetic compatibility (EMC) requirements and protecting the integrity of the vehicle's overall electrical system.

[0043] As shown in Fig. 9, the input (HV+) and input (HV-) on the battery side are connected to the first bus bar 104-1 and the second bus bar 104-2, respectively. A capacitor 114 (i.e., the capacitor 114 attached to the first lead frame 108 in Fig. 5) is connected in parallel between the first bus bar 104-1 and the second bus bar 104-2 through the first lead frame 108. The first and second bus bars 104-1 and 104-2 pass through the core 102 to effectively filter high-frequency noise and EMI. These bus bars are further connected to the output (HV+) and output (HV-) on the inverter side. On the inverter side, capacitor 114b (i.e., central capacitor 114b attached to second lead frame 110 in FIG. 7) is connected in parallel between first bus bar 104-1 and second bus bar 104-2 (via conductive portion 110b of second lead frame 110 in FIG. 7). In addition, multiple capacitors 114c (i.e., lateral capacitors 114c attached to second lead frame 110 in FIG. 7) are connected in parallel between first bus bar 104-1 and second bus bar 104-2, with one terminal connected to bus bar 104-1 or 104-2 (via conductive portion 110b in FIG. 7) and the other terminal connected to ground (via conductive portion 110c in FIG. 7).

[0044] Referring to FIG. 10 , which presents a close-up view of the second overmolding portion 112 according to an embodiment of the present invention, this design utilizes the second overmolding portion to enhance the creepage distance between the terminal portions of the second lead frame. As shown, the presence of the second overmolding portion 112 on the second lead frame increases the creepage distance between the two terminal portions 110d of the second lead frame that connect to the capacitor. This increase in creepage distance is a result of the inherent thickness of the overmolding material. Creepage distance is defined as the shortest distance measured along an insulating surface (e.g., the second overmolding portion 112) between two adjacent conductors (e.g., a capacitor) following an actual path along a curved, bent, or straight path on the insulating surface. Furthermore, in this embodiment, the second overmolding portion 112 further includes raised and / or recessed features 120 and / or recessed features 122 that protrude and / or recess from the insulating surface of the second overmolding portion 112. These raised features 120 and recessed features 122 are designed between the two terminal portions 110d of the lead frame to effectively increase the creepage distances d1-d4. The raised features 120 and recessed features 122 ensure that the creepage distances are increased regardless of whether the current path passes directly through the raised features 120 and recessed features 122 (e.g., creepage distances d1 and d3) or bypasses them (e.g., creepage distances d2 and d4). It should be noted that the raised features and recessed features referred to in the present invention are defined with respect to a reference insulating plane of the overmolding part, e.g., the second overmolding part 112.

[0045] Refer to FIG. 11 , which presents an enlarged view of two bus bars 104-1 and 104-2 with a first overmolding portion 106 molded thereon in accordance with an embodiment of the present invention. This design differs from the previously described embodiment. In this embodiment, a raised feature 120 is formed along the insulating surface (e.g., the first overmolding portion 106) between two adjacent conductors (e.g., the two bus bars 104-1 and 104-2). As with the previously described embodiment, the raised feature 120 increases the creepage distance d5 by providing a longer linear path along the uneven surface of the raised feature 120.

[0046] 12, which presents an enlarged view of two bus bars 104-1 and 104-2 with a first overmolding portion 106 molded thereon in accordance with an embodiment of the present invention. Similar to the previous embodiment, in this embodiment, a recessed feature 122 is formed along the insulating surface (e.g., the first overmolding portion 106) between two adjacent conductors (e.g., the two bus bars 104-1 and 104-2). The recessed feature 122 increases the creepage distance d6 by providing a longer linear path along the uneven surface of the recessed feature 122.

[0047] Both the recessed features 122 and raised features 120 of the present invention can be used together on the overmolding between conductors (e.g., bus bars and conductive portions of lead frames) to further improve the insulating performance of the device. This design not only improves electrical insulation, but also contributes to reducing the required safety distance and overall product size and manufacturing costs.

[0048] Referring to FIG. 13 , an exploded view of a second lead frame 110 is presented, along with a second overmolding portion 112 and a capacitor 114 mounted thereon according to another embodiment of the present invention. In addition to the advantages provided by the overmolding portion as described above, a key feature of the present invention is the use of a lead frame instead of a conventional PCB for electrical connection between a bus bar and a capacitor. Due to the manufacturing process involved, the second lead frame 110 can be easily manufactured with horizontal and vertical portions 110-1 and 110-2 by simply stamping and bending material into the desired shape. Correspondingly, the overmolding process allows the second overmolding portion 112 to be easily formed along the surface of the second lead frame 110, regardless of the molding complexity introduced by the 3D contours of the lead frame. The resulting second overmolding portion 112 also includes corresponding horizontal and vertical portions 112-1 and 112-2. This approach provides considerable flexibility, enabling 3D placement of the capacitor 114, which significantly improves space utilization and reduces manufacturing costs. In contrast, conventional methods require the use of two separate PCBs connected by pins to form the horizontal and vertical sections, a process that is not only more complicated but also significantly more expensive.

[0049] Referring to FIG. 14 , an exploded view of a second lead frame 110 is presented, along with a second overmolding portion 112 and a capacitor 114 mounted thereon according to another embodiment of the present invention. Similar to the previous embodiment, the simple manufacturing process of the second lead frame 110 allows for easy production of a lead frame with two mounting surfaces 110-3 and 110-4 at different heights by stamping and bending material into the desired shape. Accordingly, the overmolding process seamlessly forms the second overmolding portion 112 along the surface of the second lead frame 110, regardless of molding complications introduced by the uneven contours of the lead frame. The resulting second overmolding portion 112 also includes corresponding mounting surfaces 112-3 and 112-4 at different heights, with at least one of the capacitors 114 mounted to each of the mounting surfaces 112-3 and 112-4. This design offers considerable flexibility, allowing capacitors 114 to be placed at various heights, thereby significantly improving space utilization and reducing manufacturing costs. In contrast, conventional PCB approaches can only provide a single level mounting plane, resulting in inefficient use of space when capacitors at different heights need to be placed.

[0050] Another advantage of using lead frames to replace PCBs for electrical connections in busbar filters is that the thickness of the lead frames is not limited by the same limitations as the PCB. While the thickness of the copper layers in PCBs is typically limited to a maximum of 6 oz, meeting critical current and temperature requirements often necessitates the use of thicker copper layers in parallel connections. In contrast, lead frames do not face this limitation, and increasing the thickness of the lead frames can easily accommodate these requirements. For example, the thickness of the first and second lead frames can be greater than 0.07 mm or within the range of 0.2 mm to 4.0 mm, preferably between 0.4 mm and 4.0 mm. This provides significant advantages in both manufacturing process and cost efficiency.

[0051] Referring to FIG. 15 , which presents an exploded view of a busbar filter 100 having bent busbars 104 according to an alternative embodiment of the present invention, in addition to the aforementioned adjustments in the lead frame and overmolding portion, further modifications have been made to the busbar design of the present invention. Specifically, the busbars 104 are reconfigured to provide the advantage of reducing the size of the busbar filter 100. As shown in FIG. 15 , in this embodiment, the first ends 104a of the two busbars 104 are bent toward the same side of the core 102 to align with the second ends 104b in the first direction D1. Despite this bending, the core 102 can remain centrally positioned around the busbar 104, and the bend provides sufficient space for optimal placement. Similarly, the first overmolding portion 106 can be easily molded onto the surface of the bent busbar 104 due to its excellent conformability, despite the complexity introduced by the bending. This design provides considerable flexibility, allowing the length of the busbar filter 100 to be shortened along the first direction D1. As a result, it significantly improves space utilization and contributes to reducing production costs. This design also enhances inductance by increasing the overlap area between the busbar 104 and the core 102.

[0052] Referring to FIG. 16 , which illustrates busbars 104 in various bending configurations, the present invention allows busbars to be bent according to design specifications, ensuring that busbar filters effectively meet product requirements. Bending busbars offers several advantages for busbar filter design. Bending the busbars 104 optimizes space utilization, enabling a more compact and efficient layout. This bending allows for greater flexibility in routing and placement, especially in designs with constrained space or specific form factor requirements. Additionally, bending the busbars 104 can increase the overall inductance of the busbar filter due to the increased overlap area between the busbars 104 and the core 102. This improves filter performance by effectively filtering out high-frequency noise and electromagnetic interference (EMI). Furthermore, the bending process helps meet specific current handling and heat dissipation needs. Tailoring the design of the bent busbar makes it easier to increase the surface area for heat dissipation, helping to maintain temperature control under high-current conditions. This makes the design more robust, capable of handling higher power levels, and ensures that the busbar filter meets required electromagnetic compatibility (EMC) standards. Ultimately, this approach provides an improved balance of performance, compactness, and cost-effectiveness in busbar filter design. For the 400V model of the busbar filter, the proposed design reduced the volume by 20% compared to the traditional assembly structure. For the 800V model of the busbar filter, the proposed design reduced the volume by 34% and reduced the cost by 7% compared to the traditional assembly structure.

[0053] Those skilled in the art will readily appreciate that numerous modifications and variations of the devices and methods may be made while retaining the teachings of the present invention. Accordingly, the above disclosure should be construed as limited only by the scope of the appended claims.

Claims

1. a core having a through hole; two bus bars extending along a first direction through the through hole, each bus bar including a first end and a second end; a first overmolding portion formed on the two bus bars between the two bus bars and the core; the first overmolding portion fills gaps between the two bus bars and the remaining space within the through hole. Busbar filters.

2. 2. The busbar filter according to claim 1, further comprising a first capacitor assembly and / or a second capacitor assembly electrically connected to the first ends and / or the second ends of the two busbars, respectively.

3. The busbar filter according to claim 2 , wherein the first capacitor assembly and the second capacitor assembly are electrically and / or structurally symmetrical.

4. The first capacitor assembly and the second capacitor assembly include: a first lead frame attached to the first ends of the two bus bars, and at least one first capacitor attached to the first lead frame; a second lead frame attached to the second ends of the two bus bars, and at least one second capacitor attached to the second lead frame; a second overmolding portion molded on the second lead frame, the second overmolding portion fills a gap in the second lead frame. The busbar filter according to claim 2 .

5. 5. The bus bar filter of claim 4, wherein each of the two bus bars includes a first mounting hole at the first end exposed from the first overmolding portion, the first lead frame includes two lead wires, and the two lead wires of the first lead frame are respectively attached to the first mounting holes of the two bus bars.

6. 5. The bus bar filter of claim 4, wherein each of the two bus bars includes a second mounting hole at the second end exposed from the first overmolding portion, and the second lead frame includes two lead wires, the two lead wires of the second lead frame being attached to the second mounting holes of the two bus bars, respectively.

7. 5. The busbar filter of claim 4, wherein the second lead frame includes a horizontal portion and a vertical portion perpendicularly connected to the horizontal portion, and at least one of the second capacitors is attached to the horizontal portion and at least one of the second capacitors is attached to the vertical portion.

8. 5. The busbar filter of claim 4, wherein the second lead frame includes a plurality of mounting surfaces at various heights, and at least one of the second capacitors is mounted to each of the mounting surfaces.

9. 5. The busbar filter of claim 4, wherein the second lead frame further includes two ground portions exposed from the second overmolding portion, two ground bushings are provided on the first overmolding portion at the second ends of the two bus bars, and the second lead frame is fixed to the two bus bars by fastening screws or bolts through the two ground portions and corresponding ground bushings.

10. 5. The bus bar filter of claim 4, wherein the second lead frame includes a plurality of separated conductive portions, and the gaps in the second lead frame are between the separated conductive portions.

11. The busbar filter according to claim 10 , wherein two terminals of the second capacitor are respectively connected to two of the separated conductive portions.

12. 11. The busbar filter of claim 10, wherein each of the separated conductive portions of the second lead frame includes at least one terminal portion exposed from the second overmolding portion for electrically connecting the second capacitor, and the second overmolding portion further includes a raised configuration between two of two adjacent terminal portions of different separated conductive portions connecting two terminals of the second capacitor.

13. 11. The busbar filter of claim 10, wherein each of the separated conductive portions of the second lead frame includes at least one terminal portion exposed from the second overmolding portion for electrically connecting the second capacitor, and the second overmolding portion further includes a recessed configuration between two of adjacent terminal portions of different separated conductive portions that connect two terminals of the second capacitor.

14. 11. The busbar filter of claim 10, wherein the spacing between the two busbars or the spacing between the separated conductive portions is in the range of 1.0 mm to 3.2 mm.

15. 5. The busbar filter according to claim 4, wherein the thickness of the first lead frame and the second lead frame is greater than 0.07 mm or in the range of 0.2 mm to 4.0 mm, preferably between 0.4 mm and 4.0 mm.

16. The busbar filter of claim 1 , wherein each of the two busbars includes an input terminal and an output terminal exposed from the first overmolding portion.

17. 2. The busbar filter of claim 1, wherein the first overmolding portion further includes two fixed stops on two sides of the core in the first direction, the two fixed stops fixing a position of the core relative to the two busbars.

18. 18. The busbar filter of claim 17, wherein the core includes two lateral planes defined by a normal vector in the first direction, and the two fixed stops extend along the two lateral planes, respectively, in a second direction perpendicular to the first direction and do not extend beyond the boundaries of the two lateral planes in the second direction.

19. 19. The busbar filter of claim 18, wherein the first overmolding portion does not cover or only partially covers an outer surface of the core, and the first overmolding portion covers the openings of the through holes on both of the lateral planes of the core.

20. The busbar filter of claim 1 , wherein the first ends of the two busbars are bent toward the same side of the core as the second ends in the first direction.

21. The busbar filter of claim 1 , wherein the first overmolding portion further includes a raised or recessed feature between the two busbars.

22. The bus bar filter according to claim 1 , wherein the first overmolding portion fixes the two bus bars and the core and electrically insulates the two bus bars and the core.

23. The busbar filter according to claim 1 , wherein a distance between two outer sides of the two busbars is smaller than a hole width of the through hole of the core.

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