GB2508140A

GB2508140A - Electrical distribution structures using a screened, cooled hybrid cable

Info

Publication number: GB2508140A
Application number: GB201220600A
Authority: GB
Inventors: Martin John Fitzer; Michael Arthur Smart
Original assignee: TECHNE CAST Ltd
Current assignee: TECHNE CAST Ltd
Priority date: 2012-11-16
Filing date: 2012-11-16
Publication date: 2014-05-28
Also published as: WO2014076476A1; GB201220600D0

Abstract

An electrical distribution structure 10 comprises two high voltage busbars 12. At least one data pathway is provided by electrical conductors 14. An inner layer of electrical screening material 16 is located between the busbars 12 and the data pathway 14. The structure is also encapsulated in an outer layer 18 of electrical screening material which may be contiguous with the inner layer 16. The busbars 12 may be cooled by means of a cooling fluid circulated through tubes 24 which are in thermal contact with the busbars. One application envisaged for the structure 10 is for power distribution within an electric vehicle.

Description

lmQrovements in or relatinci to electrical distribution structures The present invention relates to improvements in or relating to electrical distribution structures.

Structures used for electrical distribution must typically address a variety of requirements, some of which may be conflicting. For example, there may be a requirement for compactness and a requirement for adequate protection against interference, which will tend to increase as wiring or other components of the structure are brought more closely together. These requirements can be particularly difficult to address in applications for which space is limited, or for which other constraints are imposed, such as within the confines of an electric or hybrid vehicle.

Examples of the present invention provide an electrical distribution structure comprising: at least one high-voltage busbar; at least one data pathway; an inner layer of electrical screening material located between the busbar and the data pathway to provide screening against interference between the busbar and the data pathway; the structure being encapsulated in an outer layer of electrical screening material.

The data pathway may be provided by electrical conductors or optical fibre. The structure may further comprise at least one conduit in thermal contact with the busbar or at least one of the busbars, and defining a passage for cooling fluid through the structure. A conduit for coolant fluid may be provided along each edge of at least one busbar. The or each conduit may have couplings for conveying cooling fluid through the structure, between a cooling device and a device to be cooled.

The surfaces of the or each busbar may be covered with electrical insulation material.

The surfaces of the or each busbar may be covered with thermally conductive material which, in use, conveys heat away from the busbar or busbars. The structure may comprise a laminated busbar structure of at least two busbars separated by an electrically insulating layer, the inner layer providing screening between the data pathway and the laminated busbar structure. The electrically insulating layer of the laminated busbar structure may provide a thermally conductive path for cooling the busbar structure, during use.

The structure may further comprise additional electrical conductors providing a path through the structure for low voltage power, there being electrical screening material between the additional conductors and the busbar or busbars. The electrical screening material between the additional conductors and the busbar or busbars may be provided by the inner layer. The inner layer may substantially wholly surround the busbar or busbars.

The material of the outer layer may be continuous with the material of the inner layer.

The structure may have an outermost layer providing mechanical protection and/or protection against the environment.

The structure may be encapsulated in material forming a structural component of a machine. The structural component may be a vehicle chassis or vehicle chassis component.

Examples of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic transverse section through an electrical distribution structure in accordance with one example of the invention; and Fig. 2 is a highly diagrammatic illustration of part of a vehicle chassis structure incorporating an electrical distribution structure of the type illustrated in Fig. 1.

Fig. 1 illustrates an electrical distribution structure 10 comprising at least one high-voltage busbar 12, there being two busbars 12 in this example. At least one data pathway 14 is provided by electrical conductors. An inner layer of electrical screening material 16 is located between the busbars 12 and the data pathway 14 to provide screening against interference between the busbars 12 and the data pathway 16. The structure 10 is encapsulated in an outer layer 18 of electrical screening material.

One application envisaged for the structure 10 is for power distribution within an electric vehicle. Typically, this involves the distribution of power by current which is nominally at DC, but which is subjected to rapid switching for various power and control purposes, giving rise to potential issues of electromagnetic interference (EMI) and radio frequency interference (RH).

In more detail, the structure 10 provides power distribution by means of the busbars 12 and a data pathway 14, within the same structure. The busbars 12 are in the form of a laminated busbar structure. Each busbar 12 has a cross section which is substantially continuous along the length of the structure 10 and is in the form of a wide, relatively thin sheet of conducting material such as copper, aluminium or another metal. The use of a wide, relatively thin sheet of conducting material allows the structure 10 to take advantage of the skin effect, as is conventional in the design of busbars for rapid switching DC, or for AC. Thus, greater current carrying capacity is provided than would be the case for a circular conductor of the same cross-sectional area and material. In addition, the use of two adjacent busbars is expected to reduce EMI and RFI levels in rapid switching DC applications, if the two busbars 12 are used for opposite polarity within the DC system so that the interference effects of current pulses created by the rapid switching will largely be cancelled out.

The two busbars 12 are separated by an electrical insulation at 20, and the outer surfaces of the busbars 12 are covered with two further layers 22 of electrically insulating material. In this example, the layers 20, 22 also provide thermal conductivity to convey heat away from the busbars 12. The layers 20, 22 may be formed of an insulating dielectric material with enhanced thermal conductivity properties, such as a resin or composite material incorporating ceramic material.

Two pipes 24 run along the length of the structure 10, close to the edges of the busbars 12. The passages 26 of the pipes 24 provide conduits for coolant fluid through the structure 10. The pipes 24 are in thermal contact with the layers 20, 22 and consequently, coolant material in the passage 26 will be in thermal contact with the busbars 12, through the layers 20, 22. There may be two layers 20, as shown, separated by a thermally conductive layer 27, such as a sheet of aluminium. The layer 27 maintains thermal contact between the pipes 24. The layer 27 may be omitted, if desired, in which case only a single layer 20 will be required.

In this example, lines of electrically insulating material 28 are provided between each pipe 24 and each busbar 12. The material 28 may be an appropriate insulating resin, for example. The material 28 also serves as an electrical field damper at the edge of the busbars 12, helping to reduce and/or eliminate possible voltage discharge effects.

Suitable materials can include UP polyester epoxy vinyl ester or silicone elastomers.

One of the layers 22 is located between the busbars 12 and the data pathway 14. The outer surface of this layer 22 is covered by the screen layer 26. Thus, the busbars 12 are electrically insulated by the layers 22 and are screened from the data pathway 14 by the layer 16. In addition, the layer 16 extends around the edges of the busbars 12, outside the pipes 24 and across the outer surface of the other layer 22. Thus, the inner screen layer 16 wholly surrounds the busbars 12.

The data pathway 14 lies outside the screening layer 16, as has been described. The data pathway 14 may consist of cables or optical fibres. Cables may be in the form of flat (ribbon) data cables, which may either be insulated, double insulated or screened.

Other forms of cable may be used to provide the data pathway 14.

The screening layer 16 seeks to provide the structure 10 with appropriate levels of electromagnetic compatibility (EMC), i.e. resistance against RFI or EMI for the data pathway 14 in the light of the close proximity of the busbars 12. Materials chosen for the screening layer 16 can include aluminium, copper or nickel or combinations of these or other materials, the material being chosen according to the intended application of the structure 10, and the expected frequency of interference to be screened out.

Additional electrical conductors are provided at 30, across the other outer face of the screening layer 16. Thus, electrical screening is provided between the conductors 30 and the busbars 12, by the screening layer 16. The conductors at 30 are intended to provide a low voltage power distribution system. Insulated, double insulated, screened, unscreened or double screened cables may be used.

The screening layer 16 further extends around the edges of the data pathway 14 and the conductors at 30, to provide the outer screening layers 18. The material of the outer layers 18 is therefore continuous with the material of the inner layer 16.

In this example, the structure 10 which has been described is fully encapsulated within an outer protective layer 32 particularly for protection against mechanical damage and/or environmental conditions. Various materials can be chosen for the outer layer 32, according to the environment in which the structure 10 is expected to be used. For example, a cross-linked polyethylene or similar material can be used, particularly by heat shrinking around the structure 10. Composite materials such as glass reinforced plastic, Kevlar, carbon fibre or stainless steel could be incorporated in appropriate substrate materials, such as synthetic resins, to provide additional robustness for the layer 32.

The structure lOis expected to have a number of advantages, during use. The structure is compact, improving its utility in a number of situations in which space is restricted.

Compactness is enhanced by the incorporation of the cooling pipes 24, which allow heat to be removed from the busbars 12, allowing the busbars 12 to be smaller and also lighter in weight. Efficient cooling of the busbars 12 allows them to be built of lighter material, such as aluminium, rather than copper, achieving a further weight saving.

Incorporating the data pathway 14 and the conductors 30 close to the busbars 12 also enhances compactness, providing a structure which can distribute power as well as command and control signals and coolant. This compact structure incorporates sufficient screening and insulation to avoid unacceptable levels of interference between the components of the structure (particularly between the busbars 12 and the data pathway 14). The structure 10 is also screened externally by the outer layers 18 to reduce external interference caused by or suffered by the structure 10.

Fig. 2 illustrates one example of use of a structure built in accordance with the principles of the previous description of Fig. 1. In Fig. 2, a very simple form of vehicle chassis is indicated at 34, having wheels 36. The chassis 34 incorporates a structure 10. That is, the structure 10 is encapsulated in the material which forms a structural component of the machine, which in this case is a vehicle chassis or vehicle chassis component.

When encapsulated in this way, the outer layer 52 may be provided by the material of the chassis 34, or the material of the chassis may be provided in addition to the outer layer 32. The material of the chassis may be a structural composite material of the type commonly used for vehicle chassis, such as a carbon fibre material.

The various components of the structure 10 allow power to be distributed around the chassis 34. For example, the busbars 12 may be connected to a main vehicle battery 38 to provide DC power which is conditioned by control systems 40 for driving a motor 42.

As noted above, the conditioning of the DC power will typically include rapid switching for various power and control reasons, such as power electronics converters, IGBT (insulated-gate bipolar transistor) systems, switching by thyristors etc. These give rise to potential scope for EMI or RFI issues, addressed by the various screening layers within the structure 10. Other control connections can be made to the control systems 40 by means of the data pathway 14 and also by means of the conductors 30, which allows the distribution of low voltage power around the chassis 34. Again, consequent EMI and RFI risks are addressed within the structure 10. The pipes 24 can be tapped at appropriate couplings 43, for example to provide coolant fluid for apparatus around the vehicle chassis 34. For example, coolant fluid can be conveyed through the structure 10 between a cooling device 44 and a device to be cooled, such as the motor 42. This is in addition to the cooling provided for the busbars 12.

Many variations and modifications can be made to the apparatus described above, without departing from the scope of the present invention. In particular, many different materials, sizes, relative sizes and combinations of the components described above can be formed for particular applications of a structure of the type described.

In addition to application in road vehicles, it is envisaged that the ability to combine power, data and cooling may also find application in areas such as wind generators and other low carbon generation applications.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims 1. An electrical distribution structure comprising: at least one high-voltage busbar; at least one data pathway; an inner layer of electrical screening material located between the busbar and the data pathway to provide screening against interference between the busbar and the data pathway; the structure being encapsulated in an outer layer of electrical screening material.
2. A structure according to claim 1, wherein the data pathway is provided by electrical conductors or optical fibre.
3. A structure according to any of the preceding claims, further comprising at least one conduit in thermal contact with the busbar or at least one of the busbars, and defining a passage for coolant fluid through the structure.
4. A structure according to claim 3, wherein a conduit for coolant fluid is provided along each edge of at least one busbar.
5. A structure according to claim 3 or 4, wherein the or each conduit has couplings for conveying coolant fluid through the structure, between a cooling device and a device to be cooled.
6. A structure according to any of the preceding claims, wherein the surfaces of the or each busbar are covered with electrical insulation material.
7. A structure according to any of the preceding claims, wherein the surfaces of the or each busbar are covered with thermally conductive material which, in use, conveys heat away from the busbar or busbars.
8. A structure according to any of the preceding claims, comprising a laminated busbar structure of at least two busbars separated by an electrically insulating layer, the inner layer providing screening between the data pathway and the laminated busbar structure.
9. A structure according to claim 8, wherein the electrically insulating layer of the laminated busbar structure provides a thermally conductive path for cooling the busbar structure, during use.
10. A structure according to any of the preceding claims further comprising additional electrical conductors providing a path through the structure for low voltage power, there being electrical screening material between the additional conductors and the busbar or busbars.
11. A structure according to claim 10, wherein the electrical screening material between the additional conductors and the busbar or busbars is provided by the inner layer. C')
12. A structure according to any of the preceding claims, wherein the inner layer o substantially wholly surrounds the busbar or busbars. (1
13. A structure according to any of the preceding claims, wherein the material of the outer layer is continuous with the material of the inner layer.
14. A structure according to any of the preceding claims, having an outermost layer providing mechanical protection and/or protection against the environment.
15. A structure according to any of the preceding claims, wherein the structure is encapsulated in material forming a structural component of a machine.
16. A structure according to claim 15, wherein the structural component is a vehicle chassis or vehicle chassis component.
17. An electrical distribution structure substantially as described above, with reference to the accompanying drawings.
18. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims. C') a, (1