Hybrid electric propulsion system for an aircraft and method of operating the same

Abstract

The invention relates to a hybrid electric propulsion system for an aircraft and a method of operating the same, the propulsion system including a gas turbine engine and an electric machine coupled to the gas turbine engine. A method of operating the propulsion system includes determining, by one or more computing devices, a baseline power output of the gas turbine engine, operating, by the one or more computing devices, the gas turbine engine to provide the baseline power output, determining, by the one or more computing devices, a desired power output that is greater than or less than the baseline power output, and providing, by the one or more computing devices, power to the gas turbine engine or extracting, by the one or more computing devices, power from the gas turbine engine using the electric machine such that an effective power output of the gas turbine engine matches the determined desired power output.

Description

[0001] This application is a divisional application of Chinese patent application filed on June 8, 2018 (priority date June 9, 2017), application number 201810587403.9, entitled "Hybrid Electric Propulsion System for Aircraft and Operating Method Thereof". Technical Field

[0002] The subject matter of this invention generally relates to hybrid electric propulsion systems for aircraft, and methods for operating gas turbine engines in exemplary hybrid electric propulsion systems to minimize short-cycle damage. Background Technology

[0003] A typical helicopter generally consists of a main rotor assembly and a tail rotor assembly. The gas turbine engine includes an output shaft configured to drive both the main rotor assembly and the tail rotor assembly. Compared to, for example, fixed-wing aircraft, helicopters are operated more frequently, resulting in a flight envelope characterized by numerous small cycles. Consequently, the power output demand on the gas turbine engine within the helicopter's flight envelope increases and decreases relatively frequently.

[0004] If the power output demand increases at least somewhat, the gas turbine engine speed increases to provide additional power output. Conversely, if the power output demand decreases at least somewhat, the gas turbine engine decelerates to provide the reduced power output. However, these additional increases and decreases in gas turbine engine speed can cause small-cycle damage to the gas turbine engine over its lifespan. Therefore, operating the gas turbine engine of the propulsion system in a manner that reduces the number of small cycles in the helicopter's flight envelope would be useful. Summary of the Invention

[0005] Various aspects and advantages of the invention will be set forth in part in the description which follows, or will be apparent from the description, or may be learned by practice of the invention.

[0006] In one exemplary embodiment of this disclosure, a method for operating a hybrid electric propulsion system of an aircraft is provided. The hybrid electric propulsion system includes a gas turbine engine and an electric motor coupled to the gas turbine engine. The method includes: determining a reference power output of the gas turbine engine by one or more computing devices; operating the gas turbine engine by the one or more computing devices to provide the reference power output; determining a desired power output greater than or less than the reference power output by the one or more computing devices; and using the electric motor, providing power to the gas turbine engine by the one or more computing devices, or extracting power from the gas turbine engine by the one or more computing devices, such that the effective power output of the gas turbine engine matches the determined desired power output.

[0007] In some exemplary aspects, the hybrid electric propulsion system further includes an energy storage unit electrically connected to the motor.

[0008] For example, in some exemplary aspects, using the motor, power is supplied to the gas turbine engine by the one or more computing devices, or power is extracted from the gas turbine engine by the one or more computing devices, such that the effective power output of the gas turbine engine matches the determined desired power output, including: power is supplied from the energy storage unit to the motor by the one or more computing devices, or power is extracted from the motor to the energy storage unit by the one or more computing devices.

[0009] For example, in some exemplary aspects, using the motor, providing power to the gas turbine engine by the one or more computing devices, or extracting power from the gas turbine engine by the one or more computing devices, such that the effective power output of the gas turbine engine matches the determined desired power output includes: using the motor, providing differential power to the gas turbine engine by the one or more computing devices, or extracting differential power from the gas turbine engine by the one or more computing devices, wherein the differential power is between approximately one percent and approximately twenty percent of the reference power output.

[0010] For example, in some exemplary aspects, the method further includes determining by the one or more computing devices that the average value of the desired power output is greater than or less than the reference power output of the gas turbine engine, and wherein determining by the one or more computing devices that the reference power output of the gas turbine engine includes modifying the reference power output by the one or more computing devices in response to determining that the average value of the desired power output is greater than or less than the reference power output of the gas turbine engine.

[0011] For example, in some exemplary aspects, the method includes determining the state of charge of the energy storage unit by the one or more computing devices, and wherein determining a reference power output of the gas turbine engine by the one or more computing devices includes modifying the reference power output by the one or more computing devices in response to determining the state of charge of the energy storage unit.

[0012] For example, in some exemplary aspects, determining the charge state of the energy storage unit by the one or more computing devices also includes determining by the one or more computing devices that the charge state is greater than or less than a predetermined threshold.

[0013] For example, in some exemplary aspects, determining the charge state of the energy storage unit by the one or more computing devices also includes determining by the one or more computing devices that the change in the charge state over a period of time is greater than or less than a predetermined threshold.

[0014] In some exemplary aspects, the gas turbine engine is a turboshaft engine including an output shaft, and wherein the electric motor is coupled to the output shaft. For example, in some exemplary aspects, the aircraft is a helicopter with a thruster, and wherein the output shaft drives the thruster. For example, in some exemplary aspects, determining the desired power output, which is greater than or less than the reference power output, by the one or more computing devices includes: receiving input from a set of helicopters by the one or more computing devices; and determining the desired power output by the one or more computing devices based on a vehicle model and the input received from the set of helicopters.

[0015] In some exemplary aspects, operating the gas turbine engine by the one or more computing devices to provide the reference power output includes: rotating the core of the gas turbine engine at a first rotational speed, and wherein power is provided to the gas turbine engine by the one or more computing devices using the motor or extracted from the gas turbine engine by the one or more computing devices, such that the effective power output of the gas turbine engine matches the determined desired power output, includes: rotating the core of the gas turbine engine at substantially the first rotational speed.

[0016] In an exemplary embodiment of this disclosure, a hybrid electric propulsion system for an aircraft is provided. The propulsion system includes: a gas turbine engine including a turbine and an output shaft, the turbine being driven coupled to the output shaft. The propulsion system also includes a motor coupled to the output shaft and a controller. The controller includes a memory and one or more processors, the memory storing instructions that, when executed by the one or more processors, cause the hybrid electric propulsion system to perform functions. The functions include: determining a reference power output of the gas turbine engine; operating the gas turbine engine to provide the reference power output; determining a desired power output greater than or less than the reference power output; and using the motor to provide power to or extract power from the gas turbine engine such that the effective power output of the gas turbine engine matches the determined desired power output.

[0017] In some exemplary embodiments, the gas turbine engine is a turboshaft engine. For example, in some exemplary embodiments, the aircraft is a helicopter with a thruster, and the output shaft is configured to drive the thruster. For example, in some exemplary embodiments, determining the desired power output includes: receiving input from a collection of helicopters; and determining the desired power output based on a vehicle model and the input received from the collection of helicopters.

[0018] In some exemplary embodiments, the propulsion system further includes an energy storage unit electrically connected to the motor. For example, in some exemplary embodiments, using the motor to provide power to the gas turbine engine or extracting power from the gas turbine engine such that the effective power output of the gas turbine engine matches the determined desired power output includes: providing power from the energy storage unit to the motor, or extracting power from the motor to the energy storage unit.

[0019] In some exemplary embodiments, using the motor to provide power to or extract power from the gas turbine engine such that the effective power output of the gas turbine engine matches the determined desired power output includes: using the motor to provide differential power to or extract differential power from the gas turbine engine. For example, in some exemplary embodiments, the differential power is between approximately one percent and approximately twenty percent of the reference power output.

[0020] Specifically, technical solution 1 of this application relates to a method for operating a hybrid electric propulsion system of an aircraft, the hybrid electric propulsion system comprising a gas turbine engine and an electric motor, the electric motor being connected to the gas turbine engine, the method comprising:

[0021] The reference power output of the gas turbine engine is determined by one or more computing devices;

[0022] The gas turbine engine is operated by the one or more computing devices to provide the reference power output;

[0023] The desired power output, which is greater than or less than the reference power output, is determined by the one or more computing devices; and

[0024] Using the motor, power is supplied to the gas turbine engine by the one or more computing devices, or power is extracted from the gas turbine engine by the one or more computing devices, such that the effective power output of the gas turbine engine matches the determined desired power output.

[0025] Technical solution 2 of this application relates to the method according to technical solution 1, wherein the hybrid electric propulsion system further includes an energy storage unit, the energy storage unit being electrically connected to the motor.

[0026] Technical solution 3 of this application relates to a method according to technical solution 2, wherein, using the motor, power is provided to the gas turbine engine by the one or more computing devices, or power is extracted from the gas turbine engine by the one or more computing devices, such that the effective power output of the gas turbine engine matches the determined desired power output, comprising: providing electrical power from the energy storage unit to the motor by the one or more computing devices, or extracting electrical power from the motor to the energy storage unit by the one or more computing devices.

[0027] This application's technical solution 4 relates to a method according to technical solution 2, wherein, using the motor, power is provided to the gas turbine engine by the one or more computing devices, or power is extracted from the gas turbine engine by the one or more computing devices, such that the effective power output of the gas turbine engine matches the determined desired power output, comprising: using the motor, providing differential power to the gas turbine engine by the one or more computing devices, or extracting differential power from the gas turbine engine by the one or more computing devices, wherein the differential power is between approximately one percent and approximately twenty percent of the reference power output.

[0028] Technical solution 5 of this application relates to the method according to technical solution 2, and further includes:

[0029] The one or more computing devices determine that the average value of the desired power output is greater than or less than the reference power output of the gas turbine engine, and wherein determining the reference power output of the gas turbine engine by the one or more computing devices includes: modifying the reference power output by the one or more computing devices in response to determining that the average value of the desired power output is greater than or less than the reference power output of the gas turbine engine.

[0030] Technical solution 6 of this application relates to the method according to technical solution 2, and further includes:

[0031] The charge state of the energy storage unit is determined by the one or more computing devices, and the determination of the reference power output of the gas turbine engine by the one or more computing devices includes: modifying the reference power output by the one or more computing devices in response to determining the charge state of the energy storage unit.

[0032] Technical solution 7 of this application relates to the method according to technical solution 6, wherein determining the charge state of the energy storage unit by the one or more computing devices further includes determining by the one or more computing devices whether the charge state is greater than or less than a predetermined threshold.

[0033] This application's technical solution 8 relates to the method according to technical solution 6, wherein determining the charge state of the energy storage unit by the one or more computing devices further includes determining by the one or more computing devices that the change in the charge state over a time period is greater than or less than a predetermined threshold.

[0034] This application's technical solution 9 relates to the method according to technical solution 1, wherein the gas turbine engine is a turboshaft engine including an output shaft, and wherein the electric motor is connected to the output shaft.

[0035] This application's technical solution 10 relates to the method according to technical solution 9, wherein the aircraft is a helicopter with a thruster, and wherein the output shaft drives the thruster.

[0036] This application's technical solution 11 relates to the method according to technical solution 10, wherein determining the desired power output, which is greater than or less than the reference power output, by the one or more computing devices includes:

[0037] The one or more computing devices receive input from the collection of helicopters; and

[0038] The desired power output is determined by the one or more computing devices based on a vehicle model and inputs received from the set of helicopters.

[0039] This application's technical solution 12 relates to a method according to technical solution 1, wherein operating the gas turbine engine by the one or more computing devices to provide the reference power output includes: rotating the core of the gas turbine engine at a first rotational speed, and wherein providing power to the gas turbine engine by the one or more computing devices using the motor, or extracting power from the gas turbine engine by the one or more computing devices, such that the effective power output of the gas turbine engine matches the determined desired power output, includes: rotating the core of the gas turbine engine at substantially the first rotational speed.

[0040] Technical solution 13 of this application relates to a hybrid electric propulsion system for an aircraft, comprising:

[0041] A gas turbine engine, the gas turbine engine including a turbine and an output shaft, the turbine being drivenly coupled to the output shaft;

[0042] A motor, the motor being connected to the output shaft; and

[0043] The controller includes a memory and one or more processors, the memory storing instructions that, when executed by the one or more processors, cause the hybrid electric propulsion system to perform functions, including:

[0044] Determine the reference power output of the gas turbine engine;

[0045] Operate the gas turbine engine to provide the reference power output;

[0046] Determine the desired power output that is greater than or less than the reference power output; and

[0047] The motor is used to provide power to or extract power from the gas turbine engine, such that the effective power output of the gas turbine engine matches the determined desired power output.

[0048] This application's technical solution 14 relates to a hybrid electric propulsion system according to technical solution 13, wherein the gas turbine engine is a turboshaft engine.

[0049] This application's technical solution 15 relates to a hybrid electric propulsion system according to technical solution 14, wherein the aircraft is a helicopter with a thruster, and wherein the output shaft is configured to drive the thruster.

[0050] This application's technical solution 16 relates to a hybrid electric propulsion system according to technical solution 15, wherein determining the desired power output includes:

[0051] Receive input from the collection of said helicopters; and

[0052] The desired power output is determined based on the vehicle model and the input received from the ensemble of helicopters.

[0053] This application's technical solution 17 relates to the hybrid electric propulsion system according to technical solution 13, and further includes:

[0054] An energy storage unit that can be electrically connected to the motor.

[0055] This application's technical solution 18 relates to a hybrid electric propulsion system according to technical solution 17, wherein using the motor to provide power to the gas turbine engine or extract power from the gas turbine engine such that the effective power output of the gas turbine engine matches the determined desired power output includes: providing power from the energy storage unit to the motor, or extracting power from the motor to the energy storage unit.

[0056] This application's technical solution 19 relates to a hybrid electric propulsion system according to technical solution 13, wherein using the motor to provide power to the gas turbine engine or extract power from the gas turbine engine such that the effective power output of the gas turbine engine matches the determined desired power output includes: using the motor to provide differential power to the gas turbine engine or extract differential power from the gas turbine engine.

[0057] This application's technical solution 20 relates to a hybrid electric propulsion system according to technical solution 19, wherein the differential power is between approximately one percent and approximately twenty percent of the reference power output.

[0058] These and other features, aspects, and advantages of the invention will become more readily 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 invention and, together with the description, serve to explain the principles of the invention. Attached Figure Description

[0059] This specification sets forth a complete and illustrative disclosure of the invention, including its best mode, to those skilled in the art. Reference is made to the accompanying drawings, in which:

[0060] Figure 1 This is a top view of an aircraft according to various exemplary embodiments of the present invention.

[0061] Figure 2 This is a schematic cross-sectional view of a hybrid electric propulsion assembly according to an exemplary embodiment of the present invention.

[0062] Figure 3 This is a flowchart of a method for operating a hybrid electric propulsion system for an aircraft according to an exemplary aspect of the present invention.

[0063] Figure 4 yes Figure 3 A flowchart of an exemplary aspect of the method.

[0064] Figure 5 It is a chart depicting the power output level of a gas turbine engine in a hybrid electric propulsion system operating according to exemplary aspects of this disclosure.

[0065] Figure 6 It is a computing system according to an example aspect of the present invention. Detailed Implementation

[0066] Embodiments of the present invention will now be described in detail, with one or more examples illustrated in the accompanying drawings. Numerical and alphabetical designations are used in the detailed description to refer to features in the drawings. The same or similar reference numerals are used in the drawings and description to refer to the same or similar parts of the invention.

[0067] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of individual components.

[0068] The terms "front" and "rear" refer to relative positions within a gas turbine engine or vehicle, and to the normal operating posture of the gas turbine engine or vehicle. For example, in the case of a gas turbine engine, "front" refers to the position closer to the engine inlet, and "rear" refers to the position closer to the engine nozzle or exhaust manifold.

[0069] The terms “upstream” and “downstream” refer to the relative direction of flow within a path. For example, relative to fluid flow, “upstream” refers to the direction in which the fluid flows out, and “downstream” refers to the direction in which the fluid flows in. However, when used herein, the terms “upstream” and “downstream” may also refer to electric current.

[0070] Unless the context explicitly indicates otherwise, the singular forms “a” and “the” include the plural referent.

[0071] Throughout the specification and claims, approximate language is used to modify any quantitative representations that allow for variations that do not alter their associated essential function. Therefore, values ​​modified by one or more terms such as “about,” “approximately,” and “substantially” are not limited to the specified exact values. In at least some cases, approximate language may correspond to the accuracy of the instrument used to measure the value, or the accuracy of the method or machine used to construct or manufacture the component and / or system. For example, approximate language may refer to a margin of 20%.

[0072] Throughout this specification and claims, scope limitations are combined and interchanged; such scope is definite and includes all subscopes contained herein, unless the context or language otherwise indicates otherwise. For example, all scopes disclosed herein include endpoints, and these endpoints can be independently combined with each other.

[0073] This disclosure generally relates to a method for operating a gas turbine engine in a hybrid electric propulsion system of an aircraft in a manner that reduces the number of small cycles within the aircraft's flight envelope. In at least some exemplary aspects of this disclosure, the method includes determining a reference power output of the gas turbine engine and operating the gas turbine engine to provide the reference power output. The reference power output may generally be the expected average power output of the gas turbine engine through relevant phases of the flight envelope.

[0074] At least some aspects of the exemplary method also include determining a desired power output that is greater than or less than a reference power output, and in response, providing power to or extracting power from the gas turbine engine using a motor, such that the effective power output of the gas turbine engine matches the desired power output. For example, the motor may be mechanically coupled to the motor's output shaft and may also be electrically coupled to an energy storage unit. Providing power to the motor can help drive the gas turbine engine's output shaft to increase the effective power output of the gas turbine engine's output shaft. Conversely, extracting power from the motor can create resistance to the gas turbine engine's output shaft to reduce the effective power output of the gas turbine engine's output shaft.

[0075] More specifically, using this exemplary aspect, for example when the desired power output is greater than the reference power output, the method may provide electrical power from the energy storage unit to the motor to increase the effective power output of the gas turbine engine, such that the effective power output of the gas turbine engine matches the desired power output. Alternatively, for example when the desired power output is less than the reference power output, the method may extract electrical power from the motor to the energy storage unit to reduce the effective power output of the gas turbine engine, such that the effective power output of the gas turbine engine matches the desired power output.

[0076] Furthermore, it should be recognized that, in at least some exemplary aspects of this disclosure, the above method can be used in hybrid electric propulsion systems having turboshaft engines and being incorporated into helicopters.

[0077] Operating a hybrid electric propulsion system in this exemplary manner can have the following effects: reducing the number of small cycles on the gas turbine engine of the hybrid electric propulsion system, thereby reducing wear on the gas turbine engine and increasing its service life.

[0078] Now refer to the attached diagram, Figure 1 A perspective view of an exemplary aircraft 10 according to this disclosure is provided. The aircraft 10 generally has a lateral direction T, a longitudinal direction L, and a vertical direction V. In operation, the aircraft 10 can move along or around the lateral direction T, the longitudinal direction L, and / or the vertical direction V.

[0079] exist Figure 1In the illustrated embodiment, the aircraft 10 includes a fuselage 12 with a cockpit 20. As depicted in closed circle AA, the cockpit 20 includes a total pitch input 22, a cycle pitch input 23, a tail rotor input 24, a first throttle input 26, a second throttle input 28, and an instrument panel 30. The aircraft 10 further includes a main rotor assembly 40 and a tail rotor assembly 50. The main rotor assembly 40 includes a main rotor hub 42 and a plurality of main rotor blades 44. As shown, each main rotor blade 44 extends outward from the main rotor hub 42. The tail rotor section 50 includes a tail rotor hub 52 and a plurality of tail rotor blades 54. Each tail rotor blade 54 extends outward from the tail rotor hub 52.

[0080] Additionally, aircraft 10 includes a hybrid electric propulsion assembly (unnumbered; also seen in...) Figure 2 Examples thereof (discussed below) will be described in more detail below. The hybrid electric propulsion assembly generally includes a first gas turbine engine 60 and a second gas turbine engine 62. It should be recognized that, in at least some exemplary embodiments, Figure 1 One or both of the first and second gas turbine engines 60 and 62 of the medium-sized aircraft 10 can be coupled with Figure 2 The gas turbine engine 102 is configured in a substantially similar manner, and the hybrid electric propulsion system may also include components from... Figure 2 One or more additional components of an exemplary hybrid electric propulsion system depicted in the figure.

[0081] Still refer to Figure 1 The first and second gas turbine engines 60 and 62 can be mechanically connected to each other so that they operate together. For example, the first and second gas turbine engines 60 and 62 can be connected in a gearbox by, for example, differential and one-way clutches (e.g., swashplate clutches) so that they operate together.

[0082] Furthermore, the first gas turbine engine 60 and the second gas turbine engine 62 can generate and transmit electricity to drive the rotation of the main rotor blade 44 and the tail rotor blade 54. Specifically, the rotation of the main rotor blade 44 generates lift for the aircraft 10, while the rotation of the tail rotor blade 54 generates lateral thrust at the tail rotor section 50 and counteracts the torque exerted on the fuselage 12 by the main rotor blade 44.

[0083] The total pitch input device 22 collectively (i.e., all simultaneously) adjusts the pitch angle of the main rotor blades 44 to increase or decrease the amount of lift obtained by the aircraft 10 from the main rotor blades 44 at a given rotor speed. Therefore, manipulating the total pitch input device 22 allows the aircraft 10 to move along the vertical direction V in one of two opposing directions. It should be understood that, as will be discussed in more detail below, manipulating the total pitch input device 22 can also be used to predict the desired power output provided by the hybrid electric propulsion system to the main rotor assembly 40 to generate, for example, the desired lift of the aircraft 10.

[0084] Still refer to Figure 1 The cyclic pitch input device 23 controls the movement of the aircraft 10 about the longitudinal direction L and about the lateral direction T. Specifically, the cyclic pitch input device 23 adjusts the angle of the aircraft 10, thereby allowing the aircraft 10 to move forward or backward along the longitudinal direction L or laterally in the lateral direction T. Additionally, the tail rotor input device 24 controls the pitch angle of the tail rotor blades 54. In operation, manipulating the tail rotor input device 24 moves the tail rotor section 50 along the lateral direction T, thereby changing the orientation of the aircraft 10 and causing the aircraft 10 to rotate about the vertical direction V.

[0085] At the start of flight, the first and second throttle valve input devices 26, 28 can be moved to the open position and activated during flight to provide the desired amount of power to the aircraft 10. In some embodiments, these input devices 26, 28 can be manually activated, or alternatively, in response to the total pitch input device 22 and inputs from the total pitch input device 22, they can be activated by one or more controllers (described below).

[0086] Now refer to Figure 2 A schematic diagram of a hybrid electric propulsion system 100 for an aircraft according to an exemplary embodiment of the present invention is provided. The exemplary hybrid electric propulsion system 100 can be incorporated into the system described above. Figure 1 The exemplary aircraft 10 described herein is similar to other aircraft. However, in other exemplary embodiments, the hybrid electric propulsion system 100 may be used in any other suitable aircraft, as described below.

[0087] For the described embodiment, the hybrid electric propulsion system 100 generally includes a gas turbine engine 102, a main thruster mechanically coupled to the gas turbine engine 102, an electric motor 162 also mechanically coupled to the gas turbine engine 102, an energy storage unit 164, and a controller 166. The functions of each of these components are as follows.

[0088] A cross-sectional view is first provided with reference to a gas turbine engine 102. As depicted, the gas turbine engine 102 defines a longitudinal or centerline axis 103 extending through it for reference. The gas turbine engine 102 generally includes a generally tubular housing 104 defining an inlet 106. The housing 104 surrounds a gas generator compressor 110 (i.e., a high-pressure compressor), a combustion section 130, a turbine section 140, and an exhaust section 150 arranged in a series relationship. The exemplary gas generator compressor 110 depicted includes an annular array of inlet guide vanes 112, one or more successive stages of compressor blades 114, and one stage of centrifugal rotor blades 118. Although not depicted, the gas generator compressor 110 may also include multiple fixed or variable stator blades.

[0089] Combustion section 130 generally includes a combustion chamber 132, one or more fuel nozzles 134 extending into the combustion chamber 132, and a fuel delivery system 138. The fuel delivery system 138 is configured to supply fuel to the one or more fuel nozzles 134, which in turn supply fuel to mix with compressed air entering the combustion chamber 132 from the gas generator compressor 110. Furthermore, the fuel and compressed air mixture is burned within the combustion chamber 132 to form combustion gases. As will be described in more detail below, the combustion gases drive the gas generator compressor 110 and a turbine within the turbine section 140.

[0090] More specifically, turbine section 140 includes a gas generator turbine 142 (or high-pressure turbine) and a power turbine 144 (or low-pressure turbine). The gas generator turbine 142 includes one or more consecutive stages of turbine rotor blades 146, and may also include one or more consecutive stages of stator blades (not shown). Similarly, the power turbine 144 includes one or more consecutive stages of turbine rotor blades 148, and may also include one or more consecutive stages of stator blades (not shown). Furthermore, the gas generator turbine 142 is driven to the gas generator compressor 110 via a gas generator shaft 152, and the power turbine 144 is driven to the output shaft 156 via a power turbine shaft 154.

[0091] During operation, the combustion gas drives both the gas generator turbine 142 and the power turbine 144. As the gas generator turbine 142 rotates around the central axis 103, the gas generator compressor 110 and the gas generator shaft 152 also rotate around the central axis 103. Additionally, as the power turbine 144 rotates, the power turbine shaft 154 rotates and transmits rotational energy to the output shaft 156. Therefore, it should be understood that the gas generator turbine 142 drives the gas generator compressor 110, and the power turbine 144 drives the output shaft 156.

[0092] However, it should be understood that in other exemplary embodiments, Figure 2 The gas turbine engine 102 may have any other suitable configuration. For example, in other exemplary embodiments, the combustion section 130 may include a recirculation burner, and the gas turbine engine may include any suitable number of compressors, shafts, and turbines, etc.

[0093] Still refer to Figure 2 The output shaft 156 is configured to rotate the main thruster of the hybrid electric propulsion system 100, which, for the described exemplary embodiment, is the main rotor assembly 158 (which can be connected to...). Figure 1 The exemplary main rotor assembly 40 of the aircraft 10 is configured in a substantially similar manner. It is noteworthy that the output shaft 156 is mechanically coupled to the main rotor assembly 158 via a gearbox 160. However, in other exemplary embodiments, the output shaft 156 may be coupled to the main rotor assembly 158 in any other suitable manner.

[0094] Furthermore, as mentioned above, the exemplary hybrid electric propulsion system 100 includes: a motor 162, which can be configured as a motor / generator; and an energy storage unit 164. In the depicted embodiment, the motor 162 is directly mechanically coupled to the output shaft 156 of the gas turbine engine 102 (i.e., the rotor of the motor 162 is mounted to the output shaft 156). However, in other exemplary embodiments, the motor 162 may instead be mechanically coupled to the output shaft 156 in any other suitable manner (e.g., via a suitable gear train). Therefore, it should be appreciated that the motor 162 can be configured to convert received electrical power into mechanical power (i.e., act as a motor), and can also be configured to receive mechanical power and convert this mechanical power into electrical power (i.e., act as a generator). Therefore, it should be appreciated that by increasing or decreasing the power output to or from the output shaft 156, the motor 162 can be configured to increase or decrease the effective mechanical power output of the gas turbine engine 102, and more specifically, the output shaft 156 of the gas turbine engine 102.

[0095] Specifically, in the depicted embodiments, the hybrid electric propulsion system 100 is configured to use a motor 162 to increase power to or extract power from a gas turbine engine 102 via an electrical connection between the motor 162 and an energy storage unit 164. The energy storage unit 164 can be any component suitable for receiving, storing, and providing electrical power. For example, the energy storage unit 164 can be a battery pack, such as multiple lithium-ion batteries. However, in other embodiments, any other suitable battery chemistry can be used. Furthermore, in at least some exemplary embodiments, the energy storage unit 164 can be configured to retain at least approximately twenty kilowatt-hours of electrical power. For example, in some exemplary embodiments, the energy storage unit 164 can be configured to store at least approximately thirty kilowatt-hours of electrical power, such as at least approximately fifty kilowatt-hours, such as at least approximately sixty kilowatt-hours, such as up to approximately five hundred kilowatt-hours. Moreover, the motor 162 can be a relatively high-power motor. For example, in some exemplary embodiments, the motor 162 may be configured to generate at least about 75 kilowatts of electrical power or at least about 100 horsepower of mechanical power. For example, in some exemplary embodiments, the motor 162 may be configured to generate up to about 150 kilowatts of electrical power and up to at least about 200 horsepower of mechanical power, such as up to about 750 kilowatts of electrical power and up to at least about 1,000 horsepower of mechanical power.

[0096] More specifically, in the described embodiment, controller 166 is operatively connected to, for example, motor 162 and energy storage unit 164, and configured to electrically connect these components and channel electrical power between them. Therefore, controller 166 can be configured to operate the hybrid electric propulsion system 100 between a power extraction mode and a power enhancement mode. In the power extraction mode, mechanical power from output shaft 156 is converted into electrical power by motor 162 and extracted to energy storage unit 164. This electrical power extraction can act as drag on output shaft 156, reducing the effective power output of gas turbine engine 102, and more specifically, the effective output power of output shaft 156 of gas turbine engine 102. Conversely, in the power enhancement mode, electrical power from energy storage unit 164 is supplied to motor 162 and converted into mechanical power, increasing the output power to output shaft 156. This increase in electrical power can act as thrust on output shaft 156, increasing the effective power output of gas turbine engine 102, and more specifically, the effective power output of output shaft 156 of gas turbine engine 102. (Refer to below...) Figure 3 Method 200 describes exemplary aspects of how this operation works.

[0097] It should be recognized that, in some exemplary embodiments, the hybrid electric propulsion system 100 may also include various power electronic components operable by the controller 166 to facilitate the controller 166 directing electrical power to and / or from the energy storage unit 164. These various power electronic components may also convert and / or condition the electrical power supplied between these components, if necessary or as required.

[0098] Typically, a hybrid electric propulsion system configured according to one or more of these embodiments can reduce low-cycle damage (i.e., damage / wear to various engine components due to repeated changes in power levels or loads during flight) and / or low-cycle fatigue of the gas turbine engine by operating the gas turbine engine at approximately a reference power level and using motors and energy storage units to increase power to or draw power from the output shaft as needed to meet the aircraft's desired power output. For example, the controller of the hybrid electric propulsion system can typically be configured to direct power to the motor connected to the output shaft of the gas turbine engine to increase the effective power output of the gas turbine engine when the desired power output is greater than the reference power for operating the gas turbine engine, and can also be configured to draw power from the motor connected to the output shaft of the gas turbine engine to reduce the effective power output of the gas turbine engine when the desired power output is less than the reference power for operating the gas turbine engine.

[0099] It should also be recognized that, although specific aircraft and hybrid electric propulsion systems have been illustrated and described, other configurations and / or aircraft may benefit from hybrid electric propulsion systems configured according to one or more of the exemplary embodiments described above. For example, in other exemplary embodiments, the aircraft may be any other suitable rotary-wing aircraft, commonly referred to as a helicopter. Alternatively or alternatively, the aircraft may be configured as a vertical takeoff and landing aircraft, commonly referred to as a fixed-wing aircraft, etc.

[0100] Now refer to Figure 3 A computer-implemented method 200 for operating a gas turbine engine in a hybrid electric propulsion system of an aircraft, according to an exemplary aspect of the present invention, is provided. In some exemplary aspects, Figure 3 The exemplary method 200 can be used as referenced above. Figure 2 The exemplary hybrid electric propulsion system described herein. Therefore, an exemplary hybrid electric propulsion system operating according to exemplary method 200 may generally include a gas turbine engine having an electric motor coupled thereto and an energy storage unit electrically connected to the electric motor. However, in other exemplary aspects, method 200 may alternatively be used for any other suitable hybrid electric propulsion system and / or aircraft.

[0101] An exemplary method generally includes (202) determining a reference power output of a gas turbine engine by one or more computing devices. The reference power output determined at (202) may be based on user input and may be selected based on an expected flight envelope or any other suitable manner. The reference power output is typically the expected average desired power output of the gas turbine engine for the current or expected phase of flight. Additionally, method 200 includes (204) operating the gas turbine engine by one or more computing devices to provide the reference power output. Notably, (204) operating the gas turbine engine by one or more computing devices to provide the reference power output may include providing the reference power output to the output shaft of the gas turbine engine.

[0102] Moreover, still refer to Figure 3 Exemplary method 200 includes determining a desired power output by one or more computing devices, and more specifically, in (206) determining by one or more computing devices whether the gas turbine engine has a desired power output that is greater than or less than the reference power output determined in (202).

[0103] As described above, in some exemplary aspects, for example Figure 3 In an exemplary aspect of method 200 described herein, the aircraft may be a helicopter. Therefore, for an exemplary aspect of the described method 200, determining a desired power output greater than or less than a reference power output by one or more computing devices at (206) further includes receiving input from a set of helicopters by one or more computing devices at (208), and determining the desired power output by one or more computing devices based on a vehicle model of the helicopter and the input from the set of helicopters received at (208). The vehicle model may be any suitable model for determining the desired power output based at least in part on the total position. For example, the vehicle model may be a model of the output torque relative to the total position for a particular set of parameters (e.g., ambient temperature, altitude, etc.). However, it is noteworthy that in other exemplary aspects, method 200 may determine the desired power output at (206) in any other suitable manner. For example, in other exemplary aspects, method 200 may determine the desired power output at (206) at least in part based on the state of charge of an energy storage device, the charging rate of the energy storage device, etc.

[0104] Moreover, still refer to Figure 3 The exemplary method 200 further includes (212) using an electric motor to provide power to the gas turbine engine by one or more computing devices, or using one or more computing devices to extract power from the gas turbine engine, such that the effective power output of the gas turbine engine is matched to the desired power output determined in (206). For example, in some exemplary aspects, the aircraft may be including a main rotor (see... Figure 1For helicopters, the gas turbine engine can be a turboshaft engine including an output shaft, which drives the main rotor, and an electric motor is connected to the output shaft (see...). Figure 2 Using this exemplary aspect, the motor can accordingly increase power to or extract power from the gas turbine engine, more precisely, increase power to or extract power from the output shaft of the gas turbine engine, such that the effective power output matches the desired power output.

[0105] More specifically, for Figure 3 In an exemplary aspect, the hybrid electric propulsion system also includes an energy storage unit electrically connected to (or potentially connected to) a motor. Using this exemplary aspect, in (212) providing power to the gas turbine engine by the motor using one or more computing devices, or extracting power from the gas turbine engine by one or more computing devices, such that the effective power output of the gas turbine engine matches the desired power output, includes in (214) providing electrical power from the energy storage unit to the motor by one or more computing devices, or extracting electrical power from the motor to the energy storage unit by one or more computing devices. In this way, the motor can increase or decrease the effective power output of the gas turbine engine by acting as resistance on the output shaft of the gas turbine engine (i.e., when the energy storage unit extracts electrical power from the motor), or by acting as thrust on the output shaft of the gas turbine engine (i.e., when the energy storage unit provides electrical power to the motor).

[0106] Furthermore, as depicted, in some exemplary aspects, (212) using an electric motor to supply power to the gas turbine engine by one or more computing devices, or using one or more computing devices to extract power from the gas turbine engine, includes (216) using an electric motor to supply differential power to the gas turbine engine by one or more computing devices, or using one or more computing devices to extract differential power from the gas turbine engine. The differential power may be between approximately one percent and approximately twenty percent of the reference power output, which is expressed in horsepower.

[0107] By way of example only, in some exemplary aspects of method 200, method 200 may determine at (202) that a baseline power output equals 3000 horsepower, and may operate the gas turbine engine at (204) to provide 3000 horsepower. Furthermore, in this particular example, method 200 may determine at (206) that the desired power output is 3200 horsepower. Method 200 may then use an electric motor to provide power to the gas turbine engine such that the effective power output of the gas turbine engine matches the desired power output. More specifically, method 200 may provide electrical power from an energy storage unit to the electric motor such that the electric motor can provide additional power to the output shaft of the gas turbine engine, such that the effective power output of the gas turbine engine, or more precisely, the effective power output of the gas turbine engine's output shaft, matches the desired power output. It is noteworthy that in this example, the differential power provided by the electric motor to the output shaft of the gas turbine engine is approximately 200 horsepower.

[0108] Again, by way of example only, in another exemplary aspect, method 200 may determine at (202) that a reference power output equals 4000 horsepower, and at (204) the gas turbine engine may be operated to provide 4000 horsepower. Moreover, in this example, method 200 may determine at (206) that the desired power output is 3600 horsepower. Method 200 may then use an electric motor to extract power from the gas turbine engine, more precisely from the output shaft of the gas turbine engine, such that the effective power output of the gas turbine engine matches the desired power output. More specifically, method 200 may extract electrical power from the electric motor into an energy storage unit, the motor being coupled to the output shaft of the gas turbine engine and acting as a resistance on the output shaft in this power extraction to reduce the effective power output of the output shaft. Thus, the electric motor can reduce the reference power output of the gas turbine engine, such that the effective power output of the gas turbine engine matches the desired power output.

[0109] Of course, in other exemplary aspects, the reference power output can be any other suitable value, and similarly, the differential power output can be any other suitable value.

[0110] Now refer to Figure 4 It depicts Figure 3 A flowchart of an exemplary aspect of method 200. For example, as... Figure 4 As described herein, in certain exemplary aspects of method 200, during the operation of the gas turbine engine in a hybrid electric propulsion system, it can be determined that a reference power output needs to be adjusted. Therefore, for Figure 4 An exemplary aspect of this is that determining the reference power output of the gas turbine engine by one or more computing devices in (202) further includes modifying the reference power output of the gas turbine engine by one or more computing devices in (218).

[0111] More specifically, in some exemplary aspects, as depicted by the dashed lines, method 200 may further include (220) determining by one or more computing devices that the average value of the desired power output is greater than or less than the reference power output of the gas turbine engine. Using this exemplary aspect, (218) modifying the reference power output of the gas turbine engine by one or more computing devices includes (222) modifying the reference power output of the gas turbine engine by one or more computing devices in response to determining in (220) that the average value of the desired power output is greater than or less than the reference power output of the gas turbine engine.

[0112] Alternatively, as also shown in dashed lines, method 200 may include (224) determining the state of charge of the energy storage unit by one or more computing devices. Determining the state of charge of the energy storage unit by one or more computing devices at (224) may further include (226) determining by one or more computing devices that the state of charge of the energy storage unit is greater than or less than a predetermined threshold. Alternatively, in other exemplary aspects, determining the state of charge of the energy storage unit by one or more computing devices at (224) may further include (228) determining by one or more computing devices that the change in the state of charge over a period of time is greater than or less than a predetermined threshold (i.e., the rate of change of the state of charge is greater than or less than a predetermined threshold).

[0113] Therefore, it should be recognized that, in some exemplary aspects, the modification of the reference power output of the gas turbine engine by one or more computing devices in (218) may also include, in (230) in response to determining the charge state of the energy storage unit in (224), for example, in response to determining in (226) that the charge state of the energy storage unit is greater than or less than a predetermined threshold, and / or in (228) determining that the change in charge state over a period of time is greater than or less than a predetermined threshold, the modification of the reference power output of the gas turbine engine by one or more computing devices.

[0114] A hybrid electric propulsion system operating an aircraft according to one or more exemplary aspects of method 200 described above can allow the motor and energy storage unit to provide the differential power required by the aircraft between the reference power output of the gas turbine engine and the desired power output of the gas turbine engine (e.g., for at least about thirty minutes, for example, for at least about one hour, for example, for at least about two hours, for example, up to about 95% of the flight time of a particular flight). This allows the gas turbine engine to operate in a consistent state, i.e., at a consistent power level for longer periods. This can significantly reduce the number of small cycles of the gas turbine engine throughout the operation of the hybrid electric propulsion system in the flight envelope, extending the life of the gas turbine engine.

[0115] For example, refer to Figure 3In the described embodiments, operating the gas turbine engine at (204) by one or more computing devices to provide a reference power output also includes rotating the core of the gas turbine engine (e.g., a gas generator compressor and a gas generator turbine) at a first rotational speed at (232). Furthermore, for the depicted exemplary aspect, using an electric motor, providing power to the gas turbine engine by one or more computing devices, or extracting power from the gas turbine engine by one or more computing devices, such that the effective power output of the gas turbine engine matches the desired power output, includes rotating the core of the gas turbine engine at a substantially first rotational speed (e.g., within a five percent margin) at (234). Therefore, it should be appreciated that the difference in effective power output in these cases is made up by providing power to and extracting power from an electric motor coupled to the output shaft of the gas turbine engine.

[0116] Moreover, now briefly refer to Figure 5 A figure 300 is provided, which depicts the power output level of a gas turbine engine in a hybrid electric propulsion system operating according to an exemplary aspect of the present disclosure. Figure 300 depicts the effective power output on a first y-axis 302 relative to the x-axis 304. As depicted, the gas turbine engine operates approximately at a first reference power output 306 in a first time period, at a second reference power output 308 in a second time period, and at a third reference power output 310 in a third time period.

[0117] It is worth noting that graph 300 also depicts line 312 in dashed lines, which shows the desired power output. As shown, the desired power output undergoes many cycles (i.e., increases and decreases in power output) within the flight envelope. The difference between the reference power output and the effective power output is compensated by using a motor connected to the output shaft of the gas turbine engine and an energy storage unit electrically connected to the motor to either increase power to or extract power from the gas turbine engine.

[0118] Graph 300 also displays the charge state of the energy storage unit via a flight envelope on a second y-axis 315 at the same time interval relative to the x-axis 304. As depicted, for the illustrated exemplary aspect, the reference power output is modified based on the charge state (i.e., increased when the charge state falls below a threshold and decreased when the charge state exceeds a threshold). For example, for the depicted embodiment, in response to the charge state falling below a minimum threshold, the first reference power output at 306 is increased to a second reference power output at 308, and similarly, for the depicted embodiment, in response to the charge state rising above a maximum threshold, the second reference power output at 308 is decreased to a third reference power output at 310. However, it is worth noting that in other exemplary aspects, one or more of these changes in the reference power output may be in response to, for example, an average expected power output greater than or less than the reference power output over a predetermined amount of time, a rate of change of the charge state, or a combination thereof.

[0119] Now refer to Figure 6 This paper depicts an example computing system 400 according to an embodiment of the present invention. The computing system 400 can be used as, for example, a controller 166 in a hybrid electric propulsion system 100. The computing system 400 may include one or more computing devices 410. The computing device 410 may include one or more processors 410A and one or more memory devices 410B. The one or more processors 410A may include any suitable processing means, such as a microprocessor, microcontroller, integrated circuit, logic device, and / or other suitable processing means. The one or more memory devices 410B 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.

[0120] One or more memory devices 410B may store information accessible by one or more processors 410A, including computer-readable instructions 410C executable by one or more processors 410A. Instructions 410C may be any set of instructions that, when executed by one or more processors 410A, cause one or more processors 410A to perform an operation. In some embodiments, instructions 410C may be executed by one or more processors 410A to cause one or more processors 410A to perform operations, such as any operations and functions configured to be performed by computing system 400 and / or computing device 410, operations for operating a hybrid electric propulsion system of an aircraft as described herein (e.g., method 200), and / or any other operations or functions of one or more computing devices 410. Thus, in one or more exemplary embodiments, exemplary method 200 may be a computer-implemented method. Instructions 410C may be software written in any suitable programming language or may be implemented in hardware. Furthermore and / or alternatively, instructions 410C may be executed in logically and / or virtually separate threads on processor 410A. The memory device 410B may further store data 410D that can be accessed by the processor 410A. For example, the data 410D may include data indicating power flow, data indicating the power demand of each load in the hybrid electric propulsion system, and data indicating the operating parameters of the hybrid electric propulsion system, including power output demand, gas turbine engine speed, power level of energy storage unit, etc.

[0121] The computing device 410 may also include a network interface 410E for communicating, for example, with other components of the system 400 (e.g., via a network). The network interface 410E may include any suitable components for interfacing with one or more networks, including, for example, a transmitter, receiver, port, controller, antenna, and / or other suitable components. One or more external display devices (not depicted) may be configured to receive one or more commands from the computing device 410.

[0122] The techniques discussed herein refer to computer-based systems and the actions taken by and from computer-based systems, as well as the information sent to and from computer-based systems. Those skilled in the art will recognize that the inherent flexibility of computer-based systems allows for a wide range of possible configurations, combinations, and the division of tasks and functionalities between and within components. For example, the processes discussed herein can be implemented using a single computing device or multiple computing devices operating in combination. Databases, memory, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

[0123] While specific features of various embodiments may be shown in some figures but not in others, this is merely for convenience. According to the principles of the invention, any feature of the figures may be referenced and / or claimed in conjunction with any feature of any other figure.

[0124] This written description uses examples to disclose the invention, including the best mode, and also enables those skilled in the art to practice the invention, including making and using any apparatus or system and performing any of the covered methods. The patentable scope of the invention is defined by the claims and may include other examples that may be conceived by those skilled in the art. Such other examples are within the scope of the claims if they 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.

Claims

1. A hybrid electric propulsion system for an aircraft, comprising: A gas turbine engine, the gas turbine engine including a turbine and an output shaft, the turbine being drivenly coupled to the output shaft; The motor is connected to the output shaft via a gear train; An energy storage unit, wherein the energy storage unit is electrically connected to the motor; The controller includes a memory and one or more processors, the memory storing instructions that, when executed by the one or more processors, cause the hybrid electric propulsion system to perform functions, including: Determine the reference power output of the gas turbine engine; Determine the charge state of the energy storage unit; The reference power output is modified in response to determining the charge state of the energy storage unit; Operate the gas turbine engine to provide the reference power output; Determine the desired power output that is greater than or less than the reference power output; and The motor is used to provide differential power to or extract differential power from the gas turbine engine, such that the effective power output of the gas turbine engine matches the determined desired power output.

2. The hybrid electric propulsion system according to claim 1, wherein, The gas turbine engine is a turboshaft engine.

3. The hybrid electric propulsion system according to claim 2, wherein, The aircraft is a helicopter with a thruster, wherein the output shaft is configured to drive the thruster.

4. The hybrid electric propulsion system according to claim 3, wherein, Determining the desired power output includes: Receive input from the collection of said helicopters; and The desired power output is determined based on the vehicle model and the input received from the ensemble of helicopters.

5. The hybrid electric propulsion system according to claim 1, wherein, Using the motor to provide differential power to or extract differential power from the gas turbine engine so that the effective power output of the gas turbine engine matches a determined desired power output includes: Power is supplied from the energy storage unit to the motor, or Power is extracted from the motor and transferred to the energy storage unit.

6. The hybrid electric propulsion system according to claim 1, wherein, The differential power is between approximately one percent and approximately twenty percent of the reference power output.

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