Speed ​​regulation method and control device

Abstract

Engine Speed ​​Control Method and Control Device This disclosure relates to a method for controlling the engine speed of an aircraft engine assembly (2) (1). The engine assembly (2) comprises at least one internal combustion engine (21) and an electrical machine (22) mechanically coupled to the internal combustion engine (21) and electrically connected to an onboard energy storage device (32) of the aircraft (1). The method includes steps for comparing the electrical reserve required for engine assistance with an available electrical reserve, and for controlling the engine speed of the engine assembly (2) based on the difference between the electrical power reserve required for engine assistance and the available electrical power. This disclosure also relates to a control device (23) adapted for implementing this method, as well as the engine assembly (2) and aircraft (1) incorporating the control device (23). Figure for the abstract: Fig. 1.

Description

Title of the invention: Method for regulating engine speed and control device technical field

[0001] The present invention relates to the technical field of aircraft engine control, and more particularly to engine controls comprising at least one electric machine and one combustion engine, in particular a gas turbine engine. Prior art

[0002] In order to increase the overall energy efficiency of means of transport and reduce their fuel consumption and greenhouse gas emissions, the increasing electrification of engine assemblies is being considered. In the field of aviation, there is first of all a trend towards increasing power extraction through electric machines incorporated into engine assemblies, particularly to replace pressurized air intake for auxiliary devices. Furthermore, many hybrid engine assemblies exist in which these electric machines not only extract power but also feed it into the engine assembly to provide assistance beyond simply starting the engine.Although these hybrid engine assemblies have most often been proposed for motor vehicles and incorporate piston engines, the hybridization of aircraft engine assemblies, and more specifically engine assemblies incorporating one or more gas turbine engines, has also been considered.

[0003] Hybridizing aircraft engine systems requires incorporating onboard energy storage devices into the aircraft to supply the power to be delivered to the engine system via the electric machine. These onboard energy storage devices can take the form of rechargeable electric batteries, although other energy storage devices, such as supercapacitors or flywheels, are also possible. To recharge these onboard energy storage devices, hybridization will normally further increase the electrical power drawn from the engine system during operating phases that do not require electrical assistance, particularly at idle speeds.

[0004] During idle phases on the ground and in flight, it is normally desirable to minimize thrust and therefore the engine speed. However, this speed is normally constrained by operability limits of the engine and by requirements for responsiveness to transient fluctuations in thrust, both in the direction of a sudden decrease (throttle release) and in the direction of an increase. Sudden changes in engine speed, due for example to a short circuit, can occur. The ability of combustion engines, and in particular gas turbine engines, to withstand these sudden fluctuations increases with engine speed. However, their fuel consumption also increases. Furthermore, an increase in engine speed can also lead to an increase in thrust exerted on the aircraft, which could be undesirable in certain circumstances, for example during descent.

[0005] In European patent application publication EP 3 845 750 Al, a motor assembly was proposed incorporating a gas turbine motor with two rotating shafts, as well as an electric machine coupled to each of the rotating shafts, and a method of distributing the power withdrawal between these rotating shafts as a function of the motor speed.

[0006] In the publication of French patent application FR 3 097 012 Al, it was proposed to use the hybridization of the engine assembly to improve its response to load fluctuations, in particular at idle speeds.

[0007] In the international patent application publication WO 2021 / 018524 ​​Al, it is proposed to use an on-board energy storage device to help reduce transient fluctuations in power draw on an aircraft engine assembly.

[0008] However, the ability of an on-board energy storage device to reduce transient fluctuations in power draw on an aircraft engine assembly will normally depend on its state of charge. Description of the invention

[0009] The present disclosure aims to propose a method for regulating the engine speed and a control device for an aircraft engine assembly, comprising at least one combustion engine and an electric machine mechanically coupled to the combustion engine and electrically connected to an on-board energy storage device of the aircraft, to enable electrical assistance to be provided to the engine assembly through the electric machine while taking into account the availability of the on-board energy storage device.

[0010] To this end, according to a first aspect of this disclosure, this method may include at least steps for comparing the electrical reserve required for engine assistance with an available electrical reserve and for controlling the engine speed based on the difference between the electrical reserve required for engine assistance and the available electrical reserve. The method may further include a step for estimating the electrical reserve required for engine assistance based on at least one typical engine speed. Furthermore, at least one other aircraft operating parameter, such as speed and / or The aircraft's altitude can also be taken into account in the step of estimating the electrical reserve required for engine assistance.

[0011] Thus, the engine speed can be regulated so that the available electrical reserve can cover the electrical reserve that may be required for engine assistance at that speed. In particular, the engine speed can remain an idle speed lower than a maximum rated engine speed, specifically equal to or less than 70% of said maximum rated speed. Engine speed can be understood as the rotational speed of a shaft of the engine. However, other definitions of engine speed are also conceivable: for example, engine speed can alternatively be defined in terms of thrust.

[0012] According to a second aspect, an increase in the engine speed and / or a recharge of the on-board energy storage device can be ordered, when the engine speed change command is triggered, when the electrical reserve required for engine assistance is greater than the available electrical reserve. Increasing the engine speed can involve increasing it to a higher setpoint to achieve a required electrical reserve for engine assistance equal to or less than the available electrical reserve. Recharging the onboard energy storage system increases the available electrical reserve and can potentially be done without increasing the engine speed, particularly when the amount of mechanical energy drawn by the electric motor from the combustion engine can be increased without raising the engine speed.

[0013] According to a third aspect, the electrical reserve required for engine assistance may include a required electrical power reserve, and the available electrical reserve may include an available electrical power reserve. In this case, the method may include steps for estimating the electrical power that can be supplied by the onboard energy storage device based on a current state of charge of the onboard energy storage device, and for calculating the available electrical power reserve by subtracting the electrical power consumed by electrical consumers of the aircraft from the electrical power that can be supplied by the onboard energy storage device.However, alternatively or in addition to these power levels, the electrical reserve required for motor assistance may include a required electrical energy reserve, and the available electrical reserve includes an available electrical energy reserve. Thus, it can be achieved that the needs for instantaneous electrical assistance and for the entire duration of transient assistance can be met.

[0014] According to a fourth aspect, a reduction in the engine speed can be This is triggered, during the engine speed change command, when the available electrical reserve exceeds the required electrical reserve. The reduction in engine speed can, in particular, be a reduction to a lower setpoint, where the electrical reserve required for engine assistance does not yet exceed the available electrical reserve, but remains at least equal to a lower operability limit.

[0015] A fifth aspect relates to a control device adapted to implement the process according to any one of the preceding aspects.

[0016] A sixth aspect relates to a computer program comprising instructions which lead the control device of the fifth aspect to implement the process of any of the preceding aspects.

[0017] A seventh aspect relates to an aircraft engine assembly comprising a control device according to the fourth aspect, the internal combustion engine, and the electrical machine. The internal combustion engine may be a gas turbine engine.

[0018] An eighth aspect relates to an aircraft comprising an engine assembly according to the seventh aspect, as well as an on-board energy storage device electrically connected to said electric machine of the engine assembly and which may in particular be a rechargeable battery. Brief description of the drawings

[0019] [Fig-1] The [Fig. 1] is a schematic representation of the electrical and control networks of an aircraft.

[0020] [Fig.2] Fig.2 is a flowchart of a method for regulating the operating conditions of a aircraft engine assembly of [Fig.1].

[0021] [Fig.3] Fig.3 is a flowchart of a subroutine for increasing engine speed in the process of [Fig.2].

[0022] [Fig.4] Fig.4 is a flowchart of a subroutine for reducing engine speed in the process of [Fig.2].

[0023] [Fig. 5] [Fig. 5] is a graph illustrating an example of regime evolution, state of load and electrical power over time during the execution of the process [Fig. 2], Description of embodiments

[0024] As illustrated in [Fig. 1], an aircraft 1 may comprise one or more engine assemblies 2, which may in particular each include at least one internal combustion engine 21, in particular in the form of a gas turbine engine, comprising at least one compressor 211, one turbine 212, one combustion chamber 213 disposed in an air duct between the compressor 211 and the turbine 212, and a rotating shaft 214 mechanically connecting the compressor 211 and the turbine 212. In particular, as As illustrated, such a gas turbine engine may be a fan-driven turbojet, comprising at least one additional rotating shaft 215 concentric with the rotating shaft 214 and mechanically connecting another turbine 216 downstream of the turbine 212 to another compressor 217 upstream of the compressor 211, and optionally, via a reduction gear 218, to a fan 219, which may or may not be shrouded. However, this disclosure is not limited to fan-driven turbojets or even gas turbine engines, being also applicable to other types of gas turbine engines, such as turboprops or turboshaft engines, and even to other types of combustion engines, such as piston engines.

[0025] As also illustrated in [Fig. 1], each engine assembly 2 may also include an electric machine 22 coupled to a rotating shaft of the combustion engine, such as, for example, the rotating shaft 214. This electric machine 22 may, in particular, be a motor-generator capable of alternately drawing electrical power from the engine assembly 2 or providing electrical assistance to the engine assembly 2. This electric machine 22 may be electrically connected to an electrical network 3 of the aircraft 1, for example, through a converter 31, which may, in particular, be an AC / DC converter as illustrated. The aircraft 1 may also include one or more on-board energy storage devices 32, each also connected to the electrical network 3, for example, through a converter 33, which may, in particular, be a DC / DC converter as illustrated.These onboard energy storage devices 32 can notably take the form of rechargeable batteries, configured to store energy electrochemically. However, other types of onboard energy storage devices are conceivable, as alternatives to or in combination with rechargeable batteries, such as flywheels or supercapacitors. In addition, the aircraft 1 may also include one or more electrical consumers 34 connected to the electrical grid 3.

[0026] As also illustrated in [Fig. 1], each engine assembly 2 may also include a control device 23 connected to the combustion engine 21 and to the electrical machine 22 in order to regulate the speed of the engine assembly 2. This control device 23 may, in particular, take the form of an electronic control unit. The control device 23 may be connected to the combustion engine 21 to control, for example, its fuel supply and / or the position of variable geometry elements of the combustion engine 21, such as blades, vanes, wastegates, and / or nozzles. In addition, the control device 23 may be connected to the electrical machine 22 to control the electrical power drawn from or injected into the engine assembly 2 through the electrical machine 22. Furthermore, the aircraft may include at least one other control device 35, which can be connected to the control device 23, the converters 31, 33, the on-board energy storage devices 32, and / or the electrical consumers 34, in order to regulate energy transfers through the electrical network 3. This other control device 35 can also take the form of an electronic control unit. Furthermore, although the control devices 23, 35 are presented here as two separate devices, it would also be possible to combine them into a single device, and in particular into a single electronic control unit.

[0027] The control device 23 can be adapted to implement a method of regulating the engine speed of the engine assembly 2, in particular for idle speeds, both in flight and on the ground.

[0028] Thus, as illustrated in [Fig. 2], a cycle of this regulation process, which can be repeated regularly, may include a step S10 for obtaining operating parameters of the engine assembly 2, or even of the aircraft 1. These operating parameters may include, in particular, the current operating speed Nc of the engine assembly 2, but also other parameters such as temperature, pressure, speed, altitude, etc. This step S10 may then be followed by a step S20 for estimating an electrical reserve required for possible electrical assistance of the engine assembly 2, via the electric machine, to these operating parameters, and in particular to the current operating speed Nc of the engine assembly 2. This electrical assistance may, for example, respond to a sudden demand for additional thrust, the connection of an additional load to the engine assembly, or a failure such as a short circuit.In the estimation step S20, the electrical reserve required to be able to ensure this electrical assistance, in particular at the current operating speed Nc of the motor assembly 2, can for example be estimated from a correspondence table stored in a memory accessible by the control device 23 and containing predefined correspondences between different values ​​of the required electrical reserve and at least the current operating speed Nc of the motor assembly 2. This required electrical reserve may in particular include a required electrical power reserve P.„ for the electrical assistance, but also, alternatively or in addition to this, a required electrical energy reserve E.,r to provide an electrical assistance power, according to a predetermined profile, for the entire duration of a transient electrical assistance.

[0029] As illustrated in [Fig. 2], the control method may also include a step S30 of obtaining a current state of charge SOC of the energy storage device 32, followed by a step S40 of estimating an electrical power SOP that can be supplied by the on-board energy storage device 32 at this state of charge SOC. This estimation may also be performed from a lookup table stored in a memory accessible by the control device. 23, possibly through the control device 35. The regulation process may also include a step S50 of obtaining an electrical consumption of the electrical consumers 34, which may include an electrical power Pc consumed punctually by the electrical consumers 34, but also, alternatively or in addition to this, an electrical energy Ec consumed by the electrical consumers 34 during the entire duration of the transient electrical assistance, or even an additional reserve ER, and the steps S40 and S50 may be followed by a step S60 of calculating an available electrical reserve.This available electrical reserve may include an available electrical power reserve Pd, which can, for example, be calculated by subtracting the electrical power Pc consumed by the electrical consumers 34 from the electrical power SOP that can be supplied by the on-board energy storage device 32 in the current state of charge SOC. Alternatively, or in addition to the available electrical power reserve Pd, the available electrical reserve may also include an available electrical energy reserve Ed, which can, for example, be calculated by subtracting the electrical energy Ec consumed by the electrical consumers 34 during the entire duration of the transient electrical assistance, or even the additional reserve ER, from the current state of charge SOC.Although several steps S10 to S60 are illustrated as being carried out in parallel, it is also possible to carry out at least some of them sequentially.

[0030] Step S20, which estimates the required electrical reserve for electrical assistance, and step S60, which calculates the actual available electrical reserve for this electrical assistance, can be followed by step S70, which compares the required electrical reserve to the available electrical reserve Pd. If the available electrical reserve is less than the required electrical reserve—that is, in the illustrated case, if the available electrical power reserve Pd is less than the required electrical power reserve Pd, and / or the available electrical energy reserve Ed is less than the required electrical energy reserve E—a positive rebalancing subroutine S80 can be performed.On the other hand, if the available electrical reserve is equal to or less than the required electrical reserve, that is to say, in the illustrated case, if the available electrical power reserve Pd and the available electrical energy reserve Ed are equal to or greater than, respectively, the required electrical power reserve P.„ and the required electrical energy reserve E^, a negative rebalancing subroutine S90 can be carried out.

[0031] As illustrated in [Fig. 3], the positive rebalancing subroutine S80 may first include a step S81 estimating a higher speed setpoint Nsup so that the electrical power reserve P is required for motor assistance become equal to or less than the available electrical power Pd. For this, the same correspondence table as in the estimation step S20 can be used, albeit in reverse. Then, the speed of the motor assembly 2 can be controlled in a speed increase step S82 so as to reach the upper setpoint Nsup. Alternatively or in addition to the upper speed setpoint estimation step S81 Nsup and / or the speed increase step S82, the positive rebalancing subroutine S80 can also include a step S83 for recharging the on-board energy storage device 32 with surplus electrical power generated by the electric machine 22, so as to increase the state of charge SOC of the on-board energy storage device 32 and, thereby, the electrical power SOP that can be supplied by the on-board energy storage device 32 and the electrical power Pd available for motor assistance.

[0032] As illustrated in [Fig. 4], the negative rebalancing subroutine S90 may first include a substep S91 for estimating a lower engine speed setpoint Ninf such that the electrical reserve required for engine assistance remains equal to or less than the available electrical reserve. For this purpose, the same lookup table as in the estimation step S20 may also be used in reverse, as in step S81. In parallel, a lower operability limit Nmin may be estimated in a step S92 from the operating parameters of the engine assembly 2 and optionally of the aircraft 1. Then, in a comparison step S93, the lower engine speed setpoint Ninf estimated in step S91 may be compared to the lower operability limit Nmin.If the lower speed setpoint Ninf estimated in step S91 is lower than the lower operability limit Nmin, its value can be replaced, in step S94, by that of the lower operability limit Nmin. Then, in step S95, the lower speed setpoint Ninf can be compared to the current speed Nc of engine assembly 2. If the lower speed setpoint Ninf is lower than the current speed Nc, the engine assembly 2's speed can be controlled, in a speed reduction step S96, to decrease to the lower setpoint Ninf, which, thanks to steps S93 and S94, will no longer be lower than the lower operability limit Nmin. If the lower speed setpoint Ninf is not lower than the current speed Nc, the latter can be maintained.

[0033] Figure 5 illustrates an example of the evolution of the current engine speed Nc, the electrical power reserve Pc required for engine assistance, the state of charge SOC of the on-board energy storage device 32, the electrical power SOP that can be supplied by the on-board energy storage device 32, and the electrical power Pd available for engine assistance. In this example, at the initial time t0, the electrical power Pd available for engine assistance is initially less than the electrical power reserve Pc required for engine assistance. Consequently, an increase in the current engine speed Nc towards a lower setpoint Nsup is commanded, so as to reduce the required electrical power reserve P.„ and bring it below the available electrical power Pd. When the current engine speed Nc reaches the higher setpoint Nsup at time tb, the charging of the on-board energy storage device 32 is commanded until time t2, so as to increase its state of charge SOC, the electrical power SOP that can be supplied by it, and the electrical power Pd available for engine assistance after deducting the electrical power Pc consumed by the electrical consumers 34. Thus, at time t3, during a subsequent cycle of the regulation process, the electrical power available Pd for engine assistance has become significantly greater than the required electrical power reserve P.,,, a reduction of the current motor speed Nc towards a lower setpoint Ninf which may be equal to or less than a lower operability stop Nmin, may be commanded, but without the required electrical power reserve P.„ exceeding the available electrical power Pd at the subsequent instant t4. .

[0034] Although the present invention has been described with reference to specific embodiments, it is evident that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. Furthermore, individual features of the various embodiments mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Demands

1. A method for regulating an aircraft (1) engine assembly (2), wherein the engine assembly (2) comprises at least one combustion engine (21) and an electric machine (22) mechanically coupled to the combustion engine (21) and electrically connected to an on-board energy storage device (32) of the aircraft (1), the method comprising at least the following steps: - comparison (S70) of an electrical reserve required for engine assistance with an available electrical reserve, and - speed control of the engine assembly (2) as a function of a difference between the electrical reserve required for engine assistance and the available electrical reserve; the method being characterized in that it further comprises a step of estimating (S20) the electrical reserve required for engine assistance based on at least one current speed (Nc) of the engine assembly (2).

2. A method according to claim 1, wherein at least one other aircraft operating parameter (1) is also taken into account in the estimation step (S20) of the electrical reserve required for engine assistance.

3. A method according to any one of claims 1 to 2, wherein an increase (S82) in engine speed of the engine assembly (2) and / or a recharge (S83) of the on-board energy storage device (32) are commanded, when the electrical reserve required for engine assistance is greater than the available electrical reserve.

4. A method according to any one of claims 1 to 3, wherein the electrical reserve required for motor assistance comprises a required electrical power reserve (P^) and the available electrical reserve comprises an available electrical power reserve (Pd

5. )■ A method according to claim 4, further comprising the following steps: - estimation (S40) of the electrical power (SOP) that can be supplied by the on-board energy storage device (32) based on a current state of charge (SOC) of the on-board energy storage device (32), - calculation (S50) of the available electrical power reserve (Pd) by subtraction of electrical power consumed (Pc) by electrical consumers (34) of the aircraft (1) from the electrical power (SOP) that can be supplied by the on-board energy storage device (32).

6. A method according to any one of the preceding claims, wherein the electrical reserve required for motor assistance comprises a required electrical energy reserve (E^) and the available electrical reserve comprises an available electrical energy reserve (Ed).

7. A method according to any one of the preceding claims, wherein a reduction (S96) of the engine assembly speed (2) is controlled, when the available electrical reserve is greater than the required electrical reserve.

8. Method according to claim 7, wherein the reduction (S96) of the engine assembly speed (2) is a reduction towards a lower setpoint (Ninf), where the electrical reserve required for motor assistance does not yet exceed the available electrical reserve.

9. Method according to claim 8, wherein said lower setpoint (Ninf) of the engine assembly (2) speed remains at least equal to a lower operability stop (Nmin).

10. Control device (23) adapted to implement the method according to any one of claims 1 to 9.

11. A computer program comprising instructions that cause the control device of claim 10 to perform the steps of the process according to any one of claims 1 to 9.

12. Aircraft engine assembly (2) (1) comprising a control device (23) according to claim 10, the combustion engine (21), and the electrical machine (22).

13. Aircraft engine assembly (2) according to claim 12, wherein the combustion engine (21) is a gas turbine engine.

14. Aircraft (1) comprising an engine assembly (2) according to any one of claims 12 and 13, and the on-board energy storage device (32).

15. Aircraft (1) according to claim 14, wherein the on-board energy storage device (32) is a rechargeable battery.

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