Operating method of a propulsion system for an aircraft
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-05-09
- Publication Date
- 2026-08-07
AI Technical Summary
Hybrid propulsion systems in helicopters, combining a turbine engine and an electric machine, suffer from additional mass due to the electrical power chain, leading to reduced carrying capacity, premature engine wear, and high maintenance costs, while the electric accumulator is often oversized and underutilized.
A method that optimizes the use of an electric accumulator by reserving a portion of its capacity for specific operating modes like emergency landings, using the remaining capacity for normal operations, and allowing the electric machine to act as a generator during surplus power to recharge the accumulator.
This approach reduces the additional mass burden, extends turbine engine lifespan, lowers maintenance frequency, and optimizes the use of the electric accumulator, enhancing overall efficiency and reducing operational costs.
Smart Images
Figure 00000010_0000 
Figure 00000010_0001 
Figure 00000011_0000
Abstract
Description
Description Title of the invention: Method for operating an assembly propulsion for an aircraft Technical field of the invention
[0001] = The invention relates to a method of operating a propulsion assembly for a aircraft, for example a rotary-wing aircraft such as a helicopter. Prior art
[0002] = A helicopter is conventionally equipped with a main rotor driving a wing rotating to ensure its lift and propulsion. It is also known to equip a helicopter with a tail rotor, also called an anti-rotor torque (RAC), allowing the torque exerted by the main rotor on the helicopter fuselage.
[0003] In order to rotate the main rotor and, where applicable, the anti-torque rotor, The helicopter is equipped with a propulsion system including a turboshaft engine. The tur- The turbomachine may include a so-called free turbine or a so-called linked turbine.
[0004] In the case of a turbomachine with a free turbine, a first turbine, called a high pressure drives the engine's compressor, while a second turbine, called low pressure, is connected to a reduction box also called a Box of Main transmission or BTP. This allows the rotation speed to be reduced. before transmitting torque to the helicopter's main rotor. Turbine engines free are called "double tree".
[0005] In the case of a turboshaft engine with a linked turbine, all compressor or turbine stages The turbines are attached to a single shaft. These motors are called "single-shaft" motors. The engine assembly is directly connected to the transmission via this single shaft. main.
[0006] — A free turbine turboshaft engine, although having a more complex structure, allows it to operate with near-optimal efficiency over a wide range of operating regimes. Conversely, a turboshaft engine with a linked turbine presents a less complex structure but only has one functional point optimal operation. Engine operation at different speeds from this point A decrease in optimal operating performance results in a significant drop in efficiency. There are also a high risk of pumping, particularly under strong transient regimes.
[0007] Figure 1 illustrates a prior art helicopter 1, known from the document
[0007] . FR 3 080 835. This helicopter 1] comprises a cell including a fuselage 2 and a landing gear 3, a main rotor 4 associated with a rotating wing, forming a a single lifting rotor and a counter-torque rotor 5 located at the end of a beam 6 the rear of the fuselage 2. The rotors 4, 5 are driven by a propulsion system or group 7. The propulsion system 7 includes a main gearbox 8 or BTP. The main gearbox 8 typically comprises gears forming one or more reduction stages. A first drive shaft 9 connects the main gearbox 8 to the main rotor 4. The propulsion system further comprises a turboshaft engine 10 with a linked turbine, in which all compressor and turbine stages are fixed to a single shaft forming an output shaft. The output shaft of the turboshaft engine 10 is connected to a second drive shaft 11 via a freewheel 12. The freewheel 12 allows the output shaft of the turboshaft engine 10 and the second drive shaft 11 to be rotationally coupled in a first direction of rotation, and to be rotationally decoupled in a second, opposite direction of rotation. The second drive shaft 11 is coupled to the main gearbox 8. A third drive shaft 13 connects the main gearbox 8 to the anti-torque rotor 5. The propulsion system 7 further comprises an electric machine 14, capable of forming an electric motor, said electric machine 14 being coupled, directly or indirectly, to the third transmission shaft 13. The electric machine 14 is connected to an electric accumulator 15, for example a battery or a supercapacitor, enabling the electric machine 14 to be powered when the latter operates 30 as an electric motor. Alternatively, the accumulator 15 can 8 be recharged by the electric machine 14 when the latter operates as an electric generator. The propulsion system 7 and / or the helicopter 1 also include control and / or power electronics 16, FADEC (“Full Authority Digital Engine Control”) type regulation means 17, and means 18 for controlling the fuel flow and the geometry of an inlet grid of the turbo-engine compressor 10, these different elements being connected to each other, to the electric machine 14, to the accumulator 15 and / or to the turbo-engine 10 so as to ensure the command 10 and control of the different elements. In the event of loss of turboshaft engine power or command or uncommanded stop in flight, the electric machine is capable of injecting mechanical power to the main gearbox to perform either autorotation assistance in the event of an emergency landing, or a relief flight. The disadvantage of such a solution is the additional mass associated with the electrical power chain, called Electrical Pack (EP), comprising the electric machine, the power and control electronics and the electric accumulator. This electric power pack can weigh between 200 and 300 kg for a light, single-engine helicopter. Such a helicopter is safer, but less efficient and more expensive to operate than a standard, non-hybrid helicopter. Since the failure rate of turboshaft engines is very low, this leads to the helicopter carrying additional equipment that is almost never used. However, such additional mass penalizes the helicopter's carrying capacity and forces the turboshaft engine to work at a higher power operating point. Consequently, the engine ages prematurely and incurs higher maintenance costs. Furthermore, the electrical accumulator is generally a lithium-ion battery. However, using such a battery means that, to obtain the power required for a rescue flight, for example 250 kW for 2 minutes for a light helicopter, the battery must have a much larger energy capacity than necessary, even with a high discharge rate. Consequently, the battery is energy-intensive. Presentation of the invention The invention aims to remedy, in whole or in part, the aforementioned drawbacks. To this end, the invention relates to a method of operating a propulsion assembly for an aircraft comprising a turboshaft engine and an electric machine powered by an electric accumulator, for example a battery, the turboshaft engine and the electric machine each being capable of supplying mechanical power to a power transmission chain, characterized in that the method includes a step of estimating the total available electrical capacity of the battery, a determined part of this capacity being reserved for a specific operating mode of the aircraft, the remainder being suitable for use for a normal operating mode of the aircraft. Thus, when the battery is fully charged, for example, a portion of its capacity is reserved for a specific operating mode, such as an emergency landing or a rescue flight. The remaining battery capacity (unreserved capacity) can be used to power the electric machine, which then operates as an electric motor, during normal operation, such as a conventional takeoff or landing, or during a maneuver requiring additional power in flight. When all the unreserved capacity has been consumed, it is no longer possible to power the electric machine from the battery in normal operating mode. normal operation. The additional weight due to the presence of the battery and the electric machine is thus utilized and makes it possible to significantly increase the lifespan of the turboshaft engine or to reduce the frequency of turboshaft engine maintenance operations. It should be noted that, since the accumulator and the electrical machine operate frequently in the case of the present process, it is possible to check their proper functioning and to detect any faults and thus avoid dormant faults. The electrical accumulator can be a battery, for example a Lithium-Ion type battery. It should be noted that, in such a case, given the technical limitations related to this type of battery, a significant portion of the battery's capacity is unusable, even in an emergency, for example between 10 and 20% of the total available battery capacity. The aircraft may be a rotary-wing aircraft, for example a helicopter. In this case, the power transmission system is capable of driving the rotary wing in rotation. The electrical capacity reserved for the specific operating mode can be between 35 and 45% of the total capacity of the electrical accumulator. The electric machine can operate as a generator so as to recharge the electric accumulator, in a recharge mode during the normal operating mode of the aircraft, said electric machine being driven by the turboshaft engine during the recharge mode. During normal aircraft operation, such as during cruise flight, there are instances where only a portion of the turboshaft engine's total power is used for propulsion. This portion of the total power can be diverted or utilized by operating the turboshaft engine at a higher RPM than required solely for aircraft propulsion. The diverted power then serves to drive the generator and recharge the battery. The diverted power can vary between 1% and 10%, for example, between 2% and 6% of the turboshaft engine's total power. The battery can also be recharged, fully or partially, by a ground charging station. The power taken from the turboshaft engine to drive the generator can depend on the battery charge rate and / or the flight phase and / or the aircraft flight conditions. In particular, the power drawn from the turboshaft engine to drive the generator can depend on the battery charge level and / or the turboshaft engine's power margin. The power margin depends on flight conditions or the phase aircraft flight. The power margin is the difference between the total power of the turboshaft engine and the power required to propel the aircraft. For example, if the battery charge level is between 80% and 60%, then 2.5% of the turbocharger's power output can be used if there is a power margin of at least 10%. If the charge level is less than 60%, then 2.5% of the turbocharger's power output can be used if the power margin is between 10% and 20%, and 5% of the turbocharger's power output can be used if the power margin is greater than 20%, for example. Furthermore, if the charge rate is greater than 80% then no power is taken from the power generated by the turbomotor, the accumulator may not be recharged in such a case. In one embodiment, if the power required at the power transmission chain to operate the aircraft exceeds a first threshold, then the electric machine operates as a motor to provide supplementary mechanical power to the power transmission chain, in addition to the mechanical power supplied by the turboshaft engine. Such an operating mode is called assistance mode. Preferably, if the power required at the power transmission chain to ensure the operation of the aircraft is between the first threshold and a second threshold, the second threshold being lower than the first threshold, the electric machine operates as a motor so as to provide additional mechanical power to the power transmission chain or is inactive, depending on the previous operating mode of the electric machine. Thus, if the previous operating mode of the electric machine was motor mode, then when the power demand falls between the first and second thresholds, the electric machine continues to operate in motor mode. Similarly, if the previous operating mode of the electric machine was idle mode, then when the power demand falls between the first and second thresholds, the electric machine continues to operate in idle mode. In other words, the operation of the turbomachine can be a hysteresis operation, capable of memorizing the previous operating mode and applying it in the case where the power required is between the first threshold and the second threshold. Preferably, if the power required at the power transmission chain level to ensure the operation of the aircraft is between the second threshold and a third threshold, the third threshold being lower than the second threshold, then the The electric machine is inactive and cannot provide additional mechanical power, nor can it recharge the electric battery. Preferably, if the power required at the power transmission level to operate the aircraft is below the third threshold, then the electric machine operates as a generator to recharge the battery. This mode of operation is called charging mode. The accumulator may include at least one battery comprising elements or cells each capable of storing electrical energy, a portion of these elements or cells being dedicated to powering the electrical machine only in the aircraft's specific operating mode. The electric machine can operate as a generator in the event of a turbomotor stoppage, so as to brake said turbomotor by the resisting torque generated by the generator. Of course, such a special case does not necessarily apply to all cases of turbocharger shutdown. Brief description of the figures [Fig.1] is a schematic view of a helicopter equipped with a propulsion system according to a prior art embodiment, [Fig.2] is a schematic view representing the battery capacity distribution, [Fig.3] is a flowchart representing the operation of a propulsion system in accordance with this document. Detailed description of the invention Figure [Fig. 2] illustrates the total capacity of an accumulator used for the implementation of the process as described above. This battery is a lithium-ion type and has a total capacity (CT) of 100%. A portion (C1) of the total CT capacity is unusable due to the technical limitations inherent to this type of battery. For example, portion C1 represents between 10% and 20% of the battery's total CT capacity. The total available capacity is therefore between 80% and 90% of the battery's total CT capacity. Furthermore, a second portion (C2) of the total CT capacity is reserved for specific aircraft operating modes, such as emergency landings or diversion flights. This portion (C2) typically represents between 35% and 45% of the battery's total CT capacity. The remaining C3 of the total CT capacity of the battery can be used to power the electric machine, which then operates as an electric motor, in a mode of Normal operation, for example during a standard takeoff or landing, or during a maneuver requiring extra power during flight. The C3 portion, for example, represents between 40 and 50% of the battery's total CT capacity. Figure 3 is a flowchart illustrating part of the process as described previously. This flowchart shows the operation of the electrical machine as a function of the power required at the level of the power transmission chain to ensure the operation of the aircraft. As can be seen in [Fig.3], if the power P required at the level of the power transmission chain to ensure the operation of the aircraft is greater than a first threshold SI, then the electric machine operates as a motor so as to provide additional mechanical power to the power transmission chain, in addition to the mechanical power supplied by the turboshaft engine, if the remaining capacity C3 is sufficient (so-called assistance mode). If the required power P is between the first threshold S1 and a second threshold S2, the electric machine operates as a motor so as to provide additional mechanical power to the power transmission chain (assistance mode) or is inactive, depending on the previous operating mode of the electric machine. If the required power P is between the second threshold S2 and a third threshold S3, then the electric machine is inactive and does not allow either to provide additional mechanical power or to recharge the electric accumulator (inactive mode). If the required power P is less than the third threshold S3, then the electric machine can operate as a generator in order to recharge the electric accumulator (recharge mode), depending on the charge rate of the battery and / or depending on the power margin of the turbomotor, as detailed previously.
Claims
Demands
1. Method of operating a propulsion system for an aircraft comprising a turboshaft engine (10) and an electric machine (14) powered by an electrical accumulator (15), for example a battery, the turboshaft engine (10) and the electric machine (15) being each capable of to provide mechanical power to a transmission chain power, characterized in that the process comprises a step estimation of the total available electrical capacity of the accumulator (15), a determined part (C2) of this capacity being reserved for a specific operating mode of the aircraft, the rest (C3) being suitable for use in a normal mode of operation of the aircraft.
2. A method according to the preceding claim, wherein the capacity reserved electrical (C2) for the specific operating mode is between 35 and 45% of the total battery capacity electric (15).
3. A method according to any one of the preceding claims, wherein the an electric machine functions as a generator in such a way that recharge the electric battery, in a charging mode during the normal operating mode of the aircraft, said electrical machine being driven by the turbocharger during recharging mode.
4. Method according to the preceding claim, wherein the power taken from the turboshaft engine to drive the generator is a function of the battery charge level and / or flight phase and / or aircraft flight conditions.
5. A method according to the preceding claim, in which if the power required at the transmission chain of power to ensure the operation of the aircraft, that is above a first threshold, then the electric machine functions as a motor in such a way as to provide power complementary mechanical components to the transmission chain power, in addition to the mechanical power supplied by the turbocharger,
6. A method according to the preceding claim, in which if the power required at the transmission chain of power to ensure the operation of the aircraft is between the first threshold and a second threshold, the Since the second threshold is lower than the first threshold, the machine electric functions as a motor in order to provide a mechanical power complementary to the chain of power transmission is active or inactive, depending on the mode of the previous operation of the electrical machine.
7. A method according to the preceding claim, in which if the power required at the transmission chain of power to ensure the operation of the aircraft is between the second threshold and a third threshold, the Since the third threshold is lower than the second threshold, then the The electric machine is inactive and cannot provide a additional mechanical power, nor to recharge the electric accumulator.
8. A method according to the preceding claim, in which - if the power required at the transmission chain level of power to ensure the operation of the aircraft is less than third threshold, then the electric machine operates as a generator negator in order to recharge the electric battery.
9. A method according to any one of the preceding claims, in which the accumulator includes at least one battery comprising elements or cells, each capable of accumulating energy electrical, a portion of these elements or cells being dedicated to power the electric machine only in operating mode aircraft-specific operation.
10. A method according to any one of the preceding claims, wherein the The electric machine functions as a generator in a shutdown situation. of the turbocharger, so as to brake said turbocharger by the torque resistance generated by the generator.