Spacer for busbars

Abstract

A spacer 1 for busbars 100 with two openings 10 configured to receive a section of a busbar 100 and a middle arm 2. There may be provided first and second outside arms 31, 32 that define the openings

Description

Field The present disclosure relates to a spacer for busbars. Background In next generation aircraft with more electric and hybrid propulsion systems, power electronics converters play a critical role. Power electronics converters such as DC / AC inverters, AC / DC rectifiers, and DC / DC converters are required to interface with electrical propulsion motors, turbogenerators, fuel cell and battery energy storage systems. High-performance power converter designs are an attractive topic for different applications including aerospace, automotive, and other industrial applications. To distribute electrical power to and between these components, busbars are used as an electrical connection. Busbars are typically conductive parts made of copper or aluminium to provide an electrical connection from an energy source to an electrical component. They can be rigid or flexible. Nowadays, flexible busbars are often used in aircraft due to the advantage that they are easier to accommodate in limited space and that they withstand vibrations well. Flexible busbars for direct current supply may have an uncontrolled distance from each other or other components due to their flexible nature, including possibly touching each other. This can cause difficult sizing calculations and incorrect oversizing, thereby reducing the ability to cool and dissipate heat. There is a need to provide a controlled arrangement of busbars that allows defined cooling and heat dissipation of the busbars or at least provides a useful alternative to known spacers. Summary In a first aspect there is provided a spacer for busbars is provided forthat comprises at least two openings, each opening configured to receive a section of a busbar. The spacer further comprises at least one middle arm arranged between the at least two openings, the middle arm having a width that defines a distance between busbars arranged in the openings. Aspects of the invention are thus based on the idea to provide a spacer which ensures that a controlled distance between busbars is present, wherein a minimum distance between two busbars is defined and secured by the width of a middle arm which separates the at least two openings in which the busbars are arranged. Ensuring a minimum distance between the busbars allows for a controlled heat dissipation, and further ensures that the busbars do not touch each other or are arranged too close to each other. The controlled spacing allows for a better cooling, reduces the risk of overheating and improves in general the system efficiency. This results in an improved sizing calculation of the respective technical parts, thereby potentially reducing weight. The spacer of the present invention further prevents electrical shortcuts that might occur when the busbars are touching each other. The spacer also provides for an improved vibration resistance. In environments like aviation there is a constant vibration causing the electric conductors to move around, causing mechanical damage over time. The spacer receiving the busbars holds the busbars in position, preventing them from moving. In the context of the present disclosure, the term “busbar” refers to any flexible or rigid conductor, in particular high-voltage conductor (1000 V or more), wherein advantages of the present invention are particularly present with flexible conductors. The busbar may be a solid or flat strip conductor or be made of multiple electrical connections. For example, a busbar may be a copper or aluminum strip of rectangular or circular cross-section in some embodiments. In other embodiments, the busbar may be a flexible braids conductor, i.e., an electrical conductor made from fine strands of wire braided together. Such braids are typically made from materials like copper or tinned copper and offer excellent electrical conductivity and flexibility. In some embodiments, the spacer further comprises first and second outside arms, wherein a first opening is defined between the first outside arm and the or one of the middle arms and wherein a second opening is defined between the second outside arm and the or another one of the middle arms. Accordingly, the openings are formed using one or several middle arms and two outside arms. The first and second outside arms may be configured to define a minimum distance between the busbar and parts adjacent to the spacer. Accordingly, dependent on the distance requirements to other parts such as other conductors, metal elements, or a housing, the width of the first and second outside arms may be chosen to be larger or smaller. This allows for a further improved heat dissipation reducing the risk of overheating and improving system efficiency and resulting in an improved sizing calculation of the respective technical parts. In some embodiments, the spacer is of a flexible design and configured to hold the respective busbars with a spring force. To this end, for example, the mentioned first and second outside arms may be configured to be bendable away from the at least one middle arm to broaden the opening to a allow a section of the busbar to be inserted into the opening and, subsequently, to bend back to hold the busbar in the opening with a spring force. In some embodiments, the spacer comprises resilient protrusions configured to fixate the busbars in the openings. The resilient protrusions may be arranged at leading edges of the at least one middle arm and of the outside arms. The resilient protrusions provide for a clip function that allows to hold the busbars securely in the openings once inserted. In some embodiments, the outside arms and the at least one middle arm are connected to each other at one end of the spacer by a continuous base section and extend in the same direction, wherein the spacer forms entrances to the openings at the opposite end of the spacer. Accordingly, the middle arm and the outside arms may be connected to each other at one end of the spacer and provide for the entrance to the openings at the opposite end of the spacer. This allows to insert the busbars into the openings from one side of the spacers in a simple manner. In some embodiments, the spacer comprises two openings and one middle arm, each opening configured to receive a section of a busbar. Accordingly, the spacers are configured to hold two busbars. Such embodiments may be used in a circuit implementing DC current or a two-phase alternating current. In some embodiments, the spacer comprises three openings and two middle arms, each opening configured to receive a section of a busbar. Accordingly, the spacers are configured to hold three busbars. Such embodiments may be used in a circuit implementing a three-phase alternating current. In still other embodiments, the spacer comprises four or more openings and a corresponding number of middle arms. When having three openings for three busbars, in some embodiments, a first opening is defined between the first outside arm and one of the middle arms, a second opening is defined between the second outside arm and the other of the middle arms, and a third opening is defined between the two middle arms. In some embodiments, the openings are configured to enclose a section of the busbar in three directions, i.e., at three sides. This ensures a firm placement of the busbar in the opening. The openings may have a rectangular cross-section such that they are configured to receive busbars with a rectangular cross-section. However, the openings are not necessarily strictly rectangular. For example, it may be provided that the inner side of at least one of the outside arms that limits the opening to one side is rounded off outwards. This allows the spacer to also accommodate busbars with a round shape. Further, this may increase the flexibility of the outside arm to allow it to be better bent outwards when a busbar is introduced into the opening. In some embodiments, the openings have a circular cross-section such that they are configured to receive busbars with a circular cross-section. In such case, both the inner sides of the at least one middle arm and the inner sides of the outside arms are rounded to provide for the circular cross-section. In other embodiments, the openings may have other cross-sectional shapes, such as oval. In some embodiments, the spacer is made of an insulative material such as plastic or a composite material. In some embodiments, the spacer comprises two parallel sides which define the length of the spacer. The distance between the parallel sides defines the length of the section of the busbar which is inserted into the opening. Typically, the spacer is of small length and comprises a flat form. The spacer may be configured to receive busbars of a power converter circuit used in electric and hybrid propulsion systems. In a second aspect there is provided a power converter circuit for which comprises at least two busbars and a spacer of the first aspect, wherein the at least two busbars are arranged in the openings of the spacer. The skilled person will appreciate that except where mutually exclusive, a feature or parameter described in relation to any one of the above aspects may be applied to any other aspect. Furthermore, except where mutually exclusive, any feature or parameter described herein may be applied to any aspect and / or combined with any other feature or parameter described herein. Brief description of the drawings The invention will be explained in more detail on the basis of exemplary embodiments with reference to the accompanying drawings in which: FIG. 1 is a cross-sectional view of an embodiment of a spacer for busbars that comprises two openings configured to receive two busbars, wherein the openings each comprise a rectangular cross-section with a rounded side wall; FIG. 2 is a perspective view of the spacer of FIG. 1; FIG. 3 is a cross-sectional view of another embodiment of a spacer for busbars, the spacer comprising three openings configured to receive three busbars, wherein the openings each comprise a rectangular cross-section with rounded side-walls; FIG. 4 is a cross-sectional view of another embodiment of a spacer for busbars, the spacer comprising three openings configured to receive three busbars, wherein the openings each comprise a circular cross-section; FIG. 5 a perspective view of elements of a power circuit in an aircraft, wherein the power circuit comprises two flexible busbars which are spaced from each other by means of a spacer formed in accordance with the present invention; and FIG. 6 the power circuit of FIG. 5, wherein the two flexible busbars are spaced from each other by means of two spacers. Detailed description FIGS. 5 and 6 illustrate the background of the present invention. In more electric and hybrid propulsion systems used in next generation aircraft flexible busbars are implemented for power distribution and to conduct electricity. The flexible busbars may be comprised of metallic strips or bars (such as copper strips or bars) or be formed as flexible braids conductors. FIG. 5 shows an electric arrangement in which two flexible busbars 100 are connected at one end 101 to an electric device 102 (such as a battery) and arranged in a generally bent manner with several curved areas. They pass close to a further electric device 103 which may include metallic components. The components of the electric arrangement of FIG. 5 may form part of a power converter or other electrical circuit of next generation aircraft. It is to be assured that, first, the two busbars 100 keep a constant defined distance between each other along their path, without changing distance or even touching each other, and that, second, the two busbars do not contact or come too close to other components such as electric device 103. If these requirements are met, proper sizing and cooling can be ensured. To this end, a spacer 1 is provided which keeps the two busbars 100 at a defined distance. Embodiments of the spacer 1 will be discussed with respect to FIGS. 1 to 4. FIG. 6 is similar to FIG. 5, wherein two spacers 1 are arranged at a distance to illustrate that the number of spacers 1 used to control the distance between the busbars 100 is not limited. FIG. 1 shows a first embodiment of a spacer 1 that is configured to receive two busbars and provide for a controlled distance between the busbars. The spacer 1 consist of an insulative material such as plastic or a composite material. The spacer 1 comprises a top side 6, a bottom side 7, a left side 8 and a right side 9. The spacer can be positioned freely in an aircraft. In this sense, the orientation of the sides 6-9 merely serves as a reference based on the drawing and does not imply a predetermined orientation of the spacer. The top side 6 is formed by a continuous base 4. From the base 4 two outside arms 31, 32 and one middle arm 2 extend towards the bottom side 7. The outside arms 31, 32 define the left side 8 and the right side 9 of the spacer 1. Between the middle arm 2 and the side arms 31, 32 two respective openings 10 are formed. The two openings 10 are configured to each accommodate a busbar. The middle arm 2 has a width W which defines the distance between two busbars arranged in the two openings 10. The spacer 1 forms inlets / entrances 12 to the openings 10 which are arranged at the bottom side 7 of the spacer 1. The spacer 1 is of a flexible design such that by bending the outside arms 31, 32 outwards, a busbar can be inserted into the opening 10 through the respective entrance 12. Subsequently, when the busbar has been inserted into the opening, the outside arms 31, 32 bend back and firmly hold the busbars in the spacer 1 with a spring force. There is further provided a clip function which hinders the busbars from dropping out of the openings 10 such as by vibrations. The clip function is provided by means of resilient protrusions which are formed at the leading edges 310, 200 and 320 of the outside arms 31, 32 and of the middle arm 2, wherein the leading edge 310 comprises a protrusion 311 which extends into the left entrance 12, the leading edge 200 comprises two protrusions 201 extending into both of the entrances 12, and the leading edge 320 comprising a protrusion 321 extending into the right entrance 12. In this manner, the busbars are fixed in the openings 10 once inserted. In FIG. 1, the openings 10 are of rectangular shape, wherein the sidewalls of the openings are formed by the middle arm 2 and the two outside arms 31, 32. As indicated in FIG. 1, the sidewall of the middle arm 2 runs straight, wherein the sidewall of the outside arms 31, 32 are rounded to form a rounded (concave) recess. Generally, the openings 10 of rectangular size allow for accommodation of busbars with a rectangular cross-section. However, by also providing rounded side walls, busbars of circular cross-section can also be accommodated. Two busbars 100 of rectangular size are illustrated to be arranged in the openings 10 by way of example. When the busbars are inserted in the openings 10, they are separated from each other by the middle arm 2. Accordingly, the width W of the middle arm 2 defines a specific distance between the busbars. Similarly, the outside arms 31, 32 as well as the upper base 4 define a minimum distance between the busbars and further parts. Further parts may be other conductors, metal elements, a housing, etc. FIG. 2 shows the spacer 1 of FIG. 1 in a perspective view. The spacer 1 further comprises 2 parallel sides 15, 16 which define the length of the spacer 1 and thus the length of the section of the busbars which are inserted into the openings 10. As can be seen, the spacer 1 has a rather short length and can be considered to be a flat object. FIG. 3 shows another embodiment of a spacer 1 for busbars. The spacer 1 is configured to accommodate three busbars. Thus, three openings 10 are formed. The spacer 1 comprises two middle arms 21, 22 and two outside arms 31, 32, wherein a first opening 10 is defined between the left outside arm 31 and the left middle arm 21, a second opening 10 is defined between the right outside arm 32 and the other middle arm 22, and a third opening 10 is defined between the two middle arms 21, 22. In this embodiment, the openings 10 each comprise a rectangular cross-section, wherein both side walls (of the middle arms and of the outside arms) are rounded (i.e., have partly a concave form) to be able to also accommodate busbars with a circular crosssection. Further, the spacer 1 comprises entrances 12 and protrusions 311, 211, 221, 321 at leading edges 310, 210, 220, 320 of the outside arms 31, 32 and of the middle arms 21, 22 in the same manner as described with respect to FIGS. 1 and 2. It is pointed out that the middle arms 21, 22 are also configured to be flexible, such that they may be moved away from each other when inserting a busbar into the respective opening 10. In this respect, when introducing busbars into the openings 10, a sequence is preferred in which a busbar is inserted in the middle opening first and inserted subsequently into the other openings. Three busbars 100 of rectangular size are illustrated to be arranged in the openings 10 by way of example. FIG. 4 shows a further embodiment of a spacer that is intended to accommodate round busbars. The general design of the spacer 1 corresponds to the design of the spacer of FIG. 3, wherein three openings 10 are provided by means of two middle arms 21, 22 and two outside arms 31, 32. In contrast to the embodiment in FIG. 3, the openings 10 have a circular cross-section to enclose round busbars. To this end, a first continuous circular wall 101 is formed by the inner sides of outside arm 31, base 4 and middle arm 21. A second continuous circular wall 102 is formed by the inner sides of middle arm 21, base 4 and middle arm 22. A third continuous circular wall 103 is formed by the inner sides of middle arm 22, base 4 and outside arm 32. The first, second and third continuous walls 101, 102, 103 may be perfectly circular or essentially circular. Further, similar to the other embodiments, the spacer 1 comprises entrances 12 and protrusions 311, 211,221,321 at leading edges 310, 210, 220, 320 of the outside arms 31, 32 and of the middle arms 21, 22 in the same manner as described with respect to FIGS. 1 and 2. Three busbars 100 of circular cross-section are illustrated to be arranged in the openings 10 by way of example. In the embodiment of FIGS. 3 and 4, the three busbars inserted into the three openings 10 may be busbars of a three-phase alternating current implemented in a power converter. It should be understood that the above description is intended for illustrative 5 purposes only, and is not intended to limit the scope of the present disclosure in any way. Also, those skilled in the art will appreciate that other aspects of the disclosure can be obtained from a study of the drawings, the disclosure and the appended claims. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. Various features of the various embodiments 10 disclosed herein can be combined in different combinations to create new embodiments within the scope of the present disclosure. In particular, the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein. Any ranges given herein include any and all specific values within the range and any and all sub-ranges within the given range. 15

Claims

1. A spacer (1) for busbars (100), the spacer (1) comprising:at least two openings (10), each opening (10) configured to receive a section of a busbar (100); andat least one middle arm (2, 21,22) arranged between the at least two openings (10), the middle arm (2, 21, 22) having a width (W) that defines a distance between the busbars (100) arranged in the openings (10).

2. The spacer of claim 1, wherein the spacer (1) further comprises first and second outside arms (31, 32), wherein a first opening (10) is defined between the first outside arm (31) and the or one of the middle arms (2,21, 22), and wherein a second opening (10) is defined between the second outside arm (32) and the or another one of the middle arms (2, 21, 22).

3. The spacer of claim 1, wherein the first and second outside arms (31, 32) are configured to define a minimum distance between the busbar (100) and parts adjacent to the spacer (1).

4. The spacer of any of preceding claim, wherein the spacer (1) is of a flexible design and configured to hold the respective busbars (100) with a spring force.

5. The spacer of claim 4, when dependent on claim 2, wherein the first and second outside arms (31, 32) are configured to be bendable away from the at least one middle arm (2, 21, 22).

6. The spacer of any preceding claim, wherein the spacer (1) comprises resilient protrusions (311, 201, 211, 221, 321) configured to fixate the busbars (100) in the openings (10).

7. The spacer of claim 6, when dependent on claim 2, wherein the resilient protrusions (311, 201, 211, 221, 321) are arranged at leading edges (310, 200, 210, 220, 320) of the at least one middle arm (2, 21, 22) and of the outside arms (31, 32).

8. The spacer of any preceding claim, when dependent on claim 2, wherein the outside arms (31, 32) and the at least one middle arm (2, 21, 22) are connected to each other at one end (6) of the spacer (1) by a base section (4) and extend in the same direction,wherein the spacer forms entrances (12) to the openings (10) at the opposite end (7) of the spacer (1).

9. The spacer of any preceding claim, wherein the spacer (1) comprises two openings (10) and one middle arm (2), each opening (10) configured to receive a section of a busbar (100).

10. The spacer of any one of claims 1 to 8, wherein the spacer (1) comprises three openings (10) and two middle arms (21, 22), each opening (10) configured to receive a section of a busbar (100).

11. The spacer of claim 10, when dependent on claim 2, wherein a first opening (10) is defined between the first outside arm (31) and one of the middle arms (21), a second opening (10) is defined between the second outside arm (32) and the other of the middle arms (22), and a third opening (10) is defined between the two middle arms (21, 22).

12. The spacer of any preceding claim, wherein the openings (10) are configured to enclose a section of the busbar (100) in three directions.

13. The spacer of any preceding claim, wherein the openings (10) have a rectangular cross-section.

14. The spacer of claim 13, when dependent on claim 2, wherein the inner side of at least one of the outside arms (31, 32) is rounded off outwards.

15. The spacer of any one of claims 1 to 12, wherein the openings (10) have a circular cross-section.

16. The spacer of any preceding claim, wherein the spacer (1) is made of an insulative material.

17. The spacer of any preceding claim, wherein the spacer (1) comprises two parallel sides (15, 16) which define the length of the spacer (1).

18. A power converter circuit that comprises at least two busbars (100) and a spacer (1) of any one of claims 1 to 17, wherein the at least two busbars (100) are arranged in the openings (10) of the spacer (1).

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