FR3039614A1 - HYBRID POWER SUPPLY FOR AN AIRCRAFT WITH A ROTARY REVOLVING WING - Google Patents

Abstract

The present invention relates to a hybrid power plant (5) for a rotary wing aircraft comprising two turbine engines (10, 10 ') and at least one electric machine (20, 20', 20 '') capable of delivering maximum mechanical power Pmax and powered by electrical energy storage means (22) and a main power transmission gearbox (3) mechanically driven jointly by said turbine engines (10, 10 ') and each electrical machine (20, 20', 20 '). '). An electric machine (20, 20 ', 20 ") is connected to the gas generator (11, 11') of each turbine engine (10, 10 ') when said maximum mechanical power Pmax is less than or equal to a limit power Ppal and to said main power transmission gearbox (3) when said maximum mechanical power Pmax is greater than said limit power Ppal, said limit power Ppal is specific to said aircraft and in particular a function of the mass and aerodynamics of said aircraft and the power of the aircraft. operation and emergency of said turboshaft engines (10, 10 ').

Description

Hybrid powerplant for twin-engine rotary wing aircraft

The present invention is in the technical field of motor installations of rotary wing aircraft. The invention relates to a hybrid power plant comprising at least two heat engines and at least one electric machine. The invention also relates to a rotary wing aircraft equipped with such a hybrid power plant.

A "hybrid" power plant for an aircraft designates an installation comprising at least one heat engine and at least one electric machine each capable of setting in motion a main gearbox of this "hybrid" powerplant. Such a hybrid installation also comprises a means of storing electrical energy such as a rechargeable or non-rechargeable battery.

This main power transmission allows, when the hybrid power plant equips a rotary wing aircraft, to rotate, via an output shaft of the main gearbox, at least one main rotor of a rotary wing aircraft and possibly an anti-torque rotor.

Indeed, a rotary wing aircraft is conventionally provided with at least one main rotor to ensure its lift or propulsion and usually an anti-torque rotor to oppose the yaw torque exerted by the main rotor on the fuselage of this aircraft and also to control the yaw movements of this aircraft

The electric machine can be an electric motor, fulfilling only a motor function.

The electric machine can also be reversible, thus fulfilling a motor function and an electricity generating function. This electric machine can therefore operate either in an "electric motor" mode to provide mechanical power to the main power transmission gearbox, or in an "electric generator" mode to generate electrical energy from a mechanical power .

It should be noted that an electric machine can also be a simple electrical generator that only fills the electricity generator function.

Moreover, a thermal engine is generally, on the rotary wing aircraft, a turbine engine comprising a gas generator and a free turbine, the shaft of the free turbine being the transmission member of the mechanical power of the turbine engine to the main power gearbox and eventually as needed at least one or more rotors.

In addition, the gas generator of each heat engine is generally mechanically connected to a reversible electric machine called "starter-generator". This starter-generator has two functions. It allows on the one hand in engine mode the starting of the heat engine to which it is connected and on the other hand, driven in rotation by the heat engine, to generate, in generator mode, electricity for the on-board electrical network. the aircraft to power its various equipment. This starter-generator does not provide any mechanical power to the main gearbox.

Thus, in a hybrid power plant, the main gearbox is driven jointly by the heat engines and each electric machine, except the starter-generator. Several architectures are possible for the implantation of each electric motor vis-à-vis the thermal engines and the main transmission gearbox.

For example, document FR 3003514 describes hybrid motor plant architectures. An electric machine is for example connected directly to the main gearbox. An electric machine can also be positioned between each turbine engine and the main gearbox, an electric machine then being associated with each turbine engine and mechanically connected to its free turbine of the turbine engine. In either case, the power of each electric machine adds to the power of the heat engines to drive the main gearbox.

In addition, each heat engine, and in particular in the case of a turbine engine, has different operating modes.

One distinguishes in particular the PMC regime corresponding to the Maximum Continuous Power, whose use is unlimited in time and the PMD regime corresponding to the Maximum Power of Takeoff, which provides a power superior to the PMC regime but whose use is generally limited. to 5 minutes on civil aircraft, specifically for take-off and landing as well as for short-term stationary flights of rotary wing aircraft.

In addition, to compensate for an engine failure on a multi-engine aircraft, each engine has several emergency power-over schemes designated OEI as "One Engine Inoperative" in the English language. For a turboshaft engine, a distinction is made between: - a first emergency regime, combining a super-emergency power called OEI 30 ", usable for a duration of the order of thirty consecutive seconds, -a second emergency regime, associating a maximum power emergency called OEI 2 ', usable for a period of two minutes, and a third emergency regime associating an emergency intermediate power called OEI cont, usable for an unlimited period covering for example the end of the flight.

It should be noted that some engines offer a single emergency regime, called OEI 2'30 ", in place of the OEI 30" and OEI 2 'emergency regimes, which can be used for a duration of two minutes and thirty seconds. .

The intermediate power of emergency OEI cont is intended among other things to ensure a cruising flight, while the power of super urgency OEI 30 "and the maximum emergency power OEI 2 'as well as the emergency power unique OEI 2' 30 "are intended to perform particular maneuvers such as avoiding an obstacle, hovering or landing.

In addition, the OEI 30 "super-emergency power may be used two or three times following the aircraft until the landing of the aircraft while the maximum emergency OEI 2 'power and the single emergency power OEI 2'30 "may be used several times, for a cumulative total time not exceeding a predetermined time by the manufacturer of the aircraft and appearing in the maintenance manuals, for example ten minutes.

Indeed, this overpower provided by the only available heat engine during this failure is obtained by soliciting this engine beyond its normal operation and its nominal limits. In fact, this operation subsequently requires specific maintenance and associated costs that can be significant.

In addition, the duration of use of the first OEI 30 "emergency regime, the second emergency regime 0E1 2 'and the single emergency regime OEI 2'30" are limited so as not to generate significant damage or immediately on the turbine engine or the power transmission means, such as the main gearbox.

The OEI 30 ", OEI 2 ', OEI 2'30" and OEI cont emergency boost regimes are controlled by a control box, each heat engine being connected to such a control box.

This control unit, commonly referred to by the acronym EECU for "Electronic Engine Control Unit" in English is present on the majority of aircraft to control the operation of the engine or engines. On some aircraft, this EECU control unit is replaced by a motor ECU, which is commonly referred to by the acronym FADEC for "Full Authority Digital Engine Control" in English. This FADEC engine calculator has a greater authority than the EECU control box and thus limits the intervention of the pilot in the management of the engine or engines.

It should be noted that, when all the thermal engines of the aircraft are functional, the aircraft operates under AEO regimes according to the expression "Garlic Engine Operative" in English.

The presence of these emergency overpower regimes, necessary for the flight safety of the aircraft but ultimately little used, leads to over-sizing of the engines. This over-sizing of the thermal engines is accompanied in particular by an increase in the mass of these engines and then causes an increase in the fuel consumption of the aircraft and possibly a decrease in the payload transportable by the aircraft.

Also known is the document FR 2997382 which describes a hybrid power plant of a rotary wing aircraft comprising at least two heat engines and at least one electric motor. The electric motor makes it possible, following a failure of at least one engine to provide mechanical power to compensate for the engine failure. The aircraft can then be maneuvered safely by avoiding the use of the OEI emergency overpower of each heat engine remaining operational and thus soliciting it beyond predetermined operating conditions. By cons, such a hybrid power plant requires electrical energy storage means that can be important, then generating an increase in the mass of the aircraft.

The object of the present invention is therefore to propose a hybrid power plant for a rotary wing aircraft making it possible to overcome the limitations mentioned above by making it possible to optimize the sizing of the thermal engines and electrical machines of this hybrid power plant. and improve the performance of the aircraft.

According to the invention, a hybrid power plant for a rotary wing aircraft comprises: at least two turboshaft engines, each turbine engine being provided with a gas generator and a free turbine, each turbine engine being able to provide at least one continuous maximum power. PMC and a maximum takeoff power PMD as well as emergency OEI over-powers, at least two control boxes, each control box being connected to a turbine engine, at least one electrical machine capable of providing maximum mechanical power Pmax, at least one electrical energy storage means supplying electrical energy to each electrical machine, at least one control means of each electrical machine and a main power transmission box having at least one output shaft driven mechanically in rotation at a rotation frequency NR jointly by the turbine engines and each electric machine, the turbines Ines free of the turboshaft engines, the main gearbox and each output shaft constituting a main transmission chain of mechanical power.

This hybrid power plant according to the invention is intended for multi-engine rotary wing aircraft and in particular twin-engine aircraft, that is to say having two thermal engines. An output shaft of the main gearbox is integral with a rotor of the aircraft, which may be the main rotor and / or the anti-torque rotor of the aircraft. The output shaft rotated at the rotation frequency NR is integral with the main rotor of the aircraft.

Each control box provides control and management of the operation of a heat engine. A control box is for example a EECU control box or a FADEC engine ECU.

A control means may be connected to a single electrical machine or to several electrical machines. This control means thus ensures the control and management of the operation of one or more electrical machines.

This hybrid power plant is remarkable in that an electric machine is connected to the gas generator of each turbine engine when its maximum mechanical power Pmax is less than or equal to a limiting power Ppai while the electric machine is connected to the main transmission chain mechanical power when this maximum mechanical power Pmax is greater than the limiting power Ppai, the limiting power Ppai being specific to the aircraft for which is intended the hybrid power plant and in particular function of the mass and aerodynamics of the aircraft as well as turbine engine performance, namely Maximum Continuous Power PMC, Maximum Takeoff Power PMD and 0E1 emergency overpower.

Each electric machine thus provides additional mechanical power to the main power transmission gearbox, in addition to the power supplied by the turbine engines in order to drive in rotation at least one output shaft of the main power transmission gearbox. hybrid power plant according to the invention, thus improving the performance of the hybrid power plant.

The location of each electric machine is however not trivial to optimize its contribution of mechanical power to the hybrid power plant.

Indeed, it is advantageous that a low power electric machine is connected to the gas generator of a turbine engine. This electric machine then drives in rotation the rotation shaft of this gas generator and, consequently, also provides a mechanical power to the main transmission gearbox. The term "micro-hybridization" is used to designate such a hybrid power plant architecture.

For an electric machine of greater power, it is then more efficient that the electric machine is located on the main mechanical power transmission chain of the hybrid power plant. The electric machine has different possible locations on this main transmission chain of mechanical power.

The electric machine can be implanted on a specific input of the main power gearbox and thus provides mechanical power to the main power gearbox. The hybrid power plant can then preferably comprise a single electric machine.

The electric machine can also be located between the free turbine of a turbine engine and the main gearbox. In this case, the hybrid power plant generally comprises as many electric machines as turbine engines, an electric machine being connected to the free turbine of a turbine engine. Each electric machine thus provides mechanical power to the main power gearbox.

The electric machine can also be located at the output of the main gearbox on its output shaft. The electric machine is thus positioned between the main gearbox and a rotor of the aircraft, which is preferably the main rotor of the aircraft. The hybrid power plant thus has an electric machine that provides mechanical power directly to the output shaft of the main power transmission gearbox.

A hybrid power plant architecture in which the electric machine is implanted on the main mechanical power transmission chain is referred to as "mild hybridization". The use of the mechanical power of the electric machine in addition to the mechanical power of the turboshaft engines makes it possible in particular to optimize the overall fuel consumption of the aircraft and also to increase its maximum peelable mass.

In addition, in the case of operation of a twin-engine installation with a stopped engine designated by the acronym SEO for the expression in English "Single Engine Operation" or with a slow-motion engine designated by the acronym SIO for the English expression "Super Idle Operation", the electric machine allows to restart and quickly restart the turbine engine off or idle in case of failure of the other turbine engine, particularly for a microhybrid architecture

This mechanical power of the electric machine can also be an important aid during the transient operating phases of the turboshaft engines, again especially for a micro-hybridization architecture.

This mechanical power of the electric machine can also make it possible to increase the flight range of the aircraft.

This mechanical power of the electric machine can also make it possible, during an engine failure and the use of emergency powers OE1 of the operational turbine engine, to improve the performance of the aircraft, in particular for the most critical phases of the aircraft. takeoff, landing or hovering.

In particular, during the landing or the take-off of the aircraft on or from a platform for example, this mechanical power of the electric machine makes it possible to compensate for the occurrence of a failure of a front turbine engine. that the critical point of this phase of flight has been reached and thus secure this landing or take-off. During take-off, this critical point is designated by the acronym TDP for the English expression "Take off Decision Point". During landing, this critical point is designated by the acronym LDP for the English expression "Landing Decision Point".

The choice between micro-hybridization and mild-hybridization is determined according to a limiting power that is characteristic of each aircraft. Thus, an electric machine whose maximum mechanical power Pmax is less than or equal to the power limit of the aircraft is implanted according to a microhybridization architecture. As a result, an electric machine whose maximum mechanical power Pmax is greater than the limit power of the aircraft is implanted according to a mild-hybridization architecture.

This limit power is determined according to the characteristics of the aircraft for which the hybrid powerplant is intended and mainly according to its mass and its aerodynamics as well as the performance of the turboshaft engines, namely their maximum continuous powers PMC, their maximum powers. PMD takeoffs and their emergency powers, and rotors.

This power limit is for example equal to 60 kilowatts (60kW) for a given twin-engine aircraft of 5 tons.

As part of the micro-hybridization architecture, the starter-generator of this turbine engine can be preserved. The electric machine then only has an electric motor function transforming the electrical energy supplied by the storage means into mechanical power.

The starter-generator of this turbine engine can also be deleted. The electric machine then combines three functions: a first function of starting the turbine engine by transforming electrical energy supplied by the storage means into mechanical power driving the gas generator for its start-up, a second electric motor function and a third function electric generator transforming a mechanical power supplied by the gas generator into electrical energy.

A first part of this electrical energy can then be transmitted to an electrical network on board the aircraft to supply different electrical equipment of the aircraft. A second portion of this electrical energy can be transmitted and stored by the storage means which must then be rechargeable, such as a rechargeable battery.

This micro-hybridization architecture advantageously eliminates each starter-generator of the aircraft in order to optimize the mass of the aircraft and, consequently, its performance.

As part of the architecture mild-hybridization, the electric machine can have the only function electric motor or be reversible and have the functions of electric motor and electric generator. When the machine is reversible, a first part of this electrical energy can as previously be transmitted to an electrical network on board the aircraft and a second part of this electrical energy can be transmitted and stored by the storage means which must then be rechargeable.

However, whatever the architecture of the hybrid power plant, the storage means may be non-rechargeable although the electric machine is reversible. The electric machine then supplies the electrical energy that it generates solely to the on-board electrical network of the aircraft.

Moreover, regardless of the implementation architecture of each electrical machine and whether the electric machine is reversible or not, the electric machine can be used to start a turbine engine.

In addition, regardless of this implementation architecture of each electrical machine, the electrical energy storage means may be non-rechargeable, such as a non-rechargeable battery or a thermal battery. This type of electrical energy storage means on the one hand to have generally a good mass-energy ratio stored for low to medium amount of stored electrical energy and secondly to have very quickly this energy . On the other hand, these storage means and in particular the thermal battery have only one cycle of use.

An electrical energy storage means may also be rechargeable, such as a rechargeable battery, having a large number of charge / discharge cycles. In this case, the electric machine is preferably a reversible electric machine to recharge the storage means and thus benefit from electrical energy repeatedly during the flight of the aircraft.

An electric machine of a hybrid power plant according to the invention is preferably an electrical high voltage electric machine, whether reversible or not. In fact, in order to be able to supply an electrical network of an aircraft which is at low electrical voltage, a hybrid power plant according to the invention which comprises at least one reversible electric machine also comprises a high voltage / low voltage converter, designated more simply "HT / LV converter" .This HT / BT converter converts the high voltage electrical energy generated by the reversible electric machine into low voltage electrical energy usable by the on-board electrical network.

Moreover, it is possible to combine in a hybrid power plant according to the invention each microhybridization architecture previously described with one of these architecture mild-hybridization. The hybrid power plant then benefits from these two architectures.

For example, an electric machine can be connected to each gas generator, the starter-generator of each turbine engine being removed, and an electric machine is located on a specific input of the main power transmission. The use of a single electric machine on the main transmission chain of mechanical power and the suppression of the starter-generator of each turbine engine makes it possible to limit the increase of the mass of the hybrid power plant and, consequently, of the aircraft.

In addition, a single storage means, whether rechargeable or not, can be used in common by the electrical machines of this hybrid power plant, in particular to limit its effect on the mass of the hybrid power plant. The electric machine connected to the main gearbox can also be reversible and connected to an HV / LV converter to supply the on-board electrical network of the aircraft.

Moreover, whatever the implantation architecture of each electrical machine, the current mechanical power Pref, which an electric machine provides to the output shaft of the main power transmission gearbox, is defined by a control law which may be a function of one or more operating parameters of the aircraft or its hybrid power plant. This current mechanical power Pref is less than or equal to the maximum mechanical power Pmax.

Such a parameter can be for example the current rotation frequency NR of an output shaft of the main power transmission gearbox. The current mechanical power Pref can then be defined by a first control law, such that:

Pmax being the maximum power that can be provided by each electric machine expressed in kilowatt (kW), NR being the current rotation frequency of an output shaft expressed in revolutions per minute (rpm), where ^ is a time derivative of the frequency current of rotation NR expressed in revolutions per minute per second (rpm), NRc being a reference value of current rotation frequency NR expressed in revolutions per minute (rpm), Xi and X2 being two stop coefficients without unit, and k being an anticipation coefficient expressed in seconds.

It should be noted that if this first driving law provides a result greater than the maximum mechanical power Pmax, the current mechanical power Pref is then defined equal to this maximum mechanical power Pmax, since an electric machine can not provide a current mechanical power Pref superior to this maximum mechanical power Pmax.

The two abutment coefficients Xi, X2 correspond to percentages of the setpoint value NRc and are therefore less than one. In addition, the first abutment coefficient Xi is smaller than the second abutment coefficient X2. A minimum difference between the two abutment coefficients Xi, X2 can also be defined so that a difference between the products (X2.NRC) and (Xi.NRc) is for example between 5 and 10 rpm. Typically, the two abutment coefficients Xi, X2 may be respectively equal to 97% and 99% for a reference value NRc equal to 340 rpm.

These two abutment coefficients Xi, X2 can be modified before each flight according to the desired use of each electric machine. In particular, these two abutment coefficients Xi, X2 can be defined greater than one, the current mechanical power Pref being then equal to the maximum mechanical power Pmax independently of the current rotation frequency NR of the output shaft. For example, the stop coefficient Xi is defined greater than or equal to 1.1, the first stop coefficient Xi being smaller than the second stop coefficient X2.

The time derivative ^ of the current rotation frequency NR makes it possible to anticipate the variation of this current rotation frequency NR, the anticipation coefficient k weighting this anticipation. The anticipation coefficient k is for example equal to one second.

In addition, in order to control the ramp-up time of the electric machine, a value of the time derivative of the current mechanical power Pref can be imposed. This time derivative of the current mechanical power Pref is for example equal to 1200 kilowatts per second (1200kW / s). It is also possible to use an inverse slope at the end of supply of this power, the time derivative of the current mechanical power Pref being for example equal to -1200 kW / s.

Furthermore, the value of the current rotation frequency NR of the output shaft of the main power transmission gearbox of the main rotor of the aircraft can be determined in different ways. This value can be provided by means of control of the electric machine by an avionic installation of the aircraft, via a means of communication of the control means of the electric machine.

Preferably, this value is determined by the frequency of rotation of the electric machine, the reduction ratio between the electric machine and the output shaft being known. Advantageously, the measurement made from the electric machine is more accurate than the measurement provided by the avionics installation of the aircraft.

The current mechanical power Pref can also be defined by a second control law such that PREF = f (Marg), the current mechanical power Pref then being a function of a margin Marg of power of each operating turbine engine. The margin Margin of power of a heat engine is the difference between the theoretical maximum powers of the turboshaft engines and the power required for the flight of the aircraft. For example, an electric machine provides a current mechanical power Pref as soon as the margin Marg of power is negative or zero.

Each control means of an electric machine comprises a deactivation means and a communication means. The communication means is able to communicate with an avionic installation of the aircraft and the deactivation means makes it possible to deactivate an electric machine according to different criteria.

These criteria may be inhibition criteria in particular to preserve the electrical energy present in the storage means. In particular, it is essential to preserve the electrical energy when the storage means is non-rechargeable in order to have electrical energy when the pilot of the aircraft really needs it, for example during a failure of a turbine engine or for a particular flight phase requiring significant power, such as takeoff, landing or hovering. In addition, when this storage means is non-rechargeable, for example a thermal battery, its stored electrical energy is available and usable only for a few minutes after its activation.

These inhibition criteria relate to the state of the aircraft or to its operation. These inhibition criteria correspond to phases of flight or non-flight of the aircraft for which the aircraft requires little or no power. The turboshaft engines are then sufficient to provide this power and ensure the safety of the flight. It is therefore useless to consume electrical energy whose quantity is limited.

An inhibition criterion corresponds for example to a situation where the aircraft is on the ground and therefore has by definition no need for power. In addition, the sudden arrival of electric power could endanger the aircraft and its crew. A sensor in the landing gear can provide this information.

An inhibition criterion also corresponds to the horizontal component Vy of the flight speed of the aircraft. Indeed, a rotary wing aircraft requires less power during a cruise flight. Conversely, for flights at low speeds of advancement, and in particular the stationary flights as well as the take-off and landing phases, the aircraft requires a large power. The electric machine can therefore be inhibited for a given horizontal component, for example greater than 40 knots (40kt).

An inhibition criterion may also be the pilot's voluntary transition from an OEI 30 "emergency overpower regime to an OEI 2 emergency overpower regime. This inhibition criterion is lifted as soon as the pilot reverts to the OEI 30 "emergency boosting regime. Other inhibition criteria are related to the operation of the turboshaft engines, for example an item of information that no turbine engine has failed or that the margin Marg of power is greater than a limit power margin, this power limit margin being for example equal to 5%.

The deactivation means also makes it possible to deactivate an electrical machine according to deactivation criteria, for example when the storage means can no longer supply electrical power. This is the case for example if the duration of use of a thermal battery is exceeded or if the storage means no longer contains electrical energy and needs to be recharged.

In addition, a deactivation criterion may be that the operating conditions of this electrical machine are not met, for example following a failure of an electrical machine or its control means.

However, such failures are unlikely and undesirable, the electrical machine constituting a security element of the flight of the aircraft to be available when the pilot needs it. For this purpose, when powering up the aircraft before take-off, the hybrid power plant is controlled and tested, and in particular each electrical machine, each control means and each electrical energy storage means in order to ensure their proper functioning and availability.

The deactivation means can act, according to the inhibition criteria, on the power supply circuit of the electric machine to deactivate an electric machine. The deactivation means can also, according to these inhibition criteria and also the deactivation criteria, provide a deactivation signal to the control means of the electric machine. The deactivation means can also, according to these inhibition and deactivation criteria, require that the current mechanical power Pref supplied by the electric machine has a zero value, regardless of the result provided by the control law.

In addition, the electric machine has an authorized operating zone in electric motor mode depending on the torque it provides. Thus, in the case where the electric machine reaches the maximum torque of this authorized operating zone, the current mechanical power Pref supplied by the electric machine must be limited so that the electric machine does not exceed this maximum torque. On the other hand, in the case where the electric machine reaches the minimum torque of this authorized operating zone, the current mechanical power Pref must not be reduced. In this case, the electric machine then provides no mechanical power. The hybrid power plant includes automatic protections to manage the limit torques of this authorized operating zone of each electric machine.

Independently of each piloting law, the pilot of the aircraft can anticipate a need for additional power. The pilot can then manually activate the electric machine through a manual means of activation of the electric machine. The electric machine then supplies the maximum mechanical power Pmax to the output shaft of the main power transmission gear while applying the deactivation or inhibition criteria mentioned above.

Moreover, when a means for storing electrical energy is non-rechargeable, such as a thermal battery, an electric machine can provide a current mechanical power Pref equal to the maximum mechanical power Pmax for a limited time Rame by the quantity of electrical energy present in the storage means. This limited time Rame is such that:

Etotal being the total energy available in the storage medium initially, U (t) being the electrical voltage across the storage means, l (t) being the intensity of the electric current supplied by the storage means and Tact being the date of activation of the storage medium.

In addition, the control means comprises a display means adapted to be arranged on a dashboard of the aircraft. The display means displays a first indication of the electrical energy available in the storage means and a second indication relating to the state of the electric machine. This second indication indicates on the one hand that the electric machine is ready to provide a current mechanical power Pref to the output shaft of the main power transmission gearbox and on the other hand that the electric machine provides a current mechanical power Pref to the output shaft of the main power gearbox.

The present invention also relates to a rotary wing aircraft comprising a hybrid power plant as described above and at least one main rotor secured to an output shaft of the main gearbox of this hybrid power plant, or a anti-torque rotor rotated by said hybrid power plant. The hybrid power plant comprises at least two turboshaft engines, at least two control units, at least one electrical machine, at least one electrical energy storage means, at least one control device of each electrical machine and a transmission box. power main having at least one output shaft.

Each electric machine can be implanted according to a micro-hybridization or mild-hybridization architecture and makes it possible to bring an additional mechanical power to the output shaft of the main power transmission gearbox and, consequently, to the main rotor of the power transmission. aircraft, or the anti-torque rotor. The invention and its advantages will appear in more detail in the context of the description which follows with exemplary embodiments given by way of illustration with reference to the appended figures which represent: FIG. 1, an aircraft equipped with a hybrid power plant - Figures 2 to 8, different architectures of the hybrid power plant, - Figures 9 to 13, different configurations of the display means of the hybrid power plant.

The elements present in several separate figures are assigned a single reference.

FIG. 1 represents a rotary wing aircraft 1 provided with a main rotor 2, an anti-torque rear rotor 7 and a hybrid power plant 5 as well as a dashboard 8. The aircraft 1 also comprises a electrical network 30, supplying different equipment 31,32,33 of the aircraft 1 and the dashboard 8. The main rotor 2 and the rear anti-torque rotor 7 are rotated respectively by an output shaft 4,6 of the hybrid power plant 5. The two output shafts 4,6 may have different rotational frequencies in order to drive in rotation the main rotor 2 and the rear anti-torque rotor 7. In particular, the output shaft 4 driving the main rotor 2, has a rotation frequency NR.

Different architectures of this hybrid power plant 5 are shown in FIGS. 2 to 8.

In common with these architectures, the hybrid power plant 5 comprises two turbine engines 10, 10 ', two control boxes 13, 13', each control box 13, 13 'being connected to a turbine engine 10, 10', a box of main power transmission 3, two coupling means 14,14 ', two output shafts 4,6 which are output shafts of the main power transmission gearbox 3. Each turbine engine 10,10' comprises a gas generator 11,11 'and a free turbine 12,12'. The coupling means 14, 14 'is positioned between the free turbine 12, 12' of each turbine engine 10, 10 'and the main power transmission gearbox 3. This coupling means 14, 14' is for example a wheel free or a clutch device.

Each control box 13, 13 'provides control and management of the operation of a heat engine 10, 10'. A control box 13, 13 'may be an EECU control box or a FADEC engine control unit for example.

Each architecture also comprises one or more electrical machines 20, 20 ', 20 "and a storage means 22 and one or more control means 21, 21', 21". Each electrical machine 20, 20 ', 20 "provides mechanical power to the main power transmission gearbox 3 to rotate the output shafts 4.6 and thereby the main rotor 2 and the rear anti-torque rotor. 7.

Each control means 21,21 ', 21 "is connected to at least one electrical machine 20,20', 20" and provides control and management of the operation of this electrical machine 20,20 ', 20 ".

According to a first type of architecture designated by the term "micro-hybridization" and represented in FIGS. 2 and 3, the hybrid power plant 5 comprises two electrical machines 20, 20 ', an electric machine 20, 20' being connected at the gas generator 11, 11 'of a turbine engine 10, 10'. This electric machine 20,20 'then drives in rotation the rotary shaft of this gas generator 11,11'. The hybrid power plant 5 shown in Figure 2 also comprises a starter-generator 15,15 'positioned between each turbine engine 10,10' and an electric machine 20,20 '. Each starter-generator 15, 15 'makes it possible, on the one hand, to start a 10.10' turbine engine and, on the other hand, to supply power to the on-board electrical network 30 of the aircraft 1. Each electric machine 20, 20 ' enables the electrical energy supplied by the storage means 22 to be converted into mechanical power driving the main power transmission gearbox 3. The storage means 22 is then non-rechargeable, typically a thermal battery. The hybrid power plant 5 also comprises a single control means 21 connected to the two electrical machines 20, 20 '. The hybrid power plant 5 shown in Figure 3 does not include a starter-generator 15,15 ', an electric machine 20,20' being connected directly to a gas generator 11,11 '. The electric machine 20, 20 'then performs three functions: a first start function of a turbine engine 10, 10', a second electric motor function driving the main power transmission box 3 and a third electrical generator function transforming a mechanical power supplied by the gas generator 11,11 'in electrical energy. The hybrid power plant 5 comprises two control means 21,21 ', a control means 21,21' being connected to an electric machine 20,20 '. The hybrid power plant 5 also comprises an HT / LV converter 25 making it possible to convert the high voltage electrical energy generated by the electric machine 20, 20 'in order to supply the electrical network of the aircraft 30 with electrical energy. low tension.

The storage means 22 of this hybrid power plant 5 may be non-rechargeable.

The storage means 22 of this hybrid power plant 5 can also be rechargeable, a portion of the electrical energy generated by the electric machine 20,20 'for recharging the storage means 22.

According to a second type of architecture designated by the expression "mild-hybridization" and represented in FIGS. 4 to 7, at least one electrical machine 20, 20 'is positioned on a main transmission chain of mechanical power constituted by the turbines free 12.12 ', the main power gearbox 3 and the output shafts 4.6.

An electric machine 20 can be connected, as shown in FIGS. 4 and 5, directly to the main power transmission gearbox 3. The hybrid powerplant 5 then comprises a single electric machine 20 and a single control means 21.

An electric machine 20 can also be installed, as shown in FIGS. 6 and 7, between the free turbine 12, 12 'of a turbine engine 10 and the main power transmission gearbox 3. The hybrid powerplant 5 comprises two machines 20,20 'and two control means 21,21', an electric machine 20,20 'being connected to the free turbine 12,12' and a control means 21,21 'being connected to an electric machine 20,20 .

In the context of this second type of architecture, each electric machine 20, 20 'can have the sole electric motor function, as shown in FIGS. 4 and 6, the storage means 22 then being non-rechargeable.

Each electric machine 20, 20 'can also be reversible, as shown in Figures 5 and 7. Each electric machine 20, 20' then performs the functions of electric motor and electric generator. The hybrid power plant 5 then comprises an HT / LV converter 25 making it possible to convert the high voltage electrical energy generated by the electric machine 20, 20 'into low voltage electrical energy for the on-board electrical network 30.

The storage means 22 of this hybrid power plant 5 can be non-rechargeable or rechargeable, a portion of the electrical energy generated by the electric machine 20,20 'for recharging the storage means 22 rechargeable.

The choice of the implantation of each electrical machine 20,20 'according to one or the other type of architecture is defined according to the maximum mechanical power Pmax of each electrical machine 20,20' and a power limit Ppai specific to the aircraft 1. Each electrical machine 20,20 'is implanted according to the first type of architecture if its maximum mechanical power Pmax is less than or equal to the limit power Ppai and following the second type of architecture if its power mechanical maximum Pmax is greater than the limiting power Ppai.

Furthermore, according to a third type of architecture, an example of which is shown in FIG. 8, each microhybridization architecture can be combined with a mild-hybridization architecture in a hybrid power plant 5.

In this FIG. 8, the hybrid power plant 5 comprises three electrical machines 20, 20 ', 20 ", three control means 21, 21', 21", a storage means 22 and two HT / LV 25.25 "converters. , a control means 21, 21 ', 21 "being connected to an electric machine 20, 20', 20".

A reversible electric machine 20, 20 'is connected to each gas generator 11, 11' and provides the starting functions of a turbine engine 10, 10 ', of an electric motor driving the main power transmission gearbox 3 and an electric generator. . Another reversible electric machine 20 "is connected directly to the main power transmission gearbox 3 and performs the functions of electric motor and electric generator.

The storage means 22 may or may not be rechargeable and is connected to each control means 21, 21 ', 21 "in order to supply the electrical machines 20, 20', 20" with electrical energy. The electrical machines 20, 20 'connected to a gas generator 11, 11' are connected to a first HV / LV converter 25 while the other electrical machine 20 'connected to the main power transmission box 3 is connected to a second HT / LV converter 25 ". The two 25.25 "HT / LV converters supply the on-board electrical network 30 of the aircraft 1.

Regardless of the type of architecture of the hybrid power plant 5, each electric machine 20, 20 ', 20 "brings a mechanical power to the main power transmission gearbox 3, in addition to the power supplied by the turbine engines 10 10 'to rotate the output shafts 4.6 and thereby the main rotor 2 and the rear anti-torque rotor 7. Each electric machine 20,20', 20 "thus makes it possible to improve the performance of the the hybrid power plant 5 and the aircraft 1.

Each electrical machine 20,20 ', 20 "provides a current mechanical power Pref less than or equal to the maximum mechanical power Pmax that can provide each electric machine 20,20', 20". The current mechanical power Pref can be defined by a first control law, such that:

NR being the current rotation frequency of the output shaft 4, ^ being a time derivative of the current rotation frequency NR, NRc being a reference value of the current rotation frequency NR, Xi and X2 being two stop coefficients, and k being a coefficient of anticipation.

In addition, each machine 20, 20 ', 20 "can be deactivated by a deactivation means that comprises the control means 21, 21', 21" in order to preserve the amount of electrical energy of the storage means 22. This means deactivation deactivates an electrical machine 20,20 ', 20 "according to criteria related in particular to: - each storage means 22 of electrical energy for example when the storage means 22 can no longer provide electrical power, - conditions of flight of the aircraft 1: for example when the aircraft 1 is on the ground or when the aircraft 1 has a flight speed whose horizontal component Vy is below a threshold speed VI, - the operating conditions of each turbine engine 10, 10 ': for example when information that no turbine engine 10, 10' has failed or that a margin Marg of power of each turbine engine 10, 10 'is greater than a limit power margin and - condition s of operation of each electrical machine 20,20 ', 20 "for example when an electrical machine 20,20', 20" is down.

In addition, the control means 21, 21 ', 21 "comprises a display means 40 positioned on the dashboard 8. Different configurations of this display means 40 are shown in FIGS. 9 to 13. display 40 displays a first indication 41 relating to the electrical energy available in the storage means 22 and a second indication 42 relating to the state of the electric machine 20, 20 ', 20 ".

The first indication 41 represents a diagram of an electric battery whose filling corresponds to the electrical energy contained in the storage means 22. Thus, in FIGS. 9 and 10, the first indication 41 specifies that the storage means 22 are while in FIG. 11, a portion of the electrical energy of the storage means 22 has been used. In Fig. 12, the first indication 41 indicates that the storage means 22 is nearly empty whereas in Fig. 13 the first indication 41 indicates that the storage means 22 is empty.

The second indication 42 appears in FIGS. 9 and 10 in the form of an empty rectangle signifying that at least one electrical machine 20, 20 ', 20 "is ready to supply mechanical power to the main power transmission gearbox 3. .

In FIGS. 11 and 12, the second indication 42 appears in the form of a solid rectangle signifying that at least one electrical machine 20, 20 ', 20 "provides mechanical power to the main power transmission gearbox 3 and participates thus to drive the output shafts 4,6 and thus the main rotor 2 and the anti-torque rear rotor 7 in rotation. FIGS. 11 and 12 also show the presence of the indications 43 and 44 respectively signifying that a turbine engine 10, 10 'has provided an emergency overreaction OEI 30 "and OEI 2'. has suffered a malfunction of a 10.10 'turbine engine Advantageously, at least one electrical machine 20, 20', 20 "then provides a mechanical power to partially compensate for the lack of power related to this failure.

Finally in Figure 13, no second indication 42 is visible. Since the storage means 22 are empty, no electrical machine 20, 20 ', 20 "can supply mechanical power to the main power transmission gearbox 3.

Naturally, the present invention is subject to many variations as to its implementation. Although several embodiments have been described, it is well understood that it is not conceivable to exhaustively identify all the possible modes. It is of course conceivable to replace a means described by equivalent means without departing from the scope of the present invention.

Claims (14)

1. Hybrid power plant (5) for aircraft (1) with rotary wing comprising: - at least two turboshaft engines (10, 10 '), each turbine engine (10, 10') being provided with a gas generator (11, 11 ') ') and a free turbine (12,12'), each turbine engine (10,10 ') can provide at least a Maximum Continuous Power PMC and a Maximum Takeoff Power PMD as well as emergency OEI overruns, - at minus two control boxes (13,13 '), each control box (13,13') being connected to a turbine engine (10,10 '), - at least one electric machine (20,20', 20 '') provide maximum mechanical power Pmax. at least one electrical energy storage means (22) supplying electrical energy to each electrical machine (20, 20 ', 20 "), at least one control means (21, 21', 21") of each electric machine (20,20 ', 20 ") and - a main power gearbox (3) having at least one output shaft (4,6) mechanically driven in rotation at a rotation frequency NR jointly by said turbine engines ( 10,10 ') and each electrical machine (20,20', 20 "), said free turbines (12,12 ') of said turbine engines (10,10'), said main power transmission gearbox (3) and each shaft output device (4,6) constituting a main mechanical power transmission chain (3), characterized in that an electric machine (10, 10 ') is connected to said gas generator (11, 11') of each turbine engine ( 10, 10 ') when said maximum mechanical power Pmax is less than or equal to a limit power P while said electric machine (10, 10 ') is connected to said main mechanical power transmission chain (3) when said maximum mechanical power Pmax is greater than said limit power Ppai, said limiting power Ppai being specific to said aircraft (1 ) for which said hybrid power plant (5) is intended and in particular being a function of the mass and aerodynamics of said aircraft (1) as well as of said Maximum Continuous Power PMC, said Maximum Takeoff Power PMD and said emergency over-powers OE1 said turbine engines (10, 10 '). 2. hybrid power plant (5) according to claim 1, characterized in that, when an electric machine (10,10 ') is connected to said gas generator (11,11') of each turbine engine (10,10 ') said electric machine (10, 10 ') provides each start of said turbine engine (10, 10') and a generation of an electric current capable of supplying an on-board electrical network (30) of said aircraft (1). 3. hybrid power plant (5) according to any one of claims 1 to 2, characterized in that a storage means (22) of electrical energy is non-rechargeable. 4. hybrid power plant (5) according to any one of claims 1 to 3, characterized in that a storage means (22) of electrical energy is rechargeable, at least one electric machine (20,20 ', 20). ") Providing a generation of electric current to recharge said storage means (22). 5. hybrid power plant (5) according to any one of claims 1 to 4, characterized in that, at least one electrical machine (20,20 ', 20 ") operating as a high voltage electrical generator, said power plant (5) comprises an HT / LV converter (25) capable of supplying an onboard electrical network (30) of said aircraft (1) with low voltage electricity. 6. hybrid power plant (5) according to any one of claims 1 to 5, characterized in that at least one electrical machine (20,20 ', 20 ") provides a current mechanical power Pref less than or equal to said mechanical power maximum Pmax, said current mechanical power Pref being defined as a function of said current rotation frequency NR of said output shaft (4) by a first control law, such that: Pmax being the maximum power that can be provided by each electrical machine (20,20 ', 20 "), NR being said current rotation frequency of said output shaft (4), ^ being a time derivative of said current rotation frequency NR, NRc being a reference value of the current rotation frequency NR, Xi and X2 being two stop coefficients and k being an anticipation coefficient. 7. hybrid power plant (5) according to claim 6, characterized in that said current rotation frequency NR is determined by means of the rotation frequency of said electric machine (20,20 ', 20 "). 8. hybrid power plant (5) according to any one of claims 1 to 5, characterized in that at least one electrical machine (20,20 ', 20 ") provides a current mechanical power Pref less than or equal to said power mechanical maximum Pmax, said current mechanical power Pref being a function Marg Marg of power of each turbine engine (10,10 ') operational and defined by a second control law, such that Pref = f (Marg). 9. hybrid power plant (5) according to any one of claims 1 to 8, characterized in that each control means (21,21 ', 21 ") comprises a deactivating means and a communication means capable of communicating with an avionic installation of said aircraft (1), said deactivation means being able to deactivate an electrical machine (20,20 ', 20 ") according to criteria related to: - each electrical energy storage means (22) such that said storage (22) can no longer provide electrical power, - flight conditions of said aircraft (1) such that said aircraft (1) is on the ground or said aircraft (1) has a flight speed whose horizontal component r ^ is less than a threshold speed VI, - operating conditions of each turbine engine (10, 10 '), such as information that no turbine engine (10, 10') is out of order or that a Marg margin the power of each turbine engine (10, 10 ') is greater a limit power margin and - the operating conditions of each electric machine (20,20 ', 20 ") such as an electric machine (20,20', 20") is down. Hybrid power plant (5) according to claim 9, characterized in that said deactivating means acts on a power supply circuit of an electric machine (20,20 ', 20 "), provides a deactivation signal to said means (21,21 ', 21 ") or imposes a current mechanical power Pref supplied by said electrical machine (20,20', 20") equal to a zero value in order to deactivate said electric machine (20,20 ', 20 "). 11. hybrid power plant (5) according to any one of claims 1 to 10, characterized in that said hybrid power plant (5) comprises a manual activation means (26) of each electric machine (20,20 ', 20 ") so that each electrical machine (20,20 ', 20") provides a maximum mechanical power Pmax to said output shaft (4,6) of said main power transmission gearbox (3). Hybrid power plant (5) according to one of Claims 1 to 11, characterized in that, when a storage medium (22) for the electrical energy is non-rechargeable, an electric machine (20, 20 ', 20 ") can provide a current mechanical power Pref equal to said maximum mechanical power Pmax for a limited duration Rame defined by the formula: Etotai being the total energy available in said storage means (22) initially, U (t) being the electrical voltage across said storage means (22), where (t) is the intensity of the electric current supplied by said means storage (22) and Tact being the date of activation of said storage means (22). 13. hybrid power plant (5) according to any one of claims 1 to 12, characterized in that said control means (21,21 ', 21 ") comprising a display means (40) adapted to be arranged on a dashboard of said aircraft (1), said display means (40) displays a first indication (41) relating to the electrical energy available in said storage means (22) and a second indication (42) indicating on the one hand that said electric machine (20,20 ', 20 ") is ready to supply a current mechanical power Pref to said output shaft (4,6) and on the other hand that said electric machine (20,20', 20 ") provides a current mechanical power Pref to said output shaft (4,6). 14. Aircraft (1) rotary wing comprising: - a hybrid power plant (5) according to any one of claims 1 to 13, - at least one main rotor (2) integral with an output shaft (4) of said main power transmission gearbox (3) of said hybrid powerplant (5), and - an anti-torque rotor (7) integral with an output shaft (6) of said main power transmission gearbox (3) of said hybrid power plant (5).