WO2016113459A1

WO2016113459A1 - A system provided with an arrangement for thermal management

Info

Publication number: WO2016113459A1
Application number: PCT/FI2015/050956
Authority: WO
Inventors: Mika Lohtander; Leevi PAAJANEN; Tapani SIIVO; Antti JORTIKKA; Hannu YLISIURUA; Emma PAASONEN; Jyrki MONTONEN
Original assignee: Lappeenrannan Teknillinen Yliopisto
Current assignee: Lappeenrannan Teknillinen Yliopisto
Priority date: 2015-01-15
Filing date: 2015-12-30
Publication date: 2016-07-21
Anticipated expiration: 2017-07-15

Abstract

A system provided with an arrangement for thermal management comprises one or more components (101-103) to be thermally managed, a flow-guide plate (104), and an intermediate plate (105). The intermediate plate is between the flow-guide plate and the one or more components. At least one of the mutually facing surfaces of the flow-guide plate and the intermediate plate comprise one or more grooves (106, 107) so that the flow-guide plate and the intermediate plate constitute one or more tubular channels for conducting heat transfer fluid. The intermediate plate comprises apertures for allowing the heat transfer fluid to enter and exit one or more rooms limited by the intermediate plate and the one or more components to be thermally managed. Thus, the heat transfer fluid gets into a direct contact with the one or more components to be thermally managed.

Description

A SYSTEM PROVIDED WITH AN ARRANGEMENT FOR THERMAL MANAGEMENT

Technical field

The disclosure relates generally to thermal management of devices, e.g. power electronic devices. More particularly, the disclosure relates to a system provided with an arrangement for thermal management and comprising one or more components to be thermally managed.

Background

Various devices comprise heat generating components which have to be thermally managed in order to enable proper operation of the devices. A device can be for example a power electronic device which comprises electronic components for modifying electrical currents and voltages. When an electronic component conducts electrical current, heat is produced by the internal resistance of the electronic component. In electronic components which are used as switches, the momen- tary heating rate can be especially high during transitions between conductive and non-conductive states. For example, in a transition from the conductive state to the non-conductive state, the internal resistance may have become quite high while the current has not yet decreased. Thus, the heating rate is partly proportional, linearly or non-linearly, to the switching frequency. For another example, a device can be a computer system which comprises one or more processors and one or more memory circuits. In processors and memory circuits, the heating rate is linearly or non-linearly proportional to the clock frequency and to the voltage level being used. Increasing the clock frequency means that the internal capacitances of a processor or memory circuit have to be charged and discharged at a higher rate, and thus electrical currents which produce heat in the internal resistances are increased too. Furthermore, increasing the clock frequency or the above-mentioned switching frequency increases the internal effective resistances, and thereby also the heating rate, due to the skin effect.

An arrangement for thermal management of a heat generating component, e.g. a power electronic component or a processor, comprises typically a heat-sink ele- ment against which the component is attached so that the component is against a surface of the heat sink element. The heat-sink element may comprise cooling fins for conducting heat to the ambient air and/or channels for conducting heat transfer fluid, e.g. water. A thermal management arrangement of the kind described above is, however, not free from challenges. One of the challenges relates to the joint between the component to be thermally managed and the heat-sink element. In order to provide a sufficient and reliable thermal management, the thermal resistance of the above-mentioned joint should be as low as possible. Furthermore, the heat conductivity per unit area W/Km² can be unevenly distributed over the contact area between the component and the heat-sink element. The distribution of the heat conductivity may have a stochastic nature, and a worst case situation takes place when a local minimum of the heat conductivity happens to be in a hot spot of the contact surface of the component. The heat conduction from the component to the heat-sink element can be, at least in some extend, improved by us- ing suitable gap filler material, e.g. silicone paste, between the component and the heat-sink element but the ageing of the gap filler materials may be problematic.

Summary

The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention. In accordance with the invention, there is provided a new system that is provided with an arrangement for thermal management. The thermal management may include for example cooling an object, warming an object, keeping an object at a desired temperature, or otherwise thermally managing an object.

A system according to the invention comprises: - one or more components to be thermally managed, e.g. one or more power electronic components, one or more processors, or one or more other components,

- a flow-guide plate, and - an intermediate plate between the flow-guide plate and the one or more components to be thermally managed.

At least one of mutually facing surfaces of the above-mentioned flow-guide plate and the intermediate plate comprise one or more grooves so that the flow-guide plate and the intermediate plate constitute one or more tubular channels for con- ducting heat transfer fluid. The intermediate plate comprises apertures, i.e. through holes, for allowing the heat transfer fluid to flow between the one or more tubular channels and one or more rooms limited by the intermediate plate and the one or more components to be thermally managed. Thus, the heat transfer fluid gets into a direct contact with the one or more components to be thermally man- aged. Therefore, the thermal contact between the one or more components to be thermally managed and the intermediate plate does not play such a role as in a case where the heat transfer fluid is not in a direct contact with the components.

The system further comprises a pump comprising at least one rotary part for generating pressure so as to circulate the heat transfer fluid through the tubular chan- nels. The above-mentioned flow-guide plate comprises a cavity arranged to constitute a pump chamber which contains the at least one rotary part of the pump.

In a system according to an exemplifying and non-limiting embodiment of the invention, the components comprise grooves on surfaces that are against the intermediate plate. In this exemplifying case, the grooves of the components constitute at least part of the above-mentioned one or more rooms where the heat transfer fluid can flow in contact with the components. Since the components comprise the grooves, the heat conductive surfaces of the components which are in contact with the heat transfer fluid are greater than in a case where the corresponding surfaces of the components are flat. Yet furthermore, the grooves can be designed so that the heat transfer fluid is effectively directed to hot spots of the above-mentioned heat conductive surfaces. It is worth noting that in many cases the thermal management can be either single phase thermal management or two-phase thermal management where the heat transfer fluid is vaporized or condensed when being in contact with the components to be thermally managed. A number of exemplifying and non-limiting embodiments of the invention are described in accompanied dependent claims.

Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of spe- cific exemplifying and non-limiting embodiments when read in connection with the accompanying drawings.

The verbs "to comprise" and "to include" are used in this document as open limitations that neither exclude nor require the existence of unrecited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.

Brief description of the figures

Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which: figures 1 a, 1 b, 1 c, 1 d, and 1 e illustrate a system according to the prior art as a prelude to a description of a system according to an exemplifying and non-limiting embodiment of the invention, and figures 2a, 2b, 2c, and 2d illustrates a system according to another exemplifying and non-limiting embodiment of the invention.

Description of the exemplifying embodiments

Figure 1 a shows a top view of a system according to the prior art as a prelude to a description of a system according to an exemplifying and non-limiting embodiment of the invention. Figure 1 b shows a view of a section taken along a line A-A shown in figure 1 a. The section plane is parallel with the yz-plane of a coordinate system 190. The system comprises heat generating components 101 , 102, and 103 to be thermally managed. In this exemplifying and non-limiting case, each of the com- ponents 101 -103 is a semiconductor module comprising a baseplate 1 15, a cover element 1 16 attached to the baseplate, and at least one semiconductor element 1 17 in a room limited by the baseplate and the cover element. The cover element 1 16 can be permanently attached to the baseplate 1 15 so that detaching the cover element from the baseplate requires material deformations. The baseplate 1 15 and the cover element 1 16 constitute advantageously airtight encapsulation for the at least one semiconductor element 1 17, i.e. the room containing the at least one semiconductor element 1 17 is advantageously hermetic. The at least one semiconductor element 1 17 is in a heat conductive relation with the baseplate 1 15 for example so that there is a thermally conductive and electrically insulating structure 1 18 having mechanical contacts with the semiconductor element 1 17 and with an inner surface of the baseplate 1 15 facing towards the semiconductor element. The thermally conductive and electrically insulating structure 1 18 can be for example silicon or other suitable flexible material which provides a sufficient thermal conductivity from the semiconductor element to the baseplate. The semiconductor el- ement 1 17 may comprise a controllable semiconductor element such as for example a bipolar junction transistor "BJT", an insulated gate bipolar transistor "IGBT", a thyristor, a gate-turn-off thyristor "GTO", a metal-oxide-semiconductor field-effect transistor "MOSFET", an Integrated Gate-Commutated Thyristor "IGCT", or an Injection-Enhanced Gate Transistor "IEGT". Furthermore, the semiconductor ele- ment can be a combination of a controllable semiconductor element and an anti- parallel diode. It is also possible that the semiconductor element is a mere diode. Furthermore, the semiconductor module comprises electrical main terminals for conducting the main electrical current or currents of the semiconductor module. The semiconductor module may further comprise one or more control terminals for controlling a controllable semiconductor element, e.g. an IGBT. In figures 1 a and 1 b, one of the main terminals is denoted with a reference number 1 19 and one of the control terminals is denoted with a reference number 120. The system illustrated in figures 1 a and 1 b comprises an arrangement for thermal management of the components 101 -103. The thermal management arrangement comprises a flow-guide plate 104 and an intermediate plate 105 that is between the flow-guide plate and the components 101 -103 so that there are mechanical contacts between the flow-guide plate 104 and the intermediate plate 105 and between the components and the intermediate plate. Figure 1 c shows a top view of the flow-guide plate 104, and figure 1 d shows a top view of the intermediate plate 105. In figures 1 c and 1 d, the locations of the components 101 -103 are depicted with dashed lines. Furthermore, the line A-A corresponding to the section view shown in figure 1 b is presented in also figures 1 c and 1 d. At least one of mutually facing surfaces of the flow-guide plate 104 and the intermediate plate 105 comprise one or more grooves so that the flow-guide plate and the intermediate plate constitute one or more tubular channels for conducting heat transfer fluid. In this exemplifying case, the flow guide plate 104 comprises the above-mentioned grooves. Two of the grooves are denoted with reference numbers 106 and 107 in figures 1 b and 1 c. It is however also possible that the intermediate plate 105 comprises grooves so that the flow-guide plate and the intermediate plate constitute the tubular channels. Furthermore, it is also possible that both the flow guide plate 104 and the intermediate plate 105 comprise grooves. The intermediate plate 105 comprises apertures, i.e. through holes, for allowing the heat transfer fluid to flow between the above-mentioned tubular channels and one or more rooms limited by the intermediate plate and the components to be thermally managed. Two of the apertures are denoted with reference numbers 108 and 109 in figures 1 b and 1 d. In figure 1 b, the flow of the heat transfer fluid is illustrated with dashed line arrows. The heat transfer fluid can be for example liquid such as water, gas such as air, liquid carrying solid particles, or slurry. It is worth noting that the heat transfer fluid or some components of it can be such material that is in some situations, e.g. when the temperature is low, in non-fluidic form.

In the exemplifying system illustrated in figures 1 a-1 d, the components 101 -103 comprise first grooves on surfaces which are against the intermediate plate 104. In this exemplifying case, the baseplates of the components comprise the first grooves. A bottom view of the component 102 is shown in figure 1 e. The grooves of the components constitute the above-mentioned rooms limited by the intermediate plate and the components to be thermally managed. Two of the grooves of the component 102 are denoted with reference numbers 1 13 and 1 14 in figures 1 b and 1 e. It is also possible that the intermediate plate 104 comprise second grooves on the surfaces which are against the components 101 -103. Furthermore, it is also possible that both the components 101 -103 and the intermediate plate 104 comprise grooves on the surfaces which are against each other.

In the exemplifying system illustrated in figures 1 a-1 e, there are three components 101 -103 to be thermally managed and the tubular channels constituted by the flow-guide plate 104 and the intermediate plate 105 are configured to distribute the heat transfer fluid to the components. The flow of the heat transfer fluid is illustrated with dashed line arrows in figure 1 c. The above-mentioned tubular channels constitute a piping system between the components 101 -103 so that there is no need for a separate piping system for distributing the heat transfer fluid. Figure 2a shows a top view of a system according to an exemplifying and non- limiting embodiment of the invention. Figure 2b shows a view of a section taken along a line A-A shown in figure 2a. The section plane is parallel with the yz-plane of a coordinate system 290. The system comprises heat generating components

201 and 202 to be thermally managed. The system comprises an arrangement for thermal management of the components 201 and 202. The thermal management arrangement comprises a flow-guide plate 204 and an intermediate plate 205 that is between the flow-guide plate and the components 201 and 202 so that there are mechanical contacts between the flow-guide plate 204 and the intermediate plate 205 and between the components and the intermediate plate. Figure 2c shows a top view of the flow-guide plate 204, and figure 2d shows a top view of the intermediate plate 205. In figures 2c and 2d, the locations of the components 201 and

202 are depicted with dashed lines. Furthermore, the line A-A corresponding to the section view shown in figure 2b is presented in also figures 2c and 2d. In this exemplifying case, the flow guide plate 204 comprises grooves on the surface that is against the intermediate plate 205 so that the flow-guide plate and the intermediate plate constitute tubular channels for conducting heat transfer fluid. In figures 2a and 2b, one of the grooves of the flow guide plate 204 is denoted with a refer- ence number 206. It is also possible that the intermediate plate 205 comprises grooves so that the flow-guide plate and the intermediate plate constitute the tubular channels. Furthermore, it is also possible that both the flow guide plate 204 and the intermediate plate 205 comprise grooves. The intermediate plate 205 compris- es apertures, i.e. through holes, for allowing the heat transfer fluid to flow between the above-mentioned tubular channels and rooms limited by the intermediate plate and the components 201 and 202 to be thermally managed. One of the apertures is denoted with a reference numbers 208 in figures 2d. In figure 2a, the flow of the heat transfer fluid is illustrated with dashed line arrows. The exemplifying system illustrated in figures 2a-2d comprises a pump 210 for generating pressure so as to circulate the heat transfer fluid through the above- mentioned tubular channels and the rooms limited by the intermediate plate 205 and the components 201 and 202. The pump comprises a rotary part 21 1 for generating the pressure and the flow-guide plate 204 comprises a cavity 212 arranged to constitute a pump chamber which contains the rotary part of the pump. In this exemplifying case, the pump 210 is centrifugal pump. It is also possible that the pump is a gear pump or a Root's pump in which cases there are two rotary cooperating parts in the pump chamber.

The specific examples provided in the description given above should not be con- strued as limiting the applicability and/or the interpretation of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.

Claims

What is claimed is:

1 . A system comprising:

- one or more components (101 -103, 201 , 202) to be thermally managed,

- a flow-guide plate (104, 204), and - an intermediate plate (105, 205) between the flow-guide plate and the one or more components to be thermally managed, wherein at least one of mutually facing surfaces of the flow-guide plate and the intermediate plate comprise one or more grooves (106, 107, 206) so that the flow- guide plate and the intermediate plate constitute one or more tubular channels for conducting heat transfer fluid, and the intermediate plate comprises apertures (108, 109, 208) for allowing the heat transfer fluid to flow between the one or more tubular channels and one or more rooms limited by the intermediate plate and the one or more components to be thermally managed, characterized in that the system further comprises a pump (210) comprising at least one rotary part (21 1 ) for generating pressure so as to circulate the heat transfer fluid through the tubular channels, and the flow-guide plate comprises a cavity (212) arranged to constitute a pump chamber which contains the at least one rotary part of the pump.

2. A system according to claim 1 , wherein the tubular channels constituted by the flow-guide plate and the intermediate plate are configured to distribute the heat transfer fluid to the components to be thermally managed.

3. A system according to claim 1 , wherein the pump is one of the following: a centrifugal pump, a gear pump, a Root's pump.

4. A system according to any of claims 1 -3, wherein at least one of the components comprises first grooves (1 13, 1 14) on a surface being against the intermedi- ate plate, the first grooves constituting at least part of the one or more rooms limited by the intermediate plate and the one or more components to be thermally managed.

5. A system according to any of claims 1 -4, wherein the intermediate plate comprises second grooves on a surface being against the one or more components, the second grooves constituting at least part of the one or more rooms limited by the intermediate plate and the one or more components to be thermally managed.

6. A system according any of claims 1 -5, wherein at least one of the one or more components to be thermally managed is a semiconductor module comprising a baseplate (1 15), a cover element (1 16) attached to the baseplate, at least one semiconductor element (1 17) in a room limited by the baseplate and the cover el- ement, the semiconductor element being in a heat conductive relation with the baseplate and the baseplate being against the intermediate plate.

7. A system according to claim 6, wherein the baseplate comprises grooves on a surface being against the intermediate plate, the grooves of the baseplate constituting at least part of the one or more rooms limited by the intermediate plate and the one or more components to be thermally managed.

8. A system according to claim 6 or 7, wherein the semiconductor element comprises one of the following: a bipolar junction transistor "BJT", a diode, an insulated gate bipolar transistor "IGBT", a thyristor, a gate-turn-off thyristor "GTO", a metal-oxide-semiconductor field-effect transistor "MOSFET", an Integrated Gate- Commutated Thyristor "IGCT", an Injection-Enhanced Gate Transistor "IEGT".