Capacitor assembly for inverter of electric vehicle

Abstract

The invention relates to a capacitor assembly for an inverter of an electric vehicle. A system may include a capacitor assembly including a planar bus bar including a first DC bus bar and a second DC bus bar; one or more first capacitors at a first side of the planar bus bar, the one or more first capacitors including a first bobbin having a positive terminal facing a first direction relative to the planar bus bar; and one or more second capacitors at a first side of the planar bus bar, the one or more second capacitors including a second spool having a positive terminal facing a second direction relative to the planar bus bar, the one or more first capacitors and the one or more second capacitors are alternately arranged with respect to the planar bus bar.

Description

Technical Field

[0001] Various embodiments of the present disclosure relate generally to capacitor assemblies, and more particularly to a bulk capacitor assembly for a power module of an inverter for an electric vehicle. Background Art

[0002] For traction inverters, the power module is considered an important component of the power conversion system. The efficiency of the system can be proportional to the switching losses occurring in the power module. However, the commutation unit inductance of the power conversion system can prevent mitigation of the switching losses.

[0003] The present disclosure is directed to overcoming one or more of these challenges described above. Summary of the invention

[0004] In some aspects, the technology described herein relates to a system comprising: an inverter that converts DC electricity from a battery into AC electricity to drive an electric motor, wherein the inverter comprises: a capacitor assembly, the capacitor assembly comprising: a planar bus bar, the planar bus bar comprising a first direct current (DC) bus bar and a second DC bus bar; one or more first capacitors on a first side of the planar bus bar, the one or more first capacitors comprising a first bobbin having a positive end facing a first direction relative to the planar bus bar; and one or more second capacitors on the first side of the planar bus bar, the one or more second capacitors comprising a second bobbin having a positive end facing a second direction relative to the planar bus bar, wherein the one or more first capacitors and the one or more second capacitors are arranged alternately with respect to the planar bus bar.

[0005] In some aspects, the technology described herein relates to a system wherein the first DC bus bar is positive and the second DC bus bar is negative.

[0006] In some aspects, the technology described herein relates to a system wherein the one or more first capacitors and the one or more second capacitors are arranged alternately in a single row.

[0007] In some aspects, the technology described herein relates to a system wherein the one or more first capacitors and the one or more second capacitors are arranged alternately in each of two or more rows such that each of the two or more rows includes the same arrangement of the one or more first capacitors and the one or more second capacitors.

[0008] In some aspects, the technology described herein relates to a system wherein the first DC bus bar includes an inner surface and an outer surface; wherein the second DC bus bar includes an inner surface and an outer surface, and wherein the inner surface of the first DC bus bar faces the inner surface of the second DC bus bar such that at least a portion of the first DC bus bar overlaps the second DC bus bar.

[0009] In some aspects, the technology described herein relates to a system wherein the first DC bus bar further comprises: a connection opening for the one or more first capacitors or the one or more second capacitors; and a cover covering the connection opening.

[0010] In some aspects, the technology described herein relates to a system wherein the first spool and the second spool are arranged in a horizontal direction or in a vertical direction.

[0011] In some aspects, the technology described herein relates to a system wherein an alternating arrangement of the one or more first capacitors and the one or more second capacitors reduces inductance relative to capacitors that are not alternately arranged.

[0012] In some aspects, the technology described herein relates to a system wherein the one or more first capacitors include three first capacitors, and wherein the one or more second capacitors include three second capacitors.

[0013] In some aspects, the technology described herein relates to a system wherein the first direction is substantially opposite to the second direction.

[0014] In some aspects, the technology described herein relates to a system wherein the first direction and the second direction are substantially opposite and substantially parallel to the planar bus bar in a longitudinal direction of the planar bus bar.

[0015] In some aspects, the technology described herein relates to a system, which also includes: the battery, which is configured to supply the DC power to the inverter; and the motor, which is configured to receive the AC power from the inverter to drive the motor, wherein the system is provided as a vehicle including the inverter, the battery and the motor.

[0016] In some aspects, the technology described herein relates to a system including a capacitor assembly, the capacitor assembly comprising: a planar busbar, the planar busbar comprising a first direct current (DC) busbar and a second DC busbar; one or more first capacitors on a first side of the planar busbar, the one or more first capacitors comprising a first bobbin having a positive end facing a first direction relative to the planar busbar; and one or more second capacitors on the first side of the planar busbar, the one or more second capacitors comprising a second bobbin having a positive end facing a second direction relative to the planar busbar, wherein the one or more first capacitors and the one or more second capacitors are arranged alternately relative to the planar busbar.

[0017] In some aspects, the technology described herein relates to a system wherein the first DC bus bar is positive and the second DC bus bar is negative.

[0018] In some aspects, the technology described herein relates to a system wherein the one or more first capacitors and the one or more second capacitors are arranged alternately in a single row, or wherein the one or more first capacitors and the one or more second capacitors are arranged alternately in each of two or more rows.

[0019] In some aspects, the technology described herein relates to a system wherein the first DC bus bar further comprises: a connection opening for the one or more first capacitors or the one or more second capacitors; and a cover covering the connection opening.

[0020] In some aspects, the technology described herein relates to a system comprising: a capacitor assembly, the capacitor assembly comprising: a first capacitor, the first capacitor comprising a first bobbin having a positive terminal, wherein the positive terminal of the first bobbin faces a first direction; and a second capacitor, the second capacitor comprising a second bobbin having a positive terminal, wherein the positive terminal of the second bobbin faces a second direction, wherein the first capacitors and the second capacitors are arranged alternately relative to a planar bus bar, wherein the planar bus bar comprises a first direct current (DC) bus bar and a second DC bus bar, wherein the first DC bus bar comprises an inner surface and an outer surface, and the second DC bus bar comprises an inner surface and an outer surface, and wherein the inner surface of the first DC bus bar faces the inner surface of the second DC bus bar such that at least a portion of the first DC bus bar overlaps with the second DC bus bar.

[0021] In some aspects, the technology described herein relates to a system wherein the first DC bus bar is positive and the second DC bus bar is negative.

[0022] In some aspects, the technology described herein relates to a system wherein the first capacitors and the second capacitors are arranged alternately in a single row, or wherein the first capacitors and the second capacitors are arranged alternately in each of two or more rows such that each of the two or more rows includes the same arrangement of the first capacitors and the second capacitors.

[0023] In some aspects, the technology described herein relates to a system wherein the first DC bus bar further comprises: a connection opening for the first capacitor or the second capacitor; and a cover covering the connection opening.

[0024] It is to be understood that both the general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosed embodiments, as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and, together with the description, serve to explain the principles of the disclosed embodiments.

[0026] Figure 1 An exemplary system infrastructure for a vehicle including a combined inverter and converter is shown according to one or more embodiments.

[0027] Figure 2 A simplified circuit diagram of an inverter in a connection system according to one or more embodiments is shown.

[0028] Figure 3 A power module and heat sink assembly for a combined inverter and converter according to one or more embodiments is shown.

[0029] Figure 4A A polypropylene film capacitor including an axial bobbin is shown according to one or more embodiments.

[0030] Figure 4B A polypropylene film capacitor including an axial bobbin is shown according to one or more embodiments.

[0031] Figure 5 A side view of a capacitor assembly having a planar bus bar is shown in accordance with one or more embodiments.

[0032] Figure 6 An isometric view of a capacitor assembly having planar bus bars according to one or more embodiments is shown.

[0033] Fig. 7A A single row capacitor assembly with planar bus bars is shown in accordance with one or more embodiments.

[0034] Figure 7B A dual row capacitor assembly with planar bus bars is shown in accordance with one or more embodiments.

[0035] Figure 8 A planar bus bar assembly is shown in accordance with one or more embodiments.

[0036] Fig. 9 Current flow paths in a capacitor assembly are shown in accordance with one or more embodiments.

[0037] Fig.10 A cover is shown overlapping an external connection of a capacitor in accordance with one or more embodiments.

[0038] Fig.11 A top view of a capacitor assembly having planar bus bars is shown in accordance with one or more embodiments. DETAILED DESCRIPTION

[0039] The foregoing general description and the following detailed description are merely exemplary and illustrative, and are not limitations on the claimed features. As used herein, the terms "comprises," "having," "including," or other variations thereof are intended to cover non-exclusive inclusions, such that a process, method, article, or device that includes a series of elements includes not only those elements, but may also include other elements that are not explicitly listed or inherent to such a process, method, article, or device. In this disclosure, unless otherwise stated, relative terms such as "about," "substantially," and "approximately" are used to indicate a possible variation of ±10% of the stated value. In this disclosure, unless otherwise stated, any numerical value may include a possible variation of ±10% of the stated value.

[0040] Various embodiments of the present disclosure relate generally to capacitor assemblies, and more particularly to a bulk capacitor assembly for a power module of an inverter for an electric vehicle.

[0041] The terms used below may be interpreted in their broadest reasonable manner, even when used in conjunction with the detailed description of certain specific examples of the present disclosure. In fact, certain terms may even be emphasized below; however, any term intended to be interpreted in any limiting manner will be so clearly and specifically defined in this detailed description section.

[0042] Some DC bulk capacitor designs include bulk capacitors with axial bobbins of polypropylene film capacitors. This axial bobbin structure can create a wider gap between the positive and negative bus bars connecting the parallel bobbins of the bulk capacitor. This wider gap can result in higher bus bar stray inductance and ultimately higher parasitic inductance in the bulk capacitor. The design can include a unique bus bar arrangement at the interconnect.

[0043] In a traction inverter, the power module can be considered an important component of the entire system, and the efficiency of the system is proportional to the losses occurring in the power module. Addressing the switching losses of the power module can be one of the key aspects of having an efficient, cost-effective, and robust inverter design. The commutation unit inductance of some systems limits the improvement of switching losses. There are three main elements that contribute to the overall commutation unit inductance: the power module, the DC bulk capacitor, and the busbar interconnect. One or more embodiments may provide a DC bulk capacitor design with lower parasitic inductance relative to some designs.

[0044] Figure 1 An exemplary system infrastructure for a vehicle including a combined inverter and converter according to one or more embodiments is shown. In the context of this disclosure, the combined inverter and converter may be referred to as an inverter. Figure 1 As shown, the electric vehicle 100 may include an inverter 110, a motor 190, and a battery 195. The inverter 110 may include a component that receives power from an external source and outputs power to charge the battery 195 of the electric vehicle 100. For example, the inverter 110 may convert DC power from the battery 195 in the electric vehicle 100 into AC power to drive the motor 190 of the electric vehicle 100, but the embodiment is not limited thereto. The inverter 110 may be bidirectional and may convert DC power into AC power, or, for example, convert AC power into DC power during regenerative braking. The inverter 110 may be a three-phase inverter, a single-phase inverter, or a multi-phase inverter.

[0045] Figure 2 A circuit diagram of an inverter in a connection system according to one or more embodiments is shown. For example, the inverter can be used to convert DC power from a battery in an electric vehicle into AC power to drive the electric motor of the electric vehicle, but the embodiments are not limited thereto. In addition, the inverter can be bidirectional and used to convert DC power into AC power, or convert AC power into DC power.

[0046] like Figure 2 As shown, the inverter 110 can be connected to the battery 195 (DC power source) and the motor 190. The inverter 110 can include an upper phase switch 144 and a lower phase switch 148 as components of the power module. Figure 2As shown, the first phase (ΦA) may include switches Q1 and Q4, the second phase (ΦB) may include switches Q3 and Q6, and the third phase (ΦC) may include switches Q5 and Q2. The upper phase switch 144 may include a first phase switch Q1, a second phase switch Q3, and a third phase switch Q5. The lower phase switch 148 may include a first phase switch Q4, a second phase switch Q6, and a third phase switch Q2. The switches Q1 to Q6 may be, for example, metal oxide semiconductor field effect transistors (MOSFETs), but are not limited thereto. Although Figure 2 A three-phase inverter is shown, but the present disclosure is not limited thereto and may include a single-phase or multi-phase or multi-level inverter.

[0047] The upper phase switch 144 and the lower phase switch 148 may be driven by PWM signals generated by one or more controllers to convert DC power delivered via the input terminal set 285 at the bulk capacitor 201 to three-phase AC power at the outputs U, V and W (associated with phases A, B and C, respectively) via the output terminal set 295 to the motor 190. In the present disclosure, the bulk capacitor 201 may be referred to as a capacitor element of a bulk capacitor assembly, for which various embodiments are disclosed. In addition, although Figure 2 A three-phase inverter is shown, but the present disclosure is not limited thereto and may include a single-phase or multi-phase or multi-level inverter.

[0048] Figure 3 1 shows an exploded view of a power module and heat sink assembly for an inverter according to one or more embodiments. For example, the power module 330 may be connected to Figure 1 and Figure 2 The inverter 110 shown is compatible and can be used for switching operations of the inverter 110. As shown, the power module 330 is located between the first cooling channel 323 and the second cooling channel 326 of the heat sink assembly 320. The power module 330 may include one or more silicon carbide (SiC)-based power modules that provide relatively high power density and efficiency required to extend battery range and performance, although other semiconductor switches may be relied upon. The power module 330 may include circuits and components configured to convert direct current (DC) from an electric vehicle battery into alternating current (AC) current (and vice versa), which can be used by, for example, an electric motor 190 that drives a propulsion system.

[0049] The power module 330 can be mounted on one or more power board assemblies. The power module 330 can include a combination of transistors, diodes, metal oxide semiconductor field effect transistors (MOSFETs), insulated gate bipolar transistors (IGBTs), and thyristor commutators (SCRs). The power module 330 can include a combination of transistors configured as half-bridge and H-bridge configurations, which can allow the switching capability of the direction of the current through the motor from a single voltage power supply. The power module 330 can also include three or more transistors for inverting applications, such as switching direct current (DC) electricity to alternating current (AC) electricity. During operation, the first cooling channel 323 and the second cooling channel 326 can provide cooling for the power module 330, the bulk capacitor 201, and the busbars that can be connected to the power module 330 and the bulk capacitor 201.

[0050] Figure 4A A polypropylene film capacitor including an axial bobbin is shown according to one or more embodiments. Figure 4A Capacitor 400 is shown. Capacitor 400 may include a bobbin 410 that may be axially aligned in a longitudinal direction relative to capacitor 400. Bobbin 410 may include a positive terminal 420 and a negative terminal 430. For example, a polypropylene film capacitor bobbin may be axial in design to facilitate tapping of the positive and negative electrodes.

[0051] Figure 4B A polypropylene film capacitor including an axial bobbin is shown according to one or more embodiments. Figure 4B Capacitor 450 is shown. Capacitor 450 may include bobbin 460. Bobbin 460 may include positive terminal 470 and negative terminal 480. For example, capacitor 450 may be a polypropylene film capacitor axial bobbin. The polypropylene film capacitor bobbin may be axial in design to facilitate tapping of the positive and negative electrodes.

[0052] Figure 5 A side view of a capacitor assembly having a planar bus bar is shown in accordance with one or more embodiments. Figure 5 The capacitor assembly 500 is shown to include a planar bus bar 510, a cover 540, a first capacitor 550, and a second capacitor 570. The planar bus bar 510 may include a first DC bus bar 520 and a second DC bus bar 530. Although not shown in FIG. Figure 5 As shown in FIG. 5 , the capacitor assembly 500 may include an insulator, such as insulating paper, between the first DC bus bar 520 and the second DC bus bar 530. Figure 5Six capacitors are shown, but the capacitor assembly 500 may include two or more capacitors. For example, the first DC bus bar 520 may be positive, and the second DC bus bar 530 may be negative. The first DC bus bar 520 may include an inner surface and an outer surface, and the second DC bus bar 530 may include an inner surface and an outer surface. The inner surface of the first DC bus bar 520 may face the inner surface of the second DC bus bar 530, so that at least a portion of the first DC bus bar 520 overlaps with the second DC bus bar 530. The cover 540 may be connected to the first DC bus bar 520.

[0053] The first capacitor 550 and the second capacitor 570 may be similar to Figure 4A The capacitor 400 described in the embodiment of the present invention. The first capacitor 550 may include a positive terminal 560 and a negative terminal 565. The second capacitor 570 may include a positive terminal 580 and a negative terminal 585. The positive terminal 560 of the first capacitor 550 may face a first direction. The positive terminal 580 of the second capacitor 570 may face a second direction. The first direction may be a direction toward the planar bus bar 510 in a substantially vertical direction. The second direction may be a direction away from the planar bus bar 510 in a substantially vertical direction and may be opposite to the first direction. The first capacitor 550 and the second capacitor 570 may be arranged alternately relative to each other. One or more embodiments may address the above challenges and produce lower parasitic inductance of large-capacity capacitors.

[0054] For example, the inverter 110 (see Figure 1 ) may include a capacitor assembly 500 and a power module 330 that may be connected to the capacitor assembly 500. The capacitor assembly 500 may include a planar bus bar 510, which may include a first direct current (DC) bus bar 520 and a second DC bus bar 530. The first DC bus bar 520 may be connected to the positive DC charge of a battery (e.g., battery 195), and the second DC bus bar 530 may be connected to the negative DC charge of the battery, or vice versa. The planar bus bar 510 may be used to transfer power from the battery 195 to the connectable power module 330 and one or more DC link capacitors (e.g., capacitor 400 or capacitor 450) connected to the planar bus bar 510. The first DC bus bar 520 and the second DC bus bar 530 may be arranged to reduce the parasitic inductance of the switching loop of the power module 330.

[0055] Figure 6 An isometric view of a capacitor assembly having planar bus bars according to one or more embodiments is shown. Figure 6A capacitor assembly 600 is shown that includes a planar bus bar 610, a cover 640, a first capacitor 650, and a second capacitor 670. The planar bus bar 610 may include a first DC bus bar 620 and a second DC bus bar 630. The first DC bus bar 620 may be positive, and the second DC bus bar 630 may be negative. The first DC bus bar 620 may include an inner surface and an outer surface, and the second DC bus bar 630 may include an inner surface and an outer surface. The inner surface of the first DC bus bar 620 may face the inner surface of the second DC bus bar 630, so that at least a portion of the first DC bus bar 620 overlaps the second DC bus bar 630. The cover 540 may be connected to the first DC bus bar 620. The first capacitor 650 may include a positive terminal 660 and a negative terminal 665. The second capacitor 670 may include a positive terminal 680 and a negative terminal 685. The positive terminal 660 of the first capacitor 650 may face the first direction. The negative terminal 685 of the second capacitor 670 can face the second direction. The first direction and the second direction can be substantially opposite and substantially parallel to the planar bus bar 610 in the longitudinal direction. The first capacitor 650 and the second capacitor 670 can be arranged alternately relative to each other. For example, the negative terminal 665 of the first capacitor 650 can face the positive terminal 680 of the second capacitor 670, thereby having alternating opposite ends of the first capacitor 650 and the second capacitor 670 (e.g., the negative terminal 665 and the positive terminal 680).

[0056] Fig. 7A A single row capacitor assembly with planar bus bars is shown according to one or more embodiments. Fig. 7A A single row of capacitor assembly 700 is shown. For example, the single row of capacitors may include two or more capacitors aligned substantially in a straight line. The single row of capacitor assembly 700 may include a planar bus bar 710, a first capacitor 550, and a second capacitor 570. The planar bus bar 710 may include a first DC bus bar 720 and a second DC bus bar 730. The first capacitor 550 may include a positive terminal 560 and a negative terminal 565. The second capacitor 570 may include a positive terminal 580 and a negative terminal 585. The arrangement of the first capacitor 550 and the second capacitor 570 may be alternating, such as Figure 5 Similar to the description in .

[0057] Figure 7B A dual row capacitor assembly with planar bus bars is shown in accordance with one or more embodiments. Figure 7BA capacitor assembly 500 is shown including a dual row design. For example, the dual row capacitors may include two rows of two or more capacitors aligned substantially in a straight line. The capacitor assembly 500 as a dual row design may include a planar bus bar 510, a first capacitor 550, and a second capacitor 570. The planar bus bar may include a first DC bus bar 520 and a second DC bus bar 530. The first capacitor 550 may include a positive terminal 560 and a negative terminal 565. The second capacitor 570 may include a positive terminal 580 and a negative terminal 585. The capacitor assembly 500 as a dual row design may include a first row of capacitors 740 and a second row of capacitors 750. The first row of capacitors 740 may include alternating arrangements of first capacitors 550 and second capacitors 570, similar to Figure 5 The second row capacitor 750 may include first capacitors 550 and second capacitors 570 arranged alternately, similar to Figure 5 For example, the first row of capacitors 740 may have the same arrangement as the second row of capacitors 750. The capacitor assembly 500, which is a dual row design, may be expanded to include more than two rows as described herein (eg, three, four, or five rows of capacitors).

[0058] Compared to bulk capacitor designs where the positive and negative bus bars have wider gaps between them and / or the capacitors do not alternate, one or more embodiments as described herein can reduce parasitic inductance by more than 80%. For example, some capacitor assemblies where the capacitors do not alternate can have a parasitic inductance of 18.83 nH at 1 MHz. One or more embodiments can have a parasitic inductance of 3.62 nH at 1 MHz. One or more embodiments can have a parasitic inductance of 3.21 nH at 1 MHz.

[0059] Figure 8 A planar bus bar assembly is shown in accordance with one or more embodiments. Figure 8 Shown with Figure 5 A similar planar bus bar 510 is provided, but without the first capacitor 550 and the second capacitor 570 of the capacitor assembly 500. The planar bus bar 510 may include a cover 540. The planar bus bar 510 may include a first DC bus bar 520 and a second DC bus bar 530. The first DC bus bar 520 may include a first portion 810 and a first connector 815. The first portion 810 may extend from the first DC bus bar 520 in a substantially vertical direction. The first connector 815 may extend from the first portion 810 in a substantially vertical direction and substantially parallel to the first DC bus bar 520.

[0060] Similarly, the second DC bus bar 530 may include a second portion 820 and a second connector 825. The second portion 820 may extend from the second DC bus bar 530 in a substantially vertical direction. The second connector 825 may extend from the second portion 820 in a substantially vertical direction and substantially parallel to the second DC bus bar 530. For example, the second DC bus bar 530, the second portion 820, and the second connector 825 may be configured to receive the first capacitor 550. Similarly, the first DC bus bar 520, the first portion 810, and the first connector 815 may be configured to receive the second capacitor 570. Reversely arranging the first capacitor 550 and the second capacitor 570 in the planar bus bar 510 allows for a planar arrangement of the bus bars, which in turn can reduce parasitic inductance. As shown, the inverted arrangement of the bobbin 410 allows the first DC bus bar 520 and the second DC bus bar 530 to overlap and connect to the bobbin 410 on opposite sides of the planar bus bar 510. For example, the vertical linear connections are assembled perpendicular to the corresponding planar bus bars (eg, the first DC bus bar 520 and the second DC bus bar 530 ), ensuring electrical connection of each capacitor to the DC bus bar.

[0061] Fig. 9 Current flow paths in a capacitor assembly are shown in accordance with one or more embodiments. Fig. 9 Shows Figure 5 540 and 550, and the capacitor assembly 500 will not be repeated. The capacitor assembly 500 may include a first current flow 910 and a second current flow 920. The capacitor assembly 500 may include a first capacitor 550 and a second capacitor 570. The first capacitor may include a positive terminal 560 and a negative terminal 565. The second capacitor 570 may include a positive terminal 580 and a negative terminal 585. As shown by the direction of the arrow in the first current flow 910, the first current flow 910 may start at the cap 540 and flow through the positive terminal 560 of the first capacitor 550 in the direction of the negative terminal 565 of the first capacitor 550. The first current flow 910 may then continue through the second connector 825 and the second portion 820 of the second DC bus bar 530.

[0062] Similarly, as shown by the direction of the arrow in the second current flow 920, the second current flow 920 can start in the first portion 810 of the first DC bus 520 and flow to the first connector 815 of the first DC bus 520. The second current flow 920 can continue to the positive terminal 580 of the second capacitor 570 to the negative terminal 585 of the second capacitor 570, ending at the cover 540. The first current flow 910 and the second current flow 920 can have currents of equal magnitude but opposite directions, thereby reducing inductance. The cover 540 can compensate and reduce the inductance at the interconnection (e.g., the interconnection between the first DC bus 520, the second DC bus 530, and the first capacitor 550). For example, approximately 30 to 40% of the inductance occurs at the interconnection between the power module 330 and the capacitor (e.g., the first capacitor 550 or the second capacitor 570).

[0063] The DC current flowing through the cover 540 induces a magnetic field opposite to the induced magnetic field, thereby reducing the self-induced magnetic field and self-inductance at the cover 540. The magnetic field caused by the current flowing in each bus bar induces a self-field and a mutual field. The self-induced magnetic field determines the self-inductance of each bus bar. However, the mutual magnetic field is opposite to the self-induced field, resulting in a reduction in the total stray inductance. The capacitor assembly 500 enhances the mutual magnetic field, resulting in a reduction in the overall stray inductance and parasitic inductance at higher frequencies.

[0064] Fig.10 A cover is shown overlapping an external connection of a capacitor in accordance with one or more embodiments. Fig.10 The enlarged view shows Figure 5 The capacitor assembly 500 is shown, and for the sake of brevity, parts of the capacitor assembly 500 will not be repeated. The cover 540 can be arranged at the first DC bus bar 520, and a connection opening 1020 can be formed between the cover 540, the first DC bus bar 520, and the second DC bus bar 530. The cover 540 can be a part of the first DC bus bar 520 or an additional attachment. The cover 540 can be assembled to the first DC bus bar 520 by connection 1010 (e.g., laser welding, screw interconnection, stamped bus bar, etc.).

[0065] Fig.11 A top view of a capacitor assembly having planar bus bars is shown in accordance with one or more embodiments. Fig.11 A top view of capacitor assembly 500 is shown and may include positive connection 1110 and negative connection 1120. Positive connection 1110 and negative connection 1120 may be implemented with a marked metal spray (e.g., zinc). Positive connection 1110 may be located at positive terminal 560 of first capacitor 550. Negative connection 1120 may be located at negative terminal 585 of second capacitor 570.

[0066] Compared to a large capacitor design with a wide gap between the positive and negative busbars, one or more embodiments as described herein can reduce parasitic inductance by more than 80%. The planar busbar 510 including the overlapping first DC busbar 520 and second DC busbar 530 allows connection to the bobbin 410 on opposite sides of the planar busbar 510, thereby reducing parasitic inductance. In addition, the cover 540 induces a magnetic field opposite to the induced magnetic field, thereby reducing the self-induced magnetic field and self-inductance at the cover 540.

[0067] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

Claims

1. A system, comprising: An inverter converts direct current from a battery into alternating current to drive the motor, wherein the inverter comprises: A capacitor assembly, the capacitor assembly comprising: A planar bus bar, the planar bus bar comprising a first DC bus bar and a second DC bus bar; one or more first capacitors on a first side of the planar bus bar, the one or more first capacitors comprising a first bobbin having a positive end facing in a first direction relative to the planar bus bar; and one or more second capacitors on a first side of the planar bus bar, the one or more second capacitors comprising a second bobbin having a positive end facing in a second direction relative to the planar bus bar, The one or more first capacitors and the one or more second capacitors are arranged alternately relative to the planar bus bar.

2. The system according to claim 1, wherein: The first DC bus bar is positive and the second DC bus bar is negative.

3. The system according to claim 1, wherein: The one or more first capacitors and the one or more second capacitors are alternately arranged in a single row.

4. The system according to claim 1, wherein: The one or more first capacitors and the one or more second capacitors are alternately arranged in each of two or more rows such that each of the two or more rows includes the same arrangement of the one or more first capacitors and the one or more second capacitors.

5. The system according to claim 1, wherein: The first DC bus bar comprises an inner surface and an outer surface; Wherein, the second DC busbar comprises an inner surface and an outer surface, and The inner surface of the first DC busbar faces the inner surface of the second DC busbar, so that at least a portion of the first DC busbar overlaps with the second DC busbar.

6. The system according to claim 1, wherein: The first DC bus bar further includes: a connection opening for the one or more first capacitors or the one or more second capacitors; and A cover covers the connection opening.

7. The system according to claim 1, wherein: The first bobbin and the second bobbin are arranged in a horizontal direction or in a vertical direction.

8. The system according to claim 1, wherein: The alternating arrangement of the one or more first capacitors and the one or more second capacitors reduces inductance relative to capacitors that are not alternately arranged.

9. The system according to claim 1, wherein: The one or more first capacitors include three first capacitors, and Wherein, the one or more second capacitors include three second capacitors.

10. The system according to claim 1, wherein: The first direction and the second direction are substantially opposite.

11. The system according to claim 1, wherein: The first direction and the second direction are substantially opposite and substantially parallel to the planar bus bar in a longitudinal direction of the planar bus bar.

12. The system according to claim 1, further comprising: the battery configured to supply the DC power to the inverter; as well as The electric motor is configured to receive the alternating current from the inverter to drive the electric motor, wherein the system is provided as a vehicle including the inverter, the battery, and the electric motor.

13. A system comprising a capacitor assembly, the capacitor assembly comprising: A planar bus bar, the planar bus bar comprising a first DC bus bar and a second DC bus bar; one or more first capacitors on a first side of the planar bus bar, the one or more first capacitors comprising a first bobbin having a positive end facing in a first direction relative to the planar bus bar; as well as one or more second capacitors on a first side of the planar bus bar, the one or more second capacitors comprising a second bobbin having a positive end facing in a second direction relative to the planar bus bar, The one or more first capacitors and the one or more second capacitors are arranged alternately relative to the planar bus bar.

14. The system according to claim 13, wherein: The first DC bus bar is positive and the second DC bus bar is negative.

15. The system of claim 13, wherein: The one or more first capacitors and the one or more second capacitors are alternately arranged in a single row, or wherein the one or more first capacitors and the one or more second capacitors are alternately arranged in each of two or more rows.

16. The system of claim 13, wherein: The first DC bus bar further includes: a connection opening for the one or more first capacitors or the one or more second capacitors; and A cover covers the connection opening.

17. A system, comprising: A capacitor assembly, the capacitor assembly comprising: a first capacitor comprising a first bobbin having a positive terminal, wherein the positive terminal of the first bobbin faces in a first direction; and a second capacitor including a second bobbin having a positive terminal, wherein the positive terminal of the second bobbin faces in a second direction, The first capacitor and the second capacitor are alternately arranged relative to a planar bus bar, wherein the planar bus bar includes a first DC bus bar and a second DC bus bar, wherein the first DC bus bar comprises an inner surface and an outer surface, and the second DC bus bar comprises an inner surface and an outer surface, and The inner surface of the first DC busbar faces the inner surface of the second DC busbar, so that at least a portion of the first DC busbar overlaps with the second DC busbar.

18. The system of claim 17, wherein: The first DC bus bar is positive and the second DC bus bar is negative.

19. The system of claim 17, wherein: The first capacitors and the second capacitors are arranged alternately in a single row, or wherein the first capacitors and the second capacitors are arranged alternately in each of two or more rows such that each of the two or more rows includes the same arrangement of the first capacitors and the second capacitors.

20. The system of claim 17, wherein: The first DC bus bar further includes: a connection opening for the first capacitor or the second capacitor; and A cover covers the connection opening.

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