Speed control method and control device

Abstract

The present disclosure relates to a method for controlling the speed of an engine assembly (2) of an aircraft (1). The engine assembly (2) comprises at least a combustion engine (21) and an electric machine (22) mechanically coupled to the combustion engine (21) and electrically connected to an onboard energy storage device (32) of the aircraft (1). The method comprises steps of comparing an electrical reserve required for engine assistance with an available electrical reserve, and controlling the speed of the engine assembly (2) as a function of the difference between the electrical power reserve required for engine assistance and the available electrical power. The disclosure also relates to a control device (23) suitable for implementing this method, as well as the engine assembly (2) and aircraft (1) incorporating the control device (23).

Description

Description Title of the invention: Method for regulating speed and control device Technical Field

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

[0002] In order to increase the overall energy efficiency of means of transport, and reduce their fuel consumption and greenhouse gas emissions, increasing electrification of power units is being considered. In the field of aviation, there is firstly a trend towards increasing power extraction through electric machines incorporated into power units, in particular to replace pressurised air extractions intended for auxiliary devices. In addition, many hybrid power units in which these electric machines are not only used to extract power, but also to introduce it into the power unit in order to provide assistance beyond simple starting.Although these hybrid powertrains have most often been proposed for motor vehicles and incorporate piston engines, the hybridization of aircraft powertrains and more particularly of powertrains incorporating one or more gas turbine engines has also been considered.

[0003] The hybridization of aircraft engine assemblies requires the incorporation, in the aircraft, of on-board energy storage devices to provide the power to be introduced into the engine assembly through the electric machine. These on-board energy storage devices may notably take the form of rechargeable electric batteries, although other devices Energy storage devices, such as supercapacitors or flywheels, are also possible. In order to recharge these on-board energy storage devices, hybridization will normally further increase the electrical power draws from the engine assembly during operating phases that do not require electrical assistance, and in particular at idle speeds.

[0004] During the phases of idle speed on the ground and in flight, it is normally desirable to minimize the thrust and therefore the speed of the engine assembly. However, this speed is normally constrained by operability limits of the engine assembly and by requirements for the ability to respond to transient fluctuations in the bleed, both in the direction of a sudden decrease (load release) and in that of a sudden increase, due for example to a short circuit. The capacity of combustion engines, and in particular gas turbine engines, to absorb these sudden fluctuations increases with the engine speed. However, their fuel consumption then also increases. In addition, an increase in engine speed may also imply an increase in thrust exerted on the aircraft, which could be undesirable in certain circumstances, for example in descent phases.

[0005] In European patent application publication EP 3 845 750 A1, an engine assembly has been proposed incorporating a gas turbine engine with two rotating shafts, together with an electric machine coupled to each of the rotating shafts, and a method of distributing the power draw between these rotating shafts as a function of the engine speed.

[0006] In French patent application publication FR 3 097 012 A1, it was proposed to use hybridization of the engine assembly to improve its response to load fluctuations, particularly at idle speeds.

[0007] In international patent application publication WO 2021 / 018524 ​​A1, it is proposed to use an on-board energy storage device to help reduce transient fluctuations in power draw from an aircraft engine assembly.

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

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

[0010] For this, according to a first aspect of this disclosure, this method may comprise at least steps of comparing an electrical reserve required for engine assistance with an available electrical reserve and of controlling the speed of the engine assembly as a function of a difference between the electrical reserve required for engine assistance and the available electrical reserve. The method may further comprise a step of estimating the electrical reserve required for engine assistance on the basis of at least one current speed of the engine assembly. Furthermore, at least one other operating parameter of the aircraft, such as for example speed and / or altitude of the aircraft, may also be taken into account in the step of estimating the electrical reserve required for engine assistance.

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

[0012] According to a second aspect, an increase in the speed of the engine assembly and / or a recharge of the on-board energy storage device can be commanded, during the speed change command, when the electrical reserve required for engine assistance is greater than the available electrical reserve. The increase in the speed of the engine assembly can in particular be an increase towards a higher setpoint making it possible to reach a value of the electrical reserve required for engine assistance equal to or less than the available electrical reserve. The recharge of the on-board energy storage device makes it possible to increase the available electrical reserve, and can possibly be carried out without increasing the speed of the engine assembly, in particular when a mechanical energy draw by the electric machine from the combustion engine can be increased without increasing the engine speed.

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

[0014] According to a fourth aspect, a reduction in the engine assembly speed may be commanded, during the speed change command, when the available electrical reserve is greater than the required electrical reserve. The reduction in the engine assembly speed may in particular be a reduction to a lower setpoint, where the required electrical reserve for engine assistance does not yet exceed the available electrical reserve, but which may remain at least equal to a lower operability limit.

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

[0016] A sixth aspect relates to a computer program comprising instructions which cause the control device of the fifth aspect to carry out the method of any one of the preceding aspects.

[0017] A seventh aspect relates to an aircraft engine assembly comprising a control device according to the fourth aspect, the combustion engine, and the electric machine. The 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 electrical machine of the engine assembly and which may in particular be a rechargeable battery. Brief description of the drawings

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

[0020] [Fig. 2] Figure 2 is a flowchart of a method for regulating the speed of an engine assembly of the aircraft of Figure 1.

[0021] [Fig. 3] Figure 3 is a flowchart of a speed increase subroutine in the method of Figure 2.

[0022] [Fig. 4] Figure 4 is a flowchart of a speed reduction subroutine in the method of Figure 2.

[0023] [Fig. 5] Figure 5 is a graph illustrating an example of the evolution of regime, state of charge and electrical powers over time when executing the process of Figure 2. Description of the embodiments

[0024] As illustrated in Figure 1, an aircraft 1 may comprise one or more engine assemblies 2, which may in particular each include at least one combustion engine 21, in particular in the form of a gas turbine engine, comprising at least one compressor 211, a turbine 212, a combustion chamber 213 arranged in an air stream between the compressor 211 and the turbine 212, and a rotary shaft 214 mechanically connecting the compressor 211 and the turbine 212. In particular, as illustrated, such a gas turbine engine may be a fan turbojet, comprising at least one other rotary 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, as well as, possibly through a reducer 218, to a fan 219, which may be ducted or not. However, the present disclosure is not limited to fan turbojets or even to gas turbine engines, being also applicable to other types of gas turbine engine, such as turboprops or turboshafts, or even to other types of combustion engines, such as piston engines.

[0025] As also illustrated in Figure 1, each engine assembly 2 may also comprise an electrical machine 22 coupled to a rotary shaft of the combustion engine, such as for example to the rotary shaft 214. This electrical 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 electrical 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 comprise 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 devices On-board energy storage devices 32 may in particular take the form of rechargeable batteries, configured to store energy electrochemically. However, other types of on-board energy storage devices are conceivable, alternatively to or in combination with the rechargeable batteries, such as for example flywheels or supercapacitors. In addition, the aircraft 1 may also comprise one or more electrical consumers 34 also connected to the electrical network 3.

[0026] As also illustrated in FIG. 1, each engine assembly 2 may also comprise a control device 23 connected to the combustion engine 21 as well as to the electric 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, discharge valves and / or nozzles. Furthermore, the control device 23 may be connected to the electric machine 22 to control the electrical power taken from or injected into the engine assembly 2 through the electric machine 22.Furthermore, the aircraft may comprise at least one other control device 35, which may be connected to the control device 23, to the converters 31, 33, to the on-board energy storage devices 32, and / or to the electrical consumers 34, in order to regulate the energy transfers through the electrical network 3. This other control device 35 may 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 for regulating the speed of the engine assembly 2, in particular for slow speeds, both in flight and on the ground.

[0028] Thus, as illustrated in Fig. 2, a cycle of this regulation method, which can be repeated regularly, can include a step S10 of obtaining operating parameters of the engine assembly 2, or even of the aircraft 1. These operating parameters may include the current regime N c of the engine assembly 2, but also other parameters such as temperature, pressure, speed, altitude, etc. This step S10 can then be followed by a step S20 of estimating an electrical reserve required for possible electrical assistance of the engine assembly 2, through the electric machine, at these operating parameters, and in particular at the current speed N cof the motor assembly 2. This electrical assistance can, for example, respond to a sudden demand for additional thrust, to the connection of an additional load to the motor assembly or to a fault such as a short circuit. In the estimation step S20, the electrical reserve required to be able to provide this electrical assistance, in particular at the current speed N c of the engine assembly 2, can for example be estimated from a table of correspondences 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 speed N c of the engine assembly 2. This required electrical reserve may in particular include a reserve of required electrical power P ar for electrical assistance, but also, alternatively or in addition to this, a reserve of required electrical energy E arto provide electric assistance power, following a predetermined profile, for the entire duration of a transient electric assistance.

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

[0030] Step S20 of estimating an electrical reserve required for electrical assistance and step S60 of calculating an electrical reserve actually available for this electrical assistance may be followed by a step S70 of comparing the required electrical reserve to the available electrical reserve P d. If the available electrical reserve is less than the required electrical reserve, that is, in the illustrated case, if the available electrical power reserve P d is less than the required electrical power reserve P ar , and / or the available electrical energy reserve E d is less than the required electrical energy reserve E ar , we can carry out a positive rebalancing subroutine S80. 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 P d and the available electrical energy reserve E d are equal to or greater than, respectively, the required electrical power reserve P ar and the reserve of electrical energy required E ar , we can proceed to a negative rebalancing S90 subroutine.

[0031] As illustrated in Figure 3, the positive rebalancing subroutine S80 may first comprise a step S81 of estimating a higher speed setpoint N sup so that the electric power reserve P ar required for motor assistance becomes equal to or less than the available electrical power P d . For this, the same correspondence table as in estimation step S20 can be used, although in the opposite direction. Then, the speed of the engine assembly 2 can be controlled in a speed increase step S82 so as to reach the higher setpoint N sup . Alternatively or in addition to step S81 of estimating the upper speed setpoint N supand / or at the step S82 of increasing the speed, the subroutine S80 of positive rebalancing may also comprise a step S83 of recharging the on-board energy storage device 32 with a surplus of 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, by this means, the electrical power SOP which can be supplied by the on-board energy storage device 32 and the electrical power P d available for engine assistance.

[0032] As illustrated in Figure 4, the negative rebalancing subroutine S90 may first comprise a substep S91 of estimating a lower speed setpoint N inf such that the electrical reserve required for motor assistance remains equal to or less than the available electrical reserve. For this, the same correspondence table as in estimation step S20 can also be used in reverse, as in step S81. In parallel, a lower operability stop N min can be estimated in a step S92 from the operating parameters of the engine assembly 2 and possibly of the aircraft 1. Then, in a comparison step S93, the lower speed setpoint N in f estimated in step S91 can be compared to the lower operability stop N min . If the lower speed setting N in f estimated in step S91 is less than the lower operability stop N min , its value can be replaced, in a step S94, by that of the lower stop of operability N min . Then, in step S95, the lower speed setpoint Nin f can be compared to the current regime N c of the engine assembly 2. If the lower speed setting N in f is less than the current regime N c the speed of the engine assembly 2 can be controlled, in a speed reduction step S96, so as to decrease to the lower setpoint N in f, which, thanks to steps S93 and S94, will no longer be lower than the lower operability stop Nmin- If the lower speed setpoint N in f is not less than the current regime N c , the latter may be maintained.

[0033] Figure 5 illustrates an example of the evolution of the current engine speed N c , of the electric power reserve P ar required for motor 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 motor assistance. In this example, at the initial time t0, the electrical power P d available for motor assistance is initially less than the electric power reserve P ar required for engine assistance. As a result, an increase in the current engine speed N c to a lower setpoint N sup is controlled, so as to reduce the required electrical power reserve P ar and to make it fall below the available electrical power P d . When the current engine speed N c reaches the upper setpoint N sup at time ti, the recharging of the on-board energy storage device 32 is controlled until time t2, so as to increase its state of charge SOC, the electrical power SOP which can be supplied by it, and the electrical power P davailable for motor assistance after deduction of the electric power P c consumed by electrical consumers 34. Thus, at time t3, during a subsequent cycle of the regulation process, the available electrical power P d for the motor assistance having become largely superior to the required electrical power reserve P ar , a reduction in the current engine speed N c to a lower setpoint N in f which may be equal to or less than a lower operability stop N min , can be ordered, but without the required electrical power reserve P ar does not exceed the available electrical power P d at the subsequent time t4.

[0034] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that various modifications and changes may 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 discussed may be combined in additional embodiments. Therefore, the description and drawings are to be considered in an illustrative rather than restrictive sense.

Claims

Claims

1. Method for regulating an engine assembly (2) of an aircraft (1), in which the engine assembly (2) comprises at least one combustion engine (21) and an electrical 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 motor 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 on the basis of at least one current speed (N c ) of the engine assembly (2).

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

3. A method according to any one of claims 1 to 10, characterized in that the method comprises: 2, in which an increase (S82) in the 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 5, characterized in that the method comprises: 3, wherein the electrical reserve required for motor assistance comprises a reserve of required electrical power (P ar ) and the available electrical reserve includes a reserve of available electrical power (Pd).

5. The method of claim 4, further comprising the steps of: - estimation (S40) of an electrical power (SOP) that can be supplied by the on-board energy storage device (32) on the basis of a current state of charge (SOC) of the on-board energy storage device (32), - calculation (S50) of the available electrical power reserve (P d ) by subtracting a consumed electrical power (P c ) by electrical consumers (34) of the aircraft (1) to the electrical power (SOP) which can be supplied by the on-board energy storage device (32).

6. A method according to any preceding claim, wherein the electrical reserve required for motor assistance comprises a reserve of required electrical energy (E ar ) and the available electrical reserve includes a reserve of available electrical energy (Ed).

7. Method according to any one of the preceding claims, in which a reduction (S96) of the speed of the engine assembly (2) is commanded, when the available electrical reserve is greater than the required electrical reserve.

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

9. The method of claim 8, wherein said lower setpoint (N in f) the speed of the engine assembly (2) remains at least equal to a lower operability stop (N m in).

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

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

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

13. An 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, as well as the on-board energy storage device (32).

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

Images