CN112217308A - Power system for hypersonic operation - Google Patents

Abstract

The present invention relates to an electrical power system for hypersonic operation. A power system has an electrical power system with a stator having a plurality of poles, each pole having a conductive winding that may surround the corresponding pole and may be configured to generate a magnetic field, and a rotor that may be configured to rotate in response to the magnetic field generated by the stator. At least one of the conductive windings may be insulated with an insulating material configured to conduct heat from the at least one conductive winding when operated at temperatures above 600 ℃.

Description

Power system for hypersonic operation

Cross-referencing

The present application claims priority from U.S. provisional patent application No. 62/872,827 entitled "ELECTRIC POWER SYSTEM FOR hybrid OPERATION" filed on 11/7/2019, and the entire disclosure of which is incorporated herein by reference.

Technical Field

The subject matter described herein relates to power systems that operate at hypersonic speeds.

Background

Electric power systems or motors generate power by utilizing electrical properties and magnetic forces. A typical power system comprises inter alia a stator and a rotor. The stator includes a magnetic material, a conductive winding coupled to a magnetic circuit, and the like to generate a magnetic field when the rotor is rotated. The rotor may similarly include an electromagnetic material including poles, permanent magnets fixed to the rotor, etc., that cause the rotor to rotate based on one or more magnetic fields formed by the stator. The rotor may then be coupled to a shaft, armature, or the like, which performs the work as desired by the user. The shaft includes bearing surfaces that are lubricated to reduce wear. At the same time, the inefficiencies of the stator and rotor in converting magnetic energy to mechanical energy are dissipated from the motor to the surrounding environment in the form of heat.

For power systems used in aerospace applications that require operation at high supersonic speeds, there is a need for high power density motors and generators capable of operating at temperatures up to and above 600 ℃. Thus, these motors may need to efficiently supply high voltage functionality with materials and systems that do not degrade or lose significant efficiency due to elevated temperatures.

For example, motor power density may be limited by the ability to remove heat generated from machine losses or other inefficiencies. Sources of losses include joule heating of conductor materials associated with AC (alternating current) and DC (direct current), losses associated with eddy currents and hysteresis in structures through which electromagnetic fields pass, and mechanical losses associated with friction between moving parts and fluids. A 100kW motor, which is considered to be approximately 85-90% efficient, can manage 10-15kW of heat. To manage heat, it may be necessary to remove the heat from the motor. If heat is not removed, the machine temperature rises, thus increasing conductor and structure temperatures, creating more losses and higher temperatures, all of which ultimately lead to heat loss and machine failure. Typically, the heat is removed to the ambient environment. However, when the motor is operated in an environment already at 600 ℃, the conventional heat transfer method is not sufficient to operate efficiently.

As another example, electric machines typically use permanent magnets or permanent magnet material secured to the rotor to generate a magnetic field that generates a force that rotates the rotor. However, the energy density of the high-temperature permanent magnet is greatly reduced, resulting in performance degradation.

As yet another example, bearing systems in electric machines often use lubricating oil to reduce wear on the bearing surfaces. There are not only material limitations for lubricants when operating at temperatures in excess of 600 ℃, but additional design limitations when utilizing lubrication subsystems that supply lubrication oil to bearings in limited aerospace settings.

Disclosure of Invention

In one or more embodiments, a power system may be provided that includes an electrical power system. The power system may include a stator having a plurality of poles, each pole having a conductive winding surrounding a corresponding pole and configured to generate a magnetic field, and a rotor configured to rotate in response to the magnetic field generated by the stator. At least one of the conductive windings may be insulated with an insulating material configured to conduct heat from the at least one conductive winding when operated at temperatures greater than 600 ℃

In one or more embodiments, a power system may be provided that includes an electrical power system with a stator having a plurality of poles, each pole having a conductive winding surrounding a corresponding pole and configured to generate a magnetic field. The conductive winding may be enclosed within a first cavity of the insulator. The power system may also include a rotor configured to rotate in response to the magnetic field generated by the stator. The insulator may be fluidly connected to the cooling system to receive the liquid metal from the cooling system and to transfer the liquid metal to the cooling system after the liquid metal conducts at least some heat from at least one of the conductive windings.

In one or more embodiments, a method of forming an electric machine for a power system is provided that includes forming a conductive winding encased by an insulator in a three-dimensional printing device. The stator may be magnetically coupled to the rotor by wrapping conductive windings around poles of the stator and providing current to the conductive windings to induce current in the rotor.

Technical solution 1. a power system, comprising:

an electrical power system comprising:

a stator having a plurality of poles, each pole having a conductive winding surrounding a corresponding pole and configured to generate a magnetic field; and

a rotor configured to rotate in response to a magnetic field generated by the stator;

wherein at least one of the conductive windings is insulated with an insulating material configured to conduct heat from the at least one conductive winding when operated at temperatures above 600 ℃.

Solution 2. the power system of any of the preceding solutions, wherein the at least one of the conductive windings comprises an insulator formed from the insulating material and comprises a cavity to receive a conductive element.

Solution 3. the power system of any of the preceding claims, wherein the insulating material is a ceramic-based material comprising at least one of alumina, zirconia, magnesia, a macor composite, mullite, or mica glass.

Technical solution 4. the power system according to any preceding technical solution, wherein the rotor does not include a permanent magnet.

The power system of any of the preceding claims, wherein the cavity is a first cavity and the insulator further comprises a second cavity configured to provide a fluid flow path for fluid conducting at least some heat from the at least one conductive winding.

Solution 6. the power system of any of the preceding claims, further comprising a cooling system fluidly coupled to the insulator and configured to deliver a fluid to at least one of a heat exchanger or a heat sink.

The power system of any of the preceding claims, wherein the heat exchanger is configured to receive the fluid that receives heat from the at least one conductive winding and to transfer the heat to fuel within the fuel system.

The power system of any of the preceding claims, wherein the fluid is one of supercritical carbon dioxide, a liquid alkali metal, or a metal halide.

Solution 9. the power system of any of the preceding claims, wherein the at least one of the conductive windings is at least one of copper, silver, nickel-plated copper, or silver-plated copper.

Solution 10. the power system of any of the preceding claims, further comprising a magnetic circuit electrically coupled to windings of first and second opposing poles of the plurality of poles of the stator and comprising a first switch connected in parallel to a second switch.

Technical solution 11. the power system according to any preceding technical solution, further comprising:

a drive shaft disposed through and coupled to the rotor to rotate therewith; and

a bearing system coupled to the drive shaft, the bearing system comprising:

a bearing housing receiving at least one bearing pad on an interior surface of the bearing housing, the bearing pad including at least one opening; and

a pressurized air supply system within the bearing housing and configured to provide pressurized air through at least one opening in the bearing pad.

Claim 12. the power system of any of the preceding claims, wherein the bearing system further comprises a damping system comprising an outer damping pocket disposed within the bearing housing, an inner damping pocket disposed within the bearing housing, and a clearance pocket disposed between the inner and outer damping pockets, wherein the damping system is configured to damp radial forces induced by the drive shaft.

Technical solution 13. a power system, comprising:

an electrical power system comprising:

a stator having a plurality of poles, each pole having a conductive winding surrounding a corresponding pole and configured to generate a magnetic field, the conductive winding encased within a first cavity of an insulator; and

a rotor configured to rotate in response to the magnetic field generated by the stator;

the insulator fluidly connected to a cooling system to receive liquid metal from the cooling system and to convey the liquid metal to the cooling system after the liquid metal conducts at least some heat from at least one of the conductive windings.

Solution 14. the power system of any of the preceding claims, wherein the insulator comprises an insulating material, the insulating material being a ceramic-based material comprising at least one of alumina, zirconia, magnesia, a macor composite, mullite, or mica glass.

Solution 15. the power system of any of the preceding claims, wherein the at least one of the conductive windings is at least one of copper, silver, nickel-plated copper, or silver-plated copper.

The power system of any preceding claim, wherein the rotor does not include permanent magnets.

A method of forming an electric machine for a powertrain, comprising:

forming a conductive winding encased by an insulator with a three-dimensional printing device;

the stator and rotor are magnetically coupled by wrapping the conductive windings around poles of the stator and providing current to the conductive windings to induce current in the rotor.

The method of any of the preceding claims, wherein the conductive winding comprises an end winding within the insulator.

Claim 19 the method of any of the preceding claims, wherein the insulator comprises a first cavity separated from a second cavity by a dividing wall.

The method of any of the preceding claims, wherein the first cavity comprises the conductive winding and the second cavity is configured to receive a fluid.

Drawings

The subject matter of the invention will be better understood by reading the following description of non-limiting embodiments with reference to the attached drawings, in which:

FIG. 1 is a schematic illustration of a power system according to an embodiment;

FIG. 2 is a front perspective view of a motor of the power system according to one embodiment;

FIG. 3 is a rotor and a stator of an electric machine according to an embodiment;

FIG. 4 is a schematic diagram of a magnetic circuit of an electric machine according to an embodiment;

fig. 5 illustrates a front perspective view of an insulated conductive winding of an electric machine in accordance with an embodiment;

fig. 6 illustrates a front perspective view of an insulated conductive winding of an electric machine in accordance with an embodiment;

FIG. 7 is a schematic diagram of a power system using an electric machine according to an embodiment;

FIG. 8 is a schematic diagram of a cooling system using an electric machine according to an embodiment;

FIG. 9 is a schematic diagram of a cooling system for an electric machine according to an embodiment;

FIG. 10 is a front cut-away perspective view of a bearing system for an electric machine according to one embodiment;

FIG. 11 is a partial front perspective view of a bearing system for an electric machine according to one embodiment;

FIG. 12 is a schematic view of a bearing system for an electric machine according to an embodiment; and

FIG. 13 is a block flow diagram of a method of forming an electric machine for a power system, according to an embodiment.

Detailed Description

The embodiments described herein provide a power system for a powered system that operates at hypersonic speeds. Power systems include switched reluctance motors, which may not utilize permanent magnets or permanent magnet materials. Alternatively, the stator and rotor include salient poles that interact to rotate the rotor, and the salient poles of the stator are wound with insulated conductive windings. Specifically, an insulating material surrounds the conductive winding to provide electrical insulation, prevent stray currents, and transfer heat from the conductive winding. The insulating material may optionally further include a flow lumen or channel to provide a fluid flow path for a fluid to conduct heat from the conductive elements of the conductive winding and transfer the heat for use in association with other systems of the power system. In this manner, the power system may also include an integrated thermal management system that transfers heat from the power system to reduce thermal fatigue of components of the power system while improving efficiency. The power system may also include a bearing system for a shaft rotated by the rotor, including a gas bearing system. By utilizing readily available high pressure gas as a bearing lubricant, the need for lubricating oil and accompanying lubricating oil systems can be reduced or eliminated. As a result of these combined systems, an improved power system is provided that is efficient, wear resistant, and capable of operating at high temperatures (e.g., temperatures in excess of 600 ℃).

FIG. 1 shows a schematic diagram of a power system 100. The power system 100 may be an aerospace system, such as a jet, a fighter, or other aircraft that may reach high supersonic speeds. In one example, the hypersonic speed is five times the speed of sound (mach 5) or higher.

The power system 100 includes an electrical power system 102, which is an electrical machine that powers a drive shaft 114, a fuel system 104 that supplies fuel to an engine (not shown), and a cooling system 106 that transfers heat from the electrical power system, including introducing heat into the fuel of the fuel system 104. In one example, the engine is a turbojet engine of an aircraft. Although the power system 100 also includes other systems such as a steering system, a communication system, etc., they are not described herein.

Fig. 2 and 3 illustrate a power system 102 that may be considered an electrical machine. The power system 102 includes a housing 108 that houses a stator 110 and a rotor 112, the rotor 112 being coupleable to a drive shaft 114. The rotor 112 may be within the stator 110; however, in other example embodiments, the stator 110 may be within the rotor 112. Specifically, the rotor 112 may be concentrically disposed relative to the stator 110. In one embodiment, the rotor 112 does not use or have permanent magnets to cause rotation of the rotor 112. In particular, at high temperatures, including above 600 ℃, a significant effect on the energy density of the permanent magnet occurs. This effect results in a significantly reduced residual field, making the use of permanent magnets impractical and therefore undesirable.

As shown in fig. 3, in one example, the stator 110 and rotor 112 arrangement is that of a switched reluctance electric motor. Specifically, the stator 110 includes a plurality of poles 116a-f of corresponding electromagnets, which are typically salient poles, which in one example extend from a stator yoke 117. In this example, six poles 116a-f are spaced apart from each other around the circumference of the stator 110 and extend inward toward the rotor 112. Each pole 116a-f may include a sidewall 118a-f and terminate in an arcuate end 120a-f to allow rotation of the centrally located rotor 112 within the stator 110. The stator poles and yokes may be stamped from 35a360 non-oriented electrical steel sheet, which may include cobalt steel, such as hiperco or other similar steels having a greater saturation flux density than silicon steel. Each pole 116a-f has at least one corresponding conductive winding 122a-f wound around and at least partially surrounding each side wall 118 a-f. In one example, each conductive winding 122a-f is insulated. Specifically, each conductive winding may include a ceramic-based insulating material that at least partially surrounds a conductive material (which in one example is metallic). Alternatively, in another embodiment, a ceramic based insulating material is positioned adjacent each of the conductive windings 122a-f, including, in one example, in the triangular regions or spaces between the stator poles 116a-f outside the rotor 112.

In one example, each conductive winding is manufactured in a method as described with respect to the conductive windings shown in fig. 5 and 6. In one such example, the ceramic-based material is alumina and the conductive material is one of copper, silver, nickel-plated copper, silver-plated copper, or the like. Alternatively, the ceramic-based material may be zirconia, magnesia, macor composites, mullite, mica glass, or the like. In each case, the ceramic-based material has a melting point significantly higher than both 600 ℃ and the conductive material to allow the ceramic-based material to conduct heat from and carry heat away from the conductive material. Alternatively, the conductive material may also be a ceramic material that includes conductive properties that cause the conductive material to generate a magnetic field with respect to the rotor 112 as needed for actuation of the rotor at a desired speed.

The rotor 112 is centrally located within the stator 110 and is coupled to a drive shaft 114. Similar to the stator 110, the rotor 112 includes poles 124a-d of corresponding electromagnets, each extending from a central axis 126; however, permanent magnets or permanent magnetic materials are not included. Like the stator 110, each of the poles 124a-d is typically a salient pole. In the example shown in FIG. 3, each pole 124a-d includes a sidewall 128a-d and terminates in an arcuate end 130a-d that is arcuately opposed to arcuate ends 120a-f of stator poles 116a-f such that the outer surfaces of each termination end are complementary to each other. Similar to the stator, the rotor poles and yokes are typically stamped from 35a360 non-oriented electrical steel plates, which may include cobalt steels, such as hiperco or other similar steels, which typically have a greater saturation flux density than silicon steel.

In one exemplary embodiment, as shown in fig. 3, the stator 110 rotor 112 set includes six stator poles and four rotor poles and is considered an 6/4 switched reluctance machine. In this example, the conductive windings 122a-f on diametrically opposed teeth may be electrically connected in series or in parallel to form a phase winding. Such 6/4 switched reluctance motors have three phases that are excited by a switching converter (switching inverter). Torque is generated by the attraction of the nearest rotor pole to the energized stator pole. Switched reluctance machines may be considered synchronous motors because the energization of the conductive windings 122a-f is synchronized with the rotor position. At low speed, the phase current may be adjusted to control torque. At high speeds, the phase currents can become self-regulating and the converter need only provide commutation, no current regulation is required. In one example, increasing the phase sequence may reduce the effect of defective phases, or reduce torque ripple.

Fig. 4 shows a schematic circuit diagram of an example converter circuit 400 for supplying excitation current to the conductive windings 122 a-f. In this example, the converter circuit 400 includes a first switch 402 and a first diode 404 arranged in parallel with a second switch 406 and a second diode 408. The first conductive winding 122a is coupled between the first switch 402 and the first diode 404, and the fourth conductive winding 122d, opposite the first conductive winding 122a, is coupled between the second switch 406 and the second diode 408. A capacitor 410 is also electrically connected in parallel with both the first switch 402 and the first diode 404 and the second switch 406 and the second diode 408. In this manner, the converter circuit 400 shown uses two controllable switches and two diodes per phase. The converter circuit 400 supplies a time-varying but unipolar current to the phase windings because torque generation in a switched reluctance motor is independent of current direction. Although fig. 4 illustrates an example converter circuit topology, other converter circuit topologies may be used for the switched reluctance motor illustrated in fig. 3. These alternative topologies may reduce the number of controllable switches, impose operational constraints, and the like.

Fig. 5 and 6 illustrate example conductive windings 500 and 600 that may be used as the conductive windings 122a-f as described with respect to fig. 2-3. Fig. 5 illustrates an example conductive winding 500 that includes an insulator 502 and a conductive element 504 inserted into the insulator 502. The conductive element 504 may extend from the insulator 502. The reason the conductive element 504 extends from the insulator is for illustrative purposes with respect to the present disclosure. In particular, the conductive winding 500 may have the conductive element 504 encased in an insulator 502 when wrapped around the stator as shown in fig. 3 so that the conductive element 504 is not exposed to the environment. Alternatively, the conductive element 504 may be only partially encased in the insulator 502 such that a portion of the conductive element is exposed to the environment.

In addition to the winding 500, in fig. 5, an insulator 502 that does not include a conductive element 504 is shown for describing the interior of the insulator 502 of the exemplary embodiment shown. As shown, the insulator 502 includes a first cavity 506 and a second cavity 508 in side-by-side relationship and separated by a dividing wall 510. In the example of fig. 5, the winding 500 is shown to include conductive elements 504 inserted into each cavity. In an alternative embodiment, only a single cavity is provided. In other embodiments, only the first cavity 506 receives the conductive element 504, while the second cavity provides a fluid flow path for fluid that conducts heat from the conductive element 504 and transfers the heat to the cooling system.

As described with respect to fig. 2-3, the windings 500 and 600 of fig. 5 and 6 illustrate an insulator 502 comprising a ceramic-based insulating material. In one embodiment, the ceramic-based material is alumina. Alternatively, the ceramic-based material may also be zirconium, a macor composite, mica glass, mullite, alumina, zirconia, magnesia, and the like. In each case, the ceramic-based material has a melting point significantly higher than 600 ℃ and the conductive material of the conductive element to allow the ceramic-based material to conduct heat from the conductive material and to carry heat away from the conductive material.

The insulator 502 may be formed using a variety of manufacturing methods. By way of example, the insulator 502 may be a pre-fabricated insulated conduit or tube, and the conductive element 504 is sized and shaped to be inserted into the conduit. In another example, the insulator 502 is molded. In other example embodiments, the winding 500 is made by an additive process, including by having the insulator 502 and the conductive element 504 formed in the same process based on 3D printing.

Further, a process for manufacturing the winding may be provided such that the difference in Coefficient of Thermal Expansion (CTE) between the insulator material and the conductive element 504 does not result in ceramic fracture upon temperature cycling. For example, the CTE of alumina and copper are 8.4X 10, respectively^-6/° C and 17X 10^-6V. C. Thermomechanical analysis and experiments indicate that the desired thermomechanical stability can be achieved. In the test alumina samples, the tubes with the copper core were able to go through 1000 cycles at cycling conditions of-78 ℃ to 250 ℃, compared to less than 10 cycles for the alternative manufacturing process.

Similar to the insulator 502, the conductive element 504 may be formed by any manufacturing process. In one example, the conductive elements are pre-formed to a size and shape to be inserted into the insulator 502. Alternatively, a metal powder is placed into at least one cavity of the insulator 502, and then the insulator 502 is exposed to a high temperature to cause the powder to liquefy. Because the insulator 502 has thermal properties of a much higher melting point than the conductive material and particularly the metal powder, the metal powder can liquefy and then cool to form the conductive element. In yet another example, the conductive element 504 is made using an additive process, including a 3D printing application as described with respect to forming the insulator 502. By using these additive techniques, complex geometries may be formed, including those associated with end windings (fig. 6) that may be formed without subtractive based manufacturing techniques. In this manner, the windings may be sized and shaped to accommodate the hypersonic aeronautical system environment. Alternatively, the conductive material may be chemically deposited on the insulator 502, such as by electroplating.

Fig. 6 shows another example of a conductive winding 600. In this example, the insulator 602 in turn receives the conductive element 604 where the conductive element 604 extends from the insulator 602. In this example, an end winding section 605 is shown housing an end winding. As described above, the end winding section 605 may be manufactured using an additive process such as 3D printing to accommodate the complex geometry of the end windings. The additive process also allows the end windings to maintain a size and shape that can be used in the limited space of hypersonic aviation systems.

FIG. 7 is a schematic diagram of an example power generation system 700 using an electric machine, according to an embodiment. In this example, the power generation process fluid is used to cool an electric machine (here, generator 702) in a hypersonic aviation system. In one such example, the heat or Qout is delivered to a fuel system (not shown) to heat the fuel prior to combustion. Alternatively, the generated heat may be transferred to other systems, or alternatively to ambient air.

In the example of fig. 7, the power generation system 700 receives heat from an external source 706. In an example, the external source 706 may include high velocity ram air or heat from a vehicle engine. Process fluid (e.g. supercritical carbon dioxide — sCO)₂) Is heated and then expanded through a turbine. This generates rotating shaft power that turns the compressor 704 and generator 702 mechanically coupled to the turbine.

The regenerator heat exchanger 708 may be used to increase system efficiency, after which heat is rejected from the process fluid in the precooler heat exchanger 712. In one example, heat (Qout) is delivered to a fuel of a fuel system. In another example, the pre-cooler acts as a heat sink, dissipating heat into the surrounding environment. The coldest process fluid may then be used for the generator 702 for heat removal and lubrication. In this example, the generator 702 is an electric machine as described above with respect to fig. 2-3. In particular, in one embodiment, as described with respect to fig. 5-6, an insulator is provided where a fluid is present within a cavity or channel of the insulator to transfer heat generated by the conductive element. In other examples, cavities or channels may be formed in the delta regions between windings located between stator poles so that the cavities or channels do not interfere with the operation of the rotor, but are capable of conducting heat from within the system through the fluid medium. In particular, in one example, an alumina matrix may be provided such that the thermal resistance between the conductor element of the winding and the alumina matrix is minimized. In either case, heat is conducted by the fluid within the generator 702 for use and/or management by the power system 700. In particular, the fluid is capable of operating at temperatures above 600 ℃. In an example, the fluid can be a supercritical fluid, such as supercritical carbon dioxide (sCO)₂)。

Fig. 8 and 9 illustrate cooling systems that remove heat from the motor. In fig. 8, a cooling system 800 is provided that delivers fluid through a motor 802 and to a heat exchanger or heat sink 804. Also, in an embodiment, when a heat exchanger is provided, heat from the fluid may be used or dissipated into another system, such as a fuel system. While in example embodiments, when a heat sink is provided, excess heat may be dissipated into the ambient air. The pump 806 may then be used to convey the cooled fluid back to the motor 802.

In the example embodiment of FIG. 9, another simplified cooling system 900 is provided. In this cooling system 900, a motor 902 discharges a fluid in the form of steam and delivers the fluid to a condenser 904, and the condenser 904 extracts heat from the steam for use or discharge. The condenser 904 then condenses the fluid back into fluid form for reuse by the motor 902. In one example, the fluid may be a liquid metal. In another example, a metal halide working fluid is used within the cooling system 900 and is transported through a loop heat pipe or thermosiphon where capillary forces in the evaporator provide the driving force to circulate the fluid. With respect to liquid metals, at 600 ℃, the alkali metal may have a vapor pressure in the range of between and including 0.004 bar and 0.4 bar, resulting in the use of two-phase thermal devices such as heat pipes and/or thermosiphons to operate above 600 ℃.

In one example, the heat is transferred to an ambient environment, which may be at 600 ℃. However, when the ambient environment is unable to absorb all or part of the motor heat, an alternative heat sink, such as fuel or other similar system, may be used in addition to operating the coolant above 600 ℃. By using fuel, the heat sink is not only consumable, but the heat also generates thrust to improve operating efficiency. In examples where fuel is used as a heat sink, direct cooling of the motor with fuel may be provided to provide additional functionality and efficiency.

Fig. 10 is a front cut-away perspective view of a bearing system 1000 for an electric machine according to an embodiment. Bearing system 1000 may represent any bearing used in an electrical system of an aircraft system, including bearing systems used in connection with drive shaft 114 of electrical system 102 shown in fig. 1-4. Specifically, in one example, the power system 102 includes two bearing systems, one located near a first end of the drive shaft and a second located near an opposite second end of the drive shaft.

The bearing system 1000 includes a bearing housing 1002 that is generally circular and has a centrally located opening 1004 through which a drive shaft 1006 (fig. 11) is disposed. Although the bearing housing 1002 is shown as generally circular, the bearing housing 1002 may include other shapes depending on space and support requirements. The opening 1004 remains generally circular to support the drive shaft 1006. Specifically, the bearing housing 1002 is stationary and does not move relative to the rotating drive shaft 1006, which rotates the drive shaft 1006 relative to the bearing housing 1002.

The bearing housing includes an outer surface 1008 and an inner surface 1010 that are formed around the periphery of the opening 1004. Interior surface 1010 includes a plurality of bearing pads 1012 that are replaceably received within bearing housing 1002. In one example, four bearing pads 1012 are equally spaced apart from each other and within the interior surface 1010 of the bearing housing 1002. Alternatively, a single bearing pad 1012 is disposed around the entire interior surface 1010 of bearing housing 1002. Each bearing pad 1012 includes a plurality of openings 1014 disposed therethrough that are spaced apart on a surface of each bearing pad 1012. The plurality of openings 1014 receive pressurized air from a pressurized air supply system 1016 disposed within the bearing housing 1002.

The pressurized air supply system 1016 includes a pressurized inlet 1018, which in one example is a hydrostatic air pressurized inlet. The pressurized inlet receives pressurized air and is fluidly connected to a pressurized passage 1019 that supplies pressurized air to a plurality of openings 1014 in the bearing pads 1012 as an outlet for a pressurized air supply system 1016. In one example, each bearing pad 1012 has a separate pressurized air supply system 1016 for supplying pressurized air to the interior surface 1010 of the bearing housing at the plurality of openings 1014. Alternatively, only one pressurized air supply system 1016 is provided and pressurized air is communicated through channels within bearing housing 1002 to a plurality of openings 1014 in each bearing pad 1012.

A damping system 1020 is also disposed within bearing housing 1002. In one example, an outer damping pocket 1022 that may be filled with a damping fluid and an inner damping pocket 1024 that may also be filled with a damping fluid and aligned with and spaced apart from the outer damping pocket are disposed on either side of the pressurized inlet 1018. In particular, the air-filled damping gap pocket 1026 separates the inner damping pocket 1024 from the outer damping pocket 1022 to allow radial movement of the damping system 1020 in response to radial forces. Specifically, each of the damping pockets 1022 and 1024 is lined with a cushion spring 1030 that allows movement in response to a radial force to damp that force. Thus, if the drive shaft 1006 engages the interior surface 1010 or causes a radial force to be transferred to the interior surface 1010, the cushion spring 1030, the damping pockets 1022, 1024 (damping fluid in the damping pockets 1022, 1024), and the clearance pocket 1026 absorb the force to prevent structural failure of the bearing system 1000.

Fig. 11 illustrates a cross-sectional view of the bearing system 1000 with the drive shaft 1006 disposed therethrough, while fig. 12 illustrates a cut-away view of the example bearing system 1000 without the drive shaft 1006. As shown in both exemplary embodiments, the damping system 1020 includes arcuate damping pockets 1022, 1024 and clearance pockets 1026 to allow for absorption of forces and motion in all three dimensions.

The bearing system 1000 has a separate bearing pad 1012 that is bounded to the bearing housing 1002 by a flexible three-dimensional diaphragm formed by damping pockets 1022, 1024 and a clearance pocket 1026 that are compliant for three (3) degrees of pad motion. The bearing system 1000 also implements external pressurization, which in one example is derived from compressor bleed air. External pressurization allows for superior load bearing capacity and overall bearing performance compared to foil bearings. External pressurization also eliminates the need for oil lubrication and accompanying systems, which may be inefficient and cumbersome for hypersonic aviation systems. This is particularly the case at high altitudes where the ambient air density is low.

Fig. 13 illustrates a method 1300 of forming an electric machine for an aerospace system. The electric machine may be the power system 102 described in fig. 1, the generator 702 as described with respect to fig. 7, or the like. The method may be performed in the order described or in a different order depending on manufacturing limitations.

At 1302, a winding is formed with a conductive element encased by an insulator. The conductive element may be one or more of copper, silver, nickel-plated copper, silver-plated copper, etc., and the insulator may be a ceramic-based material including one or more of alumina, zirconia, magnesia, macor composite, mullite, mica glass, etc. In one example, the conductive elements are encased by the insulator by utilizing a 3D printing device that prints the insulator and the conductive elements. Alternatively, the conductive material may be chemically deposited on the insulator 502, such as by electroplating. By using additive techniques, complex geometries may be formed, including complex geometries associated with end windings that may be formed without using subtractive-based manufacturing techniques. As a result, the insulator may include a first cavity separated from a second cavity by a dividing wall, and the first cavity may include a conductive element.

At 1304, the stator is magnetically coupled to the rotor by disposing windings around poles of the stator and providing current to the windings to induce current in the rotor. The windings are arranged such that the difference in CTE between the insulator material and the conductive element does not cause ceramic fracture upon temperature cycling.

At 1306, a cooling system is integrated with the winding. In one example, two-phase closed loop cooling and/or liquid cooling using loop heat pipes or thermosiphons is provided. In particular, cavities or channels may be formed between the windings between the stator poles such that the cavities or channels do not interfere with the operation of the rotor, but are capable of providing a fluid that conducts heat from within the system. The fluid may be a metallic fluid. In an example, the fluid can be a supercritical fluid, such as supercritical carbon dioxide (sCO)₂). The heat can then be conducted by the fluid for other uses in the system. By integrating the cooling system with the windings during manufacturing and using a fluid to transfer heat away from the windings, the system can operate above 600 ℃.

A power system is provided for use with an aircraft system operating at hypersonic speeds where the environmental and operating conditions are at or above 600 ℃ at an altitude of 100000 feet while supporting a 100kW heat/power loss output at 20 krpm. The power system includes integrated insulation, conductors and cooling channels with functional windings supporting a switched reluctance motor arrangement. These windings are tooth windings, consisting of multiple turns in multiple layers within each coil. Cooling is integrated in the windings, including liquid cooling and/or two-phase closed loop cooling using loop heat pipes or thermosiphons. The coolant moves heat away from the power system and to a cooling system, which may dissipate the heat to the environment, or use the heat for another system of the aerospace system. The two-phase closed loop cooling system operates passively, thus improving reliability. The power system also balances the magnetic and structural properties by balancing magnetic properties, rotor dynamics, and structure so that the machine operates reliably. Accordingly, all of the stated problems are overcome and the objectives are achieved.

In one or more embodiments, a power system is provided that may include an electrical power system. The power system may include a stator having a plurality of poles, each pole having a conductive winding surrounding the corresponding pole and configured to generate a magnetic field, and a rotor configured to rotate in response to the magnetic field generated by the stator. At least one of the conductive windings is insulated with an insulating material configured to conduct heat from the at least one conductive winding when operated at temperatures greater than 600 ℃.

Optionally, the at least one of the conductive windings may include an insulator formed of an insulating material and including a cavity that receives the conductive element. In one example, the insulating material may be a ceramic-based material including at least one of alumina, zirconia, magnesia, a macor composite, mullite, or mica glass. Optionally, the rotor does not comprise permanent magnets.

Optionally, the cavity is a first cavity and the insulator further comprises a second cavity configured to provide a fluid flow path for fluid conducting at least some heat from the at least one conductive winding. In one aspect, the power system may further include a cooling system fluidly coupled to the insulator and configured to deliver a fluid to at least one of the heat exchanger or the heat sink. In one example, the heat exchanger may be configured to transfer heat from a fluid to fuel within the fuel system. In one aspect, the fluid is one of supercritical carbon dioxide, a liquid alkali metal or a metal halide. Alternatively, the at least one of the conductive windings may be at least one of copper, silver, nickel-plated copper, or silver-plated copper.

Optionally, the power system may further include a magnetic circuit electrically coupled to the windings of the first and second opposing poles of the plurality of poles of the stator, and a first switch connected in parallel to the second switch. In another aspect, the power system may further include a drive shaft disposed through and coupled to the rotor for rotation therewith, and a bearing system coupled to the drive shaft. The bearing system may include a bearing housing that receives at least one bearing pad on an interior surface of the bearing housing, the bearing pad including at least one opening. The bearing system may also include a pressurized air supply system within the bearing housing and configured to provide pressurized air through the at least one opening in the bearing pad.

Optionally, the bearing system may further comprise a damping system having an outer damping pocket disposed within the bearing housing, an inner damping pocket disposed within the bearing housing, and a clearance pocket disposed between the inner and outer damping pockets, wherein the damping system is configured to dampen radial forces induced by the drive shaft.

Optionally, the insulating material is located between a first pole and a second pole of the plurality of poles of the stator. In one aspect, the plurality of poles includes six poles equally spaced and the rotor has four poles equally spaced. In another aspect, the power system further includes a drive shaft disposed through and coupled to the rotor, wherein rotation of the rotor rotates the drive shaft.

In one or more embodiments, a power system may be provided that may include an electrical power system. The power system may include a stator having a plurality of poles, each pole having a conductive winding surrounding the corresponding pole and configured to generate a magnetic field, the conductive winding encased within a first cavity of an insulator. The power system may also include a rotor configured to rotate in response to the magnetic field generated by the stator. The insulator may be fluidly connected to the cooling system to receive the liquid metal from the cooling system and to transfer the liquid metal to the cooling system after the liquid metal conducts at least some heat from at least one of the conductive windings.

Alternatively, the insulator may comprise an insulating material, which may be a ceramic-based material comprising at least one of alumina, zirconia, magnesia, a macor composite, mullite, or mica glass. In another example, the at least one of the conductive windings may be at least one of copper, silver, nickel-plated copper, or silver-plated copper. On the other hand, the rotor may not include permanent magnets.

In one or more embodiments, a method of forming an electric machine for a power system may be provided and may include forming a conductive winding encased by an insulator with a three-dimensional printing device and magnetically coupling a stator and a rotor by wrapping the conductive winding around poles of the stator and providing current to the conductive winding to induce current in the rotor.

Alternatively, the conductive winding may comprise an end winding within an insulator. In one example, the insulator includes a first cavity separated from a second cavity by a dividing wall. In another aspect, the first cavity may include a conductive winding and the second cavity is configured to receive a fluid.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the presently described subject matter are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments "comprising" or "having" an element or a plurality of elements having a particular property may include additional such elements not having that property.

The above description is illustrative and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the subject matter presented herein without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the disclosed subject matter, they are by no means limiting and are example embodiments. Many other embodiments will be apparent to those of ordinary skill in the art upon reading the above description. The scope of the subject matter described herein should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "in which" are used as the plain-english equivalents of the respective terms "comprising" and "wherein. Furthermore, in the claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Furthermore, the limitations of the claims are not written in a device-plus-function form and are not intended to be interpreted based on 35 u.s.c. § 112(f), unless and until such claim limitations explicitly use the phrase "device for" followed by a functional expression without further structure.

This written description uses examples to disclose several embodiments of the subject matter presented herein, including the best mode, and also to enable any person skilled in the art to practice the disclosed embodiments of the subject matter, including making and using devices or systems and performing methods. The scope of patented subject matter described herein is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims (10)

1. A power system, comprising:

an electrical power system comprising:

a stator having a plurality of poles, each pole having a conductive winding surrounding a corresponding pole and configured to generate a magnetic field; and

a rotor configured to rotate in response to a magnetic field generated by the stator;

wherein at least one of the conductive windings is insulated with an insulating material configured to conduct heat from the at least one conductive winding when operated at temperatures above 600 ℃.

2. The power system of claim 1, wherein the at least one of the conductive windings comprises an insulator formed from the insulating material and includes a cavity that receives a conductive element.

3. The power system according to claim 1, wherein the insulating material is a ceramic-based material comprising at least one of alumina, zirconia, magnesia, a macor composite, mullite, or mica glass.

4. The power system of claim 1, wherein the rotor does not include permanent magnets.

5. The power system of claim 2, wherein the cavity is a first cavity and the insulator further comprises a second cavity configured to provide a fluid flow path for fluid conducting at least some heat from the at least one conductive winding.

6. The power system according to claim 2 further comprising a cooling system fluidly coupled to the insulator and configured to deliver a fluid to at least one of a heat exchanger or a heat sink.

7. The power system of claim 1, wherein the heat exchanger is configured to receive the fluid that receives heat from the at least one conductive winding and transfer the heat to fuel within the fuel system.

8. The power system of claim 7 wherein the fluid is one of supercritical carbon dioxide, a liquid alkali metal, or a metal halide.

9. The power system of claim 1, wherein the at least one of the conductive windings is at least one of copper, silver, nickel-plated copper, or silver-plated copper.

10. The power system of claim 1, further comprising a magnetic circuit electrically coupled to windings of first and second opposing poles of the plurality of poles of the stator and including a first switch connected in parallel to a second switch.

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