Method for controlling the energy architecture of a hybrid propulsion system

Abstract

Method for controlling the energy architecture of a hybrid propulsion system. Method for controlling (200) a power generation and control system of an aircraft comprising: - a hybrid propulsion system including an electrical network and a propulsive energy source, - at least one non-propulsive energy source, - a control unit for the hybrid propulsion system, and - a control unit for the overall power of the aircraft, characterized in that the method comprises: - determining an operability limit for the propulsive energy source, - monitoring the operability (220) of the propulsive energy source by the control unit for the hybrid propulsion system.and - the control (232) of power generated by the propulsion power source by the aircraft's overall power control unit when the operability of the propulsion power source is below said determined operability limit or the control (250) of power generated by the propulsion power source by the hybrid propulsion system control unit when the operability of the propulsion power source reaches or exceeds said determined operability limit. Figure for the abstract: Fig. 2,

Description

Title of the invention: Method for controlling an energy architecture of a hybrid propulsion system Technical field

[0001] The present invention relates to the general field of regulation of aircraft propulsion and non-propulsion systems, and more particularly to the control of an energy architecture of a hybrid propulsion system. Prior art

[0002] The hybridization of an aircraft propulsion system, such as a turbofan, is advantageous if it allows the dimensioning of the power sources to be relaxed. Indeed, to relax the dimensioning of the hybrid propulsion system, it is necessary to guarantee the availability of electrical power for the propulsive energy sources, and to guarantee a level of power extraction from these propulsive sources to limit the mass of the auxiliary sources.

[0003] The control of non-propulsion energy sources and electrical machines on the motor shafts then meets a dual need: - ensure and regulate the operability and performance of the propulsion system, and - regulate the aircraft's overall energy system to ensure stability from the electrical network of the hybrid propulsion system.

[0004] These two needs control the power injected or taken from the propulsion system with objectives which can then come into conflict during a mission: - to maintain the specified performance level, the propulsion system may request an injection of power from the aircraft's overall energy system, and - to ensure the power supply of the loads, the aircraft's overall energy system may require a power draw from the propulsion system.

[0005] The two control levels (of the propulsion system and the overall energy system of the aircraft) must therefore communicate with each other to ensure the overall viability of the aircraft's energy architecture and the optimization of power extractions.

[0006] For a hybrid architecture of a turbofan, patent EP 3 290 680 thus proposes triggering assistance to the propulsion system (turbomachine) in the event of reaching or exceeding an operability limit of the turbomachine. The architecture is then limited to two operating modes: either the electrical network controls the power it draws from the turbomachine, or the turbomachine controls the power it draws from the electrical network. The transition between the two modes then results in the switching of the control authority and the reversal of the power flow (power extraction or injection into the turbomachine). This creates a problem of stability of the electrical network and availability of power to guarantee the operability of the turbomachine.

[0007] It is therefore desirable to have a method for controlling an aircraft energy architecture that ensures the stability of the overall energy network and the availability of power to assist the hybrid propulsion system. Statement of the invention

[0008] The invention relates to a method for controlling a power generation and control system of an aircraft comprising: - a hybrid propulsion system comprising an electrical network and a propulsive energy source, - at least one non-propulsive energy source, - a hybrid propulsion system control unit, and - a unit for controlling the overall power of the aircraft,

[0009] characterized in that the method comprises: - the determination of an operability limit of the propulsive energy source, - monitoring the operability of the propulsion energy source by the hybrid propulsion system control unit, and - the control of a power generated by the propulsive energy source by the aircraft's overall power control unit when the operability of the propulsive energy source is lower than said determined operability limit or the control of a power generated by the propulsive energy source by the hybrid propulsion system control unit when the operability of the propulsive energy source reaches or exceeds said determined operability limit.

[0010] The energy architecture of the aircraft thus passes from a control exercised by the control unit of the hybrid propulsion system to a control exercised by the control unit of the overall power of the aircraft and vice versa according to the operability and the determined operability limit of the propulsive energy source, the operability limit being able for example to be a pumping margin, or a limit temperature or an extinction limit, etc.

[0011] According to a particular characteristic of the invention, the method also comprises the control of a power generated by the electrical network and supplied to the propulsion energy source by the control unit of the hybrid propulsion system when the operability of the propulsion energy source reaches or exceeds said determined operability limit.

[0012] Thus during an engine acceleration phase of the aircraft, during the initial state, the control of the power generated by the hybrid propulsion system is carried out by the overall power control unit of the aircraft, then when the determined operability limit is reached, the power control is carried out by the control unit of the hybrid propulsion system. This makes it possible to guarantee the operability of the hybrid propulsion system, the continuity of the power transferred to the electrical network and the overall efficiency of the energy architecture of the aircraft.

[0013] Thanks to the invention, the operability of the propulsion system is guaranteed. Control of the stability of the electrical network is facilitated by the continuity of the power draws when a first operability limit of the propulsion system is reached. In addition, thanks to the control exercised directly by the control unit of the hybrid propulsion system, it is possible to maximize the power draws from the propulsion system to the electrical network, which makes it possible to maximize the overall energy efficiency of the architecture.

[0014] According to another particular characteristic of the invention, the method also comprises:

[0015] - the determination of an energy strategy according to the operability of the source propulsion energy and the availability of the electricity network and non-propulsion energy sources,

[0016] - the application of the determined energy strategy by generating commands of power on the non-propulsive energy sources by the aircraft's overall power control unit, and by generating power commands on the propulsive energy source and the electrical network by the hybrid propulsion system control unit when the operability of the propulsive energy source reaches or exceeds said determined operability limit, or by the aircraft's overall power control unit when the operability of the propulsive energy source is below said determined operability limit.

[0017] According to another particular characteristic of the invention, the transition between the control of the power generated by the propulsive energy source by the overall power control unit of the aircraft or by the control unit of the hybrid propulsion system according to the operability of the propulsive energy source is carried out by the control unit of the hybrid propulsion system.

[0018] Another object of the invention is a power generation and control system for implementing the method according to the invention, the system comprising:

[0019] - a hybrid propulsion system comprising an electrical network and a source of propulsive energy,

[0020] - at least one non-propulsive energy source,

[0021] - a control unit of the hybrid propulsion system, and

[0022] - a unit for controlling the overall power of the aircraft.

[0023] According to a particular characteristic of the invention, the source of propulsive energy is a turbojet or a turboprop.

[0024] According to another particular characteristic of the invention, the non-propulsive energy source comprises at least one turbomachine, an energy storage means or a fuel cell.

[0025] Yet another object of the invention is an aircraft comprising a power generation and control system according to the invention. Brief description of the drawings

[0026] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not in any limiting nature.

[0027] [Fig.l] [Fig.l] schematically and partially represents a power generation and control system of an aircraft according to an embodiment of the invention.

[0028] [Fig.2] [Fig.2] schematically represents a method for controlling an aircraft architecture comprising a propulsion system and at least one non-propulsion energy source according to one embodiment of the invention.

[0029] [Fig.3] [Fig.3] schematically and partially represents the interface between the power control units of the propulsion system and the overall power of the aircraft according to one embodiment of the invention.

[0030] [Fig.4] [Fig.4] schematically represents an application of the method for controlling the power of an aircraft during an acceleration phase according to one embodiment of the invention. Description of the embodiments

[0031] Throughout the description, the electrical network comprises at least one electrical machine for converting electrical power into mechanical power and vice versa. For example, the electrical machine converts mechanical power generated by the hybrid propulsion system or by a non-propulsion energy source into electrical power usable for the electrical network.

[0032] [Fig.l] schematically and partially represents a system 100 for generating and controlling the power of an aircraft for implementing the method of the invention.

[0033] The system 100 comprises a hybrid propulsion system 150 comprising a propulsion energy source 140 and an electrical network 141. The system 100 comprises also a hybrid propulsion system control unit 160, at least one non-propulsion energy source 130 and an aircraft overall power control unit 120.

[0034] The hybrid propulsion system control unit 160 is configured to control a transfer of power P from the propulsion source 140 to the electrical network 141 and / or from the electrical network 141 to the propulsion source 140, when the propulsion energy source 140 reaches an operability limit. To do this, it sends a power command P to the global power control unit 120 which transmits this command to an electrical machine which will convert mechanical power from the propulsion energy source 140 into electrical power for the electrical network 141 or vice versa.

[0035] The operability limits are determined by the hybrid propulsion system control unit 160 which monitors the state of the propulsion system 150 and therefore determines whether a limit is actually reached during flight. The state of the propulsion system 150 is a function of the thrust control and the flight conditions.

[0036] The aircraft global power control unit 120 is configured to control a power transfer P between the propulsive energy source 140 and the electrical network 141 when the propulsive energy source 140 has not yet reached an operability limit. To do this, it sends a power command P to the hybrid propulsion system 150.

[0037] [Fig.2] schematically represents a method 200 for controlling an aircraft energy architecture 100, as presented in [Fig.1], according to an embodiment of the invention.

[0038] The energy architecture comprises at least one hybrid propulsion system comprising a propulsive energy source and an electrical network, and at least one non-propulsive energy source. A control unit of the hybrid propulsion system and a control unit of the overall power of the aircraft make it possible to control the energy architecture according to the method of the invention described below.

[0039] The hybrid propulsion system is put into operation by a thrust command. Throughout its operation, the operability of the propulsive energy source is monitored 210 in order to know whether it is at the limit of operability or not 220.

[0040] As long as the propulsive energy source is below its operability limit, the energy architecture of the aircraft is said to be in a conventional mode (mode 310 of [Fig. 3]). In the conventional mode 310, the aircraft's overall power control unit 312 controls the power taken from the hybrid propulsion system, in particular from the propulsive energy source; while the hybrid propulsion system control unit 311 controls the power distribution between the electrical machines converting mechanical power into electrical power. and conversely, the maximum permissible torques and can trigger an assistance mode (mode 320) when its operability limit is reached. Thus, the aircraft's overall power control unit 312 establishes and sends 232 power commands to the hybrid propulsion system, the non-propulsive energy sources and the electrical machines according to the power extraction constraints transmitted 230 by the hybrid propulsion system control unit and the state of the propulsive energy source, the state of the non-propulsive energy sources, the state of the electrical machines and mission data 231.

[0041] As soon as the propulsive energy source reaches or exceeds its operability limit, the energy architecture then switches to assistance mode (mode 320 in [Fig. 3]). In this mode, the hybrid propulsion system control unit 321 controls the power taken from or injected into the propulsive energy source. Indeed, the propulsive energy source can be a source or a load of power for the energy architecture of the aircraft. It is also the hybrid propulsion system control unit 321 which indicates to the aircraft's overall power control unit 322 the end of assistance mode 320. The aircraft's overall power control unit 322 sends information on the state of the non-propulsive energy sources and the electrical machines to the hybrid propulsion system control unit 321.

[0042] When the propulsive energy source of the hybrid propulsion system is at the limit of operability, it must be determined whether or not it requires a power injection 240 from its electrical network. If a power injection is necessary, the control unit of the hybrid propulsion system determines the power requirements 260 of the propulsive source and transmits the corresponding power commands to the electrical network and to the overall power control unit of the aircraft which establishes 261 and sends the power commands 262 to the non-propulsive sources according to an energy strategy established according to the mission data.

[0043] If the propulsive energy source does not require power injection, then the propulsive energy source is a power source for the aircraft. The hybrid propulsion system control unit then determines the power to be taken 250 from the propulsive energy source and transmits the corresponding power commands to the aircraft's overall power control unit. The aircraft's overall power control unit establishes 251 and sends the power commands 252 to electrical machines converting the power generated by the propulsive energy source according to an energy strategy established according to the mission data.

[0044] [Fig.4] schematically represents an application of the power control method to an acceleration phase of an aircraft, comprising at least a non-propulsive energy source and a hybrid propulsion system comprising a propulsive energy source and an electrical network, according to one embodiment of the invention.

[0045] Graph a represents the power transfer as a function of time between electrical machines 401 converting the power exchanged between the non-propulsive energy sources and the electrical network and the primary shaft of the propulsion system 403 and the secondary shaft of the propulsion system 402, the two propulsive energy sources (primary shaft and secondary shaft) belonging to the hybrid propulsion system.

[0046] Graph b represents the thrust 405 of the aircraft as a function of time. The thrust setpoint is represented by a step 404 between a minimum value and a maximum required value. This thrust 405 represents the acceleration phase of the aircraft.

[0047] Graph c represents the operability 406 of the propulsion system, as a function of time. The operability 406 of the propulsion energy sources must be between a lower limit 408 and an upper limit 407.

[0048] As long as the operability of the propulsive energy sources 406 remains between its minimum 408 and maximum 407 values, the conventional mode 410 is implemented and the control of the power generated by the propulsive energy sources is carried out by the overall power control unit of the aircraft. When the operability of the propulsive energy sources 406 exceeds its upper limit 407, the assistance mode 420 is implemented and the control of the power generated or injected to the propulsive energy sources is carried out by the control unit of the hybrid propulsion system. The transition from the conventional mode 410 to the assistance mode 420 involves a reduction in the power draws from the propulsion system, then an injection of power towards the propulsion system 401 (graph a).The return from the assistance mode 420 to the conventional mode 410 occurs at the exit from the upper operability limit 407 of the propulsion energy sources with a return to the initial power draws. Indeed, on graph a, the power draws 401, 402 and 403 at t = 600 s (transition between the conventional mode 410 and the assistance mode 420) are identical to those of t = 604 s (transition between the assistance mode 420 and the conventional mode 410).

[0049] Furthermore, in the assistance mode 420, the propulsion energy sources provide power to the electric machines or receive power from the electrical network included in the hybrid propulsion system. Thus, in graph a, in the assistance mode 420, it can be seen that the propulsion energy sources initially provide power to the electric machines 421, then in a second stage they receive power 422 from the network electric power of the hybrid propulsion system and finally, in a third stage, just before returning to conventional mode 410, the propulsive energy sources provide power to the electric machines 423.

[0050] The control method according to the invention can be applied regardless of the number of electrical machines mounted in the aircraft, regardless of the nature of the non-propulsive energy sources, regardless of the type of electrical network included in the hybrid propulsion system, and regardless of the number of drive shafts of the hybrid propulsion system.

[0051] The hybrid propulsion system may comprise a turbomachine, for example a turboprop or a turbofan.

[0052] The non-propulsive energy sources may comprise at least one fuel cell, an energy storage means, such as for example a battery, or even a turbomachine.

[0053] Furthermore, the operability limit of the propulsion energy sources of the hybrid propulsion system which determines the transition from one mode to the other may be a pumping margin, a temperature limit or even an extinction stop.

Claims

Claims

1. Method for controlling (200) a system (100) for generating and controlling power of an aircraft comprising: - a hybrid propulsion system (150) comprising an electrical network (141), an electrical machine and a propulsive energy source (140), the electrical machine being configured to convert electrical power into mechanical power and vice versa, and placed between the electrical network and the propulsive energy source, - at least one non-propulsive energy source (130), - a hybrid propulsion system control unit (160), and - an aircraft overall power control unit (120), the method comprising: - the determination of an operability limit of the propulsive energy source, - monitoring the operability (210, 220) of the propulsive energy source by the control unit of the hybrid propulsion system, and - the control (230) of a power generated by the propulsive energy source by the overall power control unit of the aircraft when the operability of the propulsive energy source is lower than said determined operability limit or the control (250) of a power generated by the propulsive energy source by the control unit of the hybrid propulsion system when the operability of the propulsive energy source reaches or exceeds said determined operability limit, characterized in that the method also comprises controlling (260) a power generated by the electrical network and supplied to the propulsion energy source by the control unit of the hybrid propulsion system when the operability of the propulsion energy source reaches or exceeds said determined operability limit.

2. A method of controlling a power generation system according to claim 1, further comprising: - determining (231, 251, 261) an energy strategy according to the operability of the propulsive energy source and the availability of the electrical network and the non-propulsive energy sources, - applying the determined energy strategy by generating (232, 252, 262) power commands on the non-propulsive energy sources by the aircraft's overall power control unit, and by generating (250, 260) power commands on the propulsive energy source and the electrical network by the hybrid propulsion system control unit when the operability of the propulsive energy source reaches or exceeds said determined operability limit, or (232) by the aircraft's overall power control unit when the operability of the propulsive energy source is lower than said determined operability limit.

3. A method of controlling a power generation system according to any one of claims 1 or 2, wherein the transition between the control of the power generated by the propulsive energy source by the overall power control unit of the aircraft or by the control unit of the hybrid propulsion system according to the operability of the propulsive energy source is carried out by the control unit of the hybrid propulsion system.

4. A method of controlling a power generation system according to any one of claims 1 to 3, wherein the operability limit of the propulsive energy source is a pumping margin or a temperature limit or a shutdown limit.

5. System (100) for generating and controlling power for implementing the method according to any one of claims 1 to 4, the system comprising: - a hybrid propulsion system (150) comprising an electrical network (141) and a propulsive energy source (140), - at least one non-propulsive energy source (130), - a control unit for the hybrid propulsion system (160), and - a unit for controlling the overall power of the aircraft (120).

6. A power generation and control system according to claim 5, wherein the propulsive energy source is a turbojet or turboprop engine.

7. A power generation and control system according to any one of claims 5 or 6, wherein the non-propulsive energy source comprises at least one turbomachine, an energy storage means or a fuel cell.

8. An aircraft comprising a power generation and control system according to any one of claims 5 to 7.

Images