Powerplant equipped with a turboshaft engine and an adaptive starting circuit and method for adaptively starting a turboshaft engine

Abstract

The present invention relates to a method for adaptively starting a turbine engine (10) comprising a gas generator (11), an electrical machine (21) mechanically connected to said gas generator (11) and electrically to one or more electrical energy sources (26-28). A maximum electrical intensity of an electrical current deliverable by said one or more electrical energy sources (26-28) is determined as a function of at least one characteristic of each electrical energy source (26-28), a maximum engine torque provided by said electrical machine (21) electrically powered by each electrical energy source (26-28) with said maximum electrical intensity is determined. Said maximum engine torque is compared with a required envelope (70) of engine torque admissible by said gas generator (11).Said maximum electrical intensity of said electrical current supplied by said electrical energy source(s) (26-28) is adapted in order to respect said envelope required for starting said gas generator (11). Abstract figure: figure 1.

Description

Title of the invention: Power plant equipped with a turboshaft engine and an adaptive starting circuit and method for adaptively starting a turboshaft engine

[0001] The invention lies in the technical field of thermal engines, in particular turboshaft engines.

[0002] The present invention relates to a power plant provided with a turboshaft engine and an adaptive starting circuit, as well as a method for adaptively starting a turboshaft engine.

[0003] A turbine engine usually comprises a gas generator and at least one working turbine. The gas generator is provided successively with a compressor, a fuel combustion chamber and at least one expansion turbine secured in rotation to the compressor by a connecting shaft. The working turbine may be free, namely mechanically detached in rotation from the expansion turbine and the compressor, and therefore from the gas generator. The working turbine is then driven in rotation by the gases leaving the expansion turbine of the gas generator. Alternatively, the working turbine may be mechanically secured in rotation with the expansion turbine, and therefore with the gas generator.

[0004] In all cases, the working turbine mechanically drives an output shaft of the turbine engine into rotation. A turbine engine can equip an aircraft, its output shaft being able to be connected, via a power transmission box, to a propeller or a rotor for example.

[0005] To start the turboshaft engine, the compressor must be driven into rotation in order to generate pressurized air which is injected into the combustion chamber, then the gases generated by the combustion of a fuel in the combustion chamber then drive the expansion turbine into rotation. This rotation of the compressor is carried out by a starter mechanically connected in rotation to a drive shaft of the compressor. This starter can be a simple electric motor or a reversible electric machine then referred to as a "starter / generator". In addition, when the compressor is started into rotation, its rotation speed must not increase too quickly so as not to blow out, i.e. extinguish, the flame generated during the first combustion of the fuel in the combustion chamber.

[0006] To obtain autonomous operation of the turboshaft engine, the rotation speed of the expansion turbine must exceed a threshold so that the compression of the air injected into the combustion chamber is sufficient.

[0007] Furthermore, during starting, the rotation speed of a starter consisting of a collector / brush type direct current machine gradually increases, which causes an increase in its counter electromotive force. The electrical intensity of the electric current supplying this type of starter, on which it is not possible to act to vary the torque, then decreases with the increase in its rotation speed.

[0008] The engine torque supplied by such a starter and rotating the compressor drive shaft cannot be controlled and is proportional to the electric current supplying this starter. Therefore, during the starting of a turboshaft engine, this engine torque may have a high peak at the beginning of the starting phase, then decreases with the increase in the rotation speed of the starter and its counter electromotive force.

[0009] The electrical voltage of this electric current is linked to the power source. When this source is an electric battery, this electrical voltage drops when the starter is started, then increases proportionally to the decreasing electrical intensity of this electric current supplying the starter.

[0010] In addition, a resistive torque of the gas generator, generated by the compressor and the expansion turbine, tends to oppose this rotation of the compressor drive shaft by the starter. It is therefore necessary to supply sufficient electrical energy to the starter to drive the compressor, with a motor torque greater than the resistive torque.

[0011] Conversely, this engine torque must not be too high so as not to cause the gas generator to accelerate too quickly, in particular so as not to extinguish the combustion chamber. In addition, too high an engine torque can cause damage to the mechanical connection between the starter and the compressor drive shaft.

[0012] In this context, the engine torque of the starter to start a turbine engine must be between a minimum torque and a maximum torque.

[0013] The starter is furthermore supplied with electrical energy by one or more sources of electrical energy, such as for example an electric battery or an electrical network. In the case of a turbine engine of a vehicle, and of an aircraft in particular, one or more on-board electric batteries can electrically supply the starter.

[0014] The electrical energy that can be provided by electric batteries used as sources of electrical energy can vary depending on their temperatures, this electrical energy decreasing with the temperature, their states of charge or even their aging. At low temperatures, an electric battery may thus prove incapable of allowing the starting of a turbine engine.

[0015] In addition, during start-up, the call for significant electrical energy by the A starter motor can also result in a significant drop in electrical voltage across an electric battery, due to the internal electrical resistance of the electric battery. The greater the electrical current drawn by the starter motor, the more the electrical voltage drops. This drop in electrical voltage can vary depending, for example, on the temperature and the state of charge of the electric battery.

[0016] The use of several electric batteries in parallel can make it possible to overcome these consequences. However, in the presence of high temperatures and / or with high charge levels, the electrical energy supplying the starter may then be too high, the starter then being likely to induce an engine torque greater than the high threshold previously mentioned.

[0017] It therefore proves complex to use a set of electrical energy sources capable of ensuring efficient starting of a turboshaft engine both at low and high temperatures, and with various load levels.

[0018] Document EP 2390485 describes a method for controlling the start-up of a turbine engine consisting of defining electrical current setpoints for a starter as a function of a starting torque previously determined for the gas turbine, and modulating an electrical intensity of the electrical current supplying the starter to obtain the desired starting torque.

[0019] Document EP 3043445 describes an electrical circuit for a rotorcraft regulating the supply of electrical energy for starting a turbine engine by exploiting several sources of electrical energy. The sources of electrical energy comprise a main source provided with electric batteries and a secondary source comprising a discharge module. A bidirectional DC-DC converter of the static type, mounted in series with the discharge module, makes it possible to regulate the operation of this discharge module as a function of the value of at least one parameter identifying the evolution of the start-up phase of the turbine engine.

[0020] Document EP 1556597 relates to an electrical machine used as a starter-generator in an aircraft. This electrical machine comprises a stator provided with several windings supplied with electric current by an electrical energy source. One or more switches and an electrical energy source are selectively controlled in order to electrically connect a capacitor, in series, with one or more of these windings to provide additional electrical energy to the stator windings so that the electrical machine generates a sufficiently high engine torque to start an engine of the aircraft.

[0021] Document WO 2022 / 208021 relates to a method and a system for starting a turbine engine comprising an electrical machine and a control system converting a direct electrical voltage into a three-phase electrical voltage for cause the electric machine to rotate at a determined speed.

[0022] Documents EP 1865172, EP, 2554799, EP 3186489, FR 3101918, EP 2295726, EP 0911515 are far from the invention.

[0023] The present invention therefore aims to allow the starting of a gas generator of a turbine engine without risk of damaging mechanical parts, both at low temperatures and at high temperatures.

[0024] The invention thus aims at an innovative method for starting a power plant equipped with a turboshaft engine and a power plant allowing the implementation of such a method.

[0025] The present invention firstly relates to a method for adaptively starting a turbine engine comprising a gas generator, an electrical machine mechanically connected to a drive shaft of the gas generator and electrically to an electrical generator provided with at least one source of electrical energy.

[0026] The electrical machine thus acts as a starter or starter-generator for the gas generator of the turbine engine. The electrical machine is mechanically connected to the drive shaft of the gas generator, via a mechanical transmission chain capable of comprising a reduction ratio, obtained for example using gears, pinions and / or toothed wheels.

[0027] The method is remarkable in that it comprises the following steps: - determination of a maximum electrical intensity of an electrical current deliverable by the electrical generator as a function of at least one characteristic of said at least one source of electrical energy, - calculation of a maximum motor torque supplied by the electric machine to the drive shaft when the electric machine is electrically powered by the electric generator with the determined maximum electrical intensity of the electric current, - comparison of this maximum engine torque with a required envelope of engine torque admissible by the gas generator, and - adaptation of said maximum electrical intensity based on this comparison in order to comply with the required envelope, - starting the gas generator with the electrical machine powered by said at least one source of electrical energy following this adaptation.

[0028] The power plant comprising the turbine engine, the electric machine and the electric generator can equip a vehicle, for example an aircraft or even in order to drive the rotation of a propeller and / or a rotor for example. The power plant can also be equipped with a computer comprising or connected to a memory. The memory can include instructions or a computer program allowing the computer to implement this method.

[0029] The electrical generator may comprise a single electrical energy source or several electrical energy sources arranged in parallel with each other. Each electrical energy source provides an electrical current, for example a direct electric current, to electrically power the electrical machine when the gas generator of the turbine engine is started.

[0030] Each electrical energy source may comprise one or more sensors for directly or indirectly measuring one or more characteristics of this electrical energy source. For example, such a characteristic of an electrical energy source may be chosen from at least its charge level, its temperature, its aging level.

[0031] Depending on one or more characteristics of such an electrical energy source as well as first pre-established charts or laws stored in the memory, the computer determines the maximum electrical intensity of the electrical current that this electrical energy source can deliver.

[0032] When the electric generator comprises a single source of electric energy, the maximum electric intensity of the electric current supplied by the electric generator is equal to the maximum individual electric intensity of the electric current of this single source of electric energy.

[0033] When the electric generator comprises several sources of electric energy, the maximum electric intensity of the electric current supplied by the electric generator is equal to the sum of the maximum individual electric intensities of the electric currents of these sources of electric energy.

[0034] Then, the calculator determines, as a function of this maximum electrical intensity that the electrical generator can deliver as well as second pre-established charts or laws stored in the memory, the maximum engine torque that the electrical machine provides when it is supplied with an electrical current having the aforementioned maximum electrical intensity.

[0035] The computer then compares this maximum engine torque with a required envelope of engine torque admissible by the gas generator stored in the memory. This required envelope is delimited by a maximum torque curve and a minimum torque curve to be respected when driving the gas generator by the electric machine. Each of these torque curves can for example decrease with the increase in the rotational speed of the gas generator. The torque curves can be established by tests, calculations and / or simulations for example.

[0036] Then, based on this comparison, the computer can control, directly or via a dedicated control unit, the electric generator to adapt, and therefore modify, the maximum electrical intensity of the electric current that the electric generator provides. This maximum electrical intensity is modified in order to cor respond, according to the second charts or the second laws, to a motor torque less than or equal to the torque values ​​of the maximum torque curve and greater than or equal to the torque values ​​of the minimum torque curve. In this way, the motor torque supplied by the electric machine respects the required envelope by being located between the maximum and minimum torque curves.

[0037] Finally, the electric machine is powered with the electric generator and mechanically drives the drive shaft of the gas generator in order to start it while respecting the required envelope of admissible engine torque. In this way, no degradation of the mechanical transmission chain between the electric machine and the gas generator is to be feared. Similarly, the start-up of the gas generator is efficient, the flame blowing phenomenon being able to be avoided.

[0038] The method according to the invention may comprise one or more of the following characteristics, taken alone or in combination.

[0039] According to one possibility, the adaptation may comprise a step of defining a target maximum electrical intensity of the electrical current that the electrical generator must supply so that the electrical machine transmits, when it is supplied by an electrical current with this target maximum electrical intensity, a maximum engine torque in accordance with the required envelope, and for example located on the maximum torque curve. This definition is carried out by the computer, using the second charts or the second laws, and the maximum torque curve.

[0040] According to a possibility compatible with the previous ones, the electric generator can comprise several sources of electric energy, and the adaptation then comprises a step of supplying electricity to the electric machine by one or more of these sources of electric energy, when the maximum engine torque is greater than the maximum torque curve of the required envelope. This step of supplying electricity is carried out as a function of the maximum electric intensity of the electric current supplied by the electric generator, so that the electric machine supplies a maximum engine torque to the gas generator included in the required envelope.

[0041] The electrical energy sources are electrically connected in parallel to each other to jointly supply the electrical machine. The electrical generator comprises source switches arranged respectively between the electrical energy sources and the electrical machine. Each source switch may comprise a contactor, a relay or a switch that can be controlled remotely, using the computer for example, in order to open or close the contactor, the relay or the switch to allow or prohibit the passage of an electric current between the terminals of this source switch, and consequently the electrical supply of the electrical machine by the electrical energy source to which this source switch is connected.

[0042] Thus, when the maximum engine torque determined is greater than the curve of maximum torque of the required envelope, the electrical supply step may comprise steps for electrically connecting or disconnecting the necessary number of electrical energy sources using the source switches so that the sum of the maximum individual electrical intensities of the electrical currents of the electrical energy sources electrically connected to the electrical machine, or even where appropriate the maximum individual electrical intensity of the electrical current of a single electrical energy source connected to the electrical machine allows, according to the second charts or the second laws, that the maximum motor torque of the electrical machine is included in the required envelope. The electrical supply may optionally comprise iterative calculations of this sum by varying the connected electrical energy sources until an adequate sum is obtained.During this power supply step, the sum of the maximum individual electrical intensities of the electrical currents of the electrical energy sources electrically connected to the electrical machine, or where appropriate the maximum individual electrical intensity of the electrical current of the single electrical energy source connected to the electrical machine, is for example equal to the target maximum electrical intensity.

[0043] For this purpose, the power supply may comprise a connection / disconnection sub-step for electrically connecting or disconnecting the source switches depending on their initial states, namely whether the source switches are electrically open or closed. The computer is connected by a wired or wireless link with each source switch, on the one hand, to check their state, and on the other hand to control them in order to electrically connect or disconnect them to a source of electrical energy.

[0044] According to a possibility compatible with the previous ones, the electric generator comprises a single source of electrical energy, and the adaptation then comprises a discharge step for electrically discharging the single source of electrical energy, when the maximum engine torque is greater than the torque values ​​of the maximum torque curve of the required envelope, until reaching a required charge level allowing it to supply an electric current with a maximum individual electrical intensity corresponding to a maximum engine torque less than or equal to the torque values ​​of the maximum torque curve of the required envelope so that the electric machine supplies an engine torque to the gas generator included in the required envelope. The gas generator is started once the discharge step is complete.

[0045] The discharging step may discharge the sole source of electrical energy into an on-board network of the vehicle equipped with the power plant for example, or into a dedicated discharging device, such as one or more electrical consumers. Once the required charge level is reached, the discharge step is complete and the gas generator can be started without risk of damaging the gas generator or the mechanical transmission chain.

[0046] The required charge level of the electrical energy source is defined so that the electrical energy source delivers an electrical current with a maximum individual electrical intensity corresponding to a maximum motor torque included in the required envelope, for example located on the maximum torque curve. The computer can calculate the required charge level according to the first charts or the first laws relating to this single electrical energy source, the characteristic(s) of this single electrical energy source and either the second charts or the second laws and the maximum torque curve, or the target maximum electrical intensity.

[0047] In addition, the computer can transmit this required charge level as well as a current charge level of the single electrical energy source to a display to display this required charge level in parallel with the current charge level in order to indicate them to an operator or a driver of the vehicle.

[0048] The computer may also calculate a time required to reach this required charge level using a measurement of an electrical intensity of a discharge electric current supplied by the single electrical energy source during the discharge step and the current charge level, as well as possibly the characteristic(s) of this single electrical energy source. The computer may possibly transmit this necessary time to the display to display it in order to indicate to an operator or a driver of the vehicle how long it will take to start.

[0049] Alternatively, this power supply step can also be carried out within the framework of an electrical generator comprising several electrical energy sources in order to reduce the maximum individual electrical intensity of an electrical current supplied by one of these electrical energy sources.

[0050] According to a possibility compatible with the previous ones, the electric generator comprises a single source of electrical energy and at least one dissipating element electrically arranged in parallel with the electric machine, and the adaptation comprises a connection step for electrically connecting to the electric generator at least one dissipating element when the maximum engine torque is greater than the torque values ​​of the maximum torque curve of the required envelope, the dissipating element(s) being electrically powered by the electric generator. Following this connection step, the single source of electrical energy delivers an electric current to terminals of the connected dissipating element(s) and to the electric machine. A portion of this electric current delivered by the single source of energy The electric current thus circulates through the dissipating element(s) and allows part of the electrical energy from this single source of electrical energy to be dissipated. The gas generator is started after the connection step.

[0051] A dissipation switch is electrically arranged in series between the electrical generator and at least one dissipating element.

[0052] The calculator determines, for example, the value of the electrical intensity of the electric current delivered by the single source of electrical energy which must be diverted from the electric machine and, consequently, the number of dissipating elements which must be connected to the single source of electrical energy. The calculator can calculate this value of the electrical intensity of the electric current delivered by the single source of electrical energy as a function of characteristics of the dissipating elements of the electric generator, and either the target maximum electrical intensity, or the second charts or the second laws and the maximum torque curve.

[0053] The computer then controls the necessary number of dissipation switches during the connection step so that the necessary number of dissipating elements are connected to the single source of electrical energy.

[0054] In this way, the dissipating elements dissipate the excess electrical intensity of the electrical current supplied by the single source of electrical energy during the dissipation step.

[0055] The dissipating elements comprise, for example, one or more electrical resistors.

[0056] Alternatively, this disconnection step can also be carried out in the context of an electrical generator comprising several sources of electrical energy in order to dissipate part of the electrical energy supplied by one of these sources of electrical energy.

[0057] According to a possibility compatible with the previous ones, an electrical energy source may comprise at least one rechargeable source, for example an electric battery or a supercapacitor. Such a rechargeable source advantageously makes it possible to optimize the mass of the electrical energy source by avoiding in particular dead masses, an electrical energy source may also comprise a primary energy storage device, therefore non-rechargeable.

[0058] Furthermore, when the power plant equips a vehicle, the electric generator can electrically supply, before starting the turboshaft engine, an on-board network of the vehicle and / or one or more pieces of equipment of the vehicle. The electrical intensity of the electric current thus consumed is generally low, but can sometimes have an electrical intensity of the order of 10% of the electrical intensity of the starting current. This electrical intensity of the electric current thus consumed by the on-board network of the vehicle and / or by one or more pieces of equipment of the vehicle, can in this case be taken into account within the framework of the invention, and deduced from the maximum electrical intensity of the electrical current supplied by the electrical generator to calculate the maximum motor torque supplied by the powered electrical machine.

[0059] The present invention also relates to a power plant provided with at least one turbine engine comprising a gas generator and an adaptive starting circuit comprising a computer, an electrical machine mechanically connected to a drive shaft of the gas generator and electrically to an electrical generator provided with at least one source of electrical energy, and configured to start the gas generator.

[0060] This power plant is configured to implement the adaptive starting method of a turbine engine previously described by means of the adaptive electrical circuit.

[0061] According to a first variant, the electric generator may comprise several sources of electrical energy arranged in parallel with each other as well as source switches electrically connecting each of the sources of electrical energy to the electric machine. The source switches are controlled independently of each other by the computer to be opened or closed electrically.

[0062] According to a second variant, the electric generator can comprise a single source of electric energy.

[0063] Whatever the variant, the electric generator and the electric machine can be electrically connected to an electrical network, for example an on-board network of a vehicle or to electrical consumers.

[0064] The electrical generator may also comprise one or more dissipating elements as well as one or more dissipation switches. The dissipating element(s) may be electrically arranged in parallel with the electrical machine, a dissipation switch electrically connecting one or more dissipating elements to the electrical generator. Alternatively, the dissipating element(s) may be electrically arranged in series with the electrical machine, a dissipation switch electrically connecting the electrical generator to an electrical line short-circuiting one or more dissipating elements.

[0065] The dissipation switch(es) are controlled independently of each other by the computer to be opened or closed electrically.

[0066] A dissipating element may comprise one or more electrical resistors.

[0067] Whatever the variant, an electrical energy source may comprise at least one rechargeable source, for example an electric battery, and / or a primary energy storage device.

[0068] Finally, the present invention relates to a vehicle equipped with the power plant described above.

[0069] The invention and its advantages will appear in more detail in the context of the description which follows with examples given for illustrative purposes with reference to the appended figures which represent: - [Fig.l], a diagram illustrating a motor installation according to the invention, - [Fig.2], a diagram illustrating a motor installation according to the invention, - [Fig. 3], a diagram illustrating a motor installation according to the invention, - [Fig.4], a diagram illustrating a motor installation according to the invention, and - [Fig.5], a block diagram of an adaptive starting process of the power plant of figures 1 to 4, and - [Fig.6], a graph representing the required envelope of admissible engine torque for starting a turboshaft engine.

[0070] Elements present in several distinct figures are assigned a single reference.

[0071] Figures 1 to 4 show various embodiments of a power plant 1 of the invention. [Fig.5] shows a block diagram of an adaptive starting method for such a power plant 1.

[0072] Whatever the embodiment, the power plant 1 comprises at least one turboshaft engine 10. The power plant 1 may be arranged within any system powered by a turboshaft engine, and in particular within a vehicle 8. For example, such a vehicle 8 may be a land, sea or air vehicle. For example, the vehicle 8 may be an aircraft equipped with a rotary wing 5 driven in rotation by the turboshaft engine 10, possibly via a power transmission chain 3.

[0073] The embodiments of the power plant 1 shown in the figures comprise a single turboshaft engine 10, although a power plant 1 according to the invention may comprise two or more turboshaft engines 10.

[0074] A turboshaft engine 10 comprises a gas generator 11 and a working turbine 15 mechanically connected to the power transmission chain 3, to drive the rotary wing 5 in rotation according to the example given. The working turbine 15 can be said to be “free”, i.e. not mechanically connected to the gas generator 11. Alternatively, the working turbine 15 can be mechanically connected to the gas generator 11.

[0075] The gas generator 11 may successively comprise a compressor, a fuel combustion chamber and an expansion turbine which are not shown in the figures. The expansion turbine is rotationally secured to the compressor by a connecting shaft.

[0076] Regardless of its arrangement, the power plant 1 according to the invention also comprises an electric machine 21 acting at least as an electric starter for the turboshaft engine 10. The electric machine 21 may comprise a motor electric machine operating only in engine mode to start the turbine engine 10. Alternatively, the electric machine 21 can operate as needed on the one hand in engine mode to start the turbine engine 10, and on the other hand in electric generator mode to transform mechanical energy transmitted by the turbine engine 10 into electrical energy.

[0077] A mechanical transmission chain 19 is arranged between the electrical machine 21 and a drive shaft 12 of the gas generator 11. Such a mechanical transmission chain 19 may comprise gears, pinions and / or toothed wheels to increase the rotational speed of the electrical machine 21 transmitted to the drive shaft 12.

[0078] The power plant 1 also comprises a computer 25. The computer 25 may comprise, for example, at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the expression “selector”. The term processor may also designate a central processing unit known by the acronym CPU, a graphics processing unit GPU, a digital unit known by the acronym DSP, a microcontroller, etc.

[0079] Alternatively to the memory that the computer 25 may include, the power plant 1 may include a memory (not shown) connected to the computer 25.

[0080] The power plant 1 according to the invention also comprises an electric generator 20 electrically connected to the electric machine 21 to supply it with electrical energy. The electric generator 20 may comprise one or more electrical energy sources 26-29, each electrical energy source 26-29 comprising, for example, one or more electric batteries.

[0081] Such an electrical energy source 26-29 may also comprise one or more usual sensors (not shown) for measuring one or more characteristics of this electrical energy source 26-29. Such a sensor may provide a raw signal carrying raw measurements made by this sensor. A sensor may also comprise an integrated computer in order to process these raw measurements, for example via usual filtering or sampling, or even the application of transformations, and provide a processed signal carrying these raw measurements thus processed.

[0082] For example, an electrical power source 26-29 may include a temperature sensor, possibly equipped with a thermometer, for measuring an internal temperature of the electrical power source 26-29.

[0083] According to another example, an electrical energy source 26-29 may comprise a charge sensor making it possible to measure an electrical charge level of the electrical energy source 26-29, namely the quantity of electrical energy that it comprises.

[0084] According to another example, an electrical energy source 26-29 may comprise a aging sensor for measuring an aging state of the electrical energy source 26-29. Such an aging sensor can, for example, perform a calculation of the aging level of the electrical energy source 26-29 based on internal parameters, such as its internal resistance and its state of charge, for example. The aging level can be taken into account to determine the value of the maximum electrical intensity of the electrical current that this electrical energy source 26-29 can provide.

[0085] The electrical generator 20 may comprise a single electrical energy source 29 as shown in FIGS. 2 to 4. Alternatively, the electrical generator 20 may comprise at least two electrical energy sources 26-28 arranged electrically in parallel with each other. The electrical generator 20 may comprise, for example, three electrical energy sources 26-28 as shown in [Fig. 1].

[0086] Each electrical energy source 26-29 and the electrical machine 21 can be electrically connected on the one hand to a common electrical ground 7 and on the other hand to an electrical network 24 of the power plant 1. The electrical network 24 can be an on-board electrical network of the vehicle 8.

[0087] Such an electrical energy source 26-29 can thus provide an electrical current, for example direct current, to power the electrical machine 21 in particular.

[0088] A starter switch 23 is electrically arranged in series between the electrical machine 21 and the electrical network 24. When the starter switch 23 is electrically closed, the electrical machine 21 can be electrically powered by the electrical generator 20 so as to rotate the gas generator 11 during a starting phase. The computer 25 can control the starter switch 23 to open and close it electrically depending on the progress of the starting phase. For this purpose, the computer 25 can be in communication, wired or wireless, with the starter switch 23.

[0089] According to the illustration of [Fig.l], a first example embodiment of the power plant 1 may comprise an electric generator 20 provided with three sources of electric energy 26, 27, 28 and three source switches 32 arranged between the electric network 24 and respectively the three sources of electric energy 26, 27, 28.

[0090] The reference “32” generally designates the source switches while the references “36, 37, 38” specifically designate one of the three source switches.

[0091] Each source switch 32 thus makes it possible to electrically connect or disconnect an electrical energy source 26, 27, 28 with the electrical network 24, for example to electrically supply the electrical machine 21.

[0092] The computer 25 can control the source switches 32 according to a stored logic. The computer 25 can be in communication, wired or wireless, with source switches 32.

[0093] According to the illustrations of figures 2 and 3, the power plant 1 according to the invention may comprise an electric generator 20 provided with dissipating elements 40 and dissipation switches 45.

[0094] The reference “40” generally designates the dissipating elements while the references “41, 42, 43, 44, 44'” specifically designate one of the dissipating elements. Similarly, the reference “45” generally designates the dissipation switches while the references “46, 47, 48, 49, 49'” specifically designate one of the dissipation switches.

[0095] The electrical generator 20 also comprises a power supply switch 22 electrically arranged in electrical series between the electrical energy source 29 and the electrical network 24. This power supply switch 22 is normally electrically closed so that the electrical energy source 29 is electrically connected to the electrical network 24 in order to supply it with electrical current. The computer 25 can control the power supply switch 22 to open it and thus electrically disconnect the electrical energy source 29 from the electrical network 24, if necessary.

[0096] Each dissipation switch 45 thus makes it possible to electrically connect or disconnect a dissipating element 40 with the electrical network 24. The computer 25 can control the dissipation switches 45 according to a stored logic. The computer 25 can be in communication, wired or wireless, with the dissipation switches 45. Each dissipating element 40 can comprise one or more electrical resistors 50, which can be electrically arranged with each other in series or in parallel, depending on the desired electrical resistance value, corresponding to the desired electrical dissipation capacity.

[0097] According to a second embodiment of the power plant 1 shown in [Fig. 2], the electric generator 20 may comprise a single source of electrical energy 29, three dissipating elements 41, 42, 43 and three dissipation switches 46, 47, 48 arranged between the electrical network 24 and respectively the three dissipating elements 41, 42, 43. The three dissipating elements 41, 42, 43 and the three dissipation switches 46, 47, 48 are thus electrically arranged in parallel with the electric machine 21.

[0098] When a dissipation switch 45 is controlled so as to be electrically closed, the dissipating element 40, with which this dissipation switch 45 is electrically arranged in series, is electrically connected to the electrical network 24 and can be powered by the electrical energy source 29 so that an electric current flows in the dissipating element 40. This dissipating element 40 then consumes and dissipates this electric current passing through it, and therefore electrical energy, for example as heat.

[0099] According to a third embodiment of the power plant 1 shown in [Fig. 3], the electric generator 20 may comprise a single source of electrical energy 29, two dissipating elements 44, 44' electrically arranged in series with the electric machine 21 and two dissipation switches 49, 49' electrically arranged in parallel with the two dissipating elements 44, 44' respectively. The two dissipation switches 49, 49' are each positioned on an electrical line 52, 52' short-circuiting one of the dissipating elements 44, 44'.

[0100] When a dissipation switch 45 is controlled so as to be electrically open, the dissipating element 40, with which this dissipation switch 45 is electrically arranged in parallel, is electrically connected to the electrical network 24 and to the electrical machine 21 and can be powered by the electrical energy source 29, the electrical line 52, 52' not being electrically connected to the electrical network 24 and consequently to the electrical energy source 29, so that an electric current flows in the dissipating element 40. This dissipating element 40 then consumes and dissipates this electric current passing through it, and therefore electrical energy, for example in heat.Conversely, when a dissipation switch 45 is controlled so as to be electrically closed, the electrical line 52, 52' short-circuits the dissipating element 40, with which this dissipation switch 45 is electrically arranged in parallel, and this dissipating element 40 are electrically connected to the electrical network 24 and to the electrical machine 21 and can be powered by the electrical energy source 29. However, the electrical current then flows in the electrical line 52, 52' without passing through the dissipating element 40. This dissipating element 40 then neither consumes nor dissipates any electrical current, and therefore no electrical energy.

[0101] Similarly, the electrical generator 20 may comprise dissipating elements 40 electrically arranged in series with an electrical energy source 26-29 and dissipation switches 45 respectively positioned on an electrical line 52, 52' electrically arranged in parallel with these dissipating elements 40.

[0102] According to the illustration of [Fig.4], a fourth example embodiment of the power plant 1 may comprise an electric generator 20 provided with a single source of electric energy 29, two electric consumers 60 and two discharge switches 65 arranged between the electric network 24 and respectively the two electric consumers 60.

[0103] The reference “60” generally designates the electrical consumers while the references “61, 62” specifically designate one of the two electrical consumers. Similarly, the reference “65” generally designates the discharge switches while the references “66, 67” specifically designate one of the two discharge switches.

[0104] The electrical generator 20 also comprises a power supply switch 22 electrically arranged in electrical series between the electrical energy source 29 and the electrical network 24. This power supply switch 22 is for example closed by default, and can be opened, if necessary, to electrically disconnect the electrical energy source 29 from the electrical network 24.

[0105] Each discharge switch 65 thus makes it possible to electrically connect or disconnect an electrical consumer 60 with the electrical network 24. The computer 25 can control the discharge switches 65 according to a stored logic. The computer 25 can be in communication, wired or wireless, with the discharge switches 65.

[0106] When a discharge switch 65 is controlled so as to be electrically closed, the electrical consumer 60, with which this discharge switch 65 is electrically arranged in series, is electrically connected to the electrical network 24 and can be powered by the electrical energy source 29 so that an electric current flows in the electrical consumer 60. This electrical consumer 60 consumes a portion of the electrical energy supplied by the electrical energy source 29. Each electrical consumer 60 may comprise one or more electrical equipment, such as an air conditioning system, screens, a radio communication system, headlights, fans, hydraulic pumps, etc.

[0107] [Fig. 5] illustrates a method for adaptively starting the power plant 1. Instructions or a computer program relating to this method can be stored in a memory of the computer 25 or in a memory connected to this computer 25. The computer 25 can then execute these instructions or this program to start the gas generator 11 of the power plant 10.

[0108] This process involves five main steps.

[0109] First of all, the method comprises a determination 100 of a maximum electrical intensity of the electrical current deliverable by the electrical generator 20. This maximum electrical intensity is determined using the calculator 25 as a function of at least one characteristic of said at least one electrical energy source 26-29. For example, the characteristic(s) of an electrical energy source 26-29 may be chosen from a list comprising at least its charge level, its temperature, its aging.

[0110] The characteristic(s) of the electrical energy source(s) 26-29 are for example measured continuously or regularly using the sensor(s) of the electrical energy source(s) 26-29. Each sensor then transmits a signal, electrical or optical, digital or analog, carrying information relating to the measured characteristic to the computer 25, by wired or wireless means.

[0111] The method may also comprise a step of measuring one or more ca characteristics of the electrical energy source(s) 26-29, carried out prior to this determination step 100.

[0112] When the electrical generator 20 comprises several electrical energy sources 26-28, the maximum electrical intensity of an electrical current deliverable by the electrical generator 20 is equal to the sum of the maximum individual electrical intensities of the electrical currents supplied by these electrical energy sources 26-28. In this case, the measurement step can also be carried out for each of these electrical energy sources 26-28.

[0113] When the electric generator 20 comprises a single source of electric energy 29, the maximum electric intensity of the electric current supplied by the electric generator 20 is equal to the maximum individual electric intensity of the electric current of this single source of electric energy 29.

[0114] During this determination step 100, the computer 25 uses first pre-established charts or laws stored in the memory. These first pre-established charts or laws are specific to each electrical energy source 26-29. These first charts or laws define the maximum individual electrical intensity of the electrical current that each electrical energy source 26-29 can provide as a function of its measured characteristic(s).

[0115] Then, the method comprises a step 200 of calculating a maximum engine torque supplied by the electric machine 21 to the drive shaft 12 when the electric machine 21 receives an electric current having the determined maximum electric intensity.

[0116] During this calculation step 200, the computer 25 uses second pre-established charts or laws stored in the memory. These second pre-established charts or laws are specific to the electrical machine 21 of the power plant 1. These second charts or laws define the maximum engine torque that the electrical machine 21 can transmit as a function of the electrical intensity of the electrical current supplying the electrical machine 21.

[0117] Then, during a comparison step 300, the maximum engine torque previously calculated is compared by the computer 25 to a required envelope 70 of engine torque admissible by the gas generator 11.

[0118] An example of such a required envelope 70 is shown in [Fig.6]. The engine torque admissible by the gas turbine 11 is shown on the ordinate while its rotational speed is shown on the abscissa. This required envelope 70 is delimited by a maximum torque curve 71 and a minimum torque curve 72 to be respected when driving the gas generator 12 by the electric machine 21. These torque curves 71, 72 decrease with the increase in the rotational speed of the gas generator 11.

[0119] Thus, this comparison step 300 makes it possible to determine whether the maximum engine torque is included in the required envelope 70, namely less than or equal to the torque values ​​of the maximum torque curve 71 and greater than or equal to the torque values ​​of the minimum torque curve 72, or whether it is outside this required envelope 71. In the latter case, the maximum engine torque may be less than the torque values ​​of the minimum torque curve 72 and greater than the torque values ​​of the maximum torque curve 71.

[0120] During an adaptation step 400, the electrical intensity of the electrical current supplied by the electrical generator 20 is adapted in order to respect the required envelope as a function of the comparison 300. This adaptation step 400 is carried out when the maximum engine torque is greater than the torque values ​​of the maximum torque curve 71 of the required envelope 70.

[0121] When the maximum engine torque is within the required envelope 70, no adaptation of the electric current is necessary. The gas generator 12 can be started without risk of damage to the power plant 1 or of starting difficulty.

[0122] When the maximum engine torque is lower than the torque values ​​of the minimum torque curve 72, the electric generator 20 of the power plant 1 cannot provide an electric current with sufficient electrical intensity to allow the gas generator 12 to start. The computer 25 then transmits a signal to an alerter to inform an operator or a driver of the vehicle 8 if necessary.

[0123] When the maximum engine torque is greater than the torque values ​​of the maximum torque curve 71, there is a risk of damage to the mechanical transmission chain between the electrical machine 21 and the gas generator 11, or even to the gas generator 11. The computer 25 can then transmit a signal to an alerter to signal it to an operator or a driver of the vehicle 8 if necessary. The latter can possibly decide to act manually on one of the electrical energy sources 26-29 to cut off its electrical supply for example or to partially discharge it depending on the information provided by the computer 25.

[0124] This adaptation step 400 advantageously makes it possible to reduce the maximum electrical intensity of the electrical current supplied by the electrical generator 20 to the electrical machine 21, when necessary, and consequently to reduce the maximum engine torque that the electrical machine 21 can transmit so that it is included in the required envelope 70. The gas generator 11 can thus be started without risk of degradation of the transmission chain 19 in particular. The computer 25 controls the electrical generator 20 to adapt the electrical intensity of the electrical current supplied by at least one energy source 26-29.

[0125] This adaptation step 400 may include a step 410 of defining a maximum target electrical intensity of the electrical current that the electrical generator 20 must provide. The computer 25 transforms the value of the maximum engine torque in accordance with the required envelope, and for example located on the maximum torque curve into this target maximum electrical intensity, using the second charts or the second laws.

[0126] Furthermore, with a power plant 1 with several electrical sources 26, 27, 28 of the type of [Fig. 1], the adaptation step 400 may comprise an electrical supply step 420 for electrically supplying the electric machine 21 with one or more of the electrical energy sources 26, 27, 28. During this electrical supply step 420, one or more source switches 36, 37, 38 are connected or disconnected so that a sufficient number of the electrical energy sources 26, 27, 28 electrically supply the electric machine 21, and thus obtain a maximum electrical intensity corresponding to a maximum motor torque conforming to the required envelope 70. This maximum electrical intensity is for example equal to the target maximum electrical intensity.

[0127] For this purpose, the electrical supply step 420 may comprise connection 425 and disconnection 426 sub-steps for electrically connecting or disconnecting the source switches 36, 37, 38 using the computer 25, depending on the initial state of each of these source switches 36, 37, 38, namely whether the source switches 36, 37, 38 are electrically open or closed. The computer 25 is connected by a wired or wireless link with each of these source switches 36, 37, 38, on the one hand, to check their state, and on the other hand to control them in order to electrically connect or disconnect them to an electrical energy source 26, 27, 28.

[0128] In the specific example shown in [Fig.l], the sum of the maximum individual electrical intensities of the electrical currents supplied by the first electrical energy source 26 and by the second electrical energy source 27 allows the electrical machine 21 to provide a maximum motor torque within the required envelope.

[0129] Therefore, during the power supply step 420, or even during the connection 425 and disconnection 426 sub-steps, the computer 25 commands the opening of the third source switch 38, the three source switches 36, 37, 38 being initially closed, so that the third electrical energy source 28 does not supply electrical current to the electrical network 24, and, consequently, to the electrical machine 21. The first and second source switches 36, 37 remain closed so that the first and second electrical sources 26, 27 jointly supply their electrical currents to the electrical network 24, and consequently, to the electrical machine 21 in order to comply with the required envelope 70.

[0130] According to another example corresponding to the power plant 1 shown in the [Fig.4] and whose electric generator 20 comprises a single source of electric energy 29, the adaptation step 400 comprises a discharge step 430 to discharge the single source of electric energy 29, until it reaches a required charge level allowing it to provide an electric current with the maximum electric intensity corresponding to a maximum engine torque included in the required envelope 70, and for example equal to the target maximum electric intensity. For this purpose, during the discharge step 420, the computer 25 can control the discharge switches 65 to close them electrically according to the comparison 300.

[0131] In the specific example, shown in [Fig. 4], the computer 25 controls the closing of the first discharge switch 66 and the second discharge switch 67 so that the first electrical consumer 61 and the second electrical consumer 62 are electrically connected to the electrical network 24 and thus consume electrical energy stored in the single electrical energy source 29. Depending on the electrical characteristics of each of the two electrical consumers 61, 62 and the electrical intensities of the electrical currents flowing through them, the computer 25 can determine the time required to reach the required charge level. The computer 25 can transmit this necessary time to a display to display it for the benefit of an operator or a driver of the vehicle 8.

[0132] Once the required charge level has been reached, the discharge step 430 is stopped, the computer 25 controls the opening of the first discharge switch 66 and the second discharge switch 67 so that the first and second electrical consumers 61, 62 are electrically disconnected from the electrical network 24 and thus no longer consume electrical energy.

[0133] Alternatively or in addition to the electrical consumers 60, during the discharge step 430, the single electrical energy source 29 can supply an electrical current to an on-board network or to equipment of the vehicle 8 which are usually used, such as air conditioning, screens, etc. This alternative avoids the use of electrical consumers 60 having no other functions than to lower the charge level of the electrical energy source 29.

[0134] According to another example corresponding to the power plant 1 shown in Figures 2 and 3, and whose electric generator 20 comprises a single source of electrical energy 29 and dissipating elements 40, the adaptation step 400 comprises a connection step 440 for electrically connecting one or more dissipating elements 40 with the electric generator 20. Once connected to the single source of electrical energy 29, a dissipating element 40 makes it possible to dissipate a portion of the electrical energy supplied by the single source of electrical energy 29, for example by releasing heat. The electric current supplied by the single source of energy electric 29 can thus be distributed and circulate on the one hand in one or more dissipating elements 40 and on the other hand in the electric machine 21.

[0135] The computer 25 then controls the dissipation switches 45 as a function of the comparison 300 so that the electrical currents passing through one or more dissipating elements 40 jointly have an electrical intensity greater than or equal to the difference between the maximum electrical intensity determined during the determination step 100 and an electrical intensity corresponding to an engine torque value located at the maximum torque curve 71, and for example equal to the target maximum electrical intensity, and less than the difference between the maximum electrical intensity determined during the determination step 100 and an electrical intensity corresponding to an engine torque value located at the minimum torque curve 72.Consequently, the electric current supplying the electric machine 21 has, for example, a maximum electric intensity equal to the target maximum electric intensity allowing the electric machine to provide a motor torque included in the required envelope 70 if the electric currents passing through the dissipating element(s) 40 connected to the electric energy source 22 jointly have an electric intensity greater than or equal to the difference between the determined maximum electric intensity and an electric intensity corresponding to a motor torque value located at the maximum torque curve 71.

[0136] In the specific example shown in [Fig.2], the computer 25 controls the closing of the first dissipation switch 46 and the third dissipation switch 48, the second dissipation switch 47 remaining electrically open. In this way, an electric current flows through the first and third dissipating elements 41, 43. No electric current flows in the second dissipating element 42.

[0137] In the specific example shown in [Fig. 3], the computer 25 controls the opening of the fifth dissipation switch 49', the fourth dissipation switch 49 remaining closed. In this way, an electric current passes through the fifth dissipating element 44' as well as the first electric line 52. The fourth dissipating element 44 and the second electric line 52' are then not crossed by any electric current.

[0138] Regardless of the manner of adapting the electrical intensity supplied by the electrical generator 20 to the electrical machine 21, during a starting step 500, the gas generator 11 is driven in rotation by the electrical machine 21. For this purpose, the computer 25 can control the starting switch 23 to electrically connect the electrical machine 21 to the electrical generator 20, via the electrical network 24.

[0139] When the adaptation step 400 includes the power supply step 420, the start-up step 500 is carried out once this power supply step 420 has been carried out, namely once the necessary source switch(es) 32 are electrically closed and the other source switch(es) 32 are electrically open.

[0140] When the adaptation step 400 includes the discharge step 430, the start step 500 is carried out once this discharge step 430 has been carried out and completed, namely once the discharge switches 65 have been electrically opened and the required charge level of the electrical energy source has been reached.

[0141] Finally, when the adaptation step 400 includes the connection step 440, the start-up 500 is carried out once this connection step 440 has been carried out, namely once the necessary dissipation switch(es) 45 are electrically closed and the other dissipation switch(es) 45 are electrically open.

[0142] Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention.

Claims

Claims

1. Method for adaptively starting a turbine engine (10) comprising a gas generator (11), an electrical machine (21) mechanically connected to a drive shaft (12) of said gas generator (11) and electrically to an electrical generator (20) provided with at least one source of electrical energy (26-29), said method comprising the following steps: - determination (100) of a maximum electrical intensity of an electrical current deliverable by said electrical generator (20) as a function of at least one characteristic of said at least one source of electrical energy (26-29), - calculation (200) of a maximum engine torque supplied by said electrical machine (21) to said drive shaft (12) when said electrical machine (21) is electrically powered by said electrical generator (20) with said maximum electrical intensity,- comparison (300) of said maximum engine torque with a required envelope (70) of engine torque admissible by said gas generator (11), - adaptation (400) of said maximum electrical intensity as a function of said comparison (300) in order to respect said required envelope (70), and - starting (500) of said gas generator (11) with said electrical machine (21) powered by said electrical generator (20) following said adaptation (500).,

2. Method according to claim 1, wherein said adaptation (400) comprises a definition (410) of a target maximum electrical intensity of said electrical current which must be supplied by said electrical generator (20) so that said electrical machine (21) transmits, when said electrical machine (21) is supplied with said electrical current with said target maximum electrical intensity, a maximum motor torque in accordance with said required envelope (70).

3. A method according to any one of claims 1 to 2, wherein said electrical generator (20) comprises several sources of electrical energy (26,27,28), and said adaptation (400) comprises an electrical supply (420) of said electrical machine (21) with one or more of said electrical energy sources (26,27,28), when said maximum engine torque is greater than a maximum torque curve (71) of said required envelope (70), as a function of said maximum individual electrical intensity of said electrical current supplied by each of said electrical energy sources (26-29), so that said electrical machine (21) supplies a maximum engine torque to said gas generator (11) included in said required envelope (70).

4. A method according to any one of claims 1 to 2, wherein said electric generator (20) comprises a single source of electrical energy (29), and said adaptation (400) comprises a discharge (430) of said single source of electrical energy (29) when said maximum engine torque is greater than a maximum torque curve (71) delimiting said required envelope (70), until reaching a required charge level allowing it to provide an electric current allowing said electric machine (21) to generate a torque included in said required envelope (70), said starting (500) of said gas generator (11) being carried out once said discharge (430) is complete.

5. Method according to any one of claims 1 to 2, wherein said electric generator (20) comprises a single source of electric energy (29), and said adaptation (400) comprises a connection (440) of said electric machine (21) with at least one dissipating element (40) electrically connected to said electric machine (21) when said maximum engine torque is greater than a maximum torque curve (71) of said required envelope (70), said at least one dissipating element (40) being electrically powered by said electric generator (20).

6. Method according to claim 5, wherein, during said connection (430), a computer (25) of a power plant (1) comprising said turbine engine (10), said electrical machine (21) and said electrical generator (20) controls at least one dissipation switch (45) electrically arranged in series between said electrical generator (20) and said at least one dissipating element (40) electrically arranged in parallel with said electrical machine (21).

7. A method according to claim 5, wherein, upon said connection (430), a computer (25) of a power plant (1) comprising said turbine engine (10), said electrical machine (21) and said electrical generator (20) controls at least one dissipation switch (45) electrically arranged in parallel with said at least one dissipating element (40), said at least one dissipating element (40) being electrically arranged in series with said electrical machine (21), said at least one dissipation switch (45) being positioned on an electrical line (52, 52') short-circuiting said at least one dissipating element (40).

8. A method according to any one of claims 5 to 7, wherein said at least one dissipating element (40) comprises one or more electrical resistors (50).

9. Method according to any one of claims 1 to 8, wherein said at least one characteristic of said at least one source of electrical energy (26-29) is chosen from its state of charge, its temperature, its aging.

10. A method according to any one of claims 1 to 9, wherein said at least one electrical energy source (26-29) comprises at least one electric battery.

11. Power plant (1) provided with at least one turbine engine (10) comprising a gas generator (11) and an adaptive starting circuit (20) comprising a computer (25), the power plant (1) comprising an electrical machine (21) mechanically connected to a drive shaft (12) of said gas generator (11) and electrically to an electrical generator (20) provided with at least one source of electrical energy (26-29), characterized in that said power plant (1) is configured to implement the method according to any one of claims 1 to 10

12. d IV. Power plant (1) according to claim 11, wherein said electric generator (20) comprises several sources of electric energy (26,27,28) arranged in parallel with each other and said power plant (1) comprises source switches (32) electrically connecting respectively each of said sources of electric energy (26,27,28) to said electric machine (21), said source switches (32) being controlled by said computer (25).

13. Power plant according to any one of claims 11 to 12, wherein said electric generator (20) comprises at least one dissipating element (40) electrically arranged in parallel with said electrical machine (21), and at least one dissipation switch (45) electrically connecting said at least one dissipating element (40) to the electrical generator (20), said at least one dissipation switch (45) being controlled by said computer (25).

14. Power plant according to any one of claims 11 to 12, wherein said electrical generator (20) comprises at least one dissipating element (40) electrically arranged in series with said electrical machine (21), and at least one dissipation switch (45) electrically arranged in parallel with said at least one dissipating element (40) and positioned on an electrical line (52, 52') short-circuiting said at least one dissipating element (40), said at least one dissipation switch (45) being controlled by said computer (25).

15. Power plant according to any one of claims 13 and 14, wherein said at least one dissipating element (40) comprises one or more electrical resistors (50).

16. Power plant according to any one of claims 11 to 15, wherein said at least one source of electrical energy (26-29) comprises at least one electric battery.

17. Vehicle (8) provided with a power plant (1), wherein said power plant (1) is according to any one of claims 11 to 15.

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