POWER ELECTRONIC MODULE WITH SUPERCONDUCTING ELECTRICAL TRACKS

Abstract

The present invention relates to a power electronic module (10) comprising: - a substrate (11) made of a ceramic material, - at least one superconducting electrical track (12) arranged on one face of the substrate (11), the superconducting electrical track (12) being made of a material having superconducting properties in a very low temperature range between 0K and 200k, and preferably between 0K and 90K, and more preferably between 20K and 90K and - at least one electronic component (13) electrically connected to the superconducting electrical track (12). Figure for abstract: Figure 1

Description

Title of the invention: POWER ELECTRONIC MODULE WITH SUPERCONDUCTOR ELECTRICAL TRACKS CONDUCTORS

[0001] The present invention relates to an electronic power module with superconducting electrical tracks.

[0002] The invention finds a particularly advantageous, but not exclusive, application in the field of power electronics, in particular with power electronic modules for electrical conversion systems, such as inverters or rectifiers for rotating electrical machines associated with the electrification of aircraft.

[0003] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and those currently in circulation, requiring the implementation of technological solutions to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0004] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of aircraft.

[0005] Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to reduce the environmental footprint of its activity.

[0006] This sustained research and development work covers new generations of aircraft engines, the lightening of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as essential complements to technological progress, aeronautical biofuels.

[0007] Electrification and hybridization of the propulsion chain of future generation aircraft nation require high electrical power to generate the thrust necessary for the aircraft to take off and maintain flight condition. All types of aircraft can be affected, namely vertical takeoff and landing (VTOL) aircraft, short takeoff and landing (STOL) aircraft or conventional takeoff and landing (CTOL) aircraft, commercial or military aircraft, helicopters or drones.

[0008] The development of increasingly powerful electrical systems (in the order of megawatts) for electric or hybrid propulsion requires the design of power electronics with the highest possible specific power.

[0009] Furthermore, the development of numerous propulsion and storage devices based on the use of liquid hydrogen (at a temperature of the order of 20 K) implies the availability of a significant source of cryogenic cooling that can be used for cooling power electronic components. In this context, the use of superconducting materials is an interesting potential route to achieve high power densities and efficiencies while taking advantage of the available cryogenic environment.

[0010] Recent studies on the development of power electronic modules suitable for superconducting systems have shown that a number of semiconductor components have improved their electrical performance at cryogenic temperature compared to room temperature. For example, a MOSFET-Si transistor has a minimum on-state resistance at 77 K reduced by a factor of 5 compared to its value at room temperature. In this context, operation at very low temperatures is envisaged for the production of electrical converters having improved performance in a cryogenic environment.

[0011] Current developments focus on adapting the packaging of power electronic modules to make them compatible with a low-temperature environment. However, existing electronic modules retain thick copper or aluminum metal tracks (typically of the order of 300 pm) with significant electrical resistance. This results in significant localized heating by the Joule effect when they are put into operation.

[0012] The invention aims to effectively remedy this drawback by proposing an electronic power module comprising: - a substrate made of a ceramic material, - at least one superconducting electrical track arranged on one face of the substrate, the superconducting electrical track being made of a material having superconducting properties in a very low temperature range between OK and 200k, and preferably between OK and 90K, and more preferably between 20K and 90K and - at least one electronic component electrically connected to the superconducting electrical track.

[0013] The invention thus makes it possible to take advantage of the superconducting properties of the electrical tracks to create a virtually non-resistive electrical circuit in an adequate low temperature range. The invention thus makes it possible to eliminate energy losses by Joule effect. The invention also makes it possible to significantly reduce the resistance in the on state between the drain and the source of a power semiconductor transistor, which reduces the electrical losses of the component. In addition, the low thermal resistance of certain ceramics at very low temperatures makes it possible to maximize the thermal conductivity of the substrate.

[0014] According to one embodiment of the invention, the superconducting electrical track is covered by a metallization layer on which the electronic component is assembled.

[0015] According to one embodiment of the invention, an insulating layer partially covers the electronic component and the superconducting electrical track to allow a connection between at least one upper electrode of the electronic component to another superconducting electrical track deposited at least partially on the insulating layer and an upper face of the electronic component.

[0016] According to one embodiment of the invention, the superconducting electrical track is made of at least one material belonging to the "Rare Earths-Bary um-Copper-Oxygen" family.

[0017] According to one embodiment of the invention, at least one interface layer is arranged between the substrate and the superconducting electrical track to improve adhesion of the superconducting track to the substrate.

[0018] According to one embodiment of the invention, the substrate is made of a ceramic material containing at least one material chosen from the following materials: sapphire, aluminum oxide (A1O), magnesia (MgO), silicon carbide (SiC), or silicon monoxide (SiO).

[0019] According to one embodiment of the invention, the substrate comprises fins arranged on a lower face intended to come into contact with a cooling fluid.

[0020] According to one embodiment of the invention, the substrate internally comprises at least one channel for circulating a cooling fluid having a cooling fluid inlet and outlet.

[0021] According to one embodiment of the invention, the cooling fluid is chosen from gaseous dihydrogen (H2), liquid dihydrogen (H2), gaseous helium (He), or liquid nitrogen (N2).

[0022] According to one embodiment of the invention, said power electronic module comprises a superconducting connection layer establishing an electrical connection between the superconducting electrical track of the power electronic module and a superconducting wire electrically connected to an electrical load, such as an electric motor.

[0023] According to one embodiment of the invention, the superconducting wire comprises a core acting as a mechanical support for at least one interface layer facilitating deposition of a superconducting layer intended to be in contact with the superconducting connection layer.

[0024] According to one embodiment of the invention, the core of the superconducting wire is arranged partly inside a receiving cavity made in the substrate, the superconducting connection layer overlapping at least partly with the portion of the core of the superconducting wire arranged inside the receiving cavity.

[0025] According to one embodiment of the invention, one end of the superconducting wire is coated with a metal layer, in particular copper or aluminum.

[0026] The present invention will be better understood and other characteristics and advantages will become apparent upon reading the detailed description which follows, comprising embodiments given by way of illustration with reference to the appended figures, presented as non-limiting examples, which may serve to complete the understanding of the present invention and the description of its embodiment and, where appropriate, contribute to its definition, in which:

[0027] [Fig-1] [Fig.l] is a schematic perspective view of an electronic module power device provided with superconducting electrical tracks according to the present invention;

[0028] [Fig.2] [Fig.2] is a cross-sectional view of the electronic module of power of [Fig.l];

[0029] [Fig.3] [Fig.3] is a graphical representation of the evolution, as a function of the temperature, of a thermal conductivity of different materials which can constitute the substrate of an electronic power module according to the invention;

[0030] [Fig.4] [Fig.4] is a graphical representation of the evolution, as a function of the temperature, of a critical current density of a superconducting material constituting electrical tracks of an electronic power module according to the invention;

[0031] [Fig.5a] [Fig.5b] Figures 5a and 5b are schematic sectional views of different embodiments of a cooling circuit of an electronic power module according to the invention;

[0032] [Fig.6] [Fig.6] is a schematic perspective view of an electronic module power according to the invention having electrically connected superconducting tracks strictly to superconducting wires connected to electrical charges;

[0033] [Fig.7] [Fig.7] is a cross-sectional view of the power electronic module of [Fig.6] showing the detail of a connection area between a superconducting track and a superconducting wire connected to an electrical load;

[0034] [Fig.8] [Fig.8] is a perspective view illustrating different layers of a superconducting wire of Figures 6 and 7.

[0035] It should be noted that the structural and / or functional elements common to the different embodiments have the same references. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0036] Figures 1 and 2 are schematic perspective and sectional views of a power electronic module 10 comprising a ceramic substrate 11 made of a ceramic material. The substrate has a mechanical support function for at least one electronic component 13 as well as for superconducting electrical tracks 12. The substrate also has a heat transfer function towards a cooling system. The substrate 11 may also have a function of receiving a protective cover and / or a function of receiving an encapsulation solution.

[0037] The substrate 11 is made of a ceramic material containing at least one material chosen for example from the following materials: sapphire, aluminum oxide (A1O), magnesia (MgO), silicon carbide (SiC), or silicon monoxide (SiO). This list is not exhaustive; these are only examples of potential materials. As illustrated in [Fig. 3], these materials have thermal conductivity properties X (expressed in W.mAK *) that are increased tenfold in a very low temperature range Temp between 20K and 90K.

[0038] The superconducting electrical tracks 12 are arranged on one face of the substrate 11. The superconducting electrical tracks 12 are made of a material having superconducting properties in a very low temperature range between 0K and 200K, and preferably between 0K and 90K, and more preferably between 20K and 90K. The superconducting properties are characterized by the absence or near absence of electrical resistance at very low temperature.

[0039] A superconducting electrical track 12 is preferably made of at least one material belonging to the Rare Earth (RE)-Barium (Ba)-Copper (Cu)-Oxygen (O) family. [Fig. 4] illustrates the fact that the critical current density Dec (expressed in A / mm2) of an electrical track 12 made of Gd (gadolinium)-Ba-Cu-O increases when the temperature Temp is lower than 90K. A superconducting electrical track 12 may be made of several materials chosen from the RE-Ba-Cu-O family.

[0040] The superconducting electrical tracks 12 are screen-printed on the substrate 11. A To this end, masking may be carried out before deposition to ensure correct location of the superconducting electrical tracks 12 on the substrate 11. The superconducting electrical tracks 12 may be produced by pulsed laser ablation deposition known as "PLD" (Pulsed Laser Deposition) or any other technique suitable for depositing superconducting electrical tracks on a substrate 11 made of ceramic. An electrical track 12 extends in a plane in a rectilinear direction or may comprise several rectilinear portions forming non-null angles between them. A superconducting electrical track 12 preferably has a thickness of a few microns.

[0041] As can be seen in [Fig.2], at least one interface layer 19 can be arranged between the substrate 11 and the superconducting electrical track 12 to improve the adhesion of the superconducting track to the substrate 11. The interface layer 19 is for example made of magnesia (MgO).

[0042] The electronic component 13 is electrically connected to the superconducting electrical track 12. The electronic component 13 may for example take the form of a power semiconductor component, such as a power diode or a switching element which may for example be constituted by a transistor (IGBT for "Insulated Gate Bipolar Transistor", HEMT for "High Electron Mobility Transistor", MOSFET for "Metal Oxide Semiconductor Field Effect Transistor" or other) with or without a freewheel diode in parallel.

[0043] The superconducting electrical track 12 is covered by a metallization layer 15 on which the electronic component 13 is assembled. In order to limit the electrical resistance of the assembly, the metallization layer 15 is a layer partially covering the superconducting electrical track 12 only at the location where the electronic component 13 is assembled. The connection between the electronic component 13 and the metallization layer 15 can be made by soldering, sintering, bonding or any other technique suitable for the application. In [Fig.2], a solder zone 16 obtained with a filler metal is arranged between the electronic component 13 and the metallization layer 15 deposited on the superconducting electrical track 12.

[0044] An insulating layer 18 partially covers the electronic component 13 and the superconducting electrical track 12 to allow a connection between at least one upper electrode of the electronic component 13 to another superconducting electrical track 12' deposited at least partially on the insulating layer 18 and an upper face of the electronic component 13. The insulating layer 18 extending at least partially between the superconducting tracks 12 and 12' thus makes it possible to avoid short circuits between two superconducting electrical tracks 12 and 12' connected to different electrical potentials.

[0045] The electronic power module 10 may include a cooling system 20 which may have different shapes. In the embodiment of [Fig.5a], the substrate 11 comprises fins 21 arranged on a lower face intended to come into contact with a cooling fluid 22. The fins 21 are arranged on the face opposite the face carrying the electronic component(s) 13. The fins 21 may be made in one piece with the rest of the substrate 11 or added and fixed to the substrate 11.

[0046] In the embodiment of [Fig.5b], the substrate 11 comprises internally, that is to say in the mass of the substrate 11, at least one channel 25 for circulation of a cooling fluid having an inlet 26 into which the cooling fluid 22 enters according to the arrow F1 and an outlet 27 from which the cooling fluid 22 leaves according to the arrow F2. The shapes of the substrate 11, such as the fins 21 or the channel(s) 25 for circulation of cooling fluid can be obtained by an additive manufacturing process or by machining.

[0047] The cooling fluid 22 is chosen from gaseous dihydrogen (H2), liquid dihydrogen (H2), gaseous helium (He), or liquid nitrogen (N2). According to a particular embodiment, the electronic module 10 can be provided with two cooling systems (with fins and with an internal circulation channel for a cooling fluid).

[0048] In the embodiment of Figures 6 and 7, the power electronic module 10 comprises a superconducting connection layer 30 establishing an electrical connection between the superconducting electrical track 12 of the power electronic module 10 and a superconducting wire 31 electrically connected to an electrical load (not shown), such as an electric motor. The electric motor may be made from superconducting or non-superconducting materials.

[0049] Like the superconducting electrical track 12, the superconducting connection layer 30 is preferably made of at least one material belonging to the TR-Ba-Cu-O family, TR being Rare Earths. The superconducting connection layer 30 may be made of several materials chosen from this family of materials. The superconducting connection layer 30 may be deposited in the same way as the superconducting electrical tracks 12. Masking may be carried out before deposition to ensure correct location of the superconducting connection layer 30 on the substrate 11. The superconducting connection layer 30 may be made by pulsed laser ablation deposition known as "PLD" (Pulsed Laser Deposition) or any other technique for depositing the superconducting connection layer 30 on the substrate 11. The superconducting connection layer 30 preferably has a thickness of a few microns.

[0050] As can be seen in [Fig.8], the superconducting wire 31 comprises a core 32 acting as a mechanical support for at least one interface layer 33 facilitating a deposition of a superconducting layer 35 intended to be in contact with the superconducting connection layer 30. The core 32 can be made of an electrically conductive or non-conductive material, metallic or not, in particular a polymer, a ceramic. Any material having sufficient mechanical properties to have a mechanical support function for the interface layer 33 and the superconducting layer 35 is conceivable. The superconducting layer 35 can be made of the same material as the superconducting connection layer 30.

[0051] At least a portion of the superconducting wire 31 is wrapped by a metal layer 38, in particular copper or aluminum. The metal layer 38 makes it possible to promote solderability of the superconducting wire 31 to connect a load of a circuit if it requires it. In the case where a copper layer 38 is used, it is possible to provide an intermediate silver layer 40 between the superconducting layer 30 and the metal layer 38. In the case, for example, where it is possible to use a load consisting of a superconducting wire without discontinuity, such as a winding wire of a motor for example, the metal layer 38 is not necessary and can therefore be omitted.

[0052] As can be seen in [Fig. 7], the core 32 of the superconducting wire 31 is arranged partly inside a receiving cavity 39 made in the substrate 11. The receiving cavity 39 has a shape complementary to the core 32 which may in particular have a cross-section having a rectangular or round shape. The receiving cavity 39 is made in the thickness of the substrate 11. A height of the receiving cavity 39 is substantially equal to a thickness or a diameter of the core 32, so that an upper face of the core 32 is flush with an upper face of the substrate 11.

[0053] The core 32 may be fixed inside the receiving cavity 39, in particular by gluing or by providing textured surfaces creating adhesion between the core 32 and the bottom of the receiving cavity 39, or by any other fixing technique suitable for holding the core 32 inside the receiving cavity 39. The superconducting connection layer 30 overlaps at least in part with the portion of the core 32 of the superconducting wire 31 arranged inside the receiving cavity 39. Such a configuration makes it possible to limit an overall thickness of the interconnection zone between the superconducting electrical track 12 and the superconducting wire 31.

[0054] This strategy for producing a superconducting connection layer 30 between a superconducting wire 31 and a power electronic module 10 with superconducting tracks thus makes it possible to obtain non-resistive electrical continuity between the power electronics and a connection wire in a very low temperature range. This takes advantage of the superconducting properties and high thermal conductivity of certain materials associated with a very low temperature environment to move towards a superconducting electromechanical assembly.

[0055] The assembly thus formed can be embedded in an encapsulation material making it possible to protect the electronic components against attacks caused by an environment in which the power module is located. Conventionally, the encapsulation material can take the form of a gel, an epoxy resin and / or a coating of an insulating material suitable for being applied to the electronic components. The encapsulation material is also known by the English term "coating".

[0056] A protective cover (not shown) may close the assembly thus formed. The protective cover may carry part of the power terminals and / or the control terminals of the electronic power circuit.

[0057] Of course, the various features, variants and / or embodiments of the present invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

[0058] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms and other variants that may be envisaged by those skilled in the art within the scope of the present invention and in particular all combinations of the different operating modes described above, which may be taken separately or in association.

Claims

Claims

1. Power electronic module (10) characterized in that it comprises: - a substrate (11) made of a ceramic material, - at least one superconducting electrical track (12) arranged on one face of the substrate (11), the superconducting electrical track (12) being made of a material having superconducting properties in a very low temperature range between 0K and 200k, and preferably between 0K and 90K, and more preferably between 20K and 90K and - at least one electronic component (13) electrically connected to the superconducting electrical track (12).

2. Power electronic module according to claim 1, characterized in that the superconducting electrical track (12) is covered by a metallization layer (15) on which the electronic component (13) is assembled.

3. Electronic power module according to claim 1 or 2, characterized in that an insulating layer (18) partly covers the electronic component (13) and the superconducting electrical track (12) to allow a connection between at least one upper electrode of the electronic component (13) to another superconducting electrical track (12') deposited at least partly on the insulating layer (18) and an upper face of the electronic component (13).

4. Power electronic module according to any one of claims 1 to 3, characterized in that the superconducting electrical track (12) is made of at least one material belonging to the "Rare Earths-Barium-Copper-Oxygen" family.

5. Power electronic module according to any one of claims 1 to 4, characterized in that at least one interface layer (19) is arranged between the substrate (11) and the superconducting electrical track (12) to improve adhesion of the superconducting track to the substrate (11).

6. Electronic power module according to any one of claims 1 to 5, characterized in that the substrate (11) is made of a ceramic material containing at least one material chosen from the following materials: sapphire, aluminum oxide (A1O), magnesia (MgO), silicon carbide (SiC), or silicon monoxide (SiO).

7. Power electronic module according to any one of the claims- indications 1 to 6, characterized in that the substrate (11) comprises fins (21) arranged on a lower face intended to come into contact with a cooling fluid (22).

8. Electronic power module according to any one of claims 1 to 7, characterized in that the substrate (11) internally comprises at least one channel (25) for circulation of a cooling fluid having an inlet (26) and an outlet (27) for cooling fluid.

9. Power electronic module according to claim 7 or 8, characterized in that the cooling fluid (22) is chosen from gaseous dihydrogen (H2), liquid dihydrogen (H2), gaseous helium (He), or liquid nitrogen (N2).

10. Power electronic module according to any one of claims 1 to 9, characterized in that it comprises a superconducting connection layer (30) establishing an electrical connection between the superconducting electrical track (12) of the power electronic module (10) and a superconducting wire (31) electrically connected to an electrical load, such as an electric motor.

11. Power electronic module according to claim 10, characterized in that the superconducting wire (31) comprises a core (32) acting as a mechanical support for at least one interface layer (33) facilitating deposition of a superconducting layer (35) intended to be in contact with the superconducting connection layer (30).

12. Power electronic module according to claim 11, characterized in that the core (32) of the superconducting wire (31) is arranged partly inside a receiving cavity (39) made in the substrate (11), the superconducting connection layer (30) overlapping at least partly with the portion of the core (32) of the superconducting wire (31) arranged inside the receiving cavity (39).

13. Power electronic module according to any one of claims 10 to 12, characterized in that one end of the superconducting wire (31) is coated with a metal layer (38), in particular copper or aluminum.

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