AC Power System for Launch Vehicle

Abstract

An AC electrical system for a vehicle and an operating method thereof are provided. In one aspect, the AC electrical system includes a first electric machine mechanically coupled to a first spool of a gas turbine engine and a second electric machine mechanically coupled to a second spool of the gas turbine engine. The system further includes a first AC bus and a second AC bus. A first electrical path electrically couples the first electric machine to the first AC bus, and a second electrical path electrically couples the second electric machine to the second AC bus. The system further includes one or more connection links and one or more power converters for selectively electrically coupling the first electrical path and the second electrical path such that power generated by one electric machine can be converted and shared with the other electric machine and electrical loads of the other path.

Description

Technical Field

[0001] The present subject matter generally relates to an AC electrical system for a vehicle (e.g., an aircraft). Background Art

[0002] Conventional commercial aircraft typically include a fuselage, a pair of wings, and a propulsion system that provides thrust. The propulsion system typically includes at least two aircraft engines, such as turbofan jet engines. Each turbofan jet engine is mounted to a respective one of the aircraft wings, e.g., at a suspended location below the wing, separate from the wing and the fuselage.

[0003] Recently, propulsion systems with hybrid electric designs have been proposed. With these propulsion systems, a power source can supply power to an electric fan to power the electric fan and can also supply power to various aircraft loads. A power system that can provide such power while maintaining robustness and redundancy in the design would be beneficial. Summary of the Invention

[0004] Aspects and advantages of the present disclosure will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the present disclosure.

[0005] In an exemplary embodiment of the present disclosure, an AC electrical system for a vehicle is provided. The AC electrical system includes a first electric machine mechanically coupled to a first spool of a gas turbine engine and a second electric machine mechanically coupled to a second spool of the gas turbine engine. The system further includes a first electrical path that electrically couples the first electric machine to a first AC bus and electrically couples the first AC bus to one or more electrical loads. The system further includes a second electrical path that electrically couples the second electric machine to a second AC bus and electrically couples the second AC bus to one or more electrical loads. The system also includes one or more power converters and one or more connection links for selectively electrically coupling the first electrical path and the second electrical path. In this way, the power generated by one electric machine can be converted and shared with the other electric machine and the electrical loads of the other path.

[0006] These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. Brief Description of the Drawings

[0007] A complete and enabling disclosure of the present disclosure, including the best mode thereof, for the ordinary skilled person in the art, is set forth in the specification, which makes reference to the accompanying drawings, in which:[[]]END]]

[0008] Figure 1is a top view of an aircraft according to various exemplary embodiments of the present disclosure;

[0009] Figure 2 is installed to Figure 1 a schematic cross-sectional view of a gas turbine engine of an aircraft;

[0010] Figure 3 is a schematic cross-sectional view of an electric fan assembly according to an exemplary embodiment of the present disclosure;

[0011] Figure 4 is a schematic diagram depicting an AC electrical system for a vehicle according to an example embodiment of the present disclosure;

[0012] Figure 5 is a schematic diagram depicting an AC electrical system for a vehicle according to an example embodiment of the present disclosure;

[0013] Figure 6 is a schematic diagram depicting an AC electrical system for a vehicle according to another example embodiment of the present disclosure;

[0014] Figure 7 is a schematic diagram depicting an AC electrical system for a vehicle according to yet another example embodiment of the present disclosure;

[0015] Figure 8 is a schematic diagram depicting an AC electrical system for a vehicle according to a further example embodiment of the present disclosure;

[0016] Figure 9 is a schematic diagram depicting an AC electrical system for a vehicle according to yet another example embodiment of the present disclosure;

[0017] Figure 10 is Figure 5 a schematic diagram of an AC electrical system, and depicts an example manner in which power can be distributed through the AC electrical system according to an example embodiment of the present disclosure;

[0018] Figure 11 is a schematic diagram of an AC electrical system for a vehicle according to an example embodiment of the present disclosure, and depicts an example manner in which power can be transmitted through the system in response to a detected power generation fault;

[0019] Figure 12 is a schematic diagram of an AC electrical system for a vehicle according to a further example embodiment of the present disclosure, and depicts an example manner in which power can be transmitted through the system in response to a detected power generation fault;

[0020] Figure 13is a schematic diagram of an AC electrical system for a vehicle according to another exemplary embodiment of the present disclosure, and depicts an exemplary manner in which power can be transferred through the system in response to a detected power generation fault;

[0021] Figure 14 is a schematic diagram of an AC electrical system for a vehicle according to yet another exemplary embodiment of the present disclosure, and depicts an exemplary manner in which power can be transferred through the system in response to a detected power generation fault;

[0022] Figure 15 is a schematic cross-sectional view of a three-spool gas turbine engine according to an exemplary embodiment of the present disclosure;

[0023] Figure 16 is a flowchart of a method for transferring power between spools of a gas turbine engine according to an aspect of the present disclosure;

[0024] Figure 17 is a flowchart of a method for transferring power between spools of a gas turbine engine according to an aspect of the present disclosure;

[0025] Figure 18 is a block diagram of an exemplary computing system according to an exemplary aspect of the present disclosure; and

[0026] Figures 19 to 22 provides various circuit diagrams depicting exemplary manners in which a first AC bus of an AC electrical system of a vehicle can be electrically coupled to a second AC bus. Detailed Description

[0027] Reference will now be made in detail to the present embodiments of the disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Similar or like designations in the drawings and description have been used to refer to similar or like parts of the disclosure.

[0028] As used herein, the term "exemplary" is used to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or better than other embodiments. Additionally, unless otherwise explicitly stated, all embodiments described herein are to be considered exemplary.

[0029] As used herein, the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to denote the position or importance of the individual components.

[0030] The terms "front" and "rear" refer to relative positions within a gas turbine engine or vehicle, and refer to the normal operating attitude of the gas turbine engine or vehicle. For example, for a gas turbine engine, "front" refers to a position closer to the engine inlet, and "rear" refers to a position closer to the engine nozzle or exhaust port.

[0031] The terms "upstream" and "downstream" refer to the relative direction with respect to the fluid flow in a fluid path. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction towards which the fluid flows.

[0032] Unless otherwise specified herein, the terms "coupled", "fixed", "attached to", etc. refer to direct coupling, fixing or attachment, as well as indirect coupling, fixing or attachment through one or more intermediate components or features.

[0033] Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural references.

[0034] As used throughout this specification and the claims, approximating language is applied to modify any quantitative representation that can vary without resulting in a change in the basic function associated therewith. Thus, values modified by terms such as "about", "approximately", and "substantially" are not limited to the precise values specified. In at least some instances, the approximating language can correspond to the precision of the instrument used to measure the value, or the precision of the method or machine used to construct or manufacture the component and / or system. For example, the approximating language can refer to within a margin of 1%, 2%, 4%, 10%, 15%, or 20%. These approximating margins can be applied to a single value, either endpoint defining a numerical range, or both endpoints, and / or the range margin between the endpoints.

[0035] Herein, as well as throughout the specification and claims, range limitations are combined and interchanged, and such ranges are identified and include all subranges subsumed therein unless the context or language indicates otherwise. For example, all ranges disclosed herein include the endpoints, and the endpoints can be combined independently of each other.

[0036] The present disclosure generally relates to an aircraft AC power system. In particular, various AC power system architectures are provided that include at least two electric machines coupled to respective spools of a multi-spool gas turbine engine. Electrical power generated by the electric machines is supplied to the engine and aircraft electrical loads. In some cases, electrical power generated by one electric machine can be directed to another electric machine or an electrical load associated with another electric machine, such as for power assist operations. In other cases, for example, in response to a detected power generation fault, electrical power generated by one electric machine can be directed to an electrical load associated with another electric machine. In such cases, the architecture of the AC power system provided herein can achieve a smooth, efficient, and safe transition of electrical power between the respective circuits associated with the first and second electric machines.

[0037] Compared to existing commercial aircraft AC power distribution systems, the architecture of the AC power system provided herein includes at least two electric machines coupled to respective spools of a gas turbine engine and includes an AC / AC converter to allow direct AC / AC bi-directional power transfer between a circuit associated with a first electric machine and a circuit associated with a second electric machine, or includes an AC / DC converter (e.g., an active rectifier) to allow DC level power transfer between circuits or channels and then converts the DC level power to AC level power before supplying it to a power assist electric machine and / or an AC electrical load associated therewith.

[0038] Advantageously, the AC power system architecture provided herein requires relatively minimal modification to existing aircraft AC power distribution systems, which is particularly useful for upgrading or overhauling legacy AC systems. Further, the AC power system architecture provided herein provides fault tolerant dual-channel independent operation and control of two electric machines of the AC system. The AC power system architecture provided herein may have other benefits and advantages in addition to those expressly noted herein.

[0039] Reference is now made to the drawings, where like numerals indicate like elements throughout all the drawings, Figure 1 A top view of an exemplary aircraft 10 is provided that can incorporate various embodiments of the present disclosure. As Figure 1As shown, aircraft 10 defines a longitudinal centerline 14 extending therethrough and a transverse direction L. Aircraft 10 extends between a front end 16 and a rear end 18 (e.g., along a longitudinal direction parallel to longitudinal centerline 14). Furthermore, aircraft 10 includes a fuselage 12 that extends longitudinally from front end 16 to rear end 18 of aircraft 10. Fuselage 12 has a port side and a starboard side. Aircraft 10 also includes a wing assembly. More specifically, the wing assembly includes a first port wing 20 and a second starboard wing 22. First wing 20 and second wing 22 each extend transversely outward relative to longitudinal centerline 14 along transverse direction L. First wing 20 and a portion of fuselage 12 together define a first side 24 of aircraft 10. Second wing 22 and another portion of fuselage 12 together define a second side 26 of aircraft 10. For the depicted embodiment, first side 24 of aircraft 10 is configured as the port side of aircraft 10, while second side 26 of aircraft 10 is configured as the starboard side of aircraft 10.

[0040] Each of the wings 20, 22 includes one or more leading edge flaps 28 and one or more trailing edge flaps 30. The aircraft 10 also includes a vertical stabilizer 32 having rudder flaps for yaw control and a pair of horizontal stabilizers 34 each having elevator flaps 36 for pitch control. The fuselage 12 additionally includes an outer surface or skin 38. It should be understood that Figure 1 The aircraft 10 is exemplary and the inventive aspects of the present disclosure are applicable to aircraft having other suitable configurations. For example, in other embodiments, the aircraft 10 may include stabilizers of any other configuration.

[0041] Apart from Figure 1 In addition, now refer to Figure 2 and Figure 3 , Figure 1 The exemplary aircraft 10 further includes a propulsion system 50 having a first thruster assembly 52 and a second thruster assembly 54 . Figure 2 A schematic cross-sectional view of the first pusher assembly 52 is provided. Figure 3 A schematic cross-sectional view is provided of the second propeller assembly 54. As shown, the first propeller assembly 52 and the second propeller assembly 54 are both configured as underwing mounted propeller assemblies.

[0042] Special References Figure 1 and 2 The first propeller assembly 52 is mounted or configured to be mounted to the first side 24 of the aircraft 10, or more specifically, to the first wing 20 of the aircraft 10. The first propeller assembly 52 generally includes a core turbine engine 104 (also referred to as a turbine) and a primary fan (reference Figure 2Referred to as "Fan 102" for short. More specifically, for the depicted embodiment, the first propulsor assembly 52 is configured as a turbofan engine 100 (the turbine 104 and the fan 102 are configured as part of the turbofan engine 100).

[0043] As Figure 2 shown, the turbofan engine 100 defines an axial direction A1 (extending parallel to the longitudinal centerline 101 providing a reference), a radial direction R1, and a circumferential direction C (extending around the axial direction A1; Figure 2 not shown in the figure). Generally, as noted, the turbofan engine 100 includes a fan section 102 and a core turbofan engine 104 disposed downstream of the fan section 102.

[0044] The core turbofan engine 104 includes a generally tubular engine nacelle 106 that defines an annular core inlet 108. The engine nacelle 106 surrounds in a serial flow relationship: a compressor section that includes a booster or low-pressure (LP) compressor 110 and a high-pressure (HP) compressor 112; a combustion section 114; a turbine section that includes a high-pressure (HP) turbine 116 and a low-pressure (LP) turbine 118; and an exhaust nozzle section 120. The compressor section, the combustion section 114, and the turbine section together define a core air flow path 121 that extends from the annular core inlet 108 through the LP compressor 110, the HP compressor 112, the combustion section 114, the HP turbine section 116, the LP turbine section 118, and the exhaust nozzle section 120. A high-pressure (HP) shaft 122 drivingly connects the HP turbine 116 to the HP compressor 112. The HP shaft 122 and the rotating components of the HP compressor 112 and the HP turbine 116 that are mechanically coupled to the HP shaft 122 together form a high-pressure spool 160. A low-pressure (LP) shaft 124 drivingly connects the LP turbine 118 to the LP compressor 110. The LP shaft 124 and the rotating components of the LP compressor 110 and the LP turbine 118 that are mechanically coupled to the LP shaft 124 together form a low-pressure spool 180.

[0045] The fan section 102 may include a fixed or variable pitch fan 126 having a plurality of fan blades 128, the plurality of fan blades 128 being coupled to a disk 130 in a spaced-apart manner. As shown, the fan blades 128 extend generally radially outward from the disk 130. For Figure 2The variable pitch fan 126, which is mechanically coupled to a suitable actuating member 132 by means of fan blades 128, with each fan blade 128 being rotatable relative to the disk 130 about a pitch axis P1, and the actuating member 132 being configured to collectively and uniformly change the pitch of the fan blades 128. The fan blades 128, the disk 130, and the actuating member 132 can rotate together about the longitudinal axis 14 by means of the LP spool 180. As described above, in some embodiments, the fan blades 128 can be fixed and not capable of rotating about their respective pitch axes.

[0046] Still referring to Figure 2 , the disk 130 is covered by a spinner or rotatable front hub 136 that is aerodynamically shaped to facilitate the flow of air through the plurality of fan blades 128. Additionally, the fan section 102 includes an annular fan casing or outer nacelle 138 that circumferentially surrounds at least a portion of the fan 126 and / or the core turbine engine 104. The nacelle 138 is supported relative to the core turbine engine 104 by a plurality of circumferentially spaced outlet guide vanes 140. The downstream section 142 of the nacelle 138 extends over the outer portion of the core turbine engine 104 to define a bypass air flow passage 144 therebetween.

[0047] It should also be understood that Figure 2 the exemplary turbofan engine 100 depicted in

[0048] is provided only as an example, and in other exemplary embodiments, the turbofan engine 100 can have any other suitable configuration. For example, in other exemplary embodiments, the turbofan engine 100 can be configured as a turboprop engine, a turbojet engine, a turbofan engine of a different configuration, a ducted fan engine (e.g., without the nacelle 138 but including stationary outlet guide vanes 140), or any other suitable gas turbine engine. For example, the gas turbine engine can be a geared gas turbine engine (e.g., having a reduction gearbox between the LP shaft 124 and the fan 126), can have any other suitable number or configuration of shafts / spools (e.g., can include an intermediate speed shaft / turbine / compressor), etc. Figure 2 As further shown, the exemplary turbofan engine 100 includes a plurality of electric motors, including a first electric motor 170 and a second electric motor 190. For this embodiment, the first electric motor 170 is mechanically coupled to the HP spool 160, and the second electric motor 190 is mechanically coupled to the LP spool 180. In this way, the first electric motor 170 is the HP motor, and the second electric motor 190 is the LP motor.

[0049] In at least some exemplary aspects, the first motor 170 may be directly mechanically coupled to the HP spool 160 to operably couple the first motor 170 with the HP spool 160. Similarly, in at least some exemplary aspects, the second motor 190 may be directly mechanically coupled to the LP spool 180 to operably couple the second motor 190 with the LP spool 180. However, alternatively, in one or more exemplary aspects, the first motor 170, the second motor 190, or both may be indirectly coupled to the HP spool 160 or the LP spool 180, respectively, via a speed-changing mechanism (e.g., a gearbox, a transmission, etc.) to allow a desired ratio of motor speed to spool speed.

[0050] Specifically, as Figure 2 shown, the second motor 190 is coaxially mounted to and rotatable with the LP shaft 124 of the LP spool 180. As used herein, "coaxially" means that the axes are aligned. Further, for the illustrated embodiment, the second motor 190 is positioned within or rearward of the turbine section of the turbofan engine 100 and inside the core air flow path 121, and thus, the second motor 190 may be referred to as an embedded motor. Similarly, the first motor 170 is coaxially mounted to and rotatable with the HP shaft 122 of the HP spool 160. The first motor 170 is also positioned inside the core air flow path 121 but within the compressor section of the turbofan engine 100, and thus, the first motor 170 may also be referred to as an embedded motor.

[0051] The first motor 170 includes a rotor 172 and a stator 174. The rotor 172 of the first motor 170 is rotatable with the HP shaft 122. The stator 174 includes current-carrying elements, such as windings or coils. In this manner, electrical power may be transmitted to the current-carrying elements, and as will be understood, when the rotor 172 rotates relative to the stator 174, electrical energy may be converted into mechanical energy in the electric mode, or vice versa in the power generation mode. The rotor 172 has rotor components for generating a rotor magnetic field for coupling to the stator magnetic field to effect energy conversion. The rotor components of the rotor 172 may be, but are not limited to, rotor magnets in the case of a permanent magnet synchronous motor, a squirrel cage in the case of an induction motor, or an excitation winding in the case of an excited synchronous motor.

[0052] Likewise, the second motor 190 includes a rotor 192 and a stator 194. The rotor 192 of the second motor 190 is rotatable with the LP shaft 124. The rotor 192 and the stator 194 may be constructed in any of the example manners described above with respect to the first motor 170.

[0053] In some alternative embodiments, the axes of the second motor 190 and / or the first motor 170 may be radially offset from the axes of the LP shaft 124 and the HP shaft 122, respectively. Additionally, in some embodiments, the second motor 190 and / or the first motor 170 may be inclined with respect to the axes of the LP shaft 124 and the HP shaft 122, respectively. Further, in one or more exemplary embodiments, the second motor 190 and / or the first motor 170 may be located outside of the core air flow path 121, e.g., within the nacelle 106 or the engine cowling 138 of the turbofan engine 100.

[0054] Additionally, for this embodiment, both the second motor 190 and the first motor 170 may operate as electric motors in the electric mode and as generators in the power generation mode. However, in alternative embodiments, one or both of the second motor 190 and the first motor 170 may be configured to operate only as an electric motor or only as a generator.

[0055] Still referring to Figure 1 and Figure 2 , the propulsion system 50 includes an electrical power distribution system 58 to allow the first and second motors 170, 190 to be electrically coupled to each other, electrically coupled to other electrically driven components of the turbofan engine 100, and electrically coupled to other components of the propulsion system 50 and / or the aircraft 10. For the depicted embodiment, the power distribution system 58 includes one or more cables or wires 60 along which electrical power may be routed.

[0056] Additionally, the propulsion system 50 further includes one or more energy storage devices 55 (e.g., one or more batteries or other electrical energy storage devices) electrically connected to the power distribution system 58 for, e.g., providing electrical power to the second thruster assembly 54 and / or receiving electrical power from its generators. Including one or more energy storage devices 55 may provide a performance gain and may increase the propulsion capabilities of the propulsion system 50 during, e.g., transient operations. More specifically, the propulsion system 50 including one or more energy storage devices 55 may be able to respond more quickly to speed change demands.

[0057] Now referring specifically to Figure 1 and 3 , the exemplary propulsion system 50 additionally includes a second thruster assembly 54 positioned or configured to be positioned at a location spaced apart from the first thruster assembly 52. As shown, the second thruster assembly 54 is mounted to the second side 26 of the aircraft 10, or more specifically, to the second wing 22 of the aircraft 10. As Figure 3As best shown, the second thruster assembly 54 is generally configured as an electric propulsion assembly including an electric motor and a thruster. More specifically, for the depicted embodiment, the electric propulsion assembly 200 includes an electric motor 206 and a thruster / fan 204. The electric propulsion assembly 200 defines an axial direction A2 and a radial direction R2 extending along a longitudinal centerline axis 202, which is extended therethrough for reference. The fan 204 is rotatable about the centerline axis 202 by the electric motor 206.

[0058] The fan 204 includes a plurality of fan blades 208 and a fan shaft 210. The plurality of fan blades 208 are attached to / can rotate with the fan shaft 210 and are spaced apart generally along the circumferential direction of the fan. In some exemplary embodiments, the plurality of fan blades 208 may be attached to the fan shaft 210 in a fixed manner, or alternatively, as in the depicted embodiment, the plurality of fan blades 208 may rotate about respective pitch axes. For example, each of the plurality of fan blades 208 defines a respective pitch axis P2 and is attached to the fan shaft 210 such that the pitch of each of the plurality of fan blades 208 can be changed, for example, uniformly, by a pitch changing mechanism 211. Changing the pitch of the plurality of fan blades 208 can increase the efficiency of the second thruster assembly 54 and / or can allow the second thruster assembly 54 to achieve a desired thrust distribution. For such an exemplary embodiment, the fan 204 may be referred to as a variable pitch fan.

[0059] In addition, for the depicted embodiment, the electric propulsion assembly 200 includes a fan housing or nacelle 212 attached to a core 214 of the fan 204 by one or more struts or exit guide vanes 216. The nacelle 212 substantially completely surrounds the fan 204, particularly the plurality of fan blades 208. Thus, for the depicted embodiment, the fan 204 may be referred to as a ducted electric fan.

[0060] Still referring particularly to Figure 3 , the fan shaft 210 is mechanically coupled to the electric motor 206 within the core 214 such that the electric motor 206 drives the fan 204 through the fan shaft 210. The fan shaft 210 is supported by one or more bearings 218 (such as one or more roller bearings, ball bearings, or any other suitable bearing). Additionally, the electric motor 206 may be an inrunner electric motor (i.e., including a rotor positioned radially inside the stator), or may be an outrunner electric motor (i.e., including a stator positioned radially inside the rotor).

[0061] A power source (such as motors 170, 190 of the first thruster assembly 52 and / or one or more energy storage devices 55) may be electrically connected to the electric motor 206 to supply power thereto. More specifically, the electric motor 206 of the electric propulsion assembly 200 is electrically coupled to the power system through a power distribution system 58, and more specifically, through one or more cables or wires 60 extending therebetween.

[0062] Given that the first thruster assembly is configured as a gas turbine engine and the second thruster assembly is configured as an electric drive fan, the propulsion system according to one or more of the above embodiments may be referred to as a gas-electric or hybrid-electric propulsion system. However, it should be understood that in other exemplary embodiments, the exemplary propulsion system may have any other suitable configuration and, further, may be integrated into the aircraft 10 in any other suitable manner. For example, in other exemplary embodiments, the hybrid-electric propulsion system may have any suitable number of gas turbine engines (e.g., one, two, three, four, etc.) distributed in any suitable manner (e.g., along the left wing, right wing, fuselage, tail position, etc. of the aircraft) and mounted in any suitable manner (e.g., under-wing mounted, over-wing mounted, integrated into the wing, mounted to the fuselage of the aircraft, mounted to the stabilizer of the engine, mounted at the rear end as a boundary layer ingestion engine, etc.). Similarly, the hybrid-electric propulsion system may have any suitable number of electric propulsion engines (e.g., one, two, three, four, etc.) distributed in any suitable manner (e.g., along the left wing, right wing, fuselage, tail position, etc. of the aircraft) and mounted in any suitable manner (e.g., under-wing mounted, over-wing mounted, integrated into the wing, mounted to the fuselage of the aircraft, mounted to the stabilizer of the engine, mounted at the rear end as a boundary layer ingestion engine, etc.). In the case where multiple gas turbine engines are provided with motors to generate electricity, each gas turbine engine may be directed to a single electric propulsion engine or a single set of electric propulsion engines, or each gas turbine engine may be in electrical communication with a common electrical bus to supply power to the electric propulsion engines.

[0063] In addition, it should be understood that although the propulsion system described herein is depicted as being incorporated into the aircraft 10, in other exemplary embodiments, the propulsion system may additionally or alternatively be incorporated into any other suitable vehicle. For example, in other exemplary embodiments, the propulsion system may be incorporated into a marine vehicle (such as a ship or a submarine) using one or more turbine engines, a locomotive vehicle using one or more turbine engines, etc.

[0064] Figure 4 is a schematic diagram depicting an AC electrical system 300 for a vehicle according to an example embodiment of the present disclosure. For example, the AC electrical system 300 may be incorporated into Figure 1In the aircraft 10. In particular, the AC electrical system 300 can form at least a part of the electrical power distribution system 58 of the aircraft 10. The AC electrical system 300 can also be incorporated into other suitable vehicles. The AC electrical system 300 is an "AC electrical system" because electrical power is distributed at an "AC level" or as alternating current.

[0065] As will be further described below, the AC electrical system 300 is capable of transferring electrical power between a first electrical path and a second electrical path of the AC electrical system 300. For example, this can enable the transfer of electrical power between the spools of a gas turbine engine. That is, electrical power generated by a first electric machine coupled to a first spool can be transferred to a second electric machine coupled to a second spool. The second electric machine can then convert the electrical energy into mechanical energy to drive or propel the second spool. In this way, the AC electrical system 300 enables the sharing of electrical power between the spools of a gas turbine engine. Additionally, electrical power generated by one electric machine can be fed to supplement or provide full power to various loads associated with another electric machine (such as local loads on the gas turbine engine and / or other vehicle loads).

[0066] As Figure 4 Schematically depicted in, the AC electrical system 300 includes a first electric machine 310 mechanically coupled to a first spool 304 of a gas turbine engine 302. The AC electrical system 300 also includes a second electric machine 340 mechanically coupled to a second spool 306 of the gas turbine engine 302. For this embodiment, the first spool 304 is the high-voltage spool of the gas turbine engine 302, and the second spool 306 is the low-voltage spool of the gas turbine engine 302. However, in other example embodiments, the first spool 304 can be the low-voltage spool, and the second spool 306 can be the high-voltage spool. In other example embodiments, particularly in an embodiment where the gas turbine engine 302 is a three-spool engine having a low-voltage spool, a medium-voltage spool, and a high-voltage spool, the first spool is the medium-voltage spool of the gas turbine engine, and the second spool is one of the low-voltage spool and the high-voltage spool of the gas turbine engine. In other embodiments, the first spool is one of the low-voltage spool and the high-voltage spool of the gas turbine engine, and the second spool is the medium-voltage spool of the gas turbine engine.

[0067] The AC electrical system 300 includes a first electrical path 312. The first electrical path 312 electrically couples various components associated with the first electric machine 310. For example, as Figure 4As shown, the first electrical channel 312 electrically couples the first motor 310 to the first AC bus 314. One or more electrical loads 316A, 316B, 316C may be electrically coupled to the first AC bus 314 via respective load lines 318A, 318B, 318C of the first electrical channel 312, for example. One or more electrical loads 316A, 316B, 316C may include, but are not limited to, an electrically driven pump, computing components, a motor, cabin lights, an air conditioning system, a cabin air pressurization system, a motor 206 associated with the Figure 3 electric propulsion assembly 200, etc. Although three electrical loads are depicted as being associated with the first electrical channel 312 in Figure 4 , it should be understood that more or fewer than three electrical loads are possible.

[0068] The AC electrical system 300 further includes a second electrical channel 342. The second electrical channel 342 electrically couples various components associated with the second motor 340. For example, as Figure 4 shown, the second electrical channel 342 electrically couples the second motor 340 to the second AC bus 344. The second AC bus 344 may be at a different voltage and a different frequency than the first AC bus 314. One or more electrical loads 346A, 346B, 346C may be electrically coupled to the second AC bus 344 via respective load lines 348A, 348B, 348C of the second electrical channel 342, for example. One or more electrical loads 346A, 346B, 346C may include, but are not limited to, an electrically driven pump, computing components, a motor, cabin lights, an air conditioning system, a cabin air pressurization system, a motor 206 associated with the Figure 3 electric propulsion assembly 200, etc. Although three electrical loads are depicted as being associated with the second electrical channel 342 in Figure 4 , it should be understood that more or fewer than three electrical loads are possible.

[0069] As Figure 4 further shown, the AC electrical system 300 includes one or more connection links that selectively electrically couple the first electrical channel 312 and the second electrical channel 342. The AC electrical system 300 further includes a power conversion system having one or more power converters operable to convert power transmitted between the first electrical channel 312 and the second electrical channel 342 through the one or more connection links such that power generated by the second motor 340 can be transmitted to the first electrical channel 312 and, in some embodiments, such that power generated by the first motor 310 can be transmitted to the second electrical channel 342.

[0070] For example, for Figure 4In the illustrated embodiment, one or more connection links of the AC electrical system 300 include a connection link 280. The connection link 280 electrically couples a first AC bus 314 of a first electrical path 312 and a second AC bus 344 of a second electrical path 342. The connection link 280 includes a first bus tie contactor 282 and a second bus tie contactor 284. The first bus tie contactor 282 and the second bus tie contactor 284 can be controlled to selectively allow power to pass therethrough. In this regard, the connection link 280 selectively electrically couples the first electrical path 312 and the second electrical path 342.

[0071] For this embodiment, one or more connection links of the AC electrical system 300 further include an AC bus link 410 that can be controlled to selectively electrically couple or connect a first AC bus 314 associated with the first electrical path 312 and a second AC bus 344 associated with the second electrical path 342. One or more bus tie contactors 412 of the AC bus link 410 can be controlled to selectively connect the first electrical path 312 and the second electrical path 342 at an AC level. Such a bus tie contactor 412 can be controlled to connect the first AC bus 314 and the second AC bus 344, for example, in response to a detected power generation fault associated with one of the motors.

[0072] As described above, the AC electrical system 300 includes a power conversion system 290 having one or more power converters. For Figure 4 the illustrated embodiment, one or more power converters of the power conversion system 290 include a power converter 292 positioned along the connection link 280. More specifically, the power converter 292 is positioned along the connection link 280 between the first bus tie contactor 282 and the second bus tie contactor 284. Generally, the power converter 292 is operable to convert the power transmitted between the first electrical path 312 and the second electrical path 342 through the connection link 280 such that power generated by one motor can be transmitted to an electrical path associated with another motor. In particular, the power converter 292 can be controlled to convert the AC voltage and frequency of the power transmitted through the connection link 280 to the AC voltage and frequency of the electrical path to which the power is transmitted. In some embodiments, as will be provided below, the AC electrical system 300 can include multiple power converters to convert the power transmitted between the first electrical path 312 and the second electrical path 342. In other embodiments, the AC electrical system 300 can include a single power converter to convert the power transmitted between the first electrical path 312 and the second electrical path 342.

[0073] As Figure 4Further shown, the AC electrical system 300 includes an energy management system 450 (EMS) for power distribution management. The EMS 450 can include one or more memory devices and one or more processors 452, which are operable to perform one or more operations, such as controlling various components of the AC electrical system 300 to control the flow of current and thus the power passing through the AC electrical system 300. For example, at least in part based on the power sharing allocation determined for the power assist operation, one or more processors 452 can control the various bus tie contactors of the AC electrical system 300 (e.g., the system's bus tie contactor, one or more power converters, etc.) to direct power from one electrical channel to another electrical channel. The EMS 450 can also include other components, such as those described in the computing system 800 depicted in Figure 18 The EMS 450 can be communicatively coupled to the bus tie contactor and / or other components in any suitable manner, such as via one or more wired or wireless communication links. Although not labeled in Figure 4 the various bus tie contactors (e.g., bus ties) are positioned along the respective channels of the AC electrical system 300. It should also be understood that such devices can be controlled to allow or "interrupt" the flow of current along their respective channels. The EMS 450 can be communicatively coupled to such bus tie contactors to precisely control the flow of current through the system 300.

[0074] An example manner in which the AC electrical system 300 can facilitate power sharing or power assist between channels will now be described. Referring to Figure 4 , one or more processors 452 can initiate a power assist operation. The power assist operation can be initiated at least in part based on data 454 received by one or more processors 452. The data 454 can indicate, for example, the required thrust output of the gas turbine engine 302. The required thrust output can be received in response to, for example, a pilot's adjustment of the thrust lever or a command from an autopilot system. The data 454 can also include the detection of bleed air, anticipated electrical load changes, etc. To achieve the required thrust output and meet the power demand of the AC electrical system 300, one or more processors 452 can determine a power sharing allocation.

[0075] Power sharing allocation can indicate whether power will be drawn from the first electric machine 310 and how much power will be drawn from the first electric machine 310 and supplied to its associated electrical loads 316A, 316B, 316C, and / or whether power generated by the first electric machine 310 and how much power generated by the first electric machine 310 will be supplied to the second electrical path 342, e.g., for assisting the second electric machine 340 to drive the second spool 306 and / or supplying power to one or more electrical loads 346A, 346B, 346C associated with the second electric machine 340. The power sharing allocation can also indicate whether power will be drawn from the second electric machine 340 and how much power will be drawn from the second electric machine 340 and supplied to its associated electrical loads 346A, 346B, 346C, and / or whether power generated by the second electric machine 340 and how much power generated by the second electric machine 340 will be supplied to the first electrical path 312, e.g., for assisting the first electric machine 310 to drive the first spool 304 and / or supplying power to one or more electrical loads 316A, 316B, 316C associated with the first electric machine 310. In this regard, one or more processors 452 can determine the manner in which power is distributed throughout the AC electrical system 300 to meet the power and mechanical power requirements of the gas turbine engine 302 and the vehicle. One or more processors 452 can control the tie contactors of the system 300 to achieve the desired power distribution.

[0076] As an example, one or more processors 452 can determine that power generated by the second electric machine 340 will be supplied to the first electric machine 310, e.g., for core power assist, where the first spool 304 is the high-pressure spool of the gas turbine engine 302 and the second spool 306 is the low-pressure spool of the gas turbine engine 302. Thus, in accordance with the determined power sharing allocation, one or more processors 452 can direct the power generated by the second electric machine 340 along the second electrical path 342 to the second AC bus 344. A portion of the power can be directed from the second AC bus 344 to the first electrical path 312 through the connection link 280. In this regard, the first tie contactor 282 and the second tie contactor 284 can be controlled to close to allow power to flow from the second electrical path 342 to the first electrical path 312. When the power passes through the power converter 292, the power converter 292 is controlled to synchronize the AC voltage and frequency of the power with the AC voltage and frequency of the first electrical path 312. In this way, the generated alternating current has a synchronized voltage level, frequency, and phase with respect to the first electrical path 312, and thus, this converted power can be safely and effectively supplied to the first AC bus 314 and continue to the first electric machine 310 for power assist. As will be appreciated, the power supplied to the first electric machine 310 can cause or assist the first electric machine 310 to drive the first spool 304.

[0077] Various embodiments will now be provided that disclose various ways in which one or more connection links can selectively electrically couple a first channel 312 and a second channel 342.

[0078] In one example embodiment, as Figure 5 shown, a DC bus link 380 can selectively electrically couple or connect a first electrical channel 312 and a second electrical channel 342. As shown, a main line 324 of the first electrical channel 312 electrically couples a first AC bus 314 to a first AC / DC converter 320. The first AC / DC converter 320 can be any suitable type of controllable device operable to convert alternating current to direct current, or vice versa. In some example embodiments, but not limited to, the first AC / DC converter 320 can be an autotransformer rectifier unit (ATRU), an isolation transformer, or some other suitable converter device.

[0079] In addition, the main line 324 of the first electrical channel 312 electrically couples the first AC / DC converter 320 to a first DC bus 322. It is noted that the first AC / DC converter 320 is a bidirectional AC / DC converter. Thus, the first AC / DC converter 320 is operable to convert alternating current to direct current in some operating modes and to convert direct current to alternating current in some other operating modes. In this way, when the first motor 310 operates in a generator mode, alternating current can be converted to direct current and directed to the first DC bus 322. Conversely, when the first motor 310 operates in a motor or drive mode, direct current from the first DC bus 322 can be converted to alternating current and directed to the first AC bus 314 and ultimately to the first motor 310 or other electrical loads electrically coupled to the first AC bus 314.

[0080] A first load line 326 of the first electrical channel 312 electrically couples the first DC bus 322 to a first load AC / DC converter 328 and electrically couples the first load AC / DC converter 328 to an electrical load 330. The first load AC / DC converter 328 is operable to convert direct current provided by the first DC bus 322 to alternating current. In this way, alternating current can be provided to the electrical load 330. In some embodiments, the first load AC / DC converter 358 is a bidirectional converter.

[0081] Similarly, a second load line 332 of the first electrical channel 312 electrically couples the first DC bus 322 to a second load AC / DC converter 334 and electrically couples the second load AC / DC converter 334 to an electrical load 336. Similar to the first load AC / DC converter 328, the second load AC / DC converter 334 is operable to convert direct current provided by the first DC bus 322 into alternating current. Accordingly, alternating current can be provided to the electrical load 336. In some embodiments, the second load AC / DC converter 334 is a bi-directional converter. As will be appreciated, in other example embodiments, more or fewer than two electrical loads may be associated with the first electrical channel 312. The first load AC / DC converter 328 and the second load AC / DC converter 334 can each be any suitable type of controllable device operable to convert alternating current to direct current and vice versa. In some example embodiments, but not limited to, the first load AC / DC converter 328 and the second load AC / DC converter 334 can be an ATRU, an isolation transformer, or some other suitable converter device.

[0082] Still referring to Figure 5 , a second electrical channel 342 electrically couples a second motor 340 to a second AC bus 344. The second AC bus 344 can be at a different voltage and a different frequency than the first AC bus 314. One or more electrical loads 346 can be electrically coupled to the second AC bus 344, for example, via a load line 348 of the second electrical channel 342. The one or more electrical loads 346 can include, but are not limited to, an electrically driven pump, computing components, cabin lights, an air conditioning system, a cabin air pressurization system, a motor 206 associated with Figure 3 the electric propulsion assembly 200, etc.

[0083] A main line 354 of the second electrical channel 342 electrically couples the second AC bus 344 to a second AC / DC converter 350. The second AC / DC converter 350 can be any suitable type of controllable device operable to convert alternating current to direct current or vice versa. In some example embodiments, but not limited to, the second AC / DC converter 350 can be an ATRU, an isolation transformer, or some other suitable converter device.

[0084] In addition, the main line 354 of the second electrical channel 342 also electrically couples the second AC / DC converter 350 to a second DC bus 352. The first DC bus 322 and the second DC bus 352, although for Figure 5The illustrated embodiments are separate components, but together form the DC bus system 372. In some embodiments, the second AC / DC converter 350 is a bidirectional AC / DC converter. Thus, when the second motor 340 operates in the generator mode, alternating current can be converted into direct current and directed to the second DC bus 352. Conversely, when the second motor 340 operates in the motor or drive mode, the direct current from the second DC bus 352 can be converted into alternating current and directed to the second AC bus 344 and ultimately to the second motor 340. However, in other example embodiments, the second AC / DC converter 350 need not be a bidirectional AC / DC converter. For example, in some embodiments, the second AC / DC converter 350 can be a unidirectional AC / DC converter.

[0085] The first load line 356 of the second electrical path 342 electrically couples the second DC bus 352 to the first load AC / DC converter 358 and electrically couples the first load AC / DC converter 358 to the electrical load 360. Similarly, the second load line 362 of the second electrical path 342 electrically couples the second DC bus 352 to the second load AC / DC converter 364 and electrically couples the second load AC / DC converter 364 to the electrical load 366. As will be appreciated, in other example embodiments, more or fewer than two electrical loads can be associated with the second electrical path 342. Further, both the first load AC / DC converter 358 and the second load AC / DC converter 364 can be any suitable type of controllable device operable to convert alternating current into direct current or vice versa. In some example embodiments, but not limited to, the first load AC / DC converter 358 and the second load AC / DC converter 364 can be an ATRU, an isolation transformer, or some other suitable converter device.

[0086] As Figure 5 As further shown, the first secondary line 368 of the second electrical path 342 electrically couples the second AC bus 344 to the first load line 356 of the second electrical path 342. As shown, the first secondary line 368 is electrically connected to the first load line 356 of the second electrical path 342 at a point between the first load AC / DC converter 358 and the electrical load 360. Similarly, the second secondary line 370 of the second electrical path 342 electrically couples the second AC bus 344 to the second load line 362 of the second electrical path 342. As shown, the second secondary line 370 is electrically connected to the second load line 362 of the second electrical path 342 at a point between the second load AC / DC converter 364 and the electrical load 366.

[0087] For Figure 5In the illustrated embodiment, as noted, the DC bus link 380 can be selectively electrically coupled or connected to the first DC bus 322 associated with the first electrical path 312 and the second DC bus 352 associated with the second electrical path 342. One or more tie contactors 382 of the DC bus link 380 can be controlled to selectively connect the first electrical path 312 and the second electrical path 342 at the DC level. In some operating modes, power can be transferred between the first electrical path 312 and the second electrical path 342 via the DC bus link 380 such that power generated by the second motor 340 can be transferred to the first motor 310, for example, for power assist, and / or to electrical loads 316, 330, 336 associated therewith. In other embodiments, power can be transferred between the first electrical path 312 and the second electrical path 342 via the DC bus link 380 such that power generated by the first motor 310 can be transferred to the second motor 340 and / or electrical loads 348, 360, 366 associated therewith.

[0088] In other embodiments, one or more connection links can include a single DC bus electrically connecting the first electrical path 312 and the second electrical path 342. In particular, in some example embodiments, Figure 5 the first DC bus 322 and the second DC bus 352 of the embodiment can be combined into a single DC bus. Figure 6 Such an embodiment is depicted. As Figure 6 shown, the AC electrical system 300 is depicted in a manner similar to that of the Figure 5 AC electrical system 300, except that the DC bus system 372 includes a single DC bus 374 instead of two separate DC buses. The single DC bus 374 is part of the first electrical path 312 and the second electrical path 342 and serves as a connection link therebetween. In this regard, power can be transferred between the first electrical path 312 and the second electrical path 342 via the single DC bus 374.

[0089] In some further embodiments, the AC electrical system 300 can include a connection link between the first AC / DC converter 320 and the second AC / DC converter 350 to electrically couple the first electrical path 312 and the second electrical path 342. For example, as Figure 7As shown, AC electrical system 300 includes a converter link 390 for selectively electrically coupling first AC / DC converter 320 and second AC / DC converter 350. Converter link 390 may include one or more bus tie contactors 392 that can be controlled to selectively allow power to be transferred from second AC / DC converter 350 to first AC / DC converter 320, or vice versa. Notably, converter link 390 can be connected to both the DC side of second AC / DC converter 350 and the DC side of first AC / DC converter 320. In this manner, power can be transferred between first and second AC / DC converters 320, 350 at a DC level, or in other words, as direct current power.

[0090] In other example embodiments, the AC electrical system 300 may include a connection link between the first AC bus 314 and the second AC bus 344 to electrically couple the first electrical channel 312 and the second electrical channel 342. Figure 8 As shown, the AC electrical system 300 includes an AC converter link 400 for selectively electrically coupling the first AC bus 314 and the second AC bus 344. Notably, the AC converter link 400 includes an AC / AC converter 402. In some embodiments, the AC / AC converter 402 may be a matrix converter, for example Figure 21 In other embodiments, the AC / AC converter 402 may be a cycloconverter, such as Figure 22 . Generally, the AC / AC converter 402 can be controlled to convert the alternating current transmitted through it so that the current has a frequency and voltage that is synchronized with the AC bus to which the power is transmitted. As previously described, the first AC bus 314 and the second AC bus 344 can have independent voltage levels, different frequencies, and can be out of phase with each other. Thus, the AC / AC converter 402 can facilitate a safe and smooth transition of power from one AC bus to another.

[0091] In other embodiments, Figure 9 As shown, the AC electrical system 300 may include a plurality of connection links, including Figure 5 DC bus link 380 (or Figure 6 A single DC bus 374; Figure 9 (not shown), Figure 7 The converter link 390 and Figure 8 AC converter link 400. Depending on mechanical and electrical requirements, power can be transmitted from one channel to another channel through one, some or all of these connecting links. It should be understood that any suitable combination of the above connecting links is possible in other embodiments.

[0092] Referring again to Figure 5 , an example manner in which the AC electrical system 300 can facilitate power sharing or power assist between the spools of a gas turbine engine will now be described. One or more processors 452 may initiate a power assist operation. The power assist operation may be initiated based at least in part on data 454 received by the one or more processors 452. The data 454 may indicate, for example, a desired thrust output of the gas turbine engine 302. The desired thrust output may be received in response to, for example, a pilot's adjustment of a thrust lever or a command from an autopilot system. The data 454 may also include detection of bleed air, anticipated electrical load changes, and the like. To achieve the desired thrust output and meet the electrical power demands of the AC electrical system 300, the one or more processors 452 may determine a power sharing allocation. The power sharing allocation may indicate whether power will be drawn from and how much power will be drawn from the first electric machine 310, or whether power will be supplied to and how much power will be supplied to the first electric machine 310, and may indicate whether power will be drawn from and how much power will be drawn from the second electric machine 340, or whether power will be supplied to and how much power will be supplied to the second electric machine 340. In this regard, the one or more processors 452 may determine the manner in which power is distributed throughout the AC electrical system 300 to meet the electrical and mechanical power demands of the gas turbine engine 302 and the vehicle. The one or more processors 452 may control controllable elements of the system 300 to achieve the desired power distribution.

[0093] For this example embodiment, the one or more processors 452 may determine that power generated by the second electric machine 340 will be supplied to the first electric machine 310, for example for core power assist, where the first spool 304 is the high voltage spool of the gas turbine engine 302 and the second spool 306 is the low voltage spool of the gas turbine engine 302. Accordingly, in accordance with the determined power sharing allocation, the one or more processors 452 may cause the power generated by the second electric machine 340 to be routed along the second electrical path 342 to the second AC bus 344. As Figure 5 shown, a portion of the power may be routed from the second AC bus 344 to the second AC / DC converter 350.

[0094] The second AC / DC converter 350 may convert alternating current to direct current. At least a portion of the direct current may be directed to the DC bus system 372, or more specifically, for Figure 5In an embodiment, it is directed to the second DC bus 352. One or more processors 452 may control one or more tie contactors 382 of the DC bus link 380 to allow power to flow from the second electrical path 342 to the first electrical path 312, or more specifically, for this embodiment, from the second DC bus 352 of the second electrical path 342 to the first DC bus 322 of the first electrical path 312. In this way, direct current can be transmitted from the second DC bus 352 of the second electrical path 342 to the first DC bus 322 of the first electrical path 312 through the DC bus link 380.

[0095] Direct current is received by the first DC bus 322, and at least a portion of the DC level power is provided to the first AC / DC converter 320, where the direct current is converted into alternating current. The first AC / DC converter 320 may convert the direct current such that the resulting alternating current has a synchronized voltage level, frequency, and phase with respect to the first AC bus 314. The alternating current is directed from the first AC / DC converter 320 to the first AC bus 314 and then to the first motor 310 to ultimately drive the first spool 304 and / or other electrical loads.

[0096] In some embodiments, the second AC / DC converter 350 is rated to handle the power demand requirements of the electrical loads 360, 366 associated with the second electrical path 342 and the power demand of the first motor 310. Thus, power only needs to be directed through the AC power system 300 as described above. However, in some embodiments, the second AC / DC converter 350 may not be rated to handle the power demand requirements of the electrical loads 360, 366 associated with the second electrical path 342 and the power demand of the first motor 310 simultaneously. To meet the power demand requirements, power may be directed along one or more of the secondary lines 368, 370 such that one or more of the first load AC / DC converter 358 and the second load AC / DC converter 364 may assist the second AC / DC converter 350 to convert the AC level power into DC level power before transmission through the DC bus link 380. Examples of this are provided below.

[0097] Figure 10 is Figure 5Schematic diagram of the AC electrical system 300, and depicts an example manner in which electrical power can be distributed by the AC electrical system 300 according to an example embodiment of the present disclosure. As shown, for this example embodiment, the second motor 340 is operable to generate 300 kW, the second AC / DC converter 350 is rated at 200 kW, the electrical load 360 is loaded at 100 kW (i.e., the electrical load 360 requires 100 kW), the electrical load 366 is not loaded (i.e., the electrical load 366 requires 0 kW), and the first motor 310 requires 200 kW. These numbers are for example purposes only.

[0098] Thus, for this example embodiment, 100 kW of the 300 kW of electrical power generated by the second motor 340 will be provided to the electrical load 360, and 200 kW of the 300 kW of electrical power generated by the second motor 340 will be provided to the first motor 310. However, as described above, the second AC / DC converter 350 is only rated at 200 kW, so not all 300 kW can pass through the second AC / DC converter 350. Thus, for this example, one or more processors 452 can control the system 300 such that 200 kW of electrical power is directed through the second AC / DC converter 350, and such that 100 kW of electrical power is directed along the second secondary line 370 from the second AC bus 344, as Figure 10 shown.

[0099] The 200 kW of electrical power directed through the second AC / DC converter 350 can be converted to DC level electrical power and directed to the second DC bus 352 of the DC bus system 372. The 100 kW of electrical power directed through the second AC / DC converter 350 and through the second DC bus 352 can be directed along the first load line 356 to the first load AC / DC converter 358. The first load AC / DC converter 358 can convert the direct current to alternating current and can direct the alternating current to the electrical load 360 to meet its required electrical power. The additional 100 kW of electrical power directed through the second AC / DC converter 350 can be transmitted from the second electrical channel 342 to the first electrical channel 312 through the DC bus link 380 and transmitted along the first electrical channel 312 to the first motor 310.

[0100] To ensure that the first motor 310 receives its required power of 200 kW, 100 kW of power is directed from the second AC bus 344 along the second secondary line 370 to the second load line 362. Since the electrical load 366 is not loaded or does not require power, the second load line 362 can be used to supplement the power supplied to the first motor 310. The 100 kW of power directed from the second AC bus 344 along the second secondary line 370 to the second load line 362 is directed through the second load AC / DC converter 364 to convert the alternating current to direct current. The DC level power is then directed to the DC bus system 372. Then, as noted, the direct current can be transmitted from the second electrical channel 342 to the first electrical channel 312 through the DC bus link 380 and along the first electrical channel 312 to the first motor 310. In this way, the second load AC / DC converter 364 assists the second AC / DC converter 350 in converting the power to direct current for transmission through the DC bus link 380. Thus, 200 kW of power can be transmitted from the second electrical channel 342 to the first electrical channel 312 and ultimately to the first motor 310.

[0101] In some alternative embodiments, the 200 kW of power directed through the second AC / DC converter 350 can be converted to DC level power and directed to the second DC bus 352 of the DC bus system 372. In such an embodiment, all 200 kW of the power directed through the second AC / DC converter 350 can be transmitted from the second electrical channel 342 to the first electrical channel 312 through the DC bus link 380 and along the first electrical channel 312 to the first motor 310. To meet the 100 kW power requirement of the electrical load 360, 100 kW of power can be directed from the second AC bus 344 along the first secondary line 368 to the first load line 356 and can be provided to the electrical load 360 to meet its power requirement. Thus, 200 kW of power can be transmitted from the second electrical channel 342 to the first electrical channel 312 and ultimately to the first motor 310 to meet its required power while still meeting the 100 kW power requirement of the electrical load 360.

[0102] As described above, DC level power can be transmitted from the second electrical channel 342 to the first electrical channel 312 through the DC bus link 380 for power sharing operations. It is noted that in addition to or in place of transmitting DC level power through the DC bus link 380, the DC level power can be transmitted through a single DC bus 374 as shown in Figure 6 and / or through as Figure 7The converter link 390 shown transfers from the second electrical channel 342 to the first electrical channel 312. In addition to or in place of power transfer via the DC bus link 380, power transfer via such a connection link may be implemented. For example, in the example above regarding Figure 10 , in addition to Figure 5 's DC bus link 380, power may be transferred from the second electrical channel 342 to the first electrical channel 312 via Figure 6 's single DC bus 374 and / or Figure 7 's converter link 390.

[0103] Furthermore, in addition to or in place of DC level power transfer via Figure 5 's DC bus link 380, Figure 6 's single DC bus 374 and / or Figure 7 's converter link 390, power may be transferred from the second electrical channel 342 to the first electrical channel 312 via the AC converter link 400 as shown in Figure 8 .

[0104] For example, regarding the example of Figure 10 and referring to Figure 7 and Figure 8 , 200 kW of power may be directed through the second AC / DC converter 350 described, and 100 kW may be directed to the electrical load 360, and 100 kW may be directed through the DC bus link 380 to the first electrical channel 312 and ultimately to the first motor 310. To meet the remaining 100 kW out of a total 200 kW demand, 100 kW of power may be directed along the AC converter link 400. The AC level power may be converted by the AC / AC converter 402 to have a voltage level, frequency, and phase synchronized with the first AC bus 314. The converted AC level power may be supplied to the first AC bus 314 and ultimately to the first motor 310. In this way, 200 kW of power required by the first motor 310 may be received. For example, in some alternative embodiments, the required 200 kW of power may be through the AC converter link 400, while the 100 kW required by the electrical load 360 may be directed to the electrical load 360 via the first secondary line 368 and the first load line 365.

[0105] Figure 11 is a schematic diagram of an AC electrical system 300 for a vehicle according to an example embodiment of the present disclosure, and depicts an example manner in which power may be transferred through the system 300 in response to a detected power generation fault.

[0106] In some example embodiments, a first electric machine 310 mechanically coupled to a first spool 304 of a gas turbine engine 302 can generate electrical power such that the generated electrical power can be provided to one or more associated electrical loads 316, 330, 336. Additionally, a second electric machine 340 mechanically coupled to a second spool 306 of the gas turbine engine 302 can generate electrical power such that the generated electrical power can be provided to one or more associated electrical loads 346, 360, 366. In such an embodiment, one or more processors 452 can receive data 456 indicative that a power generation fault associated with one of the electric machines has occurred. For example, in Figure 11 the illustrated embodiment, the data 456 indicates that a power generation fault associated with the second electric machine 340 has occurred (represented by an "X" on the second electric machine 340). A power generation fault can indicate that the second electric machine 340 does not meet the power demands of at least one electrical load associated therewith. In some embodiments, a power generation fault can indicate that the second electric machine 340 does not meet the power demands of any electrical load associated therewith.

[0107] In response to the detected power generation fault associated with the second electric machine 340, the electrical power generated by the first electric machine 310 can be transferred from a first electrical path 312 associated with the first electric machine 310 to a second electrical path 342 associated with the second electric machine 340 via one or more connection links. For example, in response to the detected power generation fault, one or more processors 452 can control various elements of the system 300 to direct the electrical power generated by the first electric machine 310 along the first electrical path 312 to a first AC bus 314, through a first AC / DC converter 320 (wherein AC level electrical power is converted to DC level electrical power), and through a DC bus system 372 to the second electrical path 342, as Figure 11 illustrated.

[0108] A portion of the DC level power transmitted to the second electrical channel 342 can be directed along their respective first load lines 356 and second load lines 362 to one or more of the electrical loads 360, 366, where the DC level power is converted by the respective first load AC / DC converter 358 and second load AC / DC converter 364 to provide AC level power to the electrical loads 360, 366. Another portion of the DC level power that has been transmitted through the DC bus system 372 can be directed to one or more electrical loads 346. In particular, the DC level power can be directed through the second AC / DC converter 350, where the DC level power is converted to AC level power. The AC level power is then directed to the second AC bus 344. The AC level power can then be directed along the load line 348 to one or more electrical loads 346. In this way, the power generated by the first motor 310 can be transmitted to the second electrical channel 342 and used to meet the power demands of the electrical loads 346, 360, 366.

[0109] In some embodiments, as Figure 11 shown, the DC bus system 372 includes a first DC bus 322 positioned along the first electrical channel 312 and a second DC bus 352 positioned along the second electrical channel 342. In such embodiments, one or more connection links include the DC bus link 380. Thus, in such embodiments, transmitting the power generated by the first motor 310 from the first electrical channel 312 associated with the first motor 310 to the second electrical channel 342 associated with the second motor 340 through one or more connection links includes directing the power from the first DC bus 322 to the second DC bus 352 at DC level through the DC bus link 380, then to one or more AC / DC converters 350, 358, 364 of the second electrical channel 342, and finally to one or more electrical loads 346, 360, 366.

[0110] In some alternative embodiments, as Figure 12As shown, the DC bus system 372 includes a single DC bus 374 connected to the first electrical channel 312 and the second electrical channel 342. In such an embodiment, one or more connection links include the single DC bus 374. That is, the single DC bus 374 is the connection link between the channels. Thus, in such an embodiment, transferring the power generated by the first motor 310 from the first electrical channel 312 associated with the first motor 310 to the second electrical channel 342 associated with the second motor 340 through one or more connection links includes guiding the power at a DC level through the single DC bus 374, and then guiding it to one or more AC / DC converters 350, 358, 364 of the second electrical channel 342, and finally guiding it to one or more electrical loads 346, 360, 366.

[0111] In some other embodiments, as Figure 13 shown, one or more connection links may include a converter link 390. Thus, in such an embodiment, transferring the power generated by the first motor 310 from the first electrical channel 312 associated with the first motor 310 to the second electrical channel 342 associated with the second motor 340 through one or more connection links includes guiding the power at a DC level from the first AC / DC converter 320 of the first electrical channel 312 to the second AC / DC converter 350 of the second electrical channel 342 through the converter link 390. In this way, power can be supplied to one or more electrical loads associated with the second electrical channel 342, such as Figure 13 the electrical load 346 depicted in

[0112] In other exemplary embodiments, as Figure 14 shown, one or more connection links may include an AC converter link 400 having an AC / AC converter 402. In such an embodiment, transferring the power generated by the first motor 310 from the first electrical channel 312 associated with the first motor 310 to the second electrical channel 342 associated with the second motor 340 through one or more connection links includes guiding the power at an AC level from the first AC bus 314 of the first electrical channel 312 through the AC / AC converter 402 to the second AC bus 344 of the second electrical channel 342 through the AC converter link 400. In some embodiments, the AC / AC converter 402 is one of a matrix converter and a cycloconverter.

[0113] It should be understood that in the case of detecting a power generation failure, in addition to Figure 11 the DC bus link 380 depicted in Figure 12 the single DC bus 374 of Figure 13The converter link 390 and the AC converter link 400) can be used to transfer power between the first electrical channel 312 and the second electrical channel 342.

[0114] Now return Figure 11 , when the target condition is satisfied, one or more processors 452 can control the tie contactor 412 of the AC bus link 410 to electrically couple the first AC bus 314 of the first electrical channel 312 and the second AC bus 344 of the second electrical channel 342. In this way, power can be directly transferred from the first AC bus 314 to the second AC bus 344 at the AC level and continue to one or more electrical loads 346, 360, 366 associated with the second electrical channel 342. Figure 11 The dashed arrow in depicts the direct transfer of power from the first AC bus 314 to the second AC bus 344 at the AC level.

[0115] In some embodiments, the target condition is satisfied when power has been transferred through one or more connection links for a predetermined time. By waiting for a period of time associated with the predetermined time before electrically coupling the first AC bus 314 and the second AC bus 344 via the AC bus link 410, transferring power from the first electrical channel 312 to the second electrical channel 342 via one or more other connection links allows the voltage levels, frequencies, and phases of the two channels 312, 342 to be synchronized. In other words, providing power first through one or more other connection links before directly coupling the first AC bus 314 and the second AC bus 344 allows the voltage level and frequency of the second AC bus 344 to be synchronized with the voltage level and frequency of the first AC bus 314 before the first AC bus 314 and the second AC bus 344 are directly electrically coupled via the AC bus link 410. This also allows the phase synchronization of the first AC bus 314 and the second AC bus 344.

[0116] In other embodiments, the target condition is satisfied when the voltage level of the first AC bus 314 and the voltage level of the second AC bus 344 are within a predetermined range of each other (e.g., within five percent of each other). In some further embodiments, the target condition is satisfied when the frequency of the first AC bus 314 and the frequency of the second AC bus 344 are within a predetermined range of each other. One or more sensors at the first AC bus 314 and the second AC bus 344 can measure such characteristics, and the sensor readings can be provided to one or more processors 452 so that one or more processors 452 can determine when the target condition is satisfied.

[0117] When the target condition is satisfied, power can be transferred through the AC bus link 410 as described above, for example, as Figure 11As shown by the dashed arrow in. This allows power to be directly transferred from the first AC bus 314 to the second AC bus 344 at the AC level. In this way, power transmission and distribution through the system 300 can be effectively achieved. In some embodiments, when the target condition is met, power can be prevented from being transferred to the second electrical channel 342 through all other connection links except the AC bus link 410. In other embodiments, when the target condition is met, power can continue to be transferred to the second electrical channel 342 through one or more connection links except the AC bus link 410.

[0118] It should be understood that the propulsion system 50 and the AC electrical system 300 depicted in the above description and the drawings are provided only as examples, and in other exemplary embodiments, the propulsion system 50 and the AC electrical system 300 may have other suitable configurations. In certain exemplary embodiments, for example Figure 15 In the exemplary embodiment depicted in, the turbine or core turbine 104 of the gas turbine engine 100 may include an intermediate-speed spool 175 in addition to the high-speed spool 160 and the low-speed spool 180. With this configuration, the low-speed spool 180 can extend directly from the low-speed turbine 118 to the fan 126, the intermediate-speed spool 175 can drive the booster compressor 110 (e.g., a low-speed compressor) using the intermediate-speed turbine 119, and the high-speed spool 160 can drive the high-speed compressor 112 using the high-speed turbine 116.

[0119] Furthermore, it should be understood that when the gas turbine engine includes three spools, as Figure 15 shown, the AC electrical system may also include a third motor 178 mechanically coupled to the third spool 175 (e.g., an intermediate-speed spool) of the gas turbine engine 100. The third electrical channel can electrically couple the third motor 178 to the third AC bus. Additionally, with this configuration, the AC electrical system may also include one or more connection links that selectively electrically couple the third electrical channel to the first electrical channel, the second electrical channel, or both in any of the example ways described herein. In this regard, the power generated by the third motor 178 can be transferred to the first electrical channel, the second electrical channel, or both, and further, the power generated by the first motor 170 can be transferred to the second electrical channel, the third electrical channel, or both, and in addition, the power generated by the second motor 190 can be transferred to the first electrical channel, the third electrical channel, or both.

[0120] Figure 16 A flowchart of a method 600 for transferring power between spools of a gas turbine engine for power-assisted operation according to one aspect of the present disclosure is provided. For purposes of illustration and discussion, Figure 16depicts steps performed in a particular order. Those of ordinary skill in the art using the disclosure provided herein will understand that the various steps of any method disclosed herein can be adjusted, modified, rearranged, or improved in various ways without departing from the scope of the disclosure.

[0121] At 602, method 600 includes determining a power sharing allocation for power-assisted operation. For example, one or more processors of an EMS can initiate a power-assisted operation at least in part based on received data. The data can indicate a required thrust output of a gas turbine engine and power required for electrical loads of the gas turbine engine and the vehicle. The power sharing allocation can indicate whether power will be drawn from a first electric machine and how much power will be drawn from the first electric machine, or whether power and how much power will be provided to the first electric machine, and can indicate whether power will be drawn from a second electric machine and how much power will be drawn from the second electric machine, or whether power and how much power will be provided to the second electric machine.

[0122] At 604, referring again to Figure 16 , method 600 includes transmitting power generated by a second electric machine mechanically coupled to a second spool of a gas turbine engine to a first electric machine mechanically coupled to a first spool of the gas turbine engine on an AC electrical system of the vehicle. For example, the vehicle can be an aircraft. In some embodiments, transmitting power at 604 includes at least one of the following: i) guiding power from the second electric machine along a second electrical path to a second AC bus positioned along the second electrical path, through a second AC / DC converter positioned along the second electrical path, at a DC level through one or more connection links to a first electrical path, through a first AC / DC converter to a first AC bus, and continuing to the first electric machine; and ii) guiding power from the second AC bus at an AC level through an AC / AC converter positioned along an AC converter link electrically coupling the first AC bus and the second AC bus, and continuing to the first AC bus and the first electric machine.

[0123] In yet another embodiment, the AC electrical system has a DC bus system that includes a first DC bus positioned along a first electrical path and a second DC bus positioned along a second electrical path. In such an embodiment, one or more connection links include a DC bus link, for example, as Figure 5 shown. Additionally, in such an embodiment, transmitting power from the second electric machine to the first electric machine includes guiding power from the second DC bus to the first DC bus at a DC level through the DC bus link and then to a first AC / DC converter, for example, to convert back to alternating current before guiding to the first AC bus and ultimately to the first electric machine.

[0124] In some further embodiments, the AC electrical system has a DC bus system that includes a single DC bus connected to a first electrical channel and a second electrical channel. In such an embodiment, one or more connection links include a single DC bus, e.g., as Figure 6 shown, and wherein transmitting power includes directing power at a DC level through the single DC bus.

[0125] In some embodiments, one or more connection links include a converter link, e.g., as Figure 7 shown. In such an embodiment, transmitting includes directing power at a DC level from a second AC / DC converter to a first AC / DC converter through the converter link.

[0126] In other embodiments, transmitting power from a second electric machine to a first electric machine includes directing power at an AC level from a second AC bus through an AC / AC converter positioned along an AC converter link that electrically couples the first AC bus and the second AC bus, e.g., as Figure 8 shown, and continuing to the first AC bus and the first electric machine. In some embodiments, the AC / AC converter is one of a matrix converter and a cycloconverter.

[0127] In some further embodiments, transmitting power from a second electric machine to a first electric machine includes directing power at DC and AC levels through a plurality of connection links, e.g., as Figure 9 shown.

[0128] Additionally, in other embodiments, the second electrical channel has a load line that electrically couples a load AC / DC converter to the DC bus system and electrically couples the load AC / DC converter to an electrical load. The second electrical channel has a secondary line that electrically connects the second AC bus to the load line at a point between the load AC / DC converter and the electrical load. In such an embodiment, transmitting the power generated by the second electric machine to the first electric machine includes directing power along the secondary line, through the load AC / DC converter and to the DC bus system, through at least one of the one or more connection links from the second electrical channel to the first electrical channel, and along the first electrical channel to the first electric machine.

[0129] Figure 17 A flowchart of a method 700 for transmitting power through an AC electrical system of a vehicle in accordance with one aspect of the present disclosure is provided. For purposes of illustration and discussion, Figure 17 the steps are depicted as being performed in a particular order. Those of ordinary skill in the art using the disclosure provided herein will understand that the various steps of any of the methods disclosed herein can be adjusted, modified, rearranged, or improved in various ways without departing from the scope of the present disclosure.

[0130] At 702, method 700 includes generating electrical power by a first electric machine mechanically coupled to a first spool of a gas turbine engine. For example, the gas turbine engine can be a multi-spool gas turbine engine for an aircraft. In some embodiments, the gas turbine engine can be a two-spool gas turbine engine having a first spool and a second spool. In other embodiments, the gas turbine engine can include more than two spools.

[0131] At 704, method 700 includes generating electrical power by a second electric machine mechanically coupled to a second spool of the gas turbine engine. In this regard, the first electric machine generates electrical power at 702 and the second electric machine generates electrical power at 704. For example, the electrical power generated by the first and second electric machines can be directed to their respective electrical loads.

[0132] At 706, method 700 includes, in response to a detected power generation fault associated with the second electric machine, transmitting electrical power generated by the first electric machine from a first electrical path associated with the first electric machine to a second electrical path associated with the second electric machine via one or more connection links. For example, one or more processors can receive data indicating that a power generation fault associated with the second electric machine has occurred. The power generation fault can indicate that the second electric machine does not meet the power demand of at least one electrical load associated with it. Thus, to ensure that the power demand of at least one electrical load associated with the second electric machine is met, the electrical power generated by the first electric machine can be transmitted from the first electrical path to the second electrical path via one or more connection links (such as any connection link disclosed herein).

[0133] For example, in some embodiments, an AC electrical system has a DC bus system that includes a first DC bus positioned along a first electrical path and a second DC bus positioned along a second electrical path. In such an embodiment, one or more connection links include DC bus links, for example, as Figure 11 shown. Thus, transmitting electrical power generated by the first electric machine from a first electrical path associated with the first electric machine to a second electrical path associated with the second electric machine via one or more connection links includes directing the electrical power from the first DC bus to the second DC bus at a DC level via the DC bus link and then to one or more AC / DC converters of the second electrical path.

[0134] In some further embodiments, an AC electrical system has a DC bus system that includes a single DC bus connected to the first and second electrical paths. One or more connection links include the single DC bus, for example, as Figure 12As shown. In such an embodiment, transmitting the power generated by the first electric machine from the first electrical path associated with the first electric machine to the second electrical path associated with the second electric machine through one or more connection links includes guiding the power at a DC level through a single DC bus and then to one or more AC / DC converters of the second electrical path.

[0135] In some embodiments, one or more connection links include a converter link, for example, as Figure 13 shown. In such an embodiment, transmitting the power at 706 includes guiding the power at a DC level from the first AC / DC converter of the first electrical path to the second AC / DC converter of the second electrical path through the converter link. As previously described, the power can be transmitted at a DC level through the converter link, or in other words, as direct current.

[0136] In other example embodiments, one or more connection links include an AC converter link having an AC / AC converter, for example, as Figure 14 shown. In such an embodiment, transmitting the power generated by the first electric machine from the first electrical path associated with the first electric machine to the second electrical path associated with the second electric machine through one or more connection links includes guiding the power at an AC level from the first AC bus of the first electrical path and through the AC / AC converter to the second AC bus of the second electrical path. In some embodiments, the AC / AC converter is one of a matrix converter and a cycloconverter.

[0137] At 708, method 700 includes, when a target condition is met, electrically coupling the first AC bus of the first electrical path and the second AC bus of the second electrical path with an AC bus link, thereby transmitting the power from the first AC bus to the second AC bus at an AC level and continuing to one or more electrical loads associated with the second electrical path. In some embodiments, the first AC bus and the second AC bus are directly electrically connected. In this way, the power can be more efficiently transmitted from one electrical path to another.

[0138] In some embodiments, the target condition is met when the power has been transmitted through one or more connection links for a predetermined time. In other embodiments, the target condition is met when the voltage level of the first AC bus and the voltage level of the second AC bus are within a predetermined range of each other (e.g., within five percent of each other). In some further embodiments, the target condition is met when the frequency of the first AC bus and the frequency of the second AC bus are within a predetermined range of each other.

[0139] Figure 18An example computing system 800 in accordance with an example embodiment of the present disclosure is provided. The computing elements or systems described herein may include one, some, or all of the components of computing system 800 and may perform the operations described below.

[0140] As Figure 18 shown, computing system 800 may include one or more computing devices 810. Computing device 810 may include one or more processors 810A and one or more memory devices 810B. One or more processors 810A may include any suitable processing device, such as a microprocessor, a microcontroller, an integrated circuit, a logic device, and / or other suitable processing device. One or more memory devices 810B may include one or more computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, hard disk drives, flash drives, and / or other memory devices.

[0141] One or more memory devices 810B may store information accessible by one or more processors 810A, including computer-executable or computer-readable instructions 810C executable by one or more processors 810A. Instructions 810C may be any set of instructions that, when executed by one or more processors 810A, cause one or more processors 810A to operate. In some embodiments, instructions 810C may be executed by one or more processors 810A to cause one or more processors 810A to operate, such as any operations and functions for which computing system 800 and / or computing device 810 is configured. Instructions 810C may be software written in any suitable programming language or may be implemented in hardware. Additionally and / or alternatively, instructions 810C may be executed in logical and / or virtual separate threads on processor 810A. Memory device 810B may further store data 810D accessible by processor 810A.

[0142] Computing device 810 may further include a network interface 810E for communicating with other components of system 800, for example, (e.g., via a network). Network interface 810E may include any suitable components for interfacing with one or more networks, including, for example, a transmitter, a receiver, a port, a controller, an antenna, and / or other suitable components. One or more controllable devices (e.g., bus tie contactors, power converters, etc.) may be configured to receive one or more commands from computing device 810 or provide one or more commands to computing device 810.

[0143] The techniques discussed herein refer to computer-based systems, actions taken by computer-based systems, information sent to computer-based systems, and information from computer-based systems. Those of ordinary skill in the art will recognize that the inherent flexibility of computer-based systems allows for a variety of possible configurations, combinations, and divisions of tasks and functions among and within components. For example, the processing discussed herein can be implemented using a single computing device or multiple computing devices working in combination. Databases, memories, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

[0144] Figures 19 to 22 Various circuit diagrams are provided that depict exemplary ways in which a first AC bus 314 can be electrically coupled to a second AC bus 344.

[0145] Figure 19 A circuit diagram for a voltage source DC link converter implementation is depicted, in which a first AC bus 314 of a first electrical path 312 is electrically coupled to a second AC bus 344 of a second electrical path 342 via a voltage DC bus. As shown, the first AC bus 314 is electrically connected to a first AC / DC converter 320. That is, lines associated with respective phases a, b, c electrically connect the first AC bus 314 to different levels or legs of the first AC / DC converter 320. The first AC / DC converter 320 is a multilevel converter having a plurality of diodes and switching elements. The switching elements can be any suitable type of switching element, such as insulated gate bipolar transistors, power MOSFETs, etc.

[0146] The first AC / DC converter 320 is electrically connected to a single DC bus 374 (associated with the single DC bus 374 of Figure 6 . The single DC bus 374 has a capacitor C2 to keep the DC bus voltage constant or nearly constant. The DC bus 374 is electrically connected to a second AC / DC converter 350. In other words, lines associated with respective phases A, B, C electrically connect the second AC bus 344 to different levels or legs of the second AC / DC converter 350. Like the first AC / DC converter 320, the second AC / DC converter 350 is a multilevel converter having a plurality of diodes and switching elements. The switching elements can be any suitable type of switching element, such as insulated gate bipolar transistors, power MOSFETs, etc. It should be understood that in other DC bus system embodiments disclosed herein (e.g., where the DC bus system includes separate DC buses as shown in Figure 5 and / or where power is transmitted through a converter link 390 as shown in Figure 7 ), the first AC bus 314 can be via as shown in Figure 19The voltage DC bus shown is electrically connected to the second AC bus 344.

[0147] Figure 20 A circuit diagram for a current source DC link converter implementation is depicted, where the first AC bus 314 of the first electrical path 312 is electrically connected to the second AC bus 344 of the second electrical path 342 via a current DC bus. As shown, the first AC bus 314 is electrically connected to the first AC / DC converter 320. In other words, the lines associated with the respective phases a, b, c electrically connect the first AC bus 314 to different levels or branches of the first AC / DC converter 320. The first AC / DC converter 320 is a multilevel converter having a plurality of diodes and switching elements. The switching elements can be any suitable type of switching element, such as insulated gate bipolar transistors, power MOSFETs, etc.

[0148] The first AC / DC converter 320 is electrically connected to a single DC bus 374 (associated with Figure 6 the single DC bus 374). The single DC bus 374 has an inductor L2 to keep the DC bus current constant or nearly constant. The DC bus 374 is electrically connected to the second AC / DC converter 350. In other words, the lines associated with the respective phases A, B, C electrically connect the second AC bus 344 to different levels or branches of the second AC / DC converter 350. The second AC / DC converter 350 is a multilevel converter having a plurality of diodes and switching elements. The switching elements can be any suitable type of switching element, such as insulated gate bipolar transistors, power MOSFETs, etc. It should be understood that in other DC bus system embodiments disclosed herein (e.g., where the DC bus system includes a separate DC bus as Figure 5 shown and / or where power is transmitted through a converter link 390 as Figure 7 shown), the first AC bus 314 can be electrically connected to the second AC bus 344 via a current DC bus as Figure 20 shown.

[0149] Figure 21Depicts a circuit diagram for a matrix converter implementation, wherein a first AC bus 314 of a first electrical channel 312 is electrically coupled via an AC converter link 400 to a second AC bus 344 of a second electrical channel 342, and wherein an AC / AC matrix converter 402A is positioned along the link 400. As shown, the AC / AC matrix converter 402A includes a plurality of switching elements. The switching elements can be any suitable type of switching element, such as insulated gate bipolar transistors, power MOSFETs, etc. For this embodiment, the AC / AC matrix converter 402A can perform voltage and current conversion in a single stage for the three phases depicted. The AC / AC matrix converter 402A is operable to convert AC-level power flowing along the AC converter link 400 such that it is synchronized with the voltage level, frequency, and phase associated with the AC bus to which the AC-level power is directed. For example, among other things, the AC / AC matrix converter 402A can be implemented as an AC / AC converter 402 for the embodiments of Figure 8 , Figure 9 , Figure 14 .

[0150] Figure 22 Depicts a circuit diagram for a cycloconverter implementation, wherein a first AC bus 314 of a first electrical channel 312 is electrically coupled via an AC converter link 400 to a second AC bus 344 of a second electrical channel 342, and wherein an AC / AC cycloconverter 402B is positioned along the link 400. As shown, the AC / AC cycloconverter 402B includes a plurality of phase-controlled switching elements. The phase-controlled switching elements can be any suitable type of switching element. The AC / AC cycloconverter 402B is operable to convert AC-level power flowing along the AC converter link 400 such that it is synchronized with the voltage level, frequency, and phase associated with the AC bus to which the AC-level power is directed. For example, among other things, the AC / AC cycloconverter 402B can be implemented as an AC / AC converter 402 for the embodiments of Figure 8 , Figure 9 , Figure 14 .

[0151] Although specific features of various embodiments may be shown in some figures and not in others, this is for convenience only. In accordance with the principles of the present disclosure, any feature of any figure can be referenced and / or claimed in combination with any feature of any other figure.

[0152] The written description uses examples to disclose the present disclosure, including the best mode, and also enables any person skilled in the art to practice the present disclosure, including making and using any device or system and performing any combined method. The patent scope of the present disclosure is defined by the claims and may include other examples that occur to those skilled in the art. If such other examples include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims, then such other examples are intended to fall within the scope of the claims.

[0153] A further aspect is provided by the subject matter of the following clauses:

[0154] 1. An AC electrical system for a vehicle, comprising: a first motor mechanically coupled to a first spool of a gas turbine engine; a second motor mechanically coupled to a second spool of the gas turbine engine; a first AC bus; a second AC bus; a first electrical path electrically coupling the first motor to the first AC bus; a second electrical path electrically coupling the second motor to the second AC bus; one or more connection links selectively electrically coupling the first electrical path and the second electrical path; and one or more power converters operable to convert power transmitted between the first electrical path and the second electrical path through the one or more connection links such that power generated by the second motor can be transmitted to the first electrical path or such that power generated by the first motor can be transmitted to the second electrical path.

[0155] 2. The AC electrical system according to any of the preceding clauses, further comprising: a DC bus system; a first AC / DC converter, the first AC / DC converter being a bidirectional AC / DC converter; and a second AC / DC converter, and wherein the first electrical path electrically couples the first AC bus to the first AC / DC converter and electrically couples the first AC / DC converter to the DC bus system, and wherein the second electrical path electrically couples the second AC bus to the second AC / DC converter and electrically couples the second AC / DC converter to the DC bus system.

[0156] 3. The AC electrical system according to any of the preceding clauses, wherein the DC bus system includes a first DC bus positioned along the first electrical path and a second DC bus positioned along the second electrical path, and wherein the one or more connection links include a DC bus link for selectively electrically coupling the first DC bus and the second DC bus of the DC bus system.

[0157] 4. The AC electrical system according to any of the preceding clauses, wherein the DC bus system includes a single DC bus, and wherein the one or more connection links include the single DC bus for selectively electrically coupling the first electrical channel and the second electrical channel.

[0158] 5. The AC electrical system according to any of the preceding clauses, wherein the DC bus system is one of a voltage DC bus and a current DC bus.

[0159] 6. The AC electrical system according to any of the preceding clauses, further comprising: a first AC / DC converter; and a second AC / DC converter, and wherein the one or more connection links include a converter link for selectively electrically coupling the first AC / DC converter and the second AC / DC converter.

[0160] 7. The AC electrical system according to any of the preceding clauses, wherein the one or more connection links include an AC converter link for selectively electrically coupling the first AC bus and the second AC bus, the AC converter link including an AC / AC converter.

[0161] 8. The AC electrical system according to any of the preceding clauses, wherein the AC / AC converter is a matrix converter.

[0162] 9. The AC electrical system according to any of the preceding clauses, wherein the AC / AC converter is a cycloconverter.

[0163] 10. The AC electrical system according to any of the preceding clauses, wherein: i) the first spool is a high-voltage spool and the second spool is a low-voltage spool; or ii) the first spool is the low-voltage spool and the second spool is the high-voltage spool.

[0164] 11. The AC electrical system according to any of the preceding clauses, further comprising: one or more processors configured to cause power generated by the second electric machine to be transmitted from the second electrical channel to the first electrical channel and the first electric machine through at least one of the one or more connection links, at least in part based on a power sharing distribution for power assist operation.

[0165] 12. The AC electrical system according to any of the preceding clauses further comprises: a DC bus system; a first AC / DC converter, the first AC / DC converter being a bidirectional AC / DC converter; and a second AC / DC converter, and wherein the first electrical path electrically couples the first AC bus to the first AC / DC converter and electrically couples the first AC / DC converter to the DC bus system, and wherein the second electrical path electrically couples the second AC bus to the second AC / DC converter and electrically couples the second AC / DC converter to the DC bus system, and wherein the second electrical path has a load line that electrically couples a load AC / DC converter to the DC bus system and electrically couples the load AC / DC converter to an electrical load, and wherein the second electrical path has a secondary line that electrically connects the second AC bus to the load line at a point between the load AC / DC converter and the electrical load.

[0166] 13. The AC electrical system according to any of the preceding clauses, wherein the one or more processors are further configured to: at least partially based on the power sharing distribution for the power assist operation, cause the power generated by the second motor to be transmitted along the secondary line, through the load AC / DC converter to the DC bus system, through at least one of the one or more connection links from the second electrical path to the first electrical path, and along the first electrical path to the first motor.

[0167] 14. The AC electrical system according to any of the preceding clauses, wherein the first spool is a medium voltage spool and the second spool is one of the low voltage spool and the high voltage spool of the gas turbine engine.

[0168] 15. A method comprises: transmitting, on an AC electrical system of a vehicle, power generated by a second motor mechanically coupled to a second spool of a gas turbine engine to a first motor mechanically coupled to a first spool of the gas turbine engine, and wherein the transmission comprises at least one of the following: i) guiding power from the second motor along a second electrical path to a second AC bus positioned along the second electrical path, through a second AC / DC converter positioned along the second electrical path, through one or more connection links at a DC level to a first electrical path, through a first AC / DC converter to a first AC bus, and continuing to the first motor; and ii) guiding power from the second AC bus at an AC level through an AC / AC converter positioned along an AC converter link electrically coupling the first AC bus and the second AC bus, and continuing to the first AC bus and the first motor.

[0169] 16. The method according to any of the preceding clauses, wherein the one or more connection links include a converter link, and wherein the transfer includes directing power from the second AC / DC converter to the first AC / DC converter at the DC level through the converter link.

[0170] 17. The method according to any of the preceding clauses, wherein the AC electrical system has a DC bus system, the DC bus system includes a first DC bus positioned along the first electrical path and a second DC bus positioned along the second electrical path, and wherein the one or more connection links include a DC bus link, and wherein the transfer includes directing power from the second DC bus to the first DC bus at the DC level through the DC bus link and then to the first AC / DC converter.

[0171] 18. The method according to any of the preceding clauses, wherein the AC electrical system has a DC bus system, the DC bus system includes a single DC bus connected to the first electrical path and the second electrical path, and wherein the one or more connection links include the single DC bus, and wherein the transfer includes directing power at the DC level through the single DC bus.

[0172] 19. The method according to any of the preceding clauses, wherein the transfer further includes directing power at the AC level from the second AC bus through the AC / AC converter positioned along the AC converter link electrically coupling the first AC bus and the second AC bus and continuing to the first AC bus and the first motor.

[0173] 20. The method according to any of the preceding clauses, wherein the AC / AC converter is one of a matrix converter and a cycloconverter.

[0174] 21. The method according to any of the preceding clauses, wherein the second electrical path has a load line that electrically couples a load AC / DC converter to the DC bus system and electrically couples the load AC / DC converter to an electrical load, and wherein the second electrical path has a secondary line that electrically connects the second AC bus to the load line at a point between the load AC / DC converter and the electrical load, and wherein the transfer further includes directing power along the secondary line, through the load AC / DC converter to the DC bus system, through at least one of the one or more connection links from the second electrical path to the first electrical path, and along the first electrical path to the first motor.

[0175] 22. A method for transmitting electrical power through an AC electrical system of a vehicle, the method comprising: generating electrical power by a first electric machine mechanically coupled to a first spool of a gas turbine engine; generating electrical power by a second electric machine mechanically coupled to a second spool of the gas turbine engine; in response to a detected power generation fault associated with the second electric machine, transmitting electrical power generated by the first electric machine from a first electrical path associated with the first electric machine to a second electrical path associated with the second electric machine through one or more connection links; and when a target condition is met, electrically coupling a first AC bus of the first electrical path and a second AC bus of the second electrical path with an AC bus link, thereby transmitting electrical power from the first AC bus to the second AC bus at an AC level and continuing to transmit to one or more electrical loads associated with the second electrical path.

[0176] 23. The method according to any of the preceding clauses, wherein the one or more connection links include a converter link, and wherein the transmission includes guiding electrical power from a first AC / DC converter of the first electrical path to a second AC / DC converter of the second electrical path at a DC level through the converter link.

[0177] 24. The method according to any of the preceding clauses, wherein the AC electrical system has a DC bus system, the DC bus system includes a first DC bus positioned along the first electrical path and a second DC bus positioned along the second electrical path, and wherein the one or more connection links include a DC bus link, and wherein the transmission includes guiding electrical power from the first DC bus to the second DC bus at a DC level through the DC bus link and then to one or more AC / DC converters of the second electrical path.

[0178] 25. The method according to any of the preceding clauses, wherein the AC electrical system has a DC bus system, the DC bus system includes a single DC bus connected to the first electrical path and the second electrical path, and wherein the one or more connection links include the single DC bus, and wherein the transmission includes guiding electrical power at a DC level through the single DC bus and then to one or more AC / DC converters of the second electrical path.

[0179] 26. The method according to any of the preceding clauses, wherein the one or more connection links include an AC converter link having an AC / AC converter, and wherein the transmission includes guiding electrical power from the first AC bus of the first electrical path at an AC level through the AC converter link and through the AC / AC converter to the second AC bus of the second electrical path.

[0180] 27. According to the method described in any of the preceding clauses, wherein the AC / AC converter is one of a matrix converter and a cycloconverter.

[0181] 28. According to the method described in any of the preceding clauses, wherein the target condition is satisfied when power has been transmitted through the one or more connection links for a predetermined time.

[0182] 29. According to the method described in any of the preceding clauses, wherein the target condition is satisfied when the voltage level of the first AC bus and the voltage level of the second AC bus are within a predetermined range of each other.

[0183] 30. According to the method described in any of the preceding clauses, wherein the target condition is satisfied when the frequency of the first AC bus and the frequency of the second AC bus are within a predetermined range of each other.

[0184] 31. A non-transitory computer-readable medium including computer-executable instructions that, when executed by one or more processors of a vehicle's computing system, cause the one or more processors to: cause power generated by a second electric machine mechanically coupled to a second spool of a gas turbine engine to be transmitted to a second AC bus electrically coupled to the second electric machine; cause the power transmitted to the second AC bus to be transmitted to one or more power converters to convert the power; and cause the power converted by the one or more power converters to be transmitted to a first AC bus electrically coupled to a first electric machine, the first electric machine being mechanically coupled to a first spool of the gas turbine engine.

[0185] 32. A method including: transmitting, on an AC electrical system of a vehicle, power generated by a second electric machine mechanically coupled to a second spool of a gas turbine engine to a first electric machine mechanically coupled to a first spool of the gas turbine engine, and wherein the transmitting includes at least one of: i) guiding power from the second electric machine along a second electrical path to a second AC bus positioned along the second electrical path, through a second AC / DC converter positioned along the second electrical path, through one or more connection links at a DC level to a first electrical path, through a first AC / DC converter to the first AC bus; and ii) guiding power from the second AC bus at an AC level through an AC / AC converter positioned along an AC converter link electrically coupling the first AC bus and the second AC bus, and continuing to guide to the first AC bus.

[0186] 33. A non - transitory computer - readable medium comprising computer - executable instructions that, when executed by one or more processors of a vehicle's computing system, cause the one or more processors to: cause electrical power generated by a second electric machine mechanically coupled to a second spool of a gas turbine engine to be transmitted through the vehicle's AC electrical system to a first electric machine mechanically coupled to a first spool of the gas turbine engine, and wherein, when causing the electrical power generated by the second electric machine to be transmitted to the first electric machine, the one or more processors cause at least one of the following: i) direct electrical power from the second electric machine along a second electrical path to a second AC bus positioned along the second electrical path, through a second AC / DC converter positioned along the second electrical path, through one or more connection links at a DC level to a first electrical path, through a first AC / DC converter to a first AC bus, and continue to the first electric machine; and ii) direct electrical power at an AC level from the second AC bus through an AC / AC converter positioned along an AC converter link electrically coupling the first AC bus and the second AC bus, and continue to direct to the first AC bus and the first electric machine.

[0187] 34. A non - transitory computer - readable medium comprising computer - executable instructions that, when executed by one or more processors of a vehicle's computing system, cause the one or more processors to: cause a first electric machine mechanically coupled to a first spool of a gas turbine engine to generate electrical power; cause a second electric machine mechanically coupled to a second spool of the gas turbine engine to generate electrical power; in response to a detected power generation fault associated with the second electric machine, cause the electrical power generated by the first electric machine to be transmitted through one or more connection links from a first electrical path associated with the first electric machine to a second electrical path associated with the second electric machine; and when a target condition is met, directly electrically couple a first AC bus of the first electrical path to a second AC bus of the second electrical path such that electrical power is transmitted from the first AC bus to the second AC bus at an AC level and continue to be transmitted to one or more electrical loads associated with the second electrical path.

[0188] 35. An AC electrical system for a vehicle, comprising: a first motor mechanically coupled to a first spool of a gas turbine engine; a second motor mechanically coupled to a second spool of the gas turbine engine; a first AC bus; a second AC bus; a first electrical path electrically coupling the first motor to the first AC bus; a second electrical path electrically coupling the second motor to the second AC bus; one or more connection links selectively electrically coupling the first electrical path and the second electrical path; one or more power converters operable to convert electrical power; and one or more processors configured to: cause the first motor to generate electrical power; cause the second motor to generate electrical power; in response to a detected power generation fault associated with the second motor, cause the electrical power generated by the first motor to be converted by the one or more power converters and transmitted through the one or more connection links from the first electrical path associated with the first motor to the second electrical path associated with the second motor; and when a target condition is met, directly electrically couple the first AC bus of the first electrical path to the second AC bus of the second electrical path so as to transmit electrical power from the first AC bus to the second AC bus at an AC level.

Claims

1. An AC electrical system for a vehicle, characterized in that, Comprising: A first electric machine, the first electric machine being mechanically coupled to a first line shaft of a gas turbine engine; A second electric machine, the second electric machine being mechanically coupled to a second line shaft of the gas turbine engine; A first AC bus; A second AC bus; A DC bus system; A first AC / DC converter, the first AC / DC converter being a bidirectional AC / DC converter; And A second AC / DC converter; A first electrical path, the first electrical path electrically coupling the first electric machine to the first AC bus, electrically coupling the first AC bus to the first AC / DC converter, and electrically coupling the first AC / DC converter to the DC bus system; A second electrical path, the second electrical path electrically coupling the second electric machine to the second AC bus, electrically coupling the second bus to the second AC / DC converter, and electrically coupling the second AC / DC converter to the DC bus system, and the second electrical path further includes a load line that electrically couples a load AC / DC converter to the DC bus system and electrically couples the load AC / DC converter to an electrical load, and wherein the second electrical path has a secondary line that electrically connects the second AC bus to the load line at a point between the load AC / DC converter and the electrical load; One or more connection links that selectively electrically couple the first AC bus and the second AC bus; And One or more power converters that are operable to convert power transmitted between the first AC bus and the second AC bus through the one or more connection links such that power generated by the second electric machine can be transmitted from the second AC bus to the first AC bus, or such that power generated by the first electric machine can be transmitted from the first AC bus to the second AC bus.

2. The AC electrical system according to claim 1, characterized in that, Wherein, The DC bus system includes a first DC bus positioned along the first electrical path and a second DC bus positioned along the second electrical path, and wherein the one or more connection links include a DC bus link for selectively electrically coupling the first DC bus and the second DC bus of the DC bus system.

3. The AC electrical system according to claim 1, wherein Wherein, The DC bus system includes a single DC bus, and wherein the one or more connection links include a single DC bus for selectively electrically coupling the first electrical path and the second electrical path.

4. The AC electrical system according to claim 1, wherein, Wherein, The DC bus system is one of a voltage DC bus and a current DC bus.

5. The AC electrical system according to claim 1, wherein, Among them, The one or more connection links include a converter link for selectively electrically coupling the first AC / DC converter and the second AC / DC converter.

6. The AC electrical system according to claim 1, characterized in that, Wherein, The one or more connection links include an AC converter link for selectively electrically coupling the first AC bus and the second AC bus, the AC converter link including an AC / AC converter.

7. The AC electrical system according to claim 6, wherein, Wherein, The AC / AC converter is a matrix converter.

8. The AC electrical system according to claim 6, characterized in that, Wherein, The AC / AC converter is a cycloconverter.

9. The AC electrical system according to claim 1, characterized in that Where: i) The first spool is a high-voltage spool, and the second spool is a low-voltage spool; or ii) The first spool is the low-voltage spool, and the second spool is the high-voltage spool.

10. The AC electrical system according to claim 1, characterized in that, Further comprising: One or more processors configured to: At least partially based on a power sharing distribution for power assist operation, cause power generated by the second motor to be transmitted from the second electrical path to the first electrical path and the first motor through at least one of the one or more connection links.

11. The AC electrical system according to claim 1, characterized in that, Wherein, The one or more processors are further configured to: At least partially based on the power sharing distribution for the power assist operation, cause power generated by the second motor to be transmitted along the secondary line, through the load AC / DC converter to the DC bus system, through at least one of the one or more connection links from the second electrical path to the first electrical path, and along the first electrical path to the first motor.

12. The AC electrical system according to claim 1, wherein, Wherein, The first spool is a medium-voltage spool, and the second spool is one of the low-voltage spool and the high-voltage spool of the gas turbine engine.

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