Electrical distribution system with transition busbars

Abstract

The invention relates to an electric current distribution system (11) comprising: a plurality of main busbars (14) and a plurality of transition busbars (15), an assembly comprising such system and a transition busbar. The main busbars (14) are divided in sets (100a-100n) comprising one first phase main busbar (14L1) configured for conducting current of a first phase (L1) and one second phase main busbar (14L2) configured for conducting current of a second phase (L2). The transition busbars (15) comprise a plurality of first ends (15a) and at least one second end (15b), are configured for being connected to said one phase main busbars (14L1) of said plurality of main busbar sets (100a-100n) and a second end (15b) of said first phase transition busbar (15L1) is configured for being electrically connected to an electric component (29).

Description

ELECTRICAL DISTRIBUTION SYSTEM WITH TRANSITION BUSBARSField of the invention

[0001] The invention relates to an electrical distribution system and an electric cabinet assembly comprising transition busbars and such transition busbar.5 Background of the invention

[0002] In the art electrical cabinets for enclosing electrical distribution systems which may include power electronics are well known. A three phased current to a known electrical cabinet is typically provided by three or six cables one / two for each phase depending on cross-sectional area of the cable and amps. Inside the electrical10 cabinet, the current is distributed by a plurality of electrical conductors in the form of busbars and cables.

[0003] Traditionally, cables or braided conductors are used as transition conductors connecting main busbars, main busbars with loads, switches, power modules or other electrical components. Such current distribution system is rigid and adds weight to the 15 electrical panel especially due to the massive aluminium or cobber busbars required for the high currents of the distribution system. The present invention solves these problems as will be described below.Summary

[0004] The inventors have identified the above-mentioned problems and challenges related to electrical distribution systems and the mounting of conductors in cabinets and solved these problems by the present invention as described below.

[0005] In an aspect, the invention relates to An electric current distribution system comprising: a plurality of main busbars and a plurality of transition busbars, wherein said plurality of main busbars are divided in a plurality of main busbar sets, wherein each of said plurality of main busbar sets comprise one first phase main busbar configured for conducting current of a first phase and one second phase main busbar configured for conducting current of a second phase, wherein said plurality of transition busbars comprise a plurality of first ends and at least one second end, wherein said plurality of first ends of a first phase transition busbar of said plurality of transition busbars are configured for being connected to said one first phase main busbars of said plurality of main busbar sets, wherein said at least one second end of said first phase transition busbar is configured for being electrically connected to an electric component, and wherein said plurality of transition busbars further comprise a second phase transition busbar wherein said plurality of first ends of said second phase transition busbar of said plurality of transition busbars are configured for being connected to said one second phase main busbars of said plurality of main busbar sets, and wherein said at least one second end of said second phase transition busbar is configured for being electrically connected to said electric component.

[0006] Distributing all current of one phase in more than one main busbar which are distributed in more than one main busbar set is in this document referred to as interleaving. According to the present invention, this interleaving is facilitated by the transition busbars at a limited space, with a limited mounting effort and without requiring crossing of the main busbars.

[0007] Interleaving is advantageous in that it has the effect, that the impact on material utilization for current conduction in a neighbouring main busbar is increased. This is because the electromagnetic field established around each individual mainbusbars conducting current of the particular phase is at least partly cancelled by other main busbars located alongside this main busbar. The higher number of different phase main busbars located alongside each other, the more the electromagnetic field of a single main busbar is cancelled out by the other main busbars of main busbar set. This is at least true when the phase main busbars are located alongside each other in a predetermined order (such as A, B, C. . . A, B, C).

[0008] Hence, cancelling as much as possible of the magnetic field has the effect that the push from this electromagnetic field to a phase current conducted by a neighbouring main busbar is reduced. Thereby, the uniformity of current distribution over the entire cross-sectional area of the neighbouring main busbar is increased and thereby it is possible to reduce the cross-sectional area of the main busbars and / or reduce heat generated from the conduction of current in the neighbouring main busbars, leading to a reduction in cost, weight and temperature increase.

[0009] An electric current distribution system should in the context of the present invention be understood as a high power / high voltage system. Hence, the electric current distribution system (commonly referred to as distribution system) is designed to conduct currents above 100 A (and up to several kilo amps) and voltages at or above 230V (and up to several kilo volts). Such distribution system is typically used in renewable energy generating systems such as wind turbines, windfarms, solar system and substations thereof, in utility grid substations, in industrial production, etc. For safety reasons and to protect the distribution system, the distribution system is typically enclosed in an electrical cabinet.

[0010] An electrical component may be an electrical conductor such as a busbar, a power handling section, power converter, inverter, transformer, generator, electric motor, breaker, high-power battery system, battery charger, or similar power systems, possibly including capacitors, reactors or inductors, power resistors, dump loads, etc. An electrical conductor should be understood as a current conductor. A power handling section should be understood as a section of the electric current distribution system that is doing something with the current flow. One example could be that the power handling section comprises switchgear via which the current flow can be shuton and shut off. Another example could be that the power handling section comprises transformers via which voltage is changed or isolation is provided. Yet another example could be that the power handling section comprises power modules / converter modules via which frequency, current and / or voltage can be changed.

[0011] A main busbar should be understood as an electrical conductor distributing current in the distribution system and thus may be implanted as cables and various types of busbars. Hence when the distribution system is enclosed in an electrical cabinet, the main busbars may be located in the back, top or bottom of the cabinet and ensure distribution of current between input terminals, power handing sections and output terminals of the distribution system. Hence, the cabinet may be supplied from one or more cables entering the electric cabinet, these cables may be connected to input terminals. Transition busbars may then connect the input terminals with the main busbars and connect the main busbars to electrical components located inside the electrical cabinet. Typically, the main busbar extends in the width (X direction) or in the hight (Y direction) of the electrical cabinet. The main busbar may be fastened to the back plate of the electrical cabinet.

[0012] The current of one phase may be too high to be conducted in one main busbar and therefore more than one main busbar is needed to conduct the phase current. Another reason for conducting the current of one phase in more than one main busbar is, according to the present invention, to reduce the impact from the electromagnetic field generated around the busbar(s) needed to conduct the phase current. In a multiphase system, when phase currents are conducted in more than one main busbar, according to the present invention, the layout of the main busbars of all phases are made in sets of main busbars. Where each main busbar set include one main busbar from each of the phases.

[0013] A transition busbar should be understood as a busbar connecting a terminal, main busbar or cable with another main busbar, another transition busbar, with an electrical component, or the like. A transition busbar may also be referred to as a connection or transition piece for connecting two or more electrical components. Typically, a transition busbar extends in two or more directions, where one of thesedirections is towards the opening of the electrical cabinet (Z direction). Another of these directions is typically perpendicular or sometimes parallel to e.g. the main busbar to which transition busbar is connected. The transition busbar may comprise two or more legs at one end and at least one leg at the other end for connecting e.g. two paralleled power modules to one main busbar or to another transition busbar or to connect two parallel main busbars to one electric component such as a switchgear.

[0014] It should be noted that a reference to an end often is a reference to terminal e.g. a part of a busbar that is designed to obtain an electric connection with another terminal. Such terminals typically have holes through which bolts / nuts can be used to force the two (or more) terminals together.

[0015] According to an advantageous embodiment of the invention, said first phase current (LI) is a DC minus and said second phase current (L2) is a DC plus.

[0016] According to an advantageous embodiment of the invention, a plurality of said first phase main busbar and a plurality of said second phase main busbar are stacked with an insulating material therebetween.

[0017] This is advantageous in that it has the effect, that interleaving can also be implemented in a DC link of a back to back power converter.

[0018] According to an advantageous embodiment of the invention, said second phase current (L2) is a neutral

[0019] The electric distribution system may be a one phase plus neutral system where the first phase current is conducted to a load from a power source and the second phase current is conducted from the load to the power source. The difference in voltage potential between the first phase main busbar and the second phase main busbar depend on the type of the electrical system.

[0020] According to an advantageous embodiment of the invention, each of said plurality of main busbar sets further comprise one third phase main busbar configured for conducting current of a third phase (L3).

[0021] According to an advantageous embodiment of the invention, each of said plurality of main busbar sets comprise one third phase main busbar configured for conducting current of a third phase, wherein said plurality of transition busbars further comprise a third phase transition busbar wherein said plurality of first ends of said third phase transition busbar of said plurality of transition busbars are configured for being electrically connected to said one third phase main busbars of said plurality of main busbar sets, and wherein said at least one second end of said third phase transition busbar is configured for being electrically connected to said electric component.

[0022] Above, the electric current distribution system is described with two and three phases, however it should be noted that distribution systems with more than three phases may benefit even more from the effect of the interleaving i.e. a cancellation of the magnetic field leading to a better utilization of the (material of the) main busbars. Thus, in distribution systems with 6 (i.e. with 60 degrees between the phases), 9, 12 or even more phases, the effect of the interleaving is even higher and thus, the value of the transition busbars of the present invention. This is because the more phases that need to be connected, the more second ends can be incorporated at the inventive transition busbar especially when this is produced by additive manufacturing.

[0023] According to an advantageous embodiment of the invention, said electric current distribution system comprise input terminals and output terminals.

[0024] In this way, the electric current distribution system is connectable to external system such as generators, grid, etc. The input terminals may be implemented as holes in the main busbar or in a transition busbar.

[0025] The connection between the input terminal and supply cable may be made via bolts penetrating terminal holes in the cable shoes of the supply cable and terminal holes referred to as input terminals.

[0026] According to an advantageous embodiment of the invention, said at least one second end of said first phase transition busbar is configured for being connected to a first phase terminal of said electric component.

[0027] In the same way the other phases L2 and L3 etc. are connected to the second and third etc. phase terminals of the electric component. In the case, that the electric component is a switchgear, the switchgear is ensuring opening and closing for a flow of electric current through the conductors. The switchgear has phase terminals on both sides of the breaking elements. On the input side, these phase input terminals are configured to receive phases LI, L2, ..., Ln and e.g. Neutral, terminals which correspond to phase output terminals LI, L2, . . ., Ln and e.g. Neutral.

[0028] According to an advantageous embodiment of the invention, said transition busbar comprise a first leg electrically connecting a first of said plurality of first ends with said at least one second end and a second leg electrically connecting a second of said plurality of first ends with said at least one second end.

[0029] Connecting the first ends with the second ends by legs that are separated is advantageous in that it has the effect that the transition busbar is able to reach over one or more main busbars without electrically connecting with these. Thereby two main busbars can be connectable to the same transition busbar even when these are not neighbouring busbars.

[0030] According to an advantageous embodiment of the invention, wherein said transition busbar comprise two first ends and one second end.

[0031] This design is relevant in that it has the effect, that it enables dividing a phase current out from e.g. one output terminal of a switchgear into two main busbars of two main busbar sets. This with one single monolithic transition busbar which may be specially designed to the layout of distribution system. Such special design may include dimensioning, lengths, angles, etc. tailor made to the particular connection between switchgear output terminal and the two main busbars. Thus, with this one inventive transition busbar, it is possible, without the need to make any crossing of main busbars to implement the interleaving. Hence, such transition busbar is advantageous in that it requires less space which in many cases is the key to be able to implement the interleaving. Put in another way, in most applications it is not possible to implement the interleaving without the transition busbar of the present inventiondue to space requirements both in terms of mounting and in terms of available footprint to such transition busbar.

[0032] It should be mentioned that the transition busbar may have 3, 4, 5, . . . , n first ends depending on the number of main busbars one phase is to be divided of separated into.

[0033] Further, it should be mentioned that the transition busbar may have 2, 3, 4, ..., n second ends depending on the number of main busbars or terminals that is conducting the phase current which is to be divided or separated via the first ends.

[0034] According to an advantageous embodiment of the invention, said plurality of first ends are monolithically joint.

[0035] According to an advantageous embodiment of the invention, said plurality of first ends are monolithically joint with said at least one second end.

[0036] The monolithically joint ends of the transition busbar is advantageous in that it has the effect, that the transition busbar has a compact design, but more important as monolithically should be understood as in one piece with no separate parts that need to be electrically connected, there are not joints with ohmic resistance in the transition busbar. This design lead at least to reduced ohmic losses, reduced risk of errors in mounting and in operation, reduced mounting time and reduced footprint.

[0037] According to an advantageous embodiment of the invention, said transition busbar a current balancing busbar.

[0038] A current balancing busbar should be understood as a variant of a transition busbar. A current balancing busbar (also sometimes referred to as a current sharing busbar) may e.g. be a transition busbar having two or more legs or sets of terminals allowing the connection of two or more electric components such as power modules i.e. allowing parallelling the power modules. This is advantageous in that it has the effect, that if such current balancing busbar is connected to e.g. two power modules, then the current into or out of these two power modules can be balanced. Such balancing is done via designing the current balancing busbar so that the current paththrough the two legs of the current balancing busbar has the same ohmic resistance. When this is achieved an equal share of current to and from the power modules is conducted via the two legs which may be an important operating parameter for the power modules. Thereby it is achieved that losses are the same in both legs leading to equal wear and temperature increase.

[0039] According to an advantageous embodiment of the invention, said current balancing busbar comprise a first leg electrically connecting a first of said plurality of first ends with said at least one second end and a second leg electrically connecting a second of said plurality of first ends with said at least one second end, wherein the dimensions of said first leg are different from the dimensions of said second leg.

[0040] Having different dimensions on legs of a current balancing busbar is advantageous in that by the dimensions of the legs it is possible to control when current flows in the current balancing busbar. Hence, if the first leg is a short current path and the second leg is a long current path then, the dimensions such as the cross-sectional area of the first leg may be smaller than the dimensions such as the cross-sectional area of the second leg to force current to flow equally between the two legs.

[0041] According to an advantageous embodiment of the invention, at least one of said transition busbars or at least one of said plurality of main busbars are manufactured by an additive manufacturing process.

[0042] Manufacturing a main busbar or a transition busbar (commonly referred to as busbar) by an additive manufacturing process is advantageous in that additive manufacturing is suitable for manufacturing complex shapes and is thus advantageous to employ for manufacturing of busbars where these are used in narrow spaces such as in an electrical cabinet. Particularly, geometrical features of the busbar, such as individual conductor branches, outgrowths, recesses, internal structures, etc. may be directly manufactured additively. Thus, using additive manufacturing for manufacturing a busbar of a high-power converter is advantageous since it may permit tailoring the geometry of the busbar to the conditions / design of the electric current distribution system and thus to the electrical cabinet comprising the electrical currentdistribution system. In particular, it is advantageous to be able to design the transition busbar so that its first and second ends are monolithically connected. This is leading to a much smaller footprint of the transition busbar and enabling the custom made connection between one electrical component and a plurality of busbars.

[0043] Hence, an electrical current distribution system according to the present invention comprising a busbar manufactured by an additive manufacturing process is advantageous in that weight and cost of materials are reduce due to less material being used for the busbars. Further, cooling of the electrical cabinet is improved in that surface area of the busbar can be increased and the busbar can be manufactured with internal cooling channels. Further, assembling of the electrical current distribution system and thus of the electric cabinet may be faster due to a reduced number of connections of busbars and to more flexible busbars compared known busbars. These effects may all contribute to a more compact design of the current distribution system.

[0044] Regarding the reduction of used material and thereby weight of the distribution system. This may be obtained e.g. by cutting of a comer of e.g. a transition busbar. This is easy in that the conductor is manufactured by an additive manufacturing process and thus easy to print. As an example of this could be mentioned a transition busbar meant for collecting current from e.g. three cables and guide this current to a main busbar. The part of the transition busbar conducting current from one cable should have first cross-sectional area, the part conducting current from two cables a second cross-sectional area larger than the first cross-sectional area and the part conducting current from three cables a third cross-sectional area larger than the first and second cross-sectional areas.

[0045] In an exemplary embodiment of the invention, wherein a cross-sectional part of at least one of said one or more main busbars or one of said plurality of transition busbars comprising a through-hole and wherein said cross-sectional part of said at least one of said one or more main busbars or one of said plurality of transition busbars is increased.

[0046] This is advantageous in that it has the effect, that the cross-sectional area that is available for conducting current is not reduced even though a through hole is made through the high-power electrical conductor. An increased / decreased cross-sectional area or a conductor should be understood as along the length of the conductor, the cross-sectional areas is changing (increasing or decreasing). Hence, if the cross- sectional area is measured a first distance from an end and a second distance from the same end, the cross-sectional area of the conductor may not be the same. It should be noted, that the same is true for the circumference of the conductor. In other words the length around the circumference of the conductor and / or the width of the conductor may change (decrease or increase) along the length of the conductor.

[0047] According to an advantageous embodiment of the invention, said transition busbar and / or said main busbar comprise an internal structure at least partly enclosed in an outer enclosure.

[0048] The enclosure or the conductor branches are considered the main current carrier depending on the design of the transition busbar. The hollow structure is advantageous in terms of weight reduction and cooling.

[0049] According to an advantageous embodiment of the invention, said electric distribution system is comprised by an electric cabinet.

[0050] In an exemplary embodiment of the invention, at least one of said one or more main busbars or one of said plurality of transition busbars is manufactured at least partly with a concave geometry in the surface of a middle segment or in one of a first end and a second end of said at least one of said one or more main busbars or one of said plurality of transition busbars.

[0051] This is advantageous in that such concave geometry may form a funnel like geometry guiding a flow of air caught by said funnel to an inlet opening of an internal cooling channel of said electrical conductor or through the electrical conductor if the design thereof allows so. It should be mentioned that air guides provided in the surface of said electrical conductor may assist in guiding a flow of air into said funnel.

[0052] In an exemplary embodiment of the invention, at least one of said plurality of main busbars or one of said plurality of transition busbars are manufactured with an airy geometry.

[0053] Airy design should be understood as a design comprising one or more conductor branches designed in such a way that air or other cooling fluid may pass through the conductor branches and thereby facilitate cooling the conductor branches. Examples of such an airy design include weblike, spongy, bionic, twisted, etc.

[0054] In an exemplary embodiment of the invention, at least a middle segment of at least one of said plurality of main busbars or one of said plurality of transition busbars comprises at least one internal channel.

[0055] Said internal channel may be a closed channel for guiding a liquid through the interior of the busbar or an open channel for guiding an air flow through the interior of the busbar. It should be mentioned that guiding an air flow through the interior of the busbar should be understood as guiding air behind the outer surface of the busbar i.e., along the side or behind a conductor branch of the busbar. Accordingly, it is understood that the conductor, in particular part of the middle segment of the conductor is manufactured with a plurality of conductor branches forming air gaps through which air can flow.

[0056] In an exemplary embodiment of the invention, said at least one internal channel is included in a cooling loop and configured to guide a cooling fluid circulated in said cooling loop through the interior of said at least one of said plurality of main busbar or said plurality of transition busbar via said at least one internal channel.

[0057] An internal channel configured to guide a cooling fluid through at least part of the busbar (note that busbar may refer to either one of a high-power electrical conductor, electrical conductor, conductor, main busbar, transition busbar and current sharing busbar) is advantageous in that in this way, the temperature of the high-power electrical conductor, especially around the internal channel, can be controlled such as reduced. Hence, an internal channel is advantageous in that it has the effect, that an efficient temperature regulation of the electrical conductor is possible.

[0058] Further, internal channels are advantageous in that heat is transported out of the electrical cabinet more efficiently than by using a fan to establish a flow of air out of the electrical cabinet. Since, at the high amps a power converter of the present invention is operating at, heat is a very important design factor. Thus, the better the temperature can be controlled, more efficient it is possible to operate the power converter. Therefore, it is important to be able to remove as much heat as possible from the inside of the electrical cabinet.

[0059] In an exemplary embodiment of the invention, at least one of said plurality of main busbars or one said plurality of transition busbars comprises at least one air guide.

[0060] A busbar comprising an air guide is advantageous in that it has the effect, that it facilitates both guiding a cooling fluid, such as air, to and possible also around an electrical component to which it is connected or passing by in an electrical cabinet. Such catching and guiding of air flow is achieved while, at the same time, improving the cooling of the busbar itself and supplying the electrical component with power without the need for additional air guiding components.

[0061] In an exemplary embodiment of the invention, at least one of said plurality of main busbars or one of said plurality of transition busbar comprises at least one integrated heat sink.

[0062] A busbar such as a middle segment hereof comprising an integrated heat sink is advantageous in that not only does such busbar facilitate improved cooling of the busbar itself, e.g. when used as a high-power busbar for conducting currents to or from a component to which it is connected. But such middle segment advantageously also enabling cooling of a component such as a power electronic component such as a power module by mounting the power modules with a thermal connection to the busbar with an integrated heat sink. Thereby eliminating or reducing the need of separate heat sinks for components such as the power module.

[0063] The heat sink may provide a larger surface area of the busbar where it is located compared to other parts of the busbar where no heat sink is located.

[0064] In addition, or alternatively a heat sink may provide a more open surface of the busbar, particularly of the middle segment, compared to parts of the busbar which have no heat sink.

[0065] In an aspect, the invention relates to an electric cabinet assembly, said electrical cabinet assembly comprising: an electric cabinet, a power conduction section comprising one or more main busbars, a power handling section comprising one or more electrical components, and a plurality of transition busbars wherein at least part of said plurality of electrical components of said power handling section is connected to one of said one or more main busbar via one of said plurality of transition busbars, the electric cabinet assembly is characterised in that at least one of said plurality of translation busbars comprise a plurality of first ends monolithically joint with at least one second end.

[0066] According to an advantageous embodiment of the invention, said transition busbar is manufactured by an additive manufacturing process.

[0067] According to an advantageous embodiment of the invention, said transition busbar comprise a higher number of first ends than second ends.

[0068] An electric cabinet assembly comprising components that are connected by conductors having ends that are monolithically joint in a relationship where there are more first ends than second ends and which may be manufactured by additive manufacturing is advantageous in that it takes up a minimum of space and do not generate heat from ohmic resistance in electric joints of the trans busbar itself. Further, the additive manufacturing method may allow legs and body of the transition busbar to have an airy design or geometry leading to an optimized cooling.

[0069] Further such busbars may be manufactured with an integrated heat sink, with air guides, etc. which may optimize cooling of the conductor and reduce the amount of material needed to manufacture the conductor. This leads to a reduction of weight of the cabinet assembly which has many spillover effects e.g. in terms of logistics and support of the cabinet assembly.

[0070] An electric cabinet assembly according to the present invention may further comprises a filtering section comprising a reactor and a cooling system. According to an advantageous embodiment of the invention, an electrical component of said power handling section is supplied from a main busbar set comprising a first, second and third phase main busbars via a transition busbar having a non-uniform geometry.

[0071] Non-uniform geometry should be understood as a geometry that change i.e. the cross-sectional area of the transition busbar change while still being monolithic. A monolithic transition busbar with a non-uniform design may be characterized in that from its ends / terminals to its middle segment, the geometry change. Such change may be from right lined outer edges / angled comers of the terminal ends to spheric shaped outer edges of the middle segment of the transition busbar. The middle segment may also be curved or twisted in any way to facilitate optimal positioning for connecting it to the electric component such as switchgear and main busbar in both ends.

[0072] According to an advantageous embodiment of the invention, supplying a plurality of main busbar sets (wherein each of said plurality of main busbar sets comprise a first phase main busbar, a second phase main busbar and a third phase main busbar via a transition busbar comprising a plurality of first ends monolithically joint with at least one second end.

[0073] This is advantageous in that it has the effect, that one terminal of an electrical component can be connected to a plurality of main busbars i.e. the transition busbar may be considered a cross point from where one phase can be divided or guided into several current flows.

[0074] According to an advantageous embodiment of the invention, said plurality first ends are monolithically joint with said at least on second end via legs, wherein said legs are non-identical.

[0075] This is advantageous in that it has the effect that with one monolithic transition busbar it is possible to connect a plurality of main busbars to the same phase terminal of an electrical component.

[0076] Non-identical should be understood as not being the same length and / not having the same cross-sectional areas. The first is advantageous in that interleaving between phase busbars of the main busbar sets can be established without crossing the individual busbars of the main busbar sets. The second is advantageous in that current sharing can be obtained i.e. ensuring that the same size of current (measured in amps) is being conducted in each of the legs of the transition busbar. This can be obtained e.g. by differentiating the cross-sectional area of the legs.

[0077] According to an advantageous embodiment of the invention, at least one of a first, second and third phase main busbars of a first main busbar set is crossing at least one of a first, second and third phase main busbars of a second main busbar set.

[0078] This is advantageous in that it has the effect, that all first phase main busbars are then adjacent to each other and thereby it is possible to establish a first, second and third phase terminals for electrically connecting the phase main busbars to other main busbars, cables in or out of the cabinet, electrical components, etc.

[0079] An alternative to said crossing is designing and mounting a transition busbar at the ends of the main busbars of the main busbar set that is gathering alle first, second and third phase current via the plurality of first ends in the at least one second end of the transition busbar.

[0080] According to an advantageous embodiment of the invention, wherein said crossing is made in proximity of terminals of said phase main busbars of said main busbars set.

[0081] In an aspect, the invention relates to a transition busbar configured for electrically connecting an electric component with a main busbar, wherein said transition busbar comprise a plurality of first ends and at least one second end, wherein said plurality of first ends are configured for being connected to a plurality of first phase main busbars of a plurality of main busbar sets, wherein said at least one second end is configured for being connected to said electric component, wherein said transition busbar comprise a first leg electrically connecting a first of said plurality of first ends with said at least one second end and a second leg electrically connecting asecond of said plurality of first ends with said at least one second end, and wherein said plurality of first ends are monolithically connected with said at least one second end.

[0082] Such transition busbar is advantageous in that it has the effect, that it facilitates interleaving of main busbars with one single component i.e. no need to preassemble a transition busbar before mounting in an electric distribution system. Other advantages of such transition busbar are presented above.

[0083] According to an advantageous embodiment of the invention, said transition busbar comprise terminal holes going through a main body of the transition busbar.

[0084] According to an advantageous embodiment of the invention, the length in a Z direction of said terminal holes are longer than the length of the width in a X direction and / or longer than the length of the hight in an Y direction

[0085] The main body is connecting the first and second ends of the transition busbar. It is the typically the second ends of the transition busbar that are connected to an electrical component via terminal holes going through the main body. The terminal holes of the first ends are typically conventional hols having the same length as the thickness (Z) of the ends. Hence, the length of the holes at the second ends are typically longer than the width (x or Y) of the second end. This is advantageous in that a more compact (less space requiring) current flow path via transition and main busbars can be designed and mounted without difficulties from the front of the system i.e. from a door opening in a cabinet.The drawings

[0086] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. The drawings illustrate embodiment of the invention and elements of different drawings can be combined within the scope of the invention:Fig. la illustrates a line diagram of a two-phase electric distribution system according to the present invention,Fig lb illustrates an implementation of a transition busbar in a three phase distribution system according to an embodiment of the invention,Fig. 2a illustrates an electric assembly according to an embodiment of the invention,Fig. 2b illustrated an implementation of a connection in the assembly of fig. 2a according to an embodiment of the invention, Fig. 3 and 4 illustrates transition busbars according to embodiments of the invention, andFig. 5 illustrates a flow diagram of designing and manufacturing a transition busbar.Detailed description

[0087] The present invention is described in view of exemplary embodiments only intended to illustrate the principles and implementation of the present invention. The skilled person will be able to provide several embodiments within the scope of the claims.

[0088] The current distribution in a conductor is sensitive to the change of magnetic fields (sometimes simply referred to as magnetic fields). For a single, long conductor subject to direct current (DC), the current is evenly distributed in the cross-sectional area of the conductor. This is true if the conductor is sufficiently long compared to its width so that if current enters the conductor in one side, it can spread and utilize the entire cross-sectional area of the conductor. If the single conductor is subject to alternate current (AC), the current is not evenly distributed in the cross-sectional area of the conductor. The outer area of the conductor has a higher current density, compared to the inner area of the conductor. This effect is referred to as “skin effect” and occurs independent of neighbouring conductors. The skin effect occurs due to the change of magnetic field generated by the flow of current in the conductor itself.

[0089] With two conductors conducting current, the magnetic field generated by the second conductor influence the distribution of current in the cross-sectional area of the first conductor. With opposing direction of currents, the current in each conductor tend to be concentrated closest to the other conductor. With equal current direction, the current in each conductor tend to be concentrated furthest away from the other conductor i.e. the current is “pushed” to the side of the conductor away from the other conductor. This effect is referred to as the “proximity effect” and is initiated by a neighbouring conductor.

[0090] In essence, current is “pushed” towards areas with the (change of) magnetic field is low or zero. Hence, if one can cancel out all net magnetic fields, there is no proximity effect or skin effects in the conductors.

[0091] In an electric circuit, the sum of currents is zero. This is true for a single-phase AC circuit connected to phase and neutral or phase to phase, for a DC circuit connectedbetween a positive pole and a negative pole, for symmetrical three phased AC systems, for 3 phase systems including neutral, for 6 phase systems including neutral, etc. For 3 phase systems including neutral, the sum of currents must include the currents in the three phases + current in neutral to be zero.

[0092] In such an electric circuit (e.g. a 3 phased system) the sum of currents are zero, and the sum of magnetic fields around each conductor is also zero, but the net field around each conductor is not zero. As an example, assume a 3 phased system with phases A, B, C. The magnetic fields acting on the conductor of phase A is the sum of the magnetic field generated by phase A, but also phase B and C. A practical layout of the three phases, can e.g. be in a row with equal distance between the phases as A-B-C. Due to the distances between the phases, the magnetic field generated by A acts much stronger on A, compared to B acting on A. The magnetic field from C has the least relative impact on A (relative due to the distance to A, if currents are the same). Hence the net sum of magnetic field at conductor A is not zero because of the distances to the neighbouring conductors.

[0093] If the phases are interleaved, i.e. distributing all current of one phase in more than one main busbar which are distributed in more than one main busbar set so that the pattern is repeated, e.g. A1-B1-C1-A2-B2-C2, there is a better cancelling out of magnetic fields, assuming that the current in A1=A2, B1=B2 and C1=C2. The magnetic field generated by A2 is impacted by the fields from B2 and C2, but as stated above, due to physical distances between the phases, there is not a complete cancellations of fields at A2 due to B2 and C2, but there are also magnetic fields contributing from Cl and Bl which will further reduce the magnetic fields at A2. If this pattern is repeated once more at a third main busbar set as A1-B1-C1-A2-B2-C2- A3-B3-C3 an even better cancelling out of the magnetic fields for the inner conductors (Bl, Cl,..., A3, B3). The more interleaving i.e. the more main busbar sets that are used, the closer one will get to a complete cancelling out of the magnetic fields in the whole assembly. So that at the infinite case the current distribution in each conductor is homogeneous across the whole cross-sectional area. Hence, by increasing the number of interleaved conductors the utilization of the conductor material increased.In this document when referring to interleaving, a reference to the above is made i.e. layout of main busbars for cancelling out magnetic fields.

[0094] The interleaving is according to the present invention established by the transition busbars 15 having a plurality of first ends 15a. The number of first ends are determined by the number of interleaved conductors i.e. by the number of main busbar sets 100.

[0095] This is schematically illustrated in fig. la where two main busbar sets 100a, lOOn are illustrated. The reference number lOOn indicated that in principle any number of main busbar sets 100 can be implanted. The higher number of main busbar sets the better cancelling out of the electromagnetic field as explained above. Often the available space in an electric cabinet is limiting for establishing the interleaving and especially this is limiting for a higher number of main busbar sets 100.

[0096] The distribution system 11 illustrated in fig. la include two phase currents indicated by arrows denoted LI and L2. It should be noted that the direction of current flow may change if the current is an AC current as indicated by the arrows. If the current is a DC current it is obviously constant in opposite directions in the illustrated first and second phase main busbars 14L1, 14L2 of two main busbar sets 100a, lOOn.

[0097] Fig. la further illustrates that the phase main busbars 14L1, 14L2 are electrically connected with an electrical component 29 via a first and a second phase transition busbar 15L1, 15L2. As illustrated the phase main busbars 14L1, 14L2 are interleaved without any of them are crossing each other. This is made possible by the transition busbars 15L1, 15L2.

[0098] Fig. lb illustrates a specific implementation of a transition busbar 15 according to an embodiment of the invention. In this illustration, two main busbar sets 100a, lOOn are illustrated with stipulated lines therebetween indicating that more main busbar sets 100 can be implemented. If more main busbar sets 100 are to be implemented and thereby increasing the number of interleaved main busbars 14 and thereby improving the cancellation of the electromagnetic fields, a transition busbar with a third leg 10 lx (illustrated with stipulated liens) can be a produced. Such three-legged (4, 5, ...n legged) transition busbar 15 is preferably made monolithic so that all ends 15a, 15b are monolithically connected to avoid ohmic and inductive resistance in joints of the transition busbar 15.

[0099] The first main busbar set 100a comprise three phase main busbars 14L1 1, 14L2 1, 14L3 1. Since only one transition busbar 15 namely the first phase transition busbar 15L1 is illustrated, only the first phase main busbar 14L1 1 is connected to one of the first end 15a thereof. The first ends 15a may be denoted according to the main busbar set then are connected to. Hence, as illustrated in fig. lb the first ends are denoted 15L1 1, 15aLl_n, ..., 15aLl_x.

[0100] In the same way, the second main busbar set lOOn comprise three phase main busbars 14Ll_n, 14L2_n, 14L3_n. Again, since only one the first phase transition busbar 15L1 is illustrated, only the first phase main busbar 14Ll_n is connected to one of the first end 15a thereof.

[0101] It is noted that the ends 15a, 15b of the transition busbars 15 may be designed as terminals configured for electrically connecting the transition busbar 15 to other busbars 14 or electrical components 29. In the same way, the of main busbars 14 and electrical components 29 are also designed with terminals configured for establish electric connection to other components. Such connection may be facilitated by holes for bolts or threaded parts for receiving bolts, clamping devices, etc.

[0102] As illustrated, the transition busbar 15 is used to electrically connect two or more busbars (or other types of conductors) with one common point of connection. Hence, the transition busbar acts like a cross field for the individual phases in the distribution system 11. Therefore, the transition busbar 15 of the present invention is advantageous in this feature and in addition that it allows interleaving of the busbars in distribution systems located in cabinets with limited space.

[0103] Fig. 2a illustrates an electric cabinet assembly comprising an electric current distribution system 11. The distribution system 11 is supplied with power by one or more, such as three phases LI, L2, L3, via one or more, such as three or six, supply cables 17. The supply cables 17 are mechanically and electrically connected to anelectric component 29 such as a switchgear 29a or circuit breaker. The switchgear 29a is in this embodiment connected to another electrical component in form of reactors 29b via electrical conductors 1. Hence, via these conductors 1 and the reactors 29b the three phase currents LI, L2, L3 are electrically connected to the main busbars (commonly denoted 14).

[0104] The cabinet 28 is divided into a power conducting section 102 which is the upper most and the lower most parts. These parts are referred to as power conducting sections 102 in that that they are mainly used for conduction of current. Between these two power conducting sections 102, a power handling section 103 is illustrated. The power handling section 103 is named as it is because in this part of the cabinet 28 the current is not only conducted, but also treated such as interrupted (shut on or off), modified in terms of e.g. frequency, etc.

[0105] From the main busbars 14 electrical components 29 are supplied with power via one or more transition busbars 15L1, 15L2, 15L3. Conventionally, transition busbars are made of cobber, are massive or braided conductors. The transition busbars 15 of the present invention are preferably manufactured by additive manufacturing and thus the geometry may be tailor made to the footprint, available space, cooling capacity, current capacity, etc. that is limiting or required from the transition busbars 15.

[0106] In the distribution system 11 of the present invention, the transition busbars 15 are connecting the main busbars 14 with the components 29The transition busbars 15 and / or the main busbars 14 may comprise predefined air gaps 6 thereby allowing the transition busbars 15 and / or the main busbars 14 to reduce weight, be flexible, be optimized for cooling and have auxiliary functions.

[0107] The electrical components 29 are as mentioned typically high-power components such as switch gear 29a, power modules 29cand reactors 29c which are designed for switching and / or conducting more than 1000 A such as up to 4000 A or even more. Power modules 29cmay comprise semiconductor switches such as IGBTs, MOSFETs, etc. and may together form a three-phased invertor or rectifier module. Areactor 29b may also be referred to as a filter, transformer or simply windings around a core.

[0108] As illustrated in fig. 2a, the power modules 29c are connected to and thus supplied from the main busbars 14 via transition busbars 15 as described above. The output from the power modules 29c may be connected to loads / supplies such as the utility grid or Power-to-X systems etc. via cables 17.

[0109] The electrical cabinet 28 enclosing the distribution system 11 may comprise openings and a fan 32 positioned in one of the openings. Hence, by controlling the fan 32, control of a flow of air through the cabinet 28 is possible.

[0110] In addition to the air flow-based cooling of components 29 in the cabinet 28, the distribution system 11 may also comprise or be connected to a liquid cooling system.

[0111] In the distribution system 11 illustrated in fig. 2a the entire current path between the reactors 29b and power modules 29c is interleaved. However, it should be noted that it may only be part of the distribution system 11 in which interleaving is implemented. Further, it should be noted that interleaving may be implemented with 2, 3 or more parallel sets of main busbars 100 at different locations in the distribution system.

[0112] Also, the transition busbars 15 are used to connect main busbars to reactor 29b and to power modules 29c. however, it should be noted that interleaving may still be facilitated only with the transition busbars 15 of the present invention in one end i.e. at the reactor or at the power module. In this case, the main busbars may have to be crossed if not the terminals of either the reactor 29b or the power modules 29c facilitates connection of two main busbars from the same phase to more than one terminal.

[0113] Fig. 2b illustrates a modified implementation of the distribution system 11 schematically illustrated in fig. 2a. More specific fig. 2b illustrates the electric connection of the switchgear 29a. The switchgear 29a is not illustrated in fig. 2b, it isto be connected to the second ends 15b of the illustrated transition busbars 15L1, 15L2, 15L3.

[0114] In fig. 2b, the upper busbars 14 are main busbars supplying the distribution system and therefore it is required that current flowing in these busbars can be interrupted, which is done by the non-illustrated switchgear. The upper transition busbars 15 are connected to the upper main busbars 14. As can be seen, the upper transition busbars 15 also in this embodiment comprise a plurality of first ends 15a and at least one second end 15b connected via legs 101. Thus, the busbars 14 may also on this side of the switchgear be interleaved or supplied from more than one source per phase. If the switchgear has two terminals per phase the transition busbar could have been a 1 end to 1 end type i.e. a conventional cobber cable or busbar.

[0115] In this embodiment, the upper transition busbars 14 are connected to the terminals of the switchgear via the terminal holes 10 through which bolts can be inserted through the transition busbars 15 (the inlet opening to the terminal holes 10 are not illustrated, the illustrated holes 10 are the outlet openings) and engaging with the threaded part of the terminals of the switchgear.

[0116] The lower set of busbars 14 are interleaved as described above and connected to the switchgear in this embodiment by transition busbars as described elsewhere in this document.

[0117] It should be noted that the illustrated sets (upper and lower) of connections between main busbars and switchgear may only be one of a plurality of such sets. Hence, if the current is high parallel sets may be needed or the distribution system may comprise a plurality of different electrical systems such as a 1500A and a 3000A systems which need to be handled separately e.g. having separate switchgear. The sum of the current in a distribution system may in embodiments be 10.000A or higher.

[0118] The interleaving illustrated in fig. 2b, could be referred to as a two- dimensional interleaving i.e. extending in the Z direction and in the X direction. If space allows it is possible to make a three-dimensional interleaving of the main busbars. The three-dimensional interleaving is implemented by positioning one ormore main busbar sets above the two illustrated busbars i.e. in the Y direction. In this way the cancelling of magnetic field is increased. A three-dimensional interleaving would require an even more specifically adapted transition busbar than the one illustrated, however it would be possible to manufacture such transition busbar e.g. by additive manufacturing.

[0119] It is noted, that on fig. 2b two different transition busbar designs are illustrated. Various designs are available including those illustrate din fig. 3 and 4.

[0120] Fig. 3 illustrates a transition busbar which in this embodiment is referred to as a first phase transition busbar 15L1 according to an embodiment of the invention. The illustrated embodiment, comprise two first ends 15aLl_l, 15aLl_2 at the end of legs 101a, 101b respectively and one second end 15b.

[0121] Each of the ends 15a, 15b comprise terminal holes 10. The terminal holes 10 in the second end 15b are traveling through the main body 15c of the transition busbar. Hence four terminal holes are provided, starting 10a in the main body 15c and ending 10b in the second end 15b. Hence, the electric component 29 (indicated with stipulated lines) is in this embodiment connected to the transition busbar 15L1 through the terminal holes going through the body of the terminal busbar 15c.

[0122] The terminals holes 10 in the first legs 15a are electrically connected to first phase main busbars 14L1 1, 14L1 2 illustrated with stipulated lines. Accordingly, this transition busbar could be referred to as first phase transition busbar 15L1.

[0123] As indicated above, it should be noted, that the legs 101 and / or ends 15a, 15b may be produced with internal cooling channels for conducting a cooling fluid such as air or liquid. Especially if the fluid is water, then a cooling system would be required with a cooling loop including a heat exchanger. The internal cooling channel may be going through one of the first ends 15a and out of another of the first ends 15a. The internal cooling channel may also simply be a used to reduce material and thereby reduce weight of the transition busbar 15 or to guide current to follow a certain current flow path through the transition busbar 15.

[0124] The legs 101 may be defined as the part of the transition busbar that is parallel to the busbar or terminal to which the transition busbar is to be connected. In fig. 3a the legs 101a, 101b are defined as the part of the transition busbar that is below the dotted lines (upper part of main busbars 14). Sometimes an end and a leg will have the same length and could therefore be referred to by both reference numbers 15 and 101. One example is the first leg 101a and first end 15aLl_2 connected to first phase main busbar 14L1 2. Sometimes an end and a leg will have different lengths. One example is the second leg 101b and the first end 15aLl_l connected to the first phase main busbar 14L1 1.

[0125] As mentioned above, the part of the transition busbar 15 between the first / second ends / legs may be referred to as a main body 15c. On fig. 3 the main body is the part of the transition busbar 15 between the dotted lines.

[0126] Also, as mentioned above, the transition busbar may comprise terminal holes 10 that are going through the main body 15c. In the embodiment illustrated in fig. 3, the length of the terminal holes 10 of the first ends 15a connecting the first ends 15a to the main busbars 14 are the same thickness (Z direction) of the first ends 15a.

[0127] The length of the terminal holes (Z direction) connecting the second end 15b to the electric component 29 are longer than the radius R of the circular second end 15b i.e. than the width and length (X and Y directions) of the second end 15b if the transition busbar had a square ends like the upper transition busbars illustrated in fig. 2b. The length of the terminal hole in the transition busbar illustrated in fig. 3 is measured from the lower point LP of the opening 10a through the main body 15c and to the opening 10b in the second end 15b.

[0128] It should be noted that the different designs of the transition busbar 15 described above, should not be limiting for the designs or geometries or structures that is possible to manufacture according to the present invention. Other designs that are possible to represent digitally and transfer to an additive manufacturing device (or extruding device) and thus manufacture by additive manufacturing (or extruding) is considered to fall with the scope of the present invention. This includes designs havingplane surfaces with internal ducts, manufactured by different materials, manufactures with protrusions or recesses, manufactured to have auxiliary functions beside conducting current, etc. Particularly, high-power conductors are advantageous to manufacture according to the present invention.

[0129] The cross-sectional area of a transition busbar according to the present invention can be exploited to its full potential. The conductor is designed and manufacture to have a cross-sectional area that is able to comply with requirements to current to be conducted without have excess of material used. The design of the present conductor may not have surplus material which is not used for conducting current when nominal current is supplied e.g. to a 1400A power module. If extra material is used, this is used for cooling the conductor or a safety margin. The amount of such extra material can be determined relatively precise by the software which is used to design the conductor. As a rule of thumb, the larger surface for cooling, the higher amps is possible to conduct. The design software may be able to put weight on amps, cooling properties (cooling medium, surface, etc.), frequency of the current when designing the geometry of the conductor, etc. when designing the conductor. Accordingly, a conducting cross-sectional area of a conductor having a weblike design may be 80mm2 may in certain embodiments be sufficient to conduct a current of 1300A due to the airy design allowing a very advantageous cooling. In fact, tests have shown that the temperature of a conventional massive busbar with a conducting cross- sectional area of 516mm2 conducting 1300A increases to a temperature where neighboring components of plastic is in risk of melting.

[0130] Hence, it should be noted that the conductor may be designed and subsequently manufactured so that a percentage of the cross-sectional area of the electrical conductor e.g., above 80% such as between 90% and 100% is used to conduct current during normal operation. This is in contrary to known massive busbars that does not exploit the material in its center to conductor current. This is at least true for most frequencies of currents conducted in high-power systems including renewable systems, vehicles and the like.

[0131] The high percentage of utilization of cross-sectional area for conducting current compared to known massive conductors is possible to obtain in that the conductor of the present invention and thus the individual conductor branches because they are designed with a cross-sectional area that sums up to be able to conduct a current of a given frequency. Further, the material reduction is also made possible because of the possibility of cooling also inside the conductor. In fact, a conductor branch may along most of its length, in some embodiments along all of its length, be cooled from all angles i.e. a 360° cooling of the conductor branches is possible.

[0132] The term monolithic is in this description used to describe the geometry or structure of an electrical conductor (transition busbar / main busbar) according to the present invention. Such conductor is preferably manufactured by an additive manufacturing process and thereby, it is manufactured as a single piece, unit or block from one end to the other or at least one end and a middle segment is manufacture as a single piece. Such conductor may thus be formed from a single material as a single piece, unit or block where its one or more ends are monolithically formed with a middle segment connecting the one or more ends i.e. monolithically formed should be understood as made in one continuous process with no need for additionally adding one part to another I.e. one or more ends are manufactured together with the middle segment as one unit with no connections such as welding, soldering, or by any clamping or fastening means, except for the type of micro binding intrinsic to the particular additive manufacturing technology utilized, such as, e.g., layer-by-layer melting, sintering, liquid binding, spraying, etc. With this said, it should be mentioned, that it is possible to add additional elements such as terminals, cooling fins, etc in a post manufacturing process e.g., by a cold spray process.

[0133] Put in another way a conductor of the present invention is the result of a process forming the conductor in one structure, a conductor composed of an electrically conductive material without joints or seams and thus constituting a conductor as a rigid whole exhibiting a rigidly fixed uniformity. To such conductor it is possible to connect additional conductors via terminals and thereby branch off one current path to two or more current paths or vice versa.

[0134] It should be mentioned that the conductor may be manufactured from more than one type of material. In this situation, the conductor could be said to be polylithic. The term polylithic should in this context be understood as a geometry or structure of an electrical conductor that is manufactured in one piece as a monolithic structure, as described above, where the conductor is manufactured from two or more materials. Hence, a polylithic conductor of the present invention is a conductor resulting from a process forming the conductor in one structure where the process is using two or more different materials. Such two or more materials may be a combination of electrical conductive or non-conductive materials.

[0135] In most embodiments, the electrical conductor 1 is designed to comply with high voltages i.e. voltages above 24V such as 110V, 230V, 400V, 690V, 1000V, 1500V and up to kV systems, just to mention a few voltage levels of an electrical installation in which the electrical conductor 1 of the present invention would be suitable. In terms of current, an electrical conductor 1 according to the present invention may be designed to conduct several hundreds of amps (16, 32, 64, and so on up to 100, 200 and so on up to e.g. 900A) up to a couple of thousand amps (1000A- 3000A). Electrical conductors may be designed to conduct higher currents than 3000A such as up to 10000A e.g. by improving cooling of the conductor in combination with an increased cross-sectional area of the conducting part of the conductor.

[0136] The present invention is particularly advantageous for electrical busbars designed for high-power electrical systems, e.g. from lOkW and up, such as 22kW, 50kW, HOkW, 150kW, 225kW, 300kW, 350kW, 500kW, 800kW, 1MW, 2MW, 3 MW, or even higher, such as e.g. 5MW or 10MW systems, with voltages of e.g. 110V, 230V, 400V, 690V, 800V, 1000V, 1500V, 6kV or e.g. lOkV, and currents from e.g. 16A, 32A or 64A, to several hundreds, e.g. 100A, 200A or 500A, or even thousands, e.g. 1000A to 4000A. A system, component or conductor may be categorized as a high-power system, component or conductor if it is operating at currents in the range of 800- 1000 A or higher.

[0137] Non-limiting examples of such electrical installations / systems include energy facilities such as grid components such as substations with grid support, voltageregulation, power to x plants, etc., energy generating systems such as wind turbines, wind farms, solar plants, etc., electric installations in a private homes and industry, industrial machines, household appliances, etc. and means for transportation such as airplanes, heavy duty vehicles, light duty vehicles such as automobiles, trains, ships, etc.

[0138] The transition or main busbar may be equipped with non-conducting portions. An example of a portion of a conductor that is primarily used for non-conducting purposes such as heat dissipation or air guidance, is an outgrowth from the surface of the conductor which is not connected at the distal end of where it is growing from the surface of the conductor. Such outgrowth or protrusion may for heat dissipation purposes preferably comprise some kind of bionic design with airgaps between branches, possibly with a continuous surface towards a direction of air flow for air guidance purposes. Such portions would be referred to as conductor branches if these were part of the middle segment conducting current form one end to the other. Such outgrowth may in principle take any form or geometry exploiting the free space around the area as long as safety clearance distances are maintained. In such examples, the fraction of current conducted by the surface area of the outgrowing conductor portion is very small if not zero.

[0139] An example of a portion of a conductor that is only used for conducting a current may in principle not be possible in that heat dissipates even from a solid block and a planar surface. What should be understood by a portion of a conductor primarily used for conducting current, is a varying structure or geometry for a middle segment of the conductor between the first and second terminals. When space is narrowed between components in an electrical system, if other conductors are to be passed, if the conductor has to pass through a current sensor or bushing, etc., the surface area of that particular portion of a conductor middle segment may be reduced to comply with available space, thereby typically increasing the conductor density to achieve a narrower outer dimension. In this example, at this particular portion of the conductor, the current conducting portion of the surface area of the conductor becomes high; possibly so high that a hot spot is created where additional cooling is required tocontinue to maintain a certain current conduction capacity. Hence, this is an example which may benefit from a combination of the conducting portion with an outgrowth portion, as described above, e.g. on each side of the narrowed part of the conductor. In this way, heat generated at the narrow space can be dissipated via the nearby outgrowths, e.g. further in combination with internal cooling channels.

[0140] As mentioned, the transition busbar or main busbar (also sometimes referred to as an electrical conductor) may have more than one first end 15a or more than one second end 15b. Hence, one end of an electrical conductor may branch off in e.g. three terminals each with a terminal hole. This may be advantageous in that the geometry of the electrical conductor is then designed specifically to the component to which it is to be connected. Branching off the ends into several terminals may also improve heat dissipation capacity at the possibly denser terminal portions, improve electrical connection between the conductor and components, and avoid additional connection pieces or shunts in order to connect adjacent components to a common conductor.

[0141] The transition busbar body 15c may comprise one or a plurality of conductor branches. The conductor branches, like the end segments 15a, 15b are at least partly made of an electric conductive material such as copper or aluminium or alloys thereof, enabling the electrical conductor to conduct a current between its end segments. The design of the conductor branch(es) may be optimized according to a specific purpose such as cooling, material consumption, flexibility (control in a particular direction), footprint, etc. Thus, depending on which parameter(s) the electrical conductor is designed according to, the conductor branches may be designed as longitudinal cylinders (or other geometries such as oval, square, etc.), web, bionic, gyroid-like design, lattice-like design, branch-like design, or sponge-like design, coil or solenoidal designs, spirals, etc.

[0142] Thus, the electrical conductor may have a perforated surface, a non-perf orated surface, a massive structure or a structure with internal channels optimizing the electrical conductor according to skin-effect and cooling, etc.

[0143] Two or more conductor branches may meet in an intersection point and two or more conductor branches may branch off from an intersection point. This has the effect, that an electrical conductor is established that maintain a desired strength (determined yield point) with a minimum of material. Among others, this may reduce the cost of the electrically conductive material and reduce the weight of the conductor. It should be mentioned that two conductor branches meeting in the intersection point may be the same two conductor branches leaving that intersection point. Alternatively, two other conductor branches may leave the intersection point, however this may be a question of definition of a conductor branch. Further one conductor branch may branch off to a plurality of conductor branches and a plurality of conductor branches may meet and form a lower number of conductor branches.

[0144] The conductor branches may be encapsulated in an outer shell. Both the outer shell and conductor branches inside the outer shell may be used to conduct current. In this embodiment, the conductor branches may also be used as a support structure for the outer shell i.e. both supporting the outer shell and conducting current.

[0145] As mentioned, the ends 15a, 15b and the body 15c is preferably monolithically formed, since they are manufacturing from a single bulk of material, which is machined to provide the electrical conductor 1. Here bulk of material should be understood as the material such as electrically conductive material of which the electrical conductor is made, e.g. a solid, powder, liquid, wire, etc. Here machined should be understood as manufactured by additive manufacturing, i.e. the electrical conductor is made in one piece without any mechanical connections of the first end 15a, second end 15b and body 15c.

[0146] It should be noted that the electrical conductor may have a non-uniform geometry / design. The design / geometry may take any machinable / printable shape. Such shape may be optimized according to conducting current (skin effect), cooling, guidance of flow of cooling fluid, other components in a panel, resistance, power loss or current displacements, etc.

[0147] As mentioned, the legs 101 of the transition busbar may have a different geometry to ensure correct current sharing between the legs. This may be necessary if a plurality of main busbar sets 100 are positions next to each other, in this situation, the length of one leg may be so long compared to another leg that current prefer flowing in the shorter leg. To compensate for this, the geometry may be changed of one or more of these legs so that the resistance and / or inductance in shorter leg will be increased to ensure substantially the same current to flow in the two (or more) legs. The current sharing may alternatively be implemented by providing a leg with a nondirect current path i.e. a conductor branch that is varying in geometry or is partly wounding. Hence it may be necessary to have transition busbars with different geometry of its legs to ensure equal resistance and / or impedance in the legs. The manufacturing of the electrical conductor 1 may as mentioned be done by an additive manufacturing process. Such manufacturing process may be based on, but not limited to, one of the following additive manufacturing processes: 3D printing, layer by layer printing, Wire Arc Additive Manufacturing, Fused Deposition Modeling FDM, Direct Energy Deposition, Direct Metal Deposition, sintering based processes, laser based processes, for example Powder Bed Fusion PBF, such as selective laser melting SLM or selective laser sintering SLS, cold spray additive manufacturing CSAM, binder jetting or binder jet 3D printing, etc. It should be mentioned that the actual additive manufacturing process used to print or build the electrical conductor 1 may not be important as long as the material of which the electrical conductor is built is an electrically conductive material.

[0148] The transition busbar illustrated in fig. 4 is an alternative design to the one illustrated in fig. 3. The first ends 15a connected to the main busbars 14 is identical to the first ends 15a on the transition busbar of fig. 3. The second end 15b is however connecting to a transition piece 104.

[0149] The transition piece 104 is advantageous in that it facilitates an alternative connection and mounting to e.g. an electrical component 29. Such alternative connection may e.g. facilitate connecting the transition piece 104 to the component 29 and then afterwards connect the transition busbar to the transition piece.

[0150] In this embodiment one second end 15b is designed with two legs 100b. These two legs are then mounted to the same transition piece 104 which again is mounted to a terminal of the component (which is not illustrated in fig. 4.) via the terminal holes 10 in the transition piece 104.

[0151] Fig. 5 illustrates method steps for machining an electrical conductor such as a transition busbar or a main busbar according to an embodiment of the invention. The particular method relates to forming an electrical conductor with two ends or two terminals, namely a first end / terminal 15a and a second end / terminal 15b via a middle segment also referred to as a body 15c, but may be used for producing any kind of electrical conductor of the present invention.

[0152] It should be mentioned that this may include manufacturing both ends and the middle segment in one process. Hence, with additive manufacturing along the longitudinal direction of the conductor, the method may start by manufacturing, such as printing, one end, then a transition to the middle segment, possibly one or more conductor branches, then the middle segment, then a transition to the second end and finally the second end. In another embodiment, the additive manufacturing occurs transversal to the conductor’s longitudinal direction, thereby for example manufacturing portions of both ends and the middle segment simultaneously, increasing the cross section with each applied layer. In another embodiment, the additive manufacturing is radial, or even arbitrary, to the conductor’s longitudinal direction, for example using cold spraying CSAM or Fused Deposition Modeling FDM while rotating or freely moving either the conductor unit being built or the nozzle, or both. Preferably, the mentioned segments are manufactured in one process, e.g. as one segment is manufactured, the next segment is being manufactured. A transition part may be made between such two segments which may start or include the first segment. Similarly, the second segment may include a transition part or is connected to such transition part.

[0153] It should also be mentioned that the method could in some embodiments comprise manufacturing the middle segment and afterwards connect the end segments. The end segments could be connected while being additive manufactured or could beconnected with an additive manufacturing thermal paste or glue after being made. The end segments could also be welded, glued or connected in any other way to the middle segment, e.g. by cold spraying CSAM.

[0154] A transition may straightforwardly be defined as a change of size of a layer compared to a previous layer. In this way a transition may be formed as a perpendicular transition between an end segment and a conductor branch of the middle segment. Alternative, subsequent layers may change in cross-sectional area and thus form a transition as a rounded transition which may be advantageous in terms of a reduced resistance for current conducted between the ends of the electrical conductor.

[0155] A monolithic conductor according to the present invention is made from one material. One or more additional materials may be used e.g. as isolation, for heat dissipation, etc. in this case the conductor may be referred to as a polylithic conductor. No matter the number of materials, a conductor produced by additive manufacturing is produced bit-by-bit starting at a first spatial coordinate (x, y, z) and ending at a second spatial coordinate. At least when the conductor is finished the first and second spatial coordinates are electrically / mechanically connected. As mentioned several methods of manufacturing a conductor exists all including some kind of material depositing, joining or soldering to manufacture a conductor in one monolithic form.

[0156] In this document a conductor may be referred to as being manufactured layer- by-layer no matter the additive manufacturing method used. Hence, if a conductor is sliced (no matter in which orientation) and one is looking at the cross-section of the conductor it is easy to imagen that the conductor is manufactured starting with material in first point, then with material in a second point and so on. Since the conductor is volumetric i.e. has a three dimensional geometry the first point is different from the second and subsequent points at least in one of the spatial X, Y and Z directions / plans. Thus, with reference to the spatial X, Y and Z planes a conductor could be said to be built from a plurality of subsequent layers even though when manufactured all material in one plane such as X=1 and Y=0 and Z=0 is not provided as a one layer or in one layer before material in a next layer (e.g. an X=2 layer) is provided.

[0157] Hence, no matter which of the processes of manufacturing a three- dimensional object such as a conductor that is used, it can be said that the conductor is manufactured layer-by-layer even though some of these manufacturing processes are based on deposited, joined or solidified with material being added together in areas, lines, pointwise, etc. This is because no matter the additive manufacturing process the conductor is manufactured one point after the other. A plurality of points in the same plan (e.g. X=3) is considered one layer also if they are not physically connected in this plane. And when all points of this layer are added, points of the next layer (e.g. X=4) is added to the points in the X=3 layer. As mentioned, a layer may be defined in any of the planes of a spatial Cartesian coordinate system.

[0158] In a step SI of this particular method, considering additively manufacturing a conductor in its longitudinal direction from the first end towards the second end, the first end segment and middle segment in the form of conductor branches of a plurality of conductor branches are monolithically formed via individual transitions that may or may not include rounded connections to shape concavely rounded interior corners between the first end segment and conductor branches of the plurality of conductor branches and to spatially separate conductor branches of said plurality of conductor branches.

[0159] The step of monolithically forming the first end segment and conductor branches may be implemented using various methods, for example methods such as additive manufacturing such as 3D printing, casting, and simply removing of material, via machining, from a bulk metal slab to form conductor branches combined with a first end segment.

[0160] More specific, a known massive conductor such as a main busbar with a length of e.g. 3-5m may conduct 1-2A per mm2. If the same busbar was made in an airy design and e.g. with an internal cooling, then due to the improved cooling the same 1-2 A per mm2 may be conducted with the same efficiency despite the removal of material. Typical conductor materials such as aluminium and copper have temperature coefficients at approximately 0.4% / deg C. If such conductor is efficiently cooled so that the temperature is e.g. 25 deg C lower compared to a conventionalconductor, the resistance is reduced by approximately 10%. Hence approximately 10% of the material can be removed without compromising the losses. Furthermore, in AC conductors the current is not evenly distributed across the conductor volume. Typically, the current density is reduced towards the center of the conductor. Taking such considerations into account can allow for further removal of material without compromising the efficiency of the conductor.

[0161] In a step S2 of the method, the first end segment becomes electrically coupled and mechanically coupled to a second end segment via the middle segment of the electrical conductor formed by the plurality of conductor branches. This may also be monolithically achieved, e.g. by continuing the additive manufacturing, as described in step S 1.

[0162] The coupling of the end segments to the middle segment could also be done by welding, gluing, male / female locking mechanism or any other way that would connect the segments both mechanically and electrically.

[0163] An optional, additional step of the method of manufacturing the conductor of the invention comprises a step prior to the step of additive manufacturing any of the first, second or middle segments. The step prior to manufacturing the electrical conductor is a step where a digital representation of the electrical conductor is designed in a software program, e.g. a 3D CAD software. The step of designing the digital representation of electrical conductor in a software program includes taking the electrical, mechanical, structural, geometry and other aspects of the physical electrical conductor into account. Thus, based on these inputs, e.g. provided by a user of the 3D CAD software, a digital representation of the conductor is provided by the 3D CAD software. When the digital representation of the electrical conductor is complete the additive manufacturing process can be started.

[0164] A further optional step may be applied i.e. a heat treatment to the finalized conductor. A heat treatment may e.g. be 4 hours at 400C and upwards depending on the material. An advantage of heat treatment is that the particles of the manufactured conductor is mutual positioning or merging leading to higher conductivity boththermal and electrical. This is at least true for Aheadd® CPI 20 / 63 aluminium powders and other aluminium-iron-zirconium power solutions. Such powders may be used in laser powder bed fusion machineries. Using this type of power and heat treatment may lead to higher thermal stability, thermal conductivity, corrosion performance and surface finishing as well as higher electrical conductivity.

[0165] The middle segment may in principle have any design / geometry, for example providing flexibility thereto allowing the electrical conductor to deform. It may be formed by conductor branches being solid or having internal cavities to reduce the amount of material that is needed to manufacture the electrical conductor. It may be formed by a web or as a hybrid between conductor branches or web just to mention a few possible designs.

[0166] Internal cavities may be used as cooling channels and / or additional surface for conducting high frequency current. Accordingly, the end segments and middle segments may be designed for the particular panel / electric system in which it is used, for a particular type of current to conduct, for having a desired or dual functionality, etc.

[0167] One such functionality, beside the above-mentioned may be as a structural support. Hence, if needed the electrical conductor may be designed to assist in carrying the weight of electric components connected thereto. Hence, its dimensions may be larger than what is needed by it for carrying the required current. Similarly, its geometry may be designed for the combined purpose of mechanical support and electric conductance. This is especially true if such support is flexible / deformable in that it may both assist in supporting and at the same time assist in absorbing vibrations.

[0168] It should be mentioned that the electrical conductor may be manufactured in two or more resolutions. The thicker layer the faster manufacturing. The layer thickness depends on the material and printing apparatus and may vary from a few millimetres to 20um, using some combinations the layer thickness is between 50um and 150um. In case of additive manufacturing resolution may be defined by thickness of the layers of which the electrical conductor is built (another word for machined andprocessed). A first resolution that is finer i.e. having thinner layer size than a second resolution may be used when manufacturing the interface between the electrical conductor and the part to which it is connected. Such interface may be the part of the terminal that is in contact with the other part. Alternatively, resolution may be determined by material deposition rate, material flow rate, etc. depending on the type of additive manufacturing used.

[0169] To avoid electric losses in connections between two electrical conductors it is preferred that the two parts have mating surfaces, which is most simply achieved by having planar surfaces, but may also be achieved by convex and concave combinations, mortise or finger joints, engaging teeth, cylinder and peg, tongue and groove, slide lock, etc., to further achieve additional advantages, e.g. larger surface area of connection, easier assembly of electrical conductors such as busbars in electrical systems by self-locking, etc., as long as good electrical connection is prioritized. The finer these interfaces are manufactured the better / the less post manufacturing processing is needed to ensure sufficiently mating surfaces, such as planar surfaces.

[0170] The second resolution manufactured e.g. with thicker layers would be more rough leading to more surface area. At least for middle and high frequency currents this may lead to conductance of more current without increasing the need for material / dimensions of the conductor. In fact, the middle segment may be manufactured intentionally with a corrugated surface to increase the current-carrying outer surface of the electrical conductor (current-carrying with medium and high frequencies) because of more efficient cooling due to the turbulence of, e.g., cooling air flow created due to the corrugated surface. It should be noted, that if the conductor includes an interior space, the inner surface of the conductors creating such interior space may also be corrugated for the same purpose. A corrugated surface has the effect, apart from offering a larger surface area, that it introduces turbulence in the flow of cooling fluid such as air. Increased speed of cooling fluid may lead to higher cooling effect.

[0171] As an example, the depth into the conductor which is used for conducting current at medium and high frequencies may in a specific embodiment be approximate1.5mm. In this specific example, the conductor is made of copper with a resistivity of approximate 1.68pQ cm, a relative permeability of approximate 1 at a frequency of 2kHz. Thus, a conductor for this particular embodiment may be hollow having conductor thickness of 2 times 1.5mm. In practice such conductor may be manufactured with a thickness of 4-5mm leaving room for a cooling in the interior or simple reduction of conductor material and thereby weight.

[0172] Knowing that skin effect also appears at e.g. 50Hz, a reference to a medium frequency with respect to skin effect is a reference to frequency starting around 500Hz where the design of the conductor may account for the skin effect. The medium frequency range may be between 500Hz and 10kHz, above 10kHz may be referred to as high frequency where skin effect is a fact (the higher frequency, the closer to the surface the current will be conducted).

[0173] Further, it should be mentioned that the outer surface may also be corrugated or designed with fins for increasing heat dissipation from the electrical conductor.

[0174] Summing up, a designer is designing a digital representation of the conductor according to electrical, mechanical, structural, etc. requirements in e.g. a 3D CAD software such as Solidworks. Files (digital representation) from such 3D developing tool is exported to e.g. a 3D printer, where the conductor is printed according to the CAD files.

[0175] In an embodiment, the side of the transition busbar or main busbar is not planer or flat. Instead, a concave geometry such as a concave geometry may be implanted to guide a flow or air e.g. into the interior of the busbar. This is especially advantageous if the busbar comprises an interior cooling channel or an airy design with air gaps. Alternatively, the side part may have a convex geometry which may add material and volume of the busbar but may be even better for guiding an air flow into the interior of the busbar.

[0176] In an embodiment the transition busbar 15 which may be connected to the component 29 in the second end 15b and to a main busbar 14 in the first end 15a. In the body / middle segment 15c of the transition busbar 15 an internal channel may beprovided. The internal channel may be connected to a heat exchanger via a cooling loop (also referred to a temperature regulation loop). Together, the internal channel, cooling loop and heat exchanger may be referred to as a cooling system (also referred to as a temperature regulation system). Such system may include dedicated controllers, valves, sensors, etc. that is needed for such system to work as desired.

[0177] The component 29 may e.g. be a reactor, a power module comprising semiconductor switches, a transformer, contactor, filter, etc. With this said heat is generated to some extent in almost every electrical component in distribution system 11 including the busbars. Thus, having internal cooling substituting known air cooling of the surface of a busbar lead to a better temperature regulation of the distribution system 11.

[0178] As an example, connections of two busbars, busbars and components, cables and busbars, etc. may lead to hot spots due to resistance in the connections. Accordingly, if possible, also the ends 15a, 15b of the transition busbar 15 is provided with internal cooling channels, in this case, as close where heat is generated, the cooling is provided. In this way it is ensured to remove heat as close to the source as possible to avoid a general temperature increase of the system 11.

[0179] The internal channel is preferably formed during manufacturing of the conductor. Hence, the channel is formed when the conductor is manufactured e.g. layer by layer by leaving out part of a layer. In this way, a cavity forming the channel may be established. It should be noted that the channel may extend through the transition between middle segment and ends and thus begin and / or end at one of these ends.

[0180] As mentioned at least the body / middle segment 15c of the busbar 15 may comprise a heat sink e.g .formed as an air penetrating heat sink.

[0181] An air penetrating heat sink should be understood as a structure of the current conducting middle segment that allows a flow of air to travel through while current is conducted through this structure. Hence, an air penetrating structure comprises a plurality of air gaps that may be uniform as in a web structure or different as in a bionic design.

[0182] In addition to the cooling system mentioned above, the transition busbar 15 may also be provided with air guide. The air guide is typically a protrusion. The air guide may also be a recess or a combination.

[0183] From the above it is clear that the invention relates to An electric current distribution system (11) comprises:- one or more current input terminals (13),- one or more main busbars (14), wherein said one or more main busbars (14) are divided in a plurality of main busbar sets (lOOa-lOOn), wherein each of said plurality of main busbar sets (lOOa-lOOn) comprise one first phase main busbar (14L1) configured for conducting current of a first phase (LI) and one second phase main busbar (14L2) configured for conducting current of a second phase (L2),- a plurality of transition busbar (15), wherein said plurality of transition busbars (15) comprise a plurality of first ends (15a) and at least one second end (15b), wherein said plurality of first ends (15a) of a first phase transition busbar (15L1) of said plurality of transition busbars (15) are configured for being connected to said one first phase main busbars (14L1) of said plurality of main busbar sets (lOOa-lOOn), wherein said at least one second end (15b) of said first phase transition busbar (15L1) is configured for being electrically connected to an electric component (29), and wherein said plurality of transition busbars (15) further comprise a second phase transition busbar (15L2) wherein said plurality of first ends (15a) of said second phase transition busbar (15L2) of said plurality of transition busbars (15) are configured for being connected to said one second phase main busbars (14L2) of said plurality of main busbar sets (lOOa-lOOn), and wherein said at least one second end (15b) of said second phase transition busbar (15L2) is configured for being electrically connected to said electric component (29), and- one or more current output terminals (12),wherein at least one of said one or more main busbars (14) or at least one of said plurality of transition busbars (15) are manufactured by an additive manufacturing process.

[0184] From the above it is now clear that the invention relates to an electric distribution system comprising a transition busbar which may be manufactured by an additive manufacturing process. This transition busbar may have different geometries with different properties. The design of the transition busbar with the plurality of first ends 15a an at least one second end 15b enables interleaving of main busbars and thereby cancelling out magnetic fields around these main busbars.

[0185] The invention has been exemplified above with the purpose of illustration rather than limitation with reference to specific embodiments. Details of specific embodiment have been provided in order to understand the aim of the invention. Please note, that detailed descriptions of well-known systems, devices, circuits, and methods have been omitted so as to not obscure the description of the invention with unnecessary details.List10. Terminal hole11. Electrical current distribution system14. Main busbar15. Transition busbar a. First end of transition busbar b. Second end of transition busbar c. Body part of transition busbar / middle segment17. Supply cable21. Ventilation opening28. Electric cabinet29. Electrical component a. Switchgear b. Reactor c. Power module32. Fan100. Main busbar set101. Legs of the transition busbar a first leg b. second leg102. power conduction section103. power handling section104. transition pieceLI. First phaseL2. Second phaseL3. Third phase

Claims

Patent claims1. An electric current distribution system (11) comprising: a plurality of main busbars (14) and a plurality of transition busbars (15), wherein said plurality of main busbars (14) are divided in a plurality of main busbar sets (lOOa-lOOn), wherein each of said plurality of main busbar sets (lOOa-lOOn) comprise one first phase main busbar (14L1) configured for conducting current of a first phase (LI) and one second phase main busbar (14L2) configured for conducting current of a second phase (L2), wherein said plurality of transition busbars (15) comprise a plurality of first ends (15a) and at least one second end (15b), wherein said plurality of first ends (15a) of a first phase transition busbar (15L1) of said plurality of transition busbars (15) are configured for being connected to said one first phase main busbars (14L1) of said plurality of main busbar sets (lOOa-lOOn), wherein said at least one second end (15b) of said first phase transition busbar (15L1) is configured for being electrically connected to an electric component (29), and wherein said plurality of transition busbars (15) further comprise a second phase transition busbar (15L2) wherein said plurality of first ends (15a) of said second phase transition busbar (15L2) of said plurality of transition busbars (15) are configured for being connected to said one second phase main busbars (14L2) of said plurality of main busbar sets (lOOa-lOOn), and wherein said at least one second end (15b) of said second phase transition busbar (15L2) is configured for being electrically connected to said electric component (29).

2. An electric current distribution system (11) according to claim 1, wherein said first phase current (LI) is a DC minus and said second phase current (L2) is a DC plus.

3. An electric current distribution system (11) according to any of claims 1 and 2, wherein a plurality of said first phase main busbars (14L1) and a plurality of saidsecond phase main busbars (14L2) are stacked with an insulating material therebetween.

4. An electric current distribution system (11) according to any of the preceding claims, wherein said second phase current (L2) is a neutral.

5. An electric current distribution system (11) according to any of the preceding claims, wherein each of said plurality of main busbar sets (lOOa-lOOn) further comprise one third phase main busbar (14L3) configured for conducting current of a third phase (L3).

6. An electric current distribution system (11) according to claim 5, wherein said plurality of transition busbars (15) further comprise a third phase transition busbar (15L3) wherein said plurality of first ends (15a) of said third phase transition busbar (15L3) of said plurality of transition busbars (15) are configured for being electrically connected to said one third phase main busbars (14L3) of said plurality of main busbar sets (lOOa-lOOn), and wherein said at least one second end (15b) of said third phase transition busbar (15L3) is configured for being electrically connected to said electric component (29).

7. An electric current distribution system (11) according to any of the preceding claims, wherein said electric current distribution system (11) comprise input terminals and output terminals.

8. An electric current distribution system (11) according to any of the preceding claims, wherein said at least one second end (15b) of said first phase transition busbar (15L1) is configured for being connected to a first phase terminal of said electric component (29).

9. An electric current distribution system (11) according to any of the preceding claims, wherein said transition busbar (15) comprise a first leg (101a) electrically connecting a first of said plurality of first ends (15a) with said at least one second end (15b) and a second leg (101b) electrically connecting a second of said plurality of first ends (15a) with said at least one second end (15b).

10. An electric current distribution system (11) according to any of the preceding claims, wherein said transition busbar (15) comprise two first ends (15a) and one second end (15b).

11. An electric current distribution system (11) according to any of the preceding claims, wherein said plurality of first ends (15a) are monolithically joint.

12. An electric current distribution system (11) according to any of the preceding claims, wherein said plurality of first ends (15a) are monolithically joint with said at least one second end (15b).

13. An electric current distribution system (11) according to any of the preceding claims, wherein said transition busbar (15) a current balancing busbar.

14. An electric current distribution system (11) according to claim 13, wherein said current balancing busbar comprise a first leg (101a) electrically connecting a first of said plurality of first ends (15a) with said at least one second end (15b) and a second leg (101b) electrically connecting a second of said plurality of first ends (15a) with said at least one second end (15b), wherein the dimensions of said first leg (101a) are different from the dimensions of said second leg (101b).

15. An electric current distribution system (11) according to any of the preceding claims, wherein at least one of said transition busbars (15) or at least one of said main busbars (14) are manufactured by an additive manufacturing process.

16. An electric current distribution system (11) according to any of the preceding claims, wherein a cross-sectional part of at least one of said one or more main busbars or one of said plurality of transition busbars comprising a through-hole and wherein said cross-sectional part of said at least one of said one or more main busbars or one of said plurality of transition busbars is increased.

17. An electric current distribution system (11) according to any of the preceding claims, wherein said transition busbar (15) and / or said main busbar (14) comprise an internal structure at least partly enclosed in an outer enclosure.

18. An electric current distribution system (11) according to any of the preceding claims, wherein said electric distribution system (11) is comprised by an electric cabinet (28).

19. An electric current distribution system (11) according to any of the preceding claims, wherein at least one of said plurality of main busbars (14) or one of said plurality of transition busbars (15) is manufactured at least partly with a concave geometry in the surface of a middle segment (15c) or in one of a first end (15a) and a second end (15b) of said at least one of said plurality of main busbars (14) or one of said plurality of transition busbars (15).

20. An electric current distribution system (11) according to any of the preceding claims, wherein at least one of said plurality of main busbars (14) or one of said plurality of transition busbars (15) are manufactured with an airy geometry.

21. An electric current distribution system (11) according to any of the preceding claims, wherein at least a middle segment (15c) of at least one of said plurality of main busbars (14) or one of said plurality of transition busbars (15) comprises at least one internal channel.

22. An electric current distribution system (11) according to any claim 21, wherein said at least one internal channel is included in a cooling loop and configured to guide a cooling fluid circulated in said cooling loop through the interior of said at least one of said main busbar (14) or said transition busbar (15) via said at least one internal channel.

23. An electric current distribution system (11) according to any of the preceding claims, wherein at least one of said plurality of main busbars (14) or one of said plurality of transition busbars (15) comprises at least one air guide.

24. An electric current distribution system (11) according to any of the preceding claims, wherein at least one of said plurality of main busbars (14) or one of said plurality of transition busbar (15) comprises at least one integrated heat sink.

25. An electric cabinet assembly, said electrical cabinet assembly comprising: an electric cabinet (28), a power conduction section (102) comprising a plurality of main busbars (14), a power handling section (103) comprising one or more electrical components (29), and a plurality of transition busbars (15) wherein at least part of said plurality of electrical components (29) of said power handling section is connected to one of said plurality of main busbar (14) via one of said plurality of transition busbars (15), the electric cabinet assembly is characterised in that at least one of said plurality of translation busbars (15) comprise a plurality of first ends (15a) monolithically joint with at least one second end (15b).

26. An. electric cabinet assembly according to claim 25, is manufactured by an additive manufacturing process.

27. An electric cabinet assembly according to any one of the preceding claims 25-26, wherein said transition busbar (15) comprise a higher number of first ends (15a) than second ends (15b).

28. An electric cabinet assembly according to any one of the preceding claims 25-27, wherein an electrical component (29) of said power handling section (103) is supplied from a main busbar set (100) comprising a first, second and third phase main busbars (14L1, 14L2, 14L3) via a transition busbar (15)29. An electric cabinet assembly according to any one of the preceding claims 25-28, wherein at least one of said plurality of transition busbar (15) is having a non-uniform geometry.

30. An electric cabinet assembly according to any one of the preceding claims 25-29, wherein said electrical component (29) of said power handling section (103) is supplying a plurality of main busbar sets (lOOa-lOOn) wherein each of said plurality of main busbar sets (lOOa-lOOn) comprise a first phase main busbar (14L1), a second phase main busbar (14L2) and a third phase main busbar (14L2) via a transition busbar (15) comprising a plurality of first ends (15a) monolithically joint with at least one second end (15b).

31. An electric cabinet assembly according to any one of the preceding claims 25-30, wherein said plurality first ends (15b) are monolithically joint with said at least on second end (15b) via legs (101), wherein said legs (101) are non-identical.

32. An electric cabinet assembly according to any one of the preceding claims 25-31, wherein at least one of a first, second and third phase main busbars (14L1, 14L2, 14L3) of a first main busbar set (100a) is crossing at least one of a first, second and third phase main busbars (14L1, 14L2, 14L3) of a second main busbar set (100b).

33. An electric cabinet assembly according to claim 32, wherein said crossing is made in proximity of terminals of said phase main busbars (14L1, 14L2, 14L3) of said main busbars set (100).

34. An electric cabinet assembly according to any one of the preceding claims 25-30, wherein said interleaving is a two- or three-dimensional interleaving.

35. A transition busbar (15) configured for electrically connecting an electric component (29) with a main busbar (14), wherein said transition busbar (15) comprise a plurality of first ends (15a) and at least one second end (15b), wherein said plurality of first ends (15a) are configured for being connected to a plurality of first phase main busbars (14L1 1, 14Ll_n) of a plurality of main busbar sets (lOOa-lOOn), wherein said at least one second end (15b) is configured for being connected to said electric component (29), wherein said transition busbar (15) comprise a first leg (101a) electrically connecting a first of said plurality of first ends (15a) with said at least one second end (15b) and a second leg (101b) electrically connecting a second of said plurality of first ends (15a) with said at least one second end (15b), and wherein said plurality of first ends (15a) are monolithically connected with said at least one second end (15b).

36. A transition busbar (15) according to claim 35, wherein said transition busbar (15) comprise terminal holes (10) going through a main body (15c) of the transition busbar (15).

37. A transition busbar (15) according to any one of the preceding claims 35-36, wherein the length in a Z direction of said terminal holes (10) is longer than the length of the width in a X direction and / or longer than the length of the hight in an Y direction.

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