Method for manufacturing an electric aircraft engine and vanes for an electric aircraft engine

Abstract

According to the present invention, at least one power electronic component (3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8) is mounted on a circuit carrier (10), particularly a ceramic substrate or a printed circuit board, and the circuit carrier (10) to which at least one power electronic component (3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8) is mounted is embedded in one of a plurality of vanes (11) of an electric aircraft engine (1). This allows for cooling of at least one power electronic component (particularly a MOSFET of an inverter for driving the electric motor of an electric aircraft engine) without additional air cooling or liquid cooling equipment (such as cooling fins or radiators), thereby reducing mass and heat losses.

Description

Detailed Description of the Invention

[0001] The present invention relates to an electric aircraft engine and a civil aircraft comprising at least one such electric aircraft engine. The present invention also relates to a method of manufacturing a vane for an electric aircraft engine.

[0002] The development of fully electric and hybrid electric aircraft equipped with fuel cells and batteries has received significant attention in recent years as this technology can help achieve a zero-emission world. The overall power electronics system is directly related to the control and transmission of energy and thus affects the performance of the operating aircraft.

[0003] U.S. Patent Application Publication No. 2007 / 157597 discloses an aircraft engine comprising at least one fan and a core engine, and at least one generator for generating electrical energy by extracting shaft power from the core engine. The at least one generator is incorporated into at least one strut extending radially in the fan flow channel and is thus disposed within the fan flow channel. In addition to the at least one generator, an electronic assembly for closed-loop power control of the at least one generator can also be incorporated into each strut.

[0004] The electric aircraft engine shown in European Patent Application Publication No. 3998213 includes a fan (rotor), an electric motor for driving the rotation of the fan, and an engine control unit (ECU) for controlling the electric motor. The rotation of the fan provides a main air flow that generates the thrust of the engine, and the ECU is disposed within a volume defined by the main flow.

[0005] Electric motors convert electrical energy supplied by batteries (particularly lithium-ion batteries, which currently lead the market) into mechanical energy to rotate the blades of each fan. Therefore, a DC / AC converter, commonly called an inverter, is required to convert the DC from the battery into AC that is supplied to the electric motor.

[0006] In inverters, all electronic components are typically housed in a single housing or, if not, placed as close together as possible. Distributing electrical components across various structural parts of an aircraft has so far proven incompatible with the task of meeting the requirements for low parasitic rectifier inductance. This is because rectifier inductance is known to increase as the distance between the DC link capacitor and the power module (power switch) increases. However, to enable rapid switching times without generating excessive turn-off overvoltage (voltage spikes), the rectifier inductance of an inverter must be minimized.

[0007] Therefore, the inverter components are assembled in close proximity to each other to substantially reduce parasitic inductance. Two power switches are connected to form a related pair of one phase of the three-phase inverter. The inverter components are generally enclosed by a housing that protects them from damage, heat, or other external elements that could impair the inverter's function. The resulting housing, with all components, has a minimum size that requires the allocation of design space. However, the design space is limited by the aircraft's top-level performance requirements (corresponding to specified ranges of values ​​for geometric and aerodynamic aircraft parameters).

[0008] For example, while smart structural technology is known to be applied to aerospace in the form of smart actuators embedded in or surface-bonded to aircraft wings or helicopter blades, existing structural components of aircraft are not typically used to house electronic components (such as power switches) in inverter circuits.

[0009] Furthermore, insert molding, also known as metal insert molding or plastic insert molding, is generally used to add inserts to injection-molded parts during the molding process, rather than after the part has cured. Typical applications of insert molding in the aerospace industry include aircraft seats, luggage box latches, handles, toilets, and user interface switches.

[0010] However, conventional inverter housings are used to install inverters in typical aircraft. These inverter housings can have various shapes, but they usually always require additional air or liquid cooling. Air cooling systems may utilize heat pipes to transport heat (particularly from stressed switching devices) and cooling fins to dissipate heat, while liquid cooling systems may utilize pressurized liquid (e.g., water) to transport heat to a radiator, from which the heat is discharged out of the system.

[0011] However, the required cooling means (such as air-cooling fins or liquid-cooling channels with liquid-filled radiators) introduce additional mass and / or aerodynamic drag, which obviously leads to increased energy consumption and limits the efficiency of electric aircraft. Furthermore, these cooling means limit the efficient use of the available space in electric aircraft, making it more difficult to meet payload volume requirements.

[0012] However, the power electronic components (e.g., power switches) of power electronic systems (e.g., inverters) used to drive electric aircraft engines have high power losses that require efficient heat dissipation. In particular, inverters, like all semiconductor devices, are sensitive to overheating and generally operate best at lower temperatures. Therefore, power electronic components (e.g., power switches) must be placed in or near areas with good heat dissipation capabilities.

[0013] Therefore, the fundamental objective of the present invention is to provide an electric aircraft engine and a method for manufacturing vanes for an electric aircraft engine that enable a reduction in mass and / or aerodynamic drag and optimal use of available installation space without impairing the electrical performance (particularly switching performance) and, consequently, the efficiency of the power electronic system.

[0014] According to the present invention, this objective is solved by providing a method for manufacturing vanes for an electric aircraft engine having the features of independent claim 1 and an electric aircraft engine having the features of independent claim 16. Advantageous embodiments of the present invention are the subject matter of the dependent claims.

[0015] More specifically, the electric aircraft engine according to the present invention comprises an electric motor, a power electronic system for supplying power to the electric motor, a fan having a plurality of blades mechanically coupled to the electric motor and rotatable about the axis of the engine, and a stator stage having a plurality of vanes at least partially arranged in the inlet or outlet air passage of the fan, wherein the power electronic system comprises a plurality of power electronic components, at least one power electronic component embedded in at least one of the plurality of vanes, at least one power electronic component mounted on a circuit carrier, in particular a ceramic substrate or a printed circuit board, and the circuit board to which the at least one power electronic component is mounted is embedded in one of the plurality of vanes.

[0016] By using existing structural components, namely the vanes of electric aircraft engines, to house power and electronic components, two main advantages are achieved. First, there is no need to provide additional installation space for the power and electronic components. Second, there is no need to provide additional cooling means (such as liquid cooling technology or air-cooled heat sinks in the form of cooling fins), which are costly, cumbersome, and heavy. The embedded power and electronic components have the advantage of high air mass flow rate from the fan and, consequently, high heat transfer from the vanes.

[0017] The heat flow generated in surface-mount electronic components is transported to the printed circuit board material by thermal conduction, where it is more or less geometrically dispersed by the copper layer content. The printed circuit board can then be mounted to the internal metal surface of the vane, which therefore functions as a heat sink for efficient heat dissipation.

[0018] In an advantageous embodiment of the present invention, at least one embedded power electronic component is provided to be a power switch.

[0019] The efficient heat extraction enabled by this invention is particularly advantageous for power switches in inverters, which typically have high power losses.

[0020] In a further particularly advantageous embodiment of the present invention, the power switch is provided to be a power semiconductor switch such as a MOSFET, IGBT, HEMT, or JFET.

[0021] High-power switches require high power dissipation capabilities, which are made possible by the high heat transfer coefficient of the vanes when air passes over the surface of the vanes at a high mass flow rate as a result of the rotation of the engine fan.

[0022] According to yet another aspect of the present invention, the embedded power electronic component is a DC bus bar that supplies power to a power converter.

[0023] By arranging the DC bus bar through the vanes, the advantages of the vanes' high cooling capacity can be reap. Furthermore, this has the advantage of allowing for smaller dimensions of the DC bus bar, which leads to an overall reduction in mass.

[0024] According to yet another preferred embodiment of the present invention, the circuit carrier is either firmly attached to the vane or integrated with the vane.

[0025] In both cases (rigid mounting or integrated design), relative motion between the circuit carrier and the vane is avoided, preventing electrical failures and malfunctions.

[0026] It is particularly preferable that the vanes be filled with embedding resin, which, after curing, ensures secure mounting of the circuit carrier and allows for a reduction in the creepage and clearance distances of the circuit carrier.

[0027] The embedding resin (after curing) not only ensures a secure attachment of the circuit carrier, but also fills the enclosure of the circuit carrier and, in most cases, encapsulates the entire circuit carrier and its electronic components in a protection block.

[0028] In a further preferred embodiment, the power electronic system includes a three-phase inverter for driving an electric motor, and the power electronic components include the power switches and passive components of the inverter.

[0029] Placing the power switches and passive components on the base does not compromise the electrical performance of the three-phase inverter. On the contrary, this arrangement strengthens the inverter components against environmental influences (such as moisture and vibration).

[0030] The passive components of the inverter preferably include at least one DC link capacitor and at least one damping resistor.

[0031] Passive components such as resistors, inductors and capacitors can be integrated into the base structure to ensure optimal cooling (without the need for additional cooling fins).

[0032] A preferred implementation form is a power electronic building block including two power switches in a half-bridge configuration, a gate driver for each switch, and a local DC link capacitor that may have a braking resistor in series. The half-bridge configuration includes high-side and low-side switch positions, and each switch position may consist of a plurality of power switches (MOSFETs or IGBTs). The DC link capacitor is arranged close to the power switch and may have a braking resistor to attenuate possible resonances with other distributed DC link capacitors. Integrating such a power electronic building block into an electric aircraft engine eliminates the need for a housing, thus reducing weight. This also creates additional installation space that can be used, for example, for energy storage means. Such integration also eliminates the cost of wiring the engine to the inverter and reduces the number of required assembly steps.

[0033] Furthermore, the half-bridge is preferably attached to one circuit carrier, and the one circuit carrier to which the half-bridge is attached is embedded in one of a plurality of vanes.

[0034] All components (especially MOSFETs) belonging to one half-bridge (one motor phase) are attached to one circuit carrier embedded in one vane. This is because a symmetric and low-inductance configuration enables equal current sharing and power loss among parallel MOSFETs.

[0035] However, alternatively, the half-bridge can be split to be attached to two circuit carriers, namely a high-side circuit carrier for the high-side power switch and a low-side circuit carrier for the low-side power switch, and a configuration with a low-inductance interconnect between the two circuit carriers can be provided preferably.

[0036] In a high-power converter, a single half-bridge can be distributed across two or more circuit carriers such that an equal number of high-side and low-side switches are placed on each circuit carrier. The circuit carriers are electrically connected in parallel. This allows for the presence of multiple parallel MOSFETs, each with smaller circuit carriers. In this embodiment, additional passive devices may be required to suppress circulating currents.

[0037] In a method for manufacturing a vane for an electric aircraft engine according to the present invention, at least one circuit carrier, particularly a ceramic substrate or printed circuit board, to which at least one power electronic component is attached, is inserted into a negative mold in the shape of a vane, and the vane is then formed from thermoplastic by injection molding and transfer molding.

[0038] By embedding power and electronic components into existing structural components (vanes) using insert molding technology, it becomes unnecessary to house these power and electronic components separately, particularly in the central housing, and to provide additional cooling for them (e.g., by a separate air-cooling or liquid-cooling system), thus saving installation space and weight. This also leads to cost savings.

[0039] Further features and details of the present invention will become apparent from the following description of embodiments based on the claims and drawings. [Brief explanation of the drawing]

[0040] [Figure 1] This is an overall perspective view of the electric aircraft engine according to the present invention, with the surrounding ducts enclosing the working components omitted for ease of explanation. [Figure 2] This figure shows a vane of an electric aircraft engine according to the present invention, into which electronic components of an inverter for driving the motor of the engine are embedded. [Figure 3] This figure shows the vane in Figure 2 with one of the vane's outer layers omitted. [Figure 4] Figure 1 schematically shows an inverter half-bridge embedded in one part of the vane. [Modes for carrying out the invention]

[0041] The electric aircraft engine 1 faces inherent and complex challenges. This is because, in order to generate sufficient thrust to lift an aircraft such as an electric vertical take-off and landing (eVTOL) aircraft, the power-to-weight ratio of the electric aircraft engine 1 must be maintained, and even improved as much as possible.

[0042] The electric aircraft engine 1 includes an electric motor that drives an engine fan 2 to provide thrust to the aircraft. The engine fan 2 includes a plurality of blades 13 radially mounted on a shaft that defines a central axis, and the blades 13 are rotatable about the central axis. This shaft is directly coupled to the rotor of an electric motor that drives the engine fan 2 at a variable speed.

[0043] Referring to Figure 1, an exemplary electric aircraft engine 1 of the present invention has a fan 2 including a fan disk 12. The fan disk 12 has an even or odd number of blades 13 spaced apart from each other in the circumferential direction of the fan disk 12, which is rotated by a shaft driven by an electric motor. The blades 13 are arranged on the fan disk 12 in a symmetrical star configuration when viewed in the direction of the central axis of the electric aircraft engine 1.

[0044] The electric aircraft engine 1 has a duct. The duct defines the longitudinal axis of the engine 1 and is open at the base surface of the engine 1. A fan 2 and an electric motor for driving the fan 2 are installed in the duct, and a plurality of fan blades 13 are configured to rotate in a plane perpendicular to the longitudinal axis of the engine 1. The duct has a favorable effect on the performance of the propulsion system. For ease of explanation, this perimeter duct is omitted in the overall engine in Figure 1.

[0045] Furthermore, the electric aircraft engine 1 includes a stator stage 14 located within a duct in the flow path of the fan 2. The stator stage 14 itself includes a plurality of circumferentially spaced vanes 11. The vanes 11 may direct air into the electric aircraft engine 1 or out of the electric aircraft engine 1. In the former case, the vanes 11 are located in front of the fan 2 (e.g., inlet guide vanes or IGV). In the latter case shown in Figure 1, the vanes 11 are located behind the fan 2 (e.g., outlet guide vanes or OGV). The vanes 11 may have angles that can be manipulated to change the angle of the airflow entering and leaving the electric aircraft engine 1.

[0046] Figure 1 shows an internal view of an electric aircraft engine 1 including a stator stage 14 with a plurality (even or odd) of outlet guide vanes 11 (located downstream of the fan 2) for heat dissipation according to an exemplary embodiment. Referring to Figure 1, the substantially radially extending outlet guide vanes 11 are arranged cylindrically around a fixed central hub 15 so as to be circumferentially spaced apart from one another. As a result, the vanes 11 are arranged on the hub 15 in a symmetrical star configuration when viewed in the direction of the central axis of the electric aircraft engine 1.

[0047] Each of the vanes 11 is radially connected between a fixed central hub 15 (which may correspond to the casing surface of an electric motor) and a corresponding inner surface position of a duct (not shown). Thus, each of the vanes 11 is also a fixed blade relative to the duct (not shown).

[0048] Each vane 11 includes an airfoil shape having a leading and trailing edge formed with a predetermined curvature for the curved side surface and an orientation corresponding to the central rotation axis. In particular, the leading edge of each fixed airfoil vane 11 is located near the trailing edge of the rotating fan blade 13. In the embodiment shown in Figure 1, the arrangement of multiple fixed vanes 11 downstream of the fan blade 13 in a duct (not shown) is configured to effectively eliminate the swirling of the airflow and generate an axial outlet airflow with improved capability in terms of pressure rise.

[0049] The airflow generated by fan 2 continuously exposes the vane 11 to a high mass flow rate of ambient air on its outer surface, providing rapid cooling of the embedded components. The engine configuration is not limited to that shown in Figure 1, and the vane 11 may include an inlet guide vane in addition to or as a substitute for the outlet guide vane.

[0050] The vanes 11, particularly the internal structure of the vanes 11, which are included in the stator stage 14 of the electric aircraft engine 1 shown in Figure 1, form the very essence of the present invention and will therefore be described in more detail below with respect to Figures 2 and 3.

[0051] The electric aircraft engine 1 necessarily includes a power electronic system for supplying power from an onboard power source to an electric motor. In particular, the electric motor may be driven by one or more inverters 9 that convert DC power from a DC power source (e.g., an onboard battery) to AC power in order to drive the electric motor.

[0052] However, the power electronic components of the power electronic system supplying power to the electric motor (particularly the power switches 3a, 3b, 4a, 4b, 5a, and 5b of the inverter 9) have high power losses, which necessitate efficient heat removal. To achieve this, the power electronic components (particularly the power switches 3a, 3b, 4a, 4b, 5a, and 5b of the inverter 9) are embedded in at least one of the multiple vanes 11 of the stator stage of the electric aircraft engine (see Figures 2 and 3). Advantageously, the vane 11 provides a high heat transfer coefficient when air flows through the fan and, consequently, through the vane 11 with a high mass flow rate, at least partially with turbulent characteristics, and comes into direct contact with the outer surface of the vane 11.

[0053] Power is supplied from the power source to embedded power electronic components 3a, 3b, 4a, 4b, 5a, 5b, 6, 7, and 8 via a known electrical connection array. Such an array is also used to conduct current from the embedded power electronic components 3a, 3b, 4a, 4b, 5a, 5b, 6, 7, and 8 to the stator windings or coils when the electric motor drives the fan blades 13.

[0054] Power converters such as inverters are typically designed so that the power semiconductor switches are positioned close to the main DC link capacitor. Therefore, the interconnection of the switches to the capacitor is generally designed to minimize parasitic inductance.

[0055] In contrast, the present invention allows power switches 3a, 3b, 4a, 4b, 5a, and 5b to be distributed across one or more vanes 11, and the main DC link capacitor to be located in a separate central position outside of the multiple vanes 11, without compromising switching performance and thus the efficiency of the power converter.

[0056] In the embodiments shown in Figures 2 and 3, the vane surface is divided into multiple portions adjacent to each other along the longitudinal direction of the vane 11's extension (corresponding to the radial direction of the engine) and shown by different shadows in Figures 2 and 3. Each of these portions of the vane 11 functions as a thermal patch for cooling the power electronic components (in particular, power switches 3a, 3b, 4a, 4b, 5a, 5b) sandwiched between the outer skins 11a, 11b of each portion of the vane 11.

[0057] The thermal patch portions of the vane 11 represent very thin sections of the vane skin 11a, 11b, separated by the intermediate portion of the vane 11, which represents the thicker portion of the vane skin 11a, 11b, where no power electronic components are embedded. These thin-walled intermediate portions of the vane 11 restrict heat flow between two adjacent, thick-walled thermal patch portions of the vane 11. The size of the thermal patch portions of the vane 11 is selected so that each patch can dissipate the same amount of thermal energy, taking into account their respective heat transfer coefficients.

[0058] Preferably, the heat dissipation area of ​​the thermal patch portion is adapted to account for the change in heat transfer coefficient along the span of each vane 11 so that all inverter half-bridges 9a, 9b, and 9c are maintained at approximately the same temperature.

[0059] The power switches 3a, 3b, 4a, 4b, 5a, and 5b of the integrated inverter 9 shown in Figures 2 and 3 represent only an example of power electronic components that can be embedded in the vane 9 to obtain the advantage of superior heat dissipation capabilities. Alternatively, or in addition, other power electronic components, such as DC bus bars supplying power to the ECU of an electric aircraft engine, can also be routed through the vane 11, resulting in the same advantageous effect.

[0060] Unlike conventional power converters in which power electronic components are typically housed in a separate central housing to provide proximity between the power switch and the DC link capacitor and achieve low parasitic rectifier inductance, the present invention here distributes the power electronic components 3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8 to existing structural components (vanes 11) of the electric aircraft engine, thereby eliminating such space-consuming, heavy, and costly solutions.

[0061] To illustrate in more detail the power electronic components 3a, 3b, 4a, 4b, 5a, and 5b embedded in the vane 11, Figure 3 shows the vane 11 of Figure 2 with one of the outer sheaths 11b omitted. As seen here, a three-phase inverter 9 comprising three inverter half-bridges 9a, 9b, and 9c is embedded in the vane 11. Each inverter half-bridge 9a, 9b, or 9c includes two power switches 3a, 3b or 3a, 3b or 5a, 5b, one on the high side and one on the low side. In this case, the power switches 3a, 3b, 4a, 4b, 5a, and 5b are preferably power MOSFETs. However, since power MOSFETs typically operate under harsh conditions of high power dissipation, high junction temperatures can lead to low reliability and ultimately premature failure of the components. Therefore, thermal management is essential in the design of power converters.

[0062] Rather than relying on air-cooled heatsinks and / or liquid cooling systems commonly used for power supplies, the present invention achieves highly efficient heat dissipation by embedding power electronic components (particularly power MOSFETs 3a, 3b, 4a, 4b, 5a, 5b) in at least one of the multiple vanes 11. It should be noted that other power semiconductor switches, such as IGBTs, can be embedded in one or more vanes 11 instead of power MOSFETs. All semiconductor devices dissipate heat to some extent; therefore, thermal considerations are always fundamental in the development of power electronics.

[0063] In this case, all power switches 3a, 3b or 4a, 4b or 5a, 5b of one inverter half-bridge 9a, 9b or 9c are located on one circuit carrier 10 (preferably a ceramic substrate or printed circuit board, PCB). The primary path for heat dissipation in the case of surface mounting (by soldering or sintering) to the circuit carrier 10 is through the circuit carrier 10. Since the circuit carrier 10 is mounted directly to the metal inner surface of the outer sheath 11a, 11b of the vane 11, the power electronic components (especially the power switches 3a, 3b, 4a, 4b, 5a, 6b) benefit from the high cooling capacity of the vane 11 during engine operation.

[0064] To provide excellent heat dissipation capabilities, the circuit carrier 10 does not necessarily need to be rigidly attached to the surface of the metal vane. Alternatively, or in addition, the metal vane 11 can be filled with embedding resin inside, which (after curing) provides secure attachment of the circuit carrier 10. Preferably, since the embedding resin has high thermal conductivity, heat moves to all sides of the vane 11. Furthermore, the embedding resin protects the power electronic components from contamination in accordance with the requirements of IEC 60664-3 and allows for a reduction in creepage distance and clearance distance to achieve low overall stray inductance.

[0065] In another alternative example to the two embodiments described above (attaching the circuit carrier 10 to the metal vane 11 and / or filling the metal vane 11 with embedding resin to fix the circuit carrier 10), one or more circuit carriers 10 can be arranged in a concave shape of the vane 11. The shape of the thermoplastic vane 11 is then formed by injection molding or transfer molding. Structural integrity can be improved by also placing a metal structure in the mold. Preferably, the finished component has high thermal conductivity to allow heat dissipation on all sides of the vane 11. As with the embedding resin solution described above, the power electronic components are protected from contamination by the use of a mold as described in IEC 60664-3, which allows for a reduction in creepage distance and spatial distance (contributing to a reduction in stray inductance and voltage overshoot in each power electronic module).

[0066] As shown in Figures 2 and 3, embedding a three-phase inverter 9 with six power switches 3a, 3b, 4a, 4b, 5a, and 5b into the vanes 11 of a duct fan is a highly complete solution that can be modified by replacing existing vanes with the vanes 11 according to the present invention. As an alternative to Figures 2 and 3, a power converter in which the power switches are distributed among multiple vanes is also conceivable. In both cases (single-vane or multi-vane solutions), the power switches 3a, 3b, 4a, 4b, 5a, and 5b have the advantage of a high air mass flow rate through the engine 1, which provides a high heat transfer coefficient to the outer surface of the vanes 9.

[0067] At the same time, the power switches 3a, 3b, 4a, 4b, 5a, 5b and other passive components 6, 7 of the inverter 9 are arranged such that their electrical performance is not compromised, regardless of their arrangement in one vane 11 or multiple vanes.

[0068] The use of insert molding technology opens up the possibility of integrating power electronic components 3a, 3b, 4a, 4b, 5a, 5b, 6, 7, and 8 into the vane 11 in a simple and cost-effective manner, while simultaneously strengthening these components against environmental influences (humidity, vibration, etc.). In insert molding, all components are fixed in thermoplastic, preventing misalignment, loosening of parts, and loosening of ends.

[0069] Figure 4 shows a schematic of an inverter half-bridge 9a surface-mounted on a circuit carrier 10 (e.g., a PCB or other substrate). The circuit carrier 10 and the inverter half-bridge 9a mounted thereon are embedded in one portion of one vane 11 of an electric aircraft engine. This vane portion acts as a thermal patch to dissipate the heat generated by the power electronic components 3a, 3b, 6, 7, and 8 of the inverter half-bridge 9a as quickly as possible into the airflow generated by the fan. In this way, overheating of the power electronic components 3a, 3b, 6, 7, and 8, which are highly sensitive to temperature peaks, is avoided. As a result, performance degradation of these power electronic components 3a, 3b, 6, 7, and 8, and unstable operation or even failure of the power converter (inverter 9) can be prevented.

[0070] As shown in Figure 4, the power switches 3a and 3b of the inverter 9 (preferably power semiconductor switches such as IGBTs or MOSFETs) are grouped in a half-bridge or phase-leg configuration. Each inverter half-bridge 9a, embedded in one thermal patch portion of one vane 11, preferably has positive and negative DC supply inputs connected to a central capacitor (not shown) via bus bars. Furthermore, each inverter half-bridge 9a has a phase output connected to an electric motor (not shown) of an electric aircraft engine.

[0071] As also shown in Figure 4, each inverter half-bridge 9a has a high-side switch 3a (connected between the positive power line and the output section) and a low-side switch 3b (connecting the output section to the negative power line). All components of one inverter half-bridge 9a are arranged on one circuit carrier 10 (preferably a ceramic substrate or PCB). In the embodiments shown in Figures 2 and 3, the circuit carrier 10 on which the power electronic components (particularly switches 3a and 3b) are mounted is directly attached to the metal inner surfaces of the outer sheaths 11a and 11b of the vanes 11, so that the heat dissipated by these power electronic components (particularly switches 3a and 3b) flows through the material of the circuit carrier 10 (mainly copper in the case of a PCB) and then through the material of the vanes 11 (metal and / or alloy and / or thermal plastic) before being dissipated to the ambient air by convection and radiation outside the vanes 11. Advantageously, the high mass flow rate of air passing through the fan, necessary to generate the required thrust of the electric aircraft, also creates a negligible thermal resistance outside the vane 11 to the ambient air. Therefore, the heat dissipated by the power-electronic components 3a, 3b, 6, 7, and 8 in Figure 4 can be efficiently removed from these heat-sensitive components without the need for costly, space- and heavy additional cooling elements (such as air-cooled fans or liquid cooling channels).

[0072] Furthermore, as shown in Figure 4, the inverter half-bridge 9a surface-mounted on one circuit carrier 10 also has passive components, namely a resistor 7 and a local DC link capacitor 6 in series. The local capacitor 6 and resistor 7 are connected in parallel with the power switches 3a and 3b between the positive and negative DC supply terminals. The local capacitor 6 is preferably selected to have a small capacitance (in the nano-farad range) but a high ripple current capability (typically several amperes). The value of the resistor 7 is selected to critically dampen or over-dampen the oscillations between the local capacitor 6 and the central capacitor (not shown) while avoiding excessive resistive losses.

[0073] The local capacitor 6 and resistor 7 are positioned on the circuit carrier 10 together with the power switches 3a and 3b, embedded along a single thermal patch portion of one vane 11. On the one hand, this ensures the minimization of parasitic rectifier inductance. On the other hand, this also allows the local capacitor 6 and resistor 7 to benefit from the high cooling capacity of the vane 11.

[0074] As enclosed by the dotted line in Figure 4, the gate drivers 8 of the power switches 3a and 3b (e.g., MOSFETs), and optionally associated protection circuits, can also be surface-mounted on the circuit carrier 10, which is also embedded in the same thermal patch portion of one vane 11 (according to Figures 2 and 3), providing the two advantages mentioned above.

[0075] However, the gate driver 8 and associated protection circuits may be surface-mounted on another circuit carrier 10 (preferably a PCB) located on the same or a different vane 11, or even located outside of multiple vanes 11.

[0076] As a further alternative, the previously described half-bridge configuration can be split into one circuit carrier for the high-side switch 3a and one circuit carrier for the low-side switch 3b, both of which are embedded in the same vane 11, preferably with low-inductance interconnects. In this case, the local capacitor 6 and resistor 7 may be located on either the circuit carrier for the high-side switch 3a or the circuit carrier for the low-side switch 3b, or on another circuit carrier in the same vane 11. The gate driver 8 may also be located on the associated high-side or low-side circuit carrier, or on another circuit carrier in the same vane 11.

Claims

1. An electric aircraft engine (1) comprising an electric motor, a power electronic system for supplying power to the electric motor, a fan (2) having a plurality of blades (13) mechanically coupled to the electric motor and rotatable about the axis of the engine, and a stator stage (14) having a plurality of vanes (11) at least partially arranged in the inlet or outlet air passage of the fan (2), wherein the power electronic system includes a plurality of power electronic components (3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8), and at least one power electronic component (3a, 4b, 4a, 4b, 5a, 5b, 6, 7, 8) is embedded in at least one of the plurality of vanes (11), in an electric aircraft engine (1), An electric aircraft engine (1) characterized in that at least one power electronic component (3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8) is mounted on a circuit carrier (10), particularly a ceramic substrate or a printed circuit board, and the circuit carrier (10) to which the at least one power electronic component (3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8) is mounted is embedded in one of the plurality of vanes (11).

2. The electric aircraft engine (1) according to claim 1, wherein the embedded at least one power electronic component is a power switch (3a, 3b, 4a, 4b, 5a, 5b).

3. The electric aircraft engine (1) according to claim 2, wherein the power switch is a power semiconductor switch such as a MOSFET (3a, 3b, 4a, 4b, 5a, 5b) or an IGBT.

4. The electric aircraft engine (1) according to any one of claims 1 to 3, wherein the embedded at least one power electronic component is a DC bus bar that supplies power to a power converter.

5. The electric aircraft engine (1) according to any one of claims 1 to 4, wherein the circuit carrier (10) is firmly attached to or integrated with the vane (11).

6. The electric aircraft engine (1) according to any one of claims 1 to 5, wherein the vane (11) is filled with a filling resin, and after curing, the filling resin ensures secure mounting of the circuit carrier (10) and allows for a reduction in the creepage distance and clearance distance of the circuit carrier (10).

7. The electric aircraft engine (1) according to any one of claims 1 to 6, wherein the power electronic system includes a three-phase inverter (9) for driving the electric motor, and the power electronic components include power switches (3a, 3b, 4a, 4b, 5a, 5b) and passive components (6, 7) of the inverter (9).

8. The electric aircraft engine (1) according to claim 7, wherein the passive components include at least one DC link capacitor (6) and at least one damping resistor (7).

9. The power electronic system is a power electronic building block comprising two power switches (3a, 3b, 4a, 4b, 5a, 5b) in a half-bridge (9a, 9b, 9c) configuration, a gate driver (8) for each switch (3a, 3b, 4a, 4b, 5a, 5b), and a local DC link capacitor (6) having a series damping resistor (7), wherein the half-bridge (9a, 9b, 9c) configuration includes high-side and low-side switch positions, each switch position comprising a plurality of parallel power devices, and the DC link capacitor (6) is positioned in close proximity to the power switches (3a, 3b, 4a, 4b, 5a, 5b) and has a damping resistor (7) to attenuate any resonance that may occur with other dispersed DC link capacitors, according to any one of claims 1 to 8.

10. The electric aircraft engine (1) according to claim 9, wherein the half-bridges (9a, 9b, 9c) are attached to a single circuit carrier (10), and the single circuit carrier (10) to which the half-bridges (9a, 9b, 9c) are attached is embedded in one of the plurality of vanes (11).

11. The electric aircraft engine (1) according to claim 9, wherein the half-bridge (9a, 9b, 9c) is divided to be mounted on two circuit carriers, namely a high-side circuit carrier for high-side power switches (3a, 4a, 5a) and a low-side circuit carrier for low-side power switches (3b, 4b, 5b), preferably comprising a low-inductance interconnection between the two circuit carriers.

12. The electric aircraft engine (1) according to claim 11, wherein the high-side circuit carrier and the low-side circuit carrier are embedded in the same vane (11).

13. Multiple embedded power electronic components (3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8) are sandwiched between the outer layers (11a, 11b) of the vane (11), forming multiple thermal patch portions along the longitudinal range of the vane (11), the thermal patch portions being sized such that all power electronic components (3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8) are maintained at the same temperature with respect to the changing heat transfer coefficient along the span of the vane (11), and are separated from each other by intermediate portions between the outer layers (11a, 11b) of the vane (11) where no power electronic components are sandwiched. The wall thickness of the outer skin (11a, 11b) in the intermediate portion of the vane (11) is smaller than the wall thickness of the outer skin (11a, 11b) in the heat patch portion of the vane (11), thereby suppressing the heat flux between the heat patch portions of the vane (11), as described in any one of claims 1 to 12.

14. The electric aircraft engine (1) according to any one of claims 1 to 13, wherein the engine (1) has a fixed central hub (15) having an even or odd number of vanes (11), and the vanes (11) having at least one embedded power electronic component (3a, 4b, 4a, 4b, 5a, 5b, 6, 7, 8) are arranged on the hub (15) in a symmetrical star configuration.

15. An aircraft comprising at least one electric aircraft engine (1) as described in any one of claims 1 to 14.

16. A method for manufacturing a vane (11) for an electric aircraft engine (1), A method characterized in that at least one circuit carrier (10), particularly a ceramic substrate or printed circuit board, to which at least one power electronic component (3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8) is attached, is inserted into a concave shape of the vane (11), and the vane (11) is then formed from thermoplastic by injection molding or transfer molding.

17. The method according to claim 16, wherein a metal structure for reinforcing the vanes (11) is inserted into the mold before the vanes (11) are formed by injection molding or transfer molding, and preferably the at least one circuit carrier (10) to which the at least one power electronic component (3a, 3b, 4a, 4b, 5a, 5b, 6, 7, 8) is attached is attached to the metal structure before insertion into the mold.

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