WO2016008509A1

WO2016008509A1 - Electric module for improved thermal management in electrical equipments

Info

Publication number: WO2016008509A1
Application number: PCT/EP2014/065081
Authority: WO
Inventors: Rebei Bel Fdhila; Lokman HOSAIN; Mats Hyttinen; Erik Persson
Original assignee: Abb Technology Ltd
Priority date: 2014-07-15
Filing date: 2014-07-15
Publication date: 2016-01-21

Abstract

A method of cooling an electric module comprising a plurality of electronic components and an electric module thereof are disclosed. The electric module (100) comprises an enclosure (110), a plurality of heat sinks (121-123) and a plurality of electronic components (131, 132). The enclosure includes an inlet (112) for entry of a cooling medium (140) within the enclosure and an outlet (114) for output of the cooling medium. The plurality of electronic components are arranged in thermal contact with the plurality of heat sinks within the enclosure and the plurality of heat sinks are arranged such that the cooling medium flows via the heat sinks from the inlet of the enclosure to its outlet. A first surface (122a) of a heat sink (122) is arranged in mechanical contact with an electronic component (132) and a second surface (122b), opposite to the first surface, of the heat sink is arranged in mechanical contact with another electronic component (131).

Description

ELECTRIC MODULE FOR IMPROVED THERMAL MANAGEMENT IN ELECTRICAL

EQUIPMENTS

TECHNICAL FIELD

The present disclosure relates generally to an electric module for thermal management in electrical equipments. The present disclosure is concerned with cooling of heat-generating electronic components, such as solid-state devices, and relates in particular to an electric module in which the electronic components are cooled via heat sinks by immersion in a cooling medium. The present disclosure is applicable in any electrical equipment including low, medium or high voltage applications, such as for instance in high voltage direct current (HVDC) power converters.

BACKGROUND

An HVDC converter station is a type of station adapted to convert high voltage direct current (DC) to alternating current (AC) or the reverse. An HVDC converter station may comprise a plurality of elements such as the converter itself (or a plurality of converters connected in series or in parallel), an alternating current switch gear, transformers, capacitors, filters, a direct current switch gear and other auxiliary elements. Electronic converters may comprise a plurality of solid-state based devices such as semiconductor devices and may be categorized as line-commutated converters using e.g. thyristors as switches or voltage source converters using transistors, such as insulated gate bipolar transistors (IGBTs) as switches (or switching devices). A plurality of solid-state semiconductor devices such as thyristors or IGBTs may be connected together, for instance in series, to form a building block of an HVDC converter, also called an HVDC converter valve.

Solid-state based devices (semiconductor devices) and other elements of the HVDC converter station may generate heat. As the operation and performance of semiconductor devices such as IGBTs is sensitive to temperature, a challenge in the construction of HVDC converter stations is thermal management such that a certain level of reliability is ensured. Prior art solutions are often based on cooling by air or water using cumbersome piping arrangements around the whole system (or converter), thereby requiring a large area for installation of the HVDC converter station. However, for applications with limited space for installation of the HVDC converter station or for applications in which it is difficult and/or expensive to install cumbersome power stations, such as for example on offshore platforms, there is a need of providing more compact solutions.

SUMMARY

An object of at least some embodiments of the present disclosure is to wholly or partly overcome the above disadvantage of prior art systems and to provide a more compact alternative to the prior art.

This and other objects are achieved by means of an electric module and a method as defined in the appended independent claims. Other embodiments are defined by the dependent claims.

According to a first general aspect, there is provided an electric module comprising an enclosure, a plurality of heat sinks and a plurality of electronic components. The enclosure includes an inlet for entry of a cooling medium within the enclosure and an outlet for output of the cooling medium. The plurality of electronic components is arranged in thermal contact with the plurality of heat sinks within the enclosure. A first surface of a heat sink is arranged in mechanical contact with an electronic component and a second surface, opposite to the first surface, of the heat sink is arranged in mechanical contact with another electronic component. The plurality of heat sinks is arranged such that the cooling medium flows via the heat sinks from the inlet of the enclosure to its outlet.

According to a second aspect, a method of cooling an electric module comprising a plurality of electronic components is provided. The method comprises the steps of arranging the electronic components in thermal contact with a plurality of heat sinks within an enclosure and arranging the plurality of heat sinks such that a cooling medium flows within the enclosure from an inlet of the enclosure to its outlet via the heat sinks. A first surface of a heat sink is arranged in mechanical contact with an electronic component and a second surface of the heat sink, which second surface is opposite to the first surface, is arranged in mechanical contact with another electronic component.

The above defined electric module and method are advantageous in that a more compact solution for cooling of a plurality of electronic components of an electric module is achieved via an arrangement of heat sinks within an enclosure in which a cooling medium flows. In the electric module, the plurality of heat sinks are arranged to guide or direct the cooling medium from the inlet of the enclosure to its outlet and a first surface of a heat sink is arranged in mechanical contact with an electronic component while a second surface of the heat sink, which second surface is opposite to the first surface, is arranged in mechanical contact with another electronic component. In other words, two electronic components may be arranged on each side of a heat sink through which the cooling medium flows. The heat sink is arranged between the two electronic components and the cooling medium is directed from the inlet of the enclosure to its outlet via the arrangement of the heat sinks. In other words, the arrangement of the heat sinks defines the flow of the cooling medium. The enclosure may be filled with the cooling medium and cooling at the level of each electrical component via the heat sinks is achieved, thereby providing a more efficient cooling. The heat sinks themselves are arranged to guide the cooling medium from one electronic component to another from the inlet of the enclosure to its outlet.

The use of heat sinks is also advantageous in that it increases the surface available for dissipation of heat generated by the electronic components, thereby providing a more efficient cooling. This, in turn, improves the reliability of the electric module as the operation of the electronic components is less affected by heat generation in the electric module. As mentioned above, the heat sinks are in addition arranged so as to guide the cooling medium from the inlet of the enclosure to its outlet and electronic components may be arranged on both sides of a heat sink, thereby providing a more compact solution.

According to an embodiment, the electric module may further comprise a flow guiding member adapted to guide the flow of the cooling medium from one heat sink to another, thereby improving the guidance of the cooling medium from one heat sink to another. The flow guiding member may for example be a barrier plate or a wing attached to the heat sink or extending from a wall (or surface) of the heat sink.

According to another embodiment, or in combination with the preceding embodiment, the heat sinks may be tilted so as to guide the cooling medium from one heat sink to another. The present embodiment is advantageous in that the flow of the cooling medium may be controlled by the respective tilt angles (relative to a common axial direction of the electric module for instance) of the heat sinks. The cooling medium may then flow from a heat sink to another at least because of gravity. According to another embodiment, the electric module may be equipped with pipes (or tubes) for guiding the cooling medium from one heat sink (or cavity of a heat sink) to another heat sink (or cavity of another heat sink). With these pipes, the cooling medium is directly directed to the heat sinks which are in direct thermal contact with the electronic components.

According to an embodiment, a heat sink may comprise a first side for entry of the cooling medium within the heat sink and a second side for exit of the cooling medium from the heat sink. The cooling medium may therefore flow through a heat sink from its entrance (first side or entry side) to its exit (second side).

According to a specific embodiment, a heat sink may comprise at least two base surfaces with a plurality of heat dissipating walls extending from a first base surface to a second base surface such that channels are formed between the base surfaces by the heat dissipating walls for guiding the cooling medium from a first side of the heat sink to a second side of the heat sink. The plurality of heat dissipating walls increase the contact area with the cooling medium, thereby further improving heat dissipation within the electric module.

According to an embodiment, the heat sinks and the electronic components may be stapled such that at least a first surface of an electronic component is arranged in thermal contact with a first heat sink and a second surface, opposite to the first surface, of the electronic component is arranged in thermal contact with a second heat sink. In this configuration, the electronic components and the heat sinks are successively arranged at different levels within the electric module with a heat sink being arranged between two consecutive electronic components. Considering a vertical stapling, the heat sinks and the electronic components are then horizontally disposed on top of each other (alternating between a heat sink and an electronic component).

According to an embodiment, the flow of the cooling medium from the inlet of the enclosure to its outlet may be zigzag shaped. The heat sinks, and any flow guiding member (or pipes), may be arranged to provide such a zigzag-shaped flow of the cooling medium from the inlet of the enclosure to its outlet. A zigzag-shaped flow may be obtained using a stapling of the heat sinks and the electronic components such as described in the preceding embodiments. In accordance with the present embodiment, the cooling medium may flow through a first heat sink from e.g. its right-hand side to its left-hand side and then flow through the next heat sink from its left-hand side to its right hand side and so on. The cooling medium may reach the next heat sink from the first heat sink by flowing along the side of the electronic component arranged between the two heat sinks and/or by being guided by means of e.g. a flow guiding member. As a result, a zigzag-shaped flow of the cooling medium is obtained.

According to an embodiment, a side for output of the cooling medium at a first heat sink may be axially aligned with a side for input of the cooling medium at a second heat sink. In this configuration, the cooling medium is directed from a first heat sink to a second heat sink in a relatively straight manner. This may be implemented with vertically positioned heat sinks, and thereby vertically positioned electronic components, wherein the flow of the cooling medium is along a vertical direction from a first side (or entry side) of a heat sink to it second side (or exit).

According to an embodiment, the heat sinks, and any flow guiding member, may be arranged such that the cooling medium flows at least at the edges of the electronic components. In particular, the plurality of electronic components may be at least partially immersed (or submerged) in the cooling medium. It will be appreciated that the enclosure may be filled with the cooling medium and thus that, although a general flow of the cooling medium is governed by the arrangement of the heat sinks, the electronic components may be in direct contact with the cooling medium too due to immersion of all the elements of the electric module in the cooling medium within the enclosure. Any side surface of the electronic components not in contact with any heat sink may then be in direct thermal contact with the cooling medium.

According to an embodiment, the electric module may further comprise a flow generating element to actively generate a flow from the inlet of the enclosure to its outlet. In particular, the flow generating element may be a pump or impeder adapted to cause the cooling medium to flow from the inlet to the outlet of the enclosure.

According to an embodiment, the electronic components may be of at least one of the following types: a capacitor, a gate drive unit, a semiconductor element, an insulated gate bipolar transistor and/or a thyristor. The present disclosure is for example concerned with thermal management in an HVDC converter station in which converters may be built based on either thyristors or IGBTs. In this respect, it may be noted that the use of IGBTs for building a power converter is advantageous since thyristors can only be turned on (not off) by control action, and thus power converters based on thyristors usually rely on an external AC system to effect the turn-off process. With IGBTs, however, both turn-on and turn-off can be controlled and voltage-source converters may be obtained. Although the present disclosure is not limited to voltage-source converters, implementations with voltage-source converters are even more advantageous since these converters are more compact than line-commutated converters.

The electronic components may be arranged in mechanical contact with the heat sinks using different techniques. An electronic component may for instance be bound on a heat sink. Further, an electronic component located between two heat sinks may itself include several discrete semiconductor devices.

According to an embodiment, the cooling medium may include liquid and/or gas. It will be appreciated that the cooling medium may also be a mixture of gas and liquid, in particular if phase change occurs because of e.g. temperature and/or pressure variation of the cooling medium in the enclosure.

According to an embodiment, the cooling medium may have dielectric properties, which is advantageous for electrical insulation purposes. The cooling medium may for example be a gas such as sulfur hexafluoride (SF₆) or a liquid such as an oil or de-ionized water. The cooling medium may advantageously be chemically inert with respect to the electronic components.

According to an embodiment, the electronic components may together define at least part of a power converter, a high voltage direct current converter or a voltage source converter.

According to an embodiment, an electric system (or electric equipment) comprising at least two electric modules as defined in any one of the preceding embodiments is provided. In the electric system, an outlet of a first electric module may be connected to an inlet of a second electric module. The first electric module and the second electric module may for example form a first converter and a second converter, respectively, of an HVDC converter station. The two converters may be electrically connected in series to provide the converting function of the HVDC converter station. The cooling medium may then be caused to circulate from a first converter to another in order to cool down the electronic components of each one of these converters. For this purpose, the electric system may, according to an embodiment, further comprise a pump for causing the cooling medium to flow (or circulate) from the first electric module to the second electric module.

The present disclosure is applicable for high voltage or low voltage power equipments in which it is desired to cool down electronic components. The present disclosure is generally advantageous for applications in which space for installation of the electric equipment is limited. In particular, the electric modules or electric systems disclosed herein are

advantageous for offshore wind farm applications.

It will be appreciated that other embodiments using all possible combinations of features recited in the above described embodiments may be envisaged. In particular, it will be appreciated that the features of the embodiments described with reference to the electric module according to the first aspect may be combined with any embodiment of the method according to the second aspect, and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplifying embodiments will now be described in more detail, with reference to the following appended drawings:

Figures la and lb show schematic views of electric modules in accordance with two embodiments;

Figures 2a-c shows perspective and cross-sectional schematic views of an electric module in accordance with another embodiment;

Figure 3 shows a schematic view of a heat sink in accordance with an embodiment;

Figure 4 shows a schematic view of an electric module in accordance with a further embodiment;

Figure 5 shows a schematic view of an electric module in accordance with yet another embodiment;

Figure 6 illustrates the outline of a method according to an embodiment; and Figure 7 shows an arrangement of heat sinks and electronic components in accordance with another embodiment.

As illustrated in the figures, the sizes of the elements, layers and regions may be exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of the embodiments. Like reference numerals refer to like elements throughout.

DETAILED DESCRIPTION

Exemplifying embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

With reference to Figure la, an electric module 100 according to an embodiment is described.

Figure la shows an electric module 100 including an enclosure 110, a plurality of heat sinks 121-123 and a plurality of electronic components 131, 132. The plurality of heat sinks 121- 123 and the plurality of electronic components 131, 132 are enclosed in the enclosure 110. The enclosure 110 has an inlet 112 for allowing entry of a cooling medium 140 within the enclosure 110 and an outlet 114 for output of the cooling medium 140.

The flow of the cooling medium 140 within the enclosure 110 is illustrated by arrows in Figure la. As depicted, the heat sinks 121-123 are arranged such that the cooling medium 140 flows from the inlet 112 of the enclosure 110 to its outlet 114 via the heat sinks 121-123. For this purpose, the electric module 100 may be equipped with flow guiding members 145-147, which may be barrier plates or extensions of the walls of the heat sinks.

More specifically, in the exemplifying embodiment shown in Figure la, the cooling medium 140 enters the enclosure 110 of the electric module 100 at the inlet 112 and is guided into a first heat sink 121 by means of a first guiding member 145, which in fact acts as some kind of walls on the path of the cooling medium 140. The cooling medium 140 enters at a first side of the heat sink 121, flows within the first heat sink 121 and exits the first heat sink 121 at a second side, opposite to the first side. The cooling medium 140 flows then along a side of a first electronic component 131 and is then guided into a second heat sink 122 by means of a second guiding member 146. Similarly, the cooling medium 140 flows within the second heat sink 122 and is guided into a third heat sink 123 by means of a third guiding member 147. The cooling medium then flows within or through the third heat sink 123 and is output from the enclosure 110 at the outlet 1 14.

The electronic components 131, 132 are arranged in thermal contact with the heat sinks 120a- c within the enclosure 110, thereby enabling dissipation of heat from the electric module as the electronic components 131 , 132 may generate heat under operation. More specifically, the electronic components 131, 132 and the heat sinks 121-123 are arranged such that a first surface 122a of the heat sink 122 is arranged in mechanical contact with a first electronic component 132 and a second surface 122b, opposite to the first surface 122a, of the heat sink 122 is arranged in mechanical contact with a second electronic component 131. In this configuration, the heat sink 122 is sandwiched between the two electronic components 131, 132 and the electronic components 131, 132 are arranged in direct contact with the heat sink 122.

The electronic components 131, 132 may be capacitors, semiconductor elements and/or power electronic components. In particular, the electronic components 131, 132 may be IGBTs which together form, when connected in series, a voltage source converter of an HVDC converter station such as described in the above. Further, it will be appreciated that the electric module depicted in Figure la may be connected to another electric module (not shown but which may be similar to the electric module described with reference to Figure la) to form the power converter of an HVDC converter station. Further, the electronic

components 131 , 132 may themselves include a number of discrete semiconductor components to form an IGBT.

The cooling medium 140 is represented by dots in Figure la (and also in the other figures) and may be a liquid, a gas or a mixture of liquid and gas. For example, the cooling medium 140 may be an oil, de-ionized water or SF₆ gas which is chemically inert with respect to the electronic components 131, 132. These types of cooling mediums are also preferable in that it provides electrical isolation of the electronic components 131, 132. With reference to Figure lb, an electric module 150 according to another embodiment is described.

Figure lb shows an electric module 150 including an enclosure 160, a plurality of heat sinks 171-173 and a plurality of electronic components 131, 132. The plurality of heat sinks 171- 173 and the plurality of electronic components 131, 132 are arranged within the enclosure 160. The enclosure 160 has an inlet 162 for allowing entry of a cooling medium 140 within the enclosure 160 and an outlet 164 for output of the cooling medium 140.

As described with reference to Figure la, a first surface 172a of the heat sink 172 may be arranged in mechanical contact with a first electronic component 132 and a second surface 172b, opposite to the first surface 172a, of the heat sink 172 may be arranged in mechanical contact with a second electronic component 131 such that the heat sink 172 is sandwiched between the two electronic components 131, 132. The electric module 150 shown in Figure lb is in general equivalent to the electric module 100 described with reference to Figure la except for the heat sinks 171-173, which (laterally) extends up to an inside wall of the enclosure 160. In this embodiment, the heat sinks 171-173 may be provided with openings at their top surfaces for outputting the cooling medium 140. For example, the cooling medium 140 may exit the heat sink 172 at its first surface (or top surface) 172a instead of exiting at a side of the heat sink such as shown in Figure la. Although not illustrated in Figure lb, it will be appreciated that a similar solution could be used for entry of the cooling medium 140 in the heat sinks 171-173 wherein the cooling medium 140 may for example enter the heat sink 172 via openings located at its second surface (or bottom surface) 172b. In the latter configuration, the heat sink may then laterally extend through the entire enclosure.

The flow of the cooling medium 140 within the enclosure 160 of the electric module 150 is illustrated by arrows in Figure lb. Except for the above mentioned difference, the same principle as that described with reference to Figure la applies here and is therefore not repeated.

With reference to Figures 2a-c, an electric module 200 according to another embodiment is described. Figure 2a shows a three-dimensional view of the electric module 200 while Figure 2b shows a cross-sectional view of an equivalent electric module and Figure 2c shows an enlargement of part of Figure 2a. Figures 2a-c show an electric module 200 including an enclosure 210 and a plurality of cells mounted on a shaft 215. Although the present disclosure is not limited to such a particular shape, the enclosure 210 is shown to be cylindrical. Further, for illustrative purposes, the enclosure 210 is represented to be transparent and the inlet for entry of a cooling medium within the enclosure 210 and its outlet for output of the cooling medium are not represented.

Figure 2a shows an electric module comprising five cells arranged beside each other (or on top of each other) along the shaft 215 while Figure 2b is a cross-sectional view showing three cells only. Each of the cells, such as for example cell 205 shown in more detail in Figure 2c, comprises a plurality of heat sinks 221-223 and a plurality of electronic components 231, 232. The electronic components 231, 232 are arranged in thermal contact with the heat sinks 221- 223 within the enclosure 210. The electric module 200 shown in Figures 2a-2c is in general equivalent to the electric module 100 described with reference to Figure la except that it shows a plurality of cells, i.e. a plurality of arrangements of heat sinks and electronic components within the enclosure.

Figures la and 2a-2c show a configuration in which the heat sinks and the electronic components are stapled such that at least a first surface 232a of an electronic component 232 is arranged in thermal contact with a first heat sink 222 and a second surface 232b, opposite to the first surface 232a, of the electronic component 232 is arranged in thermal contact with a second heat sink 223. The electronic component 232 may for example be bound to the heat sinks 222, 223. In this configuration, the heat sinks 221-223 and any flow guiding members 245-247, are arranged such that the flow of the cooling medium within the enclosure 210 is zigzag-shaped. The flow of the cooling medium 140 is illustrated by arrows in e.g. Figure la. For this purpose, referring more specifically to Figure 2b, a cooling medium entering the enclosure 210 may be guided in and out of the heat sinks 221-223 by means of flow guiding members 245-247 (such as described in more detail above with reference to Figure la).

In this configuration, the heat sinks 221-223 and any flow guiding member 245-247 are arranged such that the cooling medium flows at least at the edges of the electronic

components 231, 232. In other words, the electronic components 231, 232 are at least partially in direct thermal contact with the cooling medium. The enclosure 210 of the electric module may be filled with the cooling medium such that the heat sinks 221-223 and the electronic components 231, 232 (and any supplemental elements located in the enclosure 210) are immersed in the cooling medium. The cooling medium is forced to flow around the electronic components via the arrangement of the heat sinks and the use of flow guiding members. The electric module 200 may also be equipped with a flow generating element, like an impeller, a pump, or other actuating means, to actively generate a flow of the cooling medium from the inlet of the enclosure to its outlet.

Referring to Figure 2b, the electronic components 231, 232, such as IGBTs are arranged (or sandwiched) between the heat sinks 221-223, thereby forming a layered block wherein a layer corresponds alternatively to a heat sink or an electronic component. It will be appreciated that in this specific example, while the heat sink 222 is sandwiched between two electronic components 231, 232, only one face of the (lower) heat sink 221 and only one face of the (upper) heat sink 223 is in contact with an electronic component. These faces may be kept free, thereby providing an additional surface in direct contact with the cooling medium present in the enclosure for enhanced heat dissipation from the electronic components 131, 132, or additional elements may be arranged on these faces for cooling. In addition, other components such as e.g. gate drive units denoted 281 and 282 in Figure 2b may be arranged along the sides of the layered block for cooling. The arrangement of the heat sinks and the flow of the cooling medium within these heat sinks, as described in the present embodiments, allows for the construction of a more compact power converter.

With reference to Figure 3, a heat sink 300 according to an embodiment is described. Figure 3 shows a heat sink 300 comprising a first side 397 for entry of a cooling medium within the heat sink 300 and a second side 399 for exit of the cooling medium from the heat sink 300.

More specifically, the heat sink 300 comprises two base surfaces with a plurality of heat dissipating walls 395 extending from a first base surface 394 to a second base surface 398 such that channels 396 are formed between the base surfaces by the heat dissipating walls 395. The channels (or spaces between the heat dissipating walls 395) are designed to guide the cooling medium from the first side 397 of the heat sink 300 to the second side 399 of the heat sink 300. In other words, the heat sink 300 may be defined as a hollow parallelepiped, and more specifically as a hollow rectangular cuboid, with six rectangular faces of which one face 397 comprises openings or slits 396 for receiving a cooling medium and another face 399 (e.g. opposite to the face 397 receiving the cooling medium) comprises openings or slits (not visible in this view) for outputting the cooling medium. In the specific embodiment shown in Figure 3, the two faces 397, 399 are arranged opposite to each other and the slits are separated by walls 395 extending through the parallelepiped such that channels 396 are formed. At least two faces 394, 398 of the heat sink 300 are adapted for attaching electronic components, e.g. via bounding.

The heat sink 300 may also include an opening, or through-hole 391, for insertion and mounting on a shaft of the electric module, such as for instance the shaft 215 of the electric module 200 described with reference to Figures 2a-b. The through-hole 391 extends preferably from a center of the first base surface 394 to a center of the second base surface 398. The heat sink described with reference to Figure 3 may be used in any of the electric modules in the herein described embodiments.

With reference to Figure 4, an electric module 400 according to another embodiment is described. Figure 4 shows an electric module 400 including an enclosure 410 having an inlet 412 for entry of a cooling medium 440 within the enclosure 410 and an outlet 414 for output of the cooling medium 440. The electric module 400 further includes a plurality of heat sinks 421-423 and a plurality of electronic components 431, 432 which are arranged in thermal contact with the plurality of heat sinks 421-423 within the enclosure 410. The electric module 400 shown in Figure 4 differs from the electric modules 100, 150 and 200 described with reference to Figures la,b and 2a-c in that a side 422b for output of the cooling medium 440 at a first heat sink 422 is axially aligned with a side 423 a for input of the cooling medium 440 at a second heat sink 423. The present configuration is adapted for e.g. vertically arranged electronic components. A possible flow of the cooling medium 440 within the enclosure 410 is illustrated by arrows in Figure 4, wherein the cooling medium flows from the inlet 412 to the outlet 414 through the heat sinks 421-423. The electronic components 431-436 mounted on the heat sinks 421-423 are thereby cooled down.

With reference to Figure 5, an electric module 500 according to yet another embodiment is described. Figure 5 shows an electric module 500 which is equivalent to the electric module 400 described with reference to Figure 4 except that the heat sinks 521-523 are tilted so as to guide the cooling medium 540 from one heat sink to another. The present embodiment is also an alternative to the use of flow guiding members to direct the cooling medium from one heat sink to another, such as described with reference to Figures la,b and Figures 2a-c for instance. Generally, it will be appreciated that two electric modules may be connected together so as to form an electric system. In particular, an outlet of a first electric module may be connected to an inlet of a second electric module. Further, the electric system may be equipped with a pump for causing the cooling medium to flow or circulate from a first electric module to a second electric module.

With reference to Figure 6, a method 6000 of cooling an electric module comprising a plurality of electronic components is disclosed. The method comprises the step 6100 of arranging the electronic components in thermal contact with a plurality of heat sinks within an enclosure and the step 6200 of arranging the plurality of heat sinks such that a cooling medium flows within the enclosure from an inlet of the enclosure to its outlet via the heat sinks. In particular, a first surface of a heat sink is arranged in mechanical contact with an electronic component and a second surface of the heat sink is arranged in mechanical contact with another electronic component. The second surface may be arranged opposite to the first surface.

According to an embodiment, the electronic components may at least partially be immersed in the cooling medium and the flow of the cooling medium from the inlet of the enclosure to its outlet may be zigzag shaped. The cooling medium may flow through the heat sinks such as described with reference to Figures 1-5.

With reference to Figure 7, an arrangement 700 of heat sinks and electronic components according to another embodiment is described. The arrangement 700 shown in Figure 7 may be arranged in an enclosure of an electric module such as shown in any one of Figures 1, 2, 4 and 5. However, for not obscuring the figure, Figure 7 shows only the arrangement 700 of heat sinks 721-723 and electronic components 731, 732 together with a piping system for guiding the cooling medium from one heat sink to another.

More specifically, Figure 7 shows three heat sinks 721-723 and two electronic components 731, 732 arranged as a stack with each one of the two electronic components 731, 732 being sandwiched between two heat sinks. For example, the electronic component denoted 731 is sandwiched between the heat sinks denoted 721 and 722 and the electronic component denoted 732 is sandwiched between the heat sinks denoted 722 and 723. In this configuration, a first surface of the heat sink 722 is arranged in mechanical contact with the electronic component denoted 732 and a second surface, opposite to the first surface, of the heat sink 722 is arranged in mechanical contact with the electronic component denoted 731.

The arrangement 700 further includes a piping system for guiding the cooling medium from one heat sink to another. Figure 7 illustrates a heat sink 723 with an opening 748, e.g. an inlet, for entry of a cooling medium in its cavity. The heat sink 723 forms an enclosure in which the cooling medium enters e.g. via the opening denoted 748. The cooling medium may then exit the heat sink 723 via the bended pipe (or U-shaped pipe) 747 connecting an opening, e.g. an output, of the heat sink 723 to an opening, e.g. an inlet, of another heat sink 722. Similarly, the cooling medium may exit the heat sink 722 via another bended pipe (or U-shaped pipe) 746 connecting an opening, e.g. an output, of the heat sink 722 to an opening, e.g. an inlet, of another heat sink 721. A pipe 745 may be connected to the heat sink 721 for guiding the cooling medium to another arrangement of heat sinks and electronic components or to an exit of the enclosure. The piping system shown in Figure 7 provides also a zigzag-shaped flow of the cooling medium via the heat sinks.

It will be appreciated that the arrangement 700 of heat sinks and electronic components shown in Figure 7 may for a cell of e.g. a valve unit of an HDVC converter and that such a cell may be connected (e.g. in series) to another cell or a plurality of other cells to form the complete valve unit of the HDVC converter. The valve unit may then in its turn be connected to another valve unit to form the HDVC converter.

Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various

combinations with or without other features and elements.

Further, it will be appreciated that the heat sink shown in Figure 3 is only an example and that other kinds of heat sinks may be used in the electric modules described with reference to Figures 1, 2, 4 and 5. Generally, the heat sink may comprise a first side for entry of the cooling medium within the heat sink and a second side for exit of the cooling medium from the heat sink. Different designs and configurations of heat sinks may be envisaged.

Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

Claims

1. An electric module (100) comprising:

an enclosure (110) including an inlet (112) for entry of a cooling medium (140) within the enclosure and an outlet (114) for output of said cooling medium;

a plurality of heat sinks (121-123); and

a plurality of electronic components (131, 132) arranged in thermal contact with the plurality of heat sinks within the enclosure, wherein a first surface (122a) of a heat sink (122) is arranged in mechanical contact with an electronic component (132) and a second surface (122b), opposite to the first surface, of the heat sink is arranged in mechanical contact with another electronic component (131);

wherein the plurality of heat sinks are arranged such that the cooling medium flows via the heat sinks from the inlet of the enclosure to its outlet.

2. The electric module of claim 1, further comprising a flow guiding member (145-147) adapted to guide the flow of the cooling medium from one heat sink to another.

3. The electric module of claim 1 or 2, wherein the heat sinks are tilted so as to guide the cooling medium from one heat sink to another.

4. The electric module of any one of the preceding claims, wherein a heat sink (300) comprises a first side (397) for entry of the cooling medium within the heat sink and a second side (399) for exit of the cooling medium from the heat sink.

5. The electric module of any one of the preceding claims, wherein a heat sink (300) comprises at least two base surfaces with a plurality of heat dissipating walls (395) extending from a first base surface (392) to a second base surface (398) such that channels (396) are formed between the base surfaces by the heat dissipating walls for guiding the cooling medium from a first side (397) of the heat sink to a second side (399) of the heat sink.

6. The electrical module of any one of the preceding claims, wherein the heat sinks and the electronic components are stapled such that at least a first surface (232a) of an electronic component (232) is arranged in thermal contact with a first heat sink (222) and a second surface (232b), opposite to the first surface, of the electronic component is arranged in thermal contact with a second heat sink (223).

7. The electric module of any one of the preceding claims, wherein the heat sinks and any flow guiding member are arranged such that the flow of the cooling medium from an inlet of the enclosure to its outlet is zigzag-shaped.

8. The electric module of any one of claims 1-5, wherein a side (422b) for output of the cooling medium at a first heat sink (422) is axially aligned with a side (423a) for input of the cooling medium at a second heat sink (423).

9. The electric module of any one of the preceding claims, wherein the heat sinks and any flow guiding member are arranged such that the cooling medium flows at least at the edges of the electronic components.

10. The electric module of any one of the preceding claims, wherein the plurality of

electronic components is at least partially submerged in the cooling medium.

11. The electric module of any one of the preceding claims, further comprising a flow generating element to actively generate a flow from the inlet of the enclosure to its outlet.

12. The electric module of any one of the preceding claims, wherein the electronic

components are of at least one of the following types: a capacitor, a gate drive unit, a semiconductor element, an insulated gate bipolar transistor and/or a thyristor.

13. The electric module of any one of the preceding claims, wherein the cooling medium includes liquid and/or gas.

14. The electric module of any one of the preceding claims, wherein the cooling medium has dielectric properties.

15. The electric module of any one of the preceding claims, wherein the electronic

components together define at least part of a power converter, a high voltage direct current converter or a voltage source converter.

16. An electric system comprising at least two electric modules as defined in any one of the preceding claims, wherein an outlet of a first electric module is connected to an inlet of a second electric module.

17. The electric system of claim 17, further comprising a pump for causing the cooling medium to flow from a first electric module to a second electric module.

18. Method (6000) of cooling an electric module comprising a plurality of electronic components, said method comprising:

arranging (6100) the electronic components in thermal contact with a plurality of heat sinks within an enclosure, wherein a first surface of a heat sink is arranged in mechanical contact with an electronic component and a second surface of the heat sink, said second surface being opposite to the first surface, is arranged in mechanical contact with another electronic component; and

arranging (6200) the plurality of heat sinks such that a cooling medium flows within the enclosure from an inlet of the enclosure to its outlet via the heat sinks.

19. Method of claim 18, wherein the flow of the cooling medium from the inlet of the enclosure to its outlet is zigzag shaped.

20. Method of claim 18 or 19, wherein the electronic components are at least partially immersed in the cooling medium.