TECHNICAL FILED

The present invention relates to a converter system, and a railway vehicle comprising the converter system. Particularly, the present invention relates to a converter system provided with improved cooling of magnetic components of the converter system.

BACKGROUND AND RELATED ART

In converter systems, such as traction converter systems in railway vehicles, the design of magnetic components with regard to their cooling is challenging for several reasons. The relatively large size of these components makes them hard to rearrange in an electric filter compartment in a housing of a traction converter system. The available space and allowed weight therein are often limited. The cooling airflow for a magnetic component therein is often far from ideal, and the exact distribution of this cooling airflow generally remains unknown and it is difficult to predict cooling efficiency prior to installation. This tends to result in several tedious and expensive iterations of testing and improvement of prototypes before establishing the final design.

Some patent documents in this technical field will now be identified and briefly discussed.

GB-2534013 discloses power converter for a rail vehicle and a cooling arrangement for the converter. A blower and a ventilation duct are arranged to cool a semiconductor device.

US-2018/233266 discloses a reactor arranged such that air flows from a cooling fan through a space between an outer peripheral iron core and a j acket in the axial direction of the reactor.

US-2019/362879 discloses an air-cooled dry-type transformer. A cooling channel is located between an inner part of a winding body and an outer part of the winding body.

The obj ect of the present invention is to enhance the cooling of the magnetic components in converter systems, in particular traction converter systems for rolling stock, and enhance predictability when designing such systems.

SUMMARY OF THE INVENTION

The above-mentioned obj ect is achieved by the present invention according to the independent claims.

Preferred embodiments are set forth in the dependent claims.

The invention aims to overcome or at least alleviate problems or shortcomings associated with the related art. In general, the present invention provides a converter system having a more predictable, confined, and/or uniform cooling airflow in the immediate vicinity of the magnetic component in question.

In particular, the present invention provides a converter system comprising: a housing comprising an air inlet and an air outlet; converter circuitry, arranged inside the housing and including a magnetic component having electric windings around a ferromagnetic core. A cooling arrangement is provided, configured to provide cooling of the magnetic component. The cooling arrangement comprises a fan configured to cause an airflow through the housing from the air inlet to the air outlet; said magnetic component having opposed upstream and downstream ends and being positioned between the air inlet and the air outlet, to allow the airflow to pass the magnetic component and to cool thereby the magnetic component. The cooling arrangement having an airflow contraction collar defining an airflow-restricting path in which the magnetic component is positioned, and which is configured to cause an air pressure gradient in the airflow in a direction from the upstream end to the downstream end of the magnetic component. This attains a significantly improved cooling of the magnetic component without any need to alter other parts of a conventionally designed converter system. This improved cooling also allows use of a magnetic component, while maintaining its electric performance, which is smaller and lighter than that of a conventional design, which is an advantage in a converter system. Although defined herein as a converter system, a most preferred application of the invention is as a traction converter system. However, any description herein of the invention as traction converter system shall not in itself limit the invention of the appended claims to such a converter system.

The magnetic component may have at least one internal air channel in a direction from the upstream end to the downstream end arranged such that the air pressure gradient causes at least part of the airflow to pass through the at least one internal air channel. Preferably, the at least one internal air channel extends through the electric windings. It may include a plurality of channels beginning in a vicinity of the upstream end of the magnetic component, preferably in an upstream end of the windings. It may also include a plurality of channels ending in a vicinity of the downstream end of the magnetic component, preferably in a downstream end of the electric windings. Most preferably, the plurality of channels begin in the upstream end and continue to the downstream end of the electric windings. Providing an increased flow of cooling air inside the windings is a great advantage, since this is generally a hotter region than the outside of the windings.

The airflow contraction collar may comprise a tubular section, which preferably includes at least partly cylindrical tubular section, forming at least part of the airflow-restricting path around at least part of an outer periphery of the electrical windings. This will have the advantage of a more uniform cooling of the electrical windings, in particular of an outer periphery thereof covered form-fittingly, with a gap for the airflow, by the airflow contraction collar. The airflow contraction collar may overlap, along a general direction of the airflow through the collar, with part of, or all of the, outer periphery of the electrical windings. The form-fit of the airflow contraction collar to the magnetic components, at least the electrical windings thereof, may mean that the gap between them is constant or, while maintaining a uniform cooling of the outer periphery of the electrical windings, essentially constant.

A geometry or shape of the airflow contraction collar may vary depending on a shape of the magnetic component and other constraints. As a current preference, for a shape shown herein of a conventional magnetic component, the airflow contraction collar has two or more collar sections enclosing part of the magnetic component and forming at least part of the airflow-restricting path. The shape of the airflow contraction collar is thus adapted locally or as a whole to accommodate electrical connectors or cables for electrically connecting the magnetic component or fastening structures for the magnetic component or the airflow contraction collar itself.

The airflow-restricting path described herein is located between the magnetic component and the airflow contraction collar and, if the magnetic component is so designed, between windings and/or inside windings. The airflow-restricting path has an outer perimeter limited by an inside of the airflow contraction collar, seen in the direction from the upstream end to the downstream end of the magnetic component (this direction preferably being parallel to a vertical symmetry axis of the magnetic component). The airflow- restricting path is also limited by the magnetic component. Through the inventive design, cooling air flowing in the airflowrestricting path has a higher air speed than the cooling air flowing upstream of the airflow- restricting path.

To enable maximum cooling of the magnetic component, especially when it is the last or one of the last items (which is conventional) to receive cooling by the airflow in the converter system, the airflow contraction collar is connected to a wall of the housing and encircles the air outlet such that said airflow-restricting path ends downstream of said air outlet. In other words, to improve significantly the cooling situation, it is preferred that the magnetic component is located adj acent to the air outlet, and that the air outlet is equipped with the collar that encircles the component. Consequently, this will ensure that all the airflow generated by the fan will flow along and, as applicable, through the electrical windings/coils of the magnetic component in a more predictable and uniform sense.

From a manufacture or replacement perspective, it may be advantageous that the airflow contraction collar is fastened fixedly to the magnetic component, preferably forming a single assembly unit. The latter would be an advantage in manufacturing of the converter system and improve logistics. With such a scheme, a combination of the collar and component will not jeopardize cooling by mismatch. However, it would be fully possible and sometimes preferable to fasten individually the magnetic component and the airflow contraction collar to a wall or fastening structure of the housing.

A railway vehicle comprising, or use therein of, the converter system disclosed herein is advantageous, as it will have, as a result, of improved cooling, reduced size, reduced weight, longer life of its magnetic components and thus less need of maintenance. A railway vehicle capable of handling higher power is also a foreseen result of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a cross-sectional side view schematically illustrating a traction converter system according to an embodiment of the present invention.

Figures 2 and 3 are cross-sectional views schematically illustrating embodiments of the present invention.

Figure 4 is a schematic perspective view that shows a part of the traction converter system according to an embodiment of the present invention. Figure 5 is a schematic perspective view of a spacer member according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The converter system will now be described in detail with references to the appended figures. Throughout the figures the same, or similar, items have the same reference signs. Moreover, the items and the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

Figure 1 shows a schematic side view of a traction converter system 1 for railway vehicles according to the present invention. These types of traction converter systems comprise a housing 2 having several compartments, an air inlet 3 in a right side wall of the housing 2, and an air outlet 4 in the left end of a bottom wall of the housing 2 as illustrated in figure 1. Inside the housing 2, there is arranged a converter circuitry 5, including a magnetic component 6. The magnetic component 6 is provided with electric windings 7 around a ferromagnetic core 8 and provides part of a high-power filter function. Further, there is a cooling arrangement configured to provide cooling of the converter circuitry 5.

The cooling arrangement comprises a fan 9 configured to cause an airflow 10, illustrated by arrows in the figures, through the housing 2 from the air inlet 3 to the air outlet 4. The fan 9 draws the airflow from the air inlet 3 though the housing and pushes the airflow onwards passed the magnetic component 6 towards the air outlet 4 generally positioned in the housing 2 opposed or distally to the air inlet 3. The magnetic component 6 has opposed upstream (upper in the drawing) 1 1 and downstream (lower in the drawing) 12 ends and is positioned between the air inlet 3 and the air outlet 4, to allow the airflow 10 to pass the magnetic component 6 and to cool thereby the magnetic component 6. The magnetic component 6 shown in figure 1 is located near and above the air outlet 4.

The cooling arrangement comprises an airflow contraction collar 14 defining an airflow-restricting path 15 in which the magnetic component 6 is positioned, and which is configured to cause an air pressure gradient in the airflow 10 in a direction from the upstream end 1 1 to the downstream end 12 of the magnetic component 6. The magnetic component may include various additional components also included within the airflow contraction collar 14 to obtain cooling, and protection against heat. These additional components may be resistive components, e.g. so-called over-voltageprotection components.

The cooling arrangement further comprises at least one airflow-restricting member 16 (see figures 2 and 3) configured to be arranged in the airflowrestricting path 15.

The creation or significant strengthening of such a gradient by the airflow contraction collar 14 means that there is a higher pressure in the airflow generally at the top or upstream end 1 1 of the magnetic component 6 and a relatively lower pressure in the airflow 10 at the bottom or downstream end 12 of the magnetic component 6. The spatial orientation and/or order of the magnetic component 6, the fan 9, the inlet 3, the outlet 4, and the airflow may be different, without deviating from the function of the cooling arrangement according to the invention. For instance, the airflow contraction collar 14, with the magnetic component inside or partly inside it, could be located in or near a partition wall between compartments in the housing 2, away from the air outlet 4.

According to an embodiment, the cooling air flowing in the airflowrestricting path 15 has a higher air speed downstream of the at least one airflow-restricting member 16 than cooling air flowing upstream of said at least one airflow-restricting member 16.

According to the invention, the at least one airflow-restricting member 16 is sheet-like and having an extension essentially perpendicular to the airflow in the airflow-restricting path 15 and covering a predetermined part of the cross-sectional area of said airflow-restricting path 15. Preferably, the predetermined part is at least 25%, and could be as high as 60-80%.

According to still another embodiment illustrated by figures 2 and 3, the magnetic component 6 comprises three legs, two outer legs 17 and a middle leg 18 between the outer legs 17. The at least one airflow restricting member 16 of the middle leg 18 is structured to allow a higher airflow in comparison to the airflow allowed by the airflow restricting members 16 of the outer legs 17. More specifically, the airflow restricting member 16 of the middle leg 18 will cover a smaller part of the cross-sectional area of the airflow-restricting path 15 in comparison to the parts covered by the airflow restricting member 16 in relation to the outer legs.

In a further embodiment illustrated in figure 3, the magnetic component 6 comprises at least one internal air channel 19 in a direction from the upstream end 1 1 to the downstream end 12 arranged such that the air pressure gradient causes at least part of the airflow to pass through the at least one internal air channel 19 of the magnetic component 6. The at least one internal air channel 19 extends through the electric windings 7, and is provided with at least one spacer member 20 arranged to define said at least one internal air channel 19. Figure 3 illustrates a magnetic component

6 comprising three legs, but the embodiment described herein that includes at least one internal air channel 19 extending through the electric windings

7 is equally applicable in a magnetic component 6 that comprises two legs.

According to one embodiment, the spacer member 20 has an elongated rodlike shape, preferably having an essentially rectangular cross-section (see figure 5). For sake of simplicity, only a few spacer members are shown in figure 5, but numerous spacer members may be applied to achieve the required number of internal air channels. The spacer member is provided with a number of through going air openings 21 in a perpendicular direction in relation to the longitudinal axis of the spacer member. The openings may have a rectangular shape, but other shapes, e.g. oval or circular, is naturally also possible. Thus, numerous spacer members 20 are arranged to define the internal air channels 19 within the windings 7 and are arranged such that the openings will allow air to easily flow by the spacer member 20 through the openings and thereby increase the cooling effect.

The at least one internal air channel 19 of the magnetic component 6 may include a plurality of channels beginning in a vicinity of the upstream end 1 1 , and the at least one internal air channel 19 of the magnetic component 6 include a plurality of channels ending in a vicinity of the downstream end 12.

It is important to provide cooling of the magnetic component 6 as efficiently as possible given an available airflow 10. For this purpose, and in accordance with embodiments discussed above, the magnetic component 6 has at least one internal air channel 19 in a direction from the upstream end 1 1 to the downstream end 12 arranged such that the air pressure gradient causes at least part of the airflow 10 to pass through the at least one internal air channel 19. The interior of the windings 7 tend to be more exposed to heat than the outside thereof. Thus, the internal air channel(s) 19 are very important. To attain this internal cooling, it is even possible for the airflow contraction collar 14 to block only a downstream or lower section of the magnetic component 6, so that a relatively higher air pressure is created at an upstream or upper entry of the internal channel(s) 19 and a relatively lower air pressure is created at a downstream or lower exit of the internal channel(s) 19. However, with a very low (in relation to a height of the magnetic component) airflow contraction collar 14, a cooling effect by the airflow on an outside (of the windings primarily) of the magnetic component 6 will not be significantly increased in relation to the prior art solution. Consequently, it is found advantageous that the airflow contraction collar 14 reaches at least half way up the magnetic component 6 on one, two or more sides thereof.

Depending on the need for cooling, the at least one internal air channel 19 may extend through the electric windings, through the core, or through cooling elements (not shown) attached to the magnetic component 6.

In the design shown in figure 1 , the at least one internal air channel 19 includes a plurality of vertical channels, distributed around the windings 7, beginning in a vicinity of the upstream end 1 1 and ending in a vicinity of the downstream end 12. Other starting and ending locations are conceivable as long at the created air pressure gradient is large enough to cause a sufficient amount of cooling airflow.

Figure 4 shows the magnetic component 6 with the airflow contraction collar 14. Reference numerals generally correspond to those of figure 1. Particularly, figure 4 shows an airflow contraction collar 14 that comprises one or more collar sections 17a, 17b enclosing part of the magnetic component and forming the at least part of the airflow-restricting path 15. In other words, the airflow contraction collar 14 needs not to have the shape of a full cylinder truncated perpendicularly to its longitudinal axis.

Figure 1 shows that the airflow contraction collar 14 is arranged such that ideally all of the airflow 10 from the air inlet 3 to the air outlet 4 passes through said airflow-restricting path 15. This would be true for the design in figure 4, too. However, if at least 20% or, preferably, a maj or part of the airflow 10 from the air inlet 3 to the air outlet 4 passes through the airflow-restricting path passes through the airflow contraction collar 14 it is currently believed that a sufficient cooling can be attained. Figure 1 shows how the airflow contraction collar 14 is connected to a wall of the housing and encircles the air outlet 4 such that the airflowrestricting path 15 ends downstream in the air outlet 4. Alternatively, the airflow contraction collar 14, having sections 17a and 17b, according to the design in figure 4, could be arranged in a corresponding manner.

In one further embodiment, the airflow contraction collar 14 has a cross- sectional area less than 1.5 times relative that of the largest cross-sectional area of the magnetic component, viewed in a direction from the upstream end 1 1 to the downstream 12 end of the magnetic component 6. Thereby an efficient cooling is obtained.

In still another embodiment, the airflow contraction collar 14, in a direction from the upstream end 1 1 to the downstream end 12 of the magnetic component 6, has a length at least 0.3 times the length of the magnetic component 6 or an overlap with at least about half the height of the magnetic component 6.

In figure 4, a combination is shown, wherein the airflow contraction collar 14 is fastened fixedly to the magnetic component 6 to form a single assembly unit. This is convenient as the airflow contraction collar 14 is size-matched with the magnetic component 6 it is fastened to, in order to ensure proper cooling airflow. It would also provide an advantage in manufacturing of the converter system and improve logistics.

The traction converter system as defined herein is especially applicable for use in a railway vehicle.

The present invention is not limited to the above-described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the invention, which is defined by the appending claims.