ELECTRICAL GENERATION ARCHITECTURE FOR HYBRID TURBOMACHINE

Abstract

Hybrid electric-series aircraft propulsion system, comprising: - an electric turbogenerator (110) comprising at least one turbomachine (112) and at least one generator (114) coupled to the turbomachine, - a storage battery (125), - an HVDC bus (130) coupled to the turbogenerator and the battery (125), the turbogenerator (110) being connected to the HVDC bus (130) via an alternating current (AC) to direct current (DC) rectifier (116) connected to phases of said at least one generator (114), said battery (125) being connected directly to the high-voltage direct current (HVDC) electrical network, the turbogenerator (110) and the battery (125) sharing the power required to supply said HVDC bus (130),- a control system (115) for the rectifier (116) configured to control the rectifier (116) and manage the sharing of electrical power supplied on the HVDC bus (130) between the turbogenerator (110) and the battery (125) based on the setpoint control of at least the current (IBAT) delivered by the battery (125), by modulating the output voltage (UBUS) of the rectifier (116) via at least one control signal (CMD), in particular pulse-width modulation. Figure for the abbreviation:,

Description

Title of the invention: ELECTRICAL GENERATION ARCHITECTURE FOR HYBRID TURBOMACHINE

[0001] TECHNICAL FIELD AND PRIOR TECHNOLOGY

[0002] The present application relates to the field of electric propulsion of aircraft and to certain architectures of the type known as "series hybrid electric propulsion" suitable for both fixed-wing and rotary-wing or convertible aircraft.

[0003] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new types of aircraft and those currently in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively contributing to the fight against climate change for several years now. Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. These efforts focus particularly on hybrid architectures.The Applicant takes into consideration the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental impacts, with the aim of improving the energy efficiency of aircraft.

[0004] In a series hybrid architecture, the internal combustion engine is not directly linked to propulsion. Instead, the internal combustion engine is used to produce electricity, which then powers an electric motor. This electric motor is responsible for propelling the aircraft and drives propellers, rotors, or propulsion / lift fans.

[0005] Document EP 2844556 gives an example of a series hybrid electric propulsion architecture for aircraft.

[0006] There are purely turboelectric architectures using several turbogenerators as sources of electrical power. As with conventional turbine propulsion systems, the oversizing of the turbomachine for certain specific operating regimes, the high cost, mass, and complexity of the redundancies required to meet flight safety requirements preclude the development of an optimal propulsion architecture.

[0007] A particular series hybrid architecture combines a turbogenerator with a different electrical power source, typically an electrochemical source such as a fuel cell or a battery.

[0008] Figure 1 shows an example of such an architecture. A high-voltage direct current (HVDC) electrical network 30 is supplied by two parallel voltage sources 10, 20 for several identical propulsion units 40, each consisting of an inverter 41 capable of supplying a three-phase electric machine 43 designed to drive a propeller 45, possibly via a reduction gearbox. Each propulsion unit is generally equipped with one or more contactor or circuit breaker-type switching elements 42 to manage reconfigurations and / or the isolation of a faulty propulsion unit. The voltage inverter 41 of each unit is thus supplied via a network 30 at a nominal voltage generally on the order of several hundred to several thousand volts and typically in the form of an HVDC bus (High Voltage Direct Current, i.e."high voltage direct current") itself powered by sources 10, 20 connected in parallel.

[0009] A first source of electrical energy is a turbogenerator 10 formed of a gas turbine driving an electric generator 14. A rectifier 16 makes it possible to convert an alternating AC voltage delivered by the generator 14 into a direct DC voltage for the network 30.

[0010] A second electrical energy source 20 is here formed of at least one accumulator battery 25. In the particular embodiment example of [Fig.1], the battery 25 is connected to the network via a reversible DC / DC converter 27 of the chopper type provided between the battery 25 and the HVDC bus 30 which allows the charging and discharging of the battery to be managed.

[0011] This architecture offers the advantage of decoupling the HVDC bus voltage 30 from that of the battery 25, allowing the rectifier 16 to operate at a constant voltage. However, adding such a power converter 27 increases the weight and size, particularly due to the inductive elements it incorporates, while also reducing overall reliability. US patent 20160176534 describes such an architecture.

[0012] A lower cost and less bulky power source can be provided by directly connecting the battery 25 to the HVDC bus 30.

[0013] The applicant's French patent application FR 3 056 555 provides an example of an embodiment without an intermediate energy conversion stage between the battery and the HVDC bus. A drawback of this is that the battery tends to impose its voltage on the HVDC bus, a voltage that depends heavily on the battery's state of charge and the current it delivers. This voltage is likely to fluctuate significantly. While such an architecture eliminates the need for the DC / DC converter 27, it typically requires that the rectifier control 16 must adapt at every moment to the battery voltage and manage its charging and discharging. Description of the invention

[0014] According to one aspect, the present invention proposes a device for a hybrid electric-series aircraft propulsion system, comprising:

[0015] - an electric turbogenerator comprising at least one turbomachine and at least a generator coupled to said turbomachine,

[0016] - a battery of accumulators,

[0017] - an HVDC bus coupled to said turbogenerator and to said battery, the turbogenerator being connected to the HVDC bus via an AC to DC rectifier connected to phases of the generator, the battery being connected directly to the HVDC high voltage direct current electrical network, the device further comprising a rectifier control system configured to drive the rectifier and achieve a sharing of electrical power supplied on the HVDC bus between the turbogenerator and the battery from the setpoint control of at least the current IBat delivered by the battery, by modulating the output voltage UBus of the rectifier via at least one control signal.

[0018] This control signal is typically a pulse width modulation (PWM) signal.

[0019] According to an advantageous embodiment, the rectifier control system comprises:

[0020] - a plurality of correction stages, each correction stage being equipped with a a controller and being configured to receive a measurement of a regulation parameter of the rectifier output voltage from among a set of parameters such as a rectifier output current Idc, an HVDC bus voltage UBUs, a turbomachine rotational speed N2, a battery output current IBAT, a turbomachine mechanical torque TRQ, and to establish, from a comparison between this measurement of said regulation parameter and a reference or a limit not to be exceeded: an elementary setpoint, the respective elementary setpoints at the output of said correction stages being all homogeneous to a current or all homogeneous to a voltage,

[0021] - an elementary setpoint selection logic module configured to receive said elementary instructions and to select, based on comparisons between the respective values ​​of said elementary instructions and a predetermined priority order associated with each of said correction levels, an elementary output instruction from among said elementary instructions, said elementary output instruction selected serving as the so-called "general" setpoint from which the rectifier control signal is established.

[0022] Advantageously, the general control setpoint corresponds to a vector component IQ of phase currents along a first axis of a rotating frame linked to a rotor of the generator.

[0023] The correction stages may include at least one or more correction stages or all of the correction stages among:

[0024] - a first correction stage for controlling a battery current to a setpoint reference value developed by the avionics configured to receive an IBAT battery current measurement and to determine a basic reference battery current setpoint based on the difference between a reference battery current setpoint and the IBAT battery current measurement,

[0025] - a second correction stage to maintain a battery current above of a minimum stop, configured to receive a battery current measurement IBAT and to determine an elementary lower battery current limiting setpoint based on the difference between a typically negative minimum battery current stop setpoint IBAT_MiN, equal to the maximum permissible charging current for the battery, and the battery current measurement IBAT,

[0026] - a third correction stage to maintain a battery current below of a maximum stop, configured to receive a battery current measurement IBAt and to determine an elementary upper battery current limiting setpoint based on the difference between a maximum battery current stop setpoint IBAt_max typically equal to the maximum permissible discharge current for the battery and the battery current measurement IBAT,

[0027] - a fourth correction stage to maintain a turbomachine speed above a minimum stop, configured to receive a turbomachine speed measurement N2 and to determine an elementary lower speed limitation setpoint for the turbomachine based on the difference between a minimum turbomachine speed stop value N2m1n typically equal to the minimum allowable speed of the turbomachine power turbine and the turbomachine speed measurement,

[0028] - a fifth correction stage to maintain a turbomachine speed below a maximum stop, configured to receive a turbomachine speed measurement and to determine an elementary upper speed limitation setpoint for the turbomachine based on the difference between a maximum turbomachine speed stop setpoint N2MAx typically equal to the overspeed maximum permissible power of the turbomachine turbine and generator rotor, and the turbomachine speed measurement N2,

[0029] - a sixth correction stage to maintain a mechanical torque of the turbomachine above a minimum stop, configured to receive a mechanical torque measurement from the turbomachine TRQ and to determine an elementary lower mechanical torque limiting setpoint of the turbomachine based on the difference between a typically negative minimum mechanical torque stop setpoint of the turbomachine TRQM1N, equal to the maximum permissible torque of the transmission in engine mode, and the current mechanical torque measurement of the turbomachine TRQ,

[0030] - a seventh correction stage to maintain a mechanical torque of the turbomachine below a maximum stop, configured to receive a mechanical torque measurement from the turbomachine TRQ and to determine an elementary upper mechanical torque limiting setpoint of the turbomachine based on the difference between a maximum mechanical torque stop setpoint of the turbomachine TRQmax typically equal to the maximum allowable torque of the transmission in generator mode and the current mechanical torque measurement of the turbomachine TRQ,

[0031] - an eighth correction stage to maintain the HVDC bus voltage above of a minimum stop, configured to receive a UBus bus voltage measurement and to determine an elementary lower bus voltage limiting setpoint based on the difference between a minimum bus voltage stop setpoint Ubus_min typically equal to the minimum allowable operating voltage of the various power converters connected to the HVDC bus and the UBus bus voltage measurement,

[0032] - a ninth correction stage to maintain the HVDC bus voltage in below a maximum stop and configured to receive a bus voltage measurement Ubus and to determine an elementary upper bus voltage limiting setpoint based on the difference between the Ubus bus voltage measurement and a maximum bus voltage stop setpoint Ubus_max typically equal to the maximum allowable operating voltage of the various power converters connected to the HVDC bus,

[0033] - a tenth correction stage to maintain output electrical power of the rectifier below a maximum stop and configured to receive a UBus bus voltage measurement and an IDC bus current measurement and to evaluate an electrical power measured at the rectifier output and to determine an elementary upper power limiting setpoint based on the difference between the measured electrical power and a maximum power stop setpoint Ptgenmax typically equal to the maximum rated electrical power of the turbogenerator.

[0034] According to one possible implementation, the first correction stage can be associated with a first priority level called "LOW".

[0035] The fourth and fifth correction stages and / or sixth and seventh correction stages can be associated with a second priority level called "INTERMEDIATE" which is higher than the first priority level.

[0036] The tenth correction stage can be associated with a third priority level called "HIGH" which is higher than the second priority level.

[0037] The second and third correction stages and / or eighth and ninth correction stages can be associated with a fourth priority level called "PRIORITY" which is higher than the third priority level.

[0038] Advantageously, the elementary setpoint selection logic module comprises a plurality of selection blocks, each selection block being formed:

[0039] - of a minimum value selection unit among its inputs arranged in series with a unit for selecting the maximum value from among its inputs,

[0040] or

[0041] - of a minimum value selection unit among its inputs,

[0042] each of the selection blocks being configured to receive, among the elementary instructions, a given elementary instruction or a given pair of elementary instructions emanating from given correction stages among the correction stages receiving the same measurement of the same measurement parameter, the given elementary instruction or the given pair of elementary instructions being different from that received by said other selection blocks, the selection blocks being arranged in a succession of cascaded blocks in an order depending on the order of priority to which the given correction stage(s) is or are associated,

[0043] -a first block in the succession of cascading blocks receiving as input an elementary instruction called the reference instruction from among said elementary instructions,

[0044] - a final block in the cascade of blocks producing an output instructed to follow the aforementioned basic exit instruction,

[0045] each of said other blocks receiving as input an elementary instruction selected by a previous selection block of the plurality of selection blocks arranged in cascade, and produces, as output an elementary instruction selected from its inputs and destined for a following block of said plurality of selection blocks.

[0046] Advantageously, the generator is a three-phase synchronous rotating permanent magnet (PMM) machine.

[0047] According to an advantageous embodiment, the turbomachine has a free turbine.

[0048] According to another aspect, the present invention relates to a series hybrid propulsion aircraft comprising a device for a series hybrid electric propulsion assembly as defined above.

[0049] According to another aspect, the present invention provides a method for controlling the turbogenerator of a device as defined above and in which the HVDC bus is coupled to at least one set of propulsion loads.

[0050] According to a particular embodiment, the process comprises the following steps:

[0051] - during a first phase following the detection of an increase in demand for electrical power from said propulsion load assembly and as long as an electrical power PTgen at the output of said rectifier remains below a threshold, control the rectifier so as to maintain its output voltage UBus at a value such that the battery produces zero output current while increasing the current delivered by the rectifier so that the turbogenerator alone provides electrical power to the HVDC bus in response to said increase,

[0052] then, following the detection of an electrical power threshold Ptgen_max being reached at the rectifier output and a further increase in electrical power demand beyond said threshold from said propulsion load set, during a second phase, control the rectifier to lower its output voltage UBus so that the battery discharges while maintaining the power delivered by the rectifier at a constant value so that the turbogenerator and the battery jointly provide electrical power to the HVDC bus in response to said new increase.

[0053] According to another particular aspect, the method may comprise the following steps:

[0054] - following the detection of an increase, in particular an Rapid increase in electrical power demand from said load set and subsequent decrease in the free turbine speed N2 of the turbomachine below its setpoint value, control the rectifier so as to temporarily lower its output voltage UBUS in order to cause a discharge of the battery and thus limit the transient speed drop,

[0055] then,

[0056] - following the detection of a stabilization of power demand electrical current from said load set, drives the rectifier to increase its UBUS output voltage so as to charge the battery, then restores a constant UBUS output voltage so as to maintain zero current at the battery output.

[0057] and / or

[0058] comprising the following steps:

[0059] - following the detection of a decrease, in particular a decrease rapid, due to a demand for electrical power from said set of loads and the consequent increase in speed N2 of the free turbine of the turbomachine above its setpoint value, control the rectifier to temporarily reduce its output voltage UBus in order to recharge the battery and thus limit the transient overspeed,

[0060] then,

[0061] - following the detection of a stabilization of power demand electrical from said set of loads, drive the rectifier to increase its output voltage UBus so as to charge the battery and then restore a constant output voltage UBus so as to maintain a zero current at the output of the battery. Brief description of the drawings

[0062] The present invention will be better understood and other details, features and advantages of the present invention will become more apparent upon reading the description of a non-limiting example that follows, with reference to the accompanying drawings in which:

[0063] [Fig.l] serves to illustrate a conventional "series hybrid electric propulsion" architecture with connection of a battery to an HVDC bus via a reversible DC / DC converter.

[0064] [Fig.2] serves to illustrate an example of an "electric hybrid propulsion" architecture series » as implemented according to an embodiment of the present invention and equipped with a turbogenerator and a battery with a direct connection of the battery to an HVDC bus, a power sharing between the turbogenerator and the battery being controlled by means of a control system of an active rectifier of the turbogenerator.

[0065] [Fig.3] serves to illustrate a particular embodiment of a system of active rectifier control associated with the turbogenerator and designed to develop a rectifier control from a vector component setpoint of the generator phase current selected from several elementary setpoints;

[0066] [Fig.4] serves to illustrate an example of an implementation of a logic selection module of elementary setpoint integrated into an active rectifier control system and producing the vector component setpoint in quadrature of the generator phase current.

[0067] [Fig. 5A] [Fig. 5B] serve to illustrate, by means of power evolution curves over time and turbine speed evolution curves, a particular operating mode of a propulsion system as implemented according to the invention, in which the power delivered by the battery compensates for a transiently excess or deficit power supply from the turbogenerator following a rapid change in power demand by propulsive loads exceeding the acceleration and deceleration performance of the turbomachine.

[0068] [Fig.6] serves to illustrate by means of power evolution curves over time a particular operating mode of a propulsion unit as implemented according to the invention in which the electrical power delivered by the battery compensates for that of the turbogenerator when a maximum electrical power limit generated by the latter has been reached.

[0069] Identical, similar or equivalent parts of the different figures bear the same numerical references so as to facilitate the transition from one figure to another.

[0070] The different parts represented in the figures are not necessarily shown on a uniform scale, in order to make the figures more legible.

[0071] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0072] Reference is now made to [Fig.2] which gives a series hybrid propulsion assembly for aircraft and as implemented according to an example of an embodiment of the present invention.

[0073] This assembly comprises at least one turbogenerator 110 and at least one battery 125 of accumulators connected to the same high-voltage electrical network, here in the form of an HVDC bus 130, which allows for the supply of at least one set of propulsion electrical loads 140 from at least one propulsion chain typically comprising propulsion and / or lift motors and auxiliary converters. The set of loads 140 can be formed from a plurality of propulsion groups such as those referenced 40 and described previously in connection with [Fig. 1].

[0074] Different types of electrical power generation devices are combined here, and the electrical power is shared between the battery 125 on the one hand, and the turbogenerator 110 on the other, while maintaining certain operating parameters, such as the turbogenerator output current, the battery output current, the bus voltage, the turbogenerator output electrical power, and the turbine rotational speed, within optimal operating ranges. To achieve this, optimized control of at least one rectifier 116 is provided, integrated into the turbogenerator 110 or arranged at its output and referred to as "active" insofar as this rectifier 116 is made of forced-commutating semiconductors and designed to be controlled by a control system 115.Since the battery 125 is passive, it is the rectifier 116 of the turbogenerator 110 associated with its control system 115 that manages the sharing of power with the battery 125 to supply the HVDC bus 130.

[0075] Such an arrangement can, for example, allow the turbogenerator 110 to be sized only for the power required for a cruise flight, a The additional power required for takeoff and altitude gain is then supplied by the 125 battery. Such an architecture can also, for example, improve the transient acceleration and deceleration performance of the 110 turbogenerator, particularly when it is equipped with a free-turbine turbomachine, which has low inertia and is designed to optimize specific fuel consumption at the expense of transient performance. This arrangement also allows the 125 battery to be used as redundancy for the 110 turbogenerator and to replace it in the event of a failure.

[0076] Such an architecture is also suitable for implementing flight phases where the payloads 140, in particular their propulsion and / or lift components, are powered solely by the battery 125 in order to be able to temporarily benefit from certain advantages such as reduced noise, a less significant thermal signature.

[0077] The 125 accumulator battery is here connected directly to the HVDC 130 bus. By "connected directly" we mean that there is no intermediate power converter between the battery and the HVDC 130 bus. Thus, an output voltage of the 125 accumulator battery corresponds to a voltage on the HVDC 130 bus.

[0078] The battery 125 can be modeled in a simplified manner, as shown in [Fig. 1], by its open-circuit voltage Eo, which depends in particular on its state of charge (SOC), and by its internal resistance RBat, which depends in particular on the temperature. Other types of electrical battery models, notably the Randles type where the internal impedance is represented by RC cells, can also be used. The direct connection of the battery to the HVDC bus 130 without an intermediate energy conversion stage allows for a direct and instantaneous replacement of electrical energy in the event of a failure of the turbogenerator 110, which significantly reduces the availability requirements applicable to the latter, thus simplifying it and reducing its cost.Furthermore, the damping provided by the internal resistance of the battery 125 connected directly to the HVDC bus 130 makes it possible to significantly improve the stability of the UBus voltage regulation of the HVDC bus 130 via the active rectifier 116 of the turbogenerator 110.

[0079] The battery 125 is associated with or equipped with an electronic BMS 126 that protects it and ensures its proper functioning by monitoring the state of its electrochemical cells. Such a device 126 can provide indicative status data such as the SOC, the SOH (State of Health), and a charging current setpoint Icharge based on various parameters such as, for example, the internal temperature of the battery or its SOC.

[0080] The turbogenerator 110 connected to the same HVDC bus 130 is formed of a turbomachine 112, in particular a gas turbine which can be of the "linked turbine" type (i.e. with a compressor, one or more expansion turbines and a driven load attached to the same shaft and rotating at the same speed modulo a possible reduction or multiplication ratio) or advantageously of the "free turbine" type, this second type generally having a specific consumption at partial load significantly lower than the first type with a linked turbine.

[0081] The turbomachine 112 is controlled by a turbomachine control module 113. This module 113 includes a digital turbomachine control computer or EECU (for "Engine Electronic Control Unit"), which is configured, in particular, to regulate the rotational speed of the load driven by the turbomachine—in this case, the electric generator(s)—to its optimal setpoint. To do this, the computer acquires a speed measurement N2 of the power shaft of the turbomachine 112.

[0082] The turbomachine 112 is designed to drive the mechanical shaft of at least one electric generator 114 having n output phases, with n, for example, equal to 3, and which supplies an AC distribution busbar at the input of the active electrical rectifier 116. The generator 114 is a permanent magnet synchronous generator (PMG). This type of generator has the advantage of a significantly reduced mass compared to a three-stage wound-rotor synchronous generator. It is also suitable for high mechanical drive speeds, for example, between 10,000 and 30,000 rpm, for power outputs on the order of several hundred kW. Direct drive of the generator 114 by a free turbine is possible.

[0083] In the case where the turbogenerator 110 has several generators, these can be driven by the same turbomachine 112 for example by means of a gearbox.

[0084] The rectifier 116 enables power conversion between an AC distribution busbar at the output of the generator 114 and the HVDC bus 130. The rectifier 116 is an active rectifier controlled by the control system 115, which advantageously implements several feedback loops and consists of one or more logic modules. The rectifier 116 typically uses vector control and PWM (Pulse Width Modulation) to rectify the alternating voltages from the generator and supply electrical energy to an HVDC bus in the form of a continuous and controlled UBus voltage.

[0085] From the electromotive forces emf of the generator 114 and according to the control CMD of the control system 115, the rectifier 116 thus delivers the direct voltage UBus whose value is controlled by the control system 115.

[0086] The IBat current delivered by the battery 125 to the HVDC network 130 can be defined by the following expression:

[0087] j _ eq-ubus BAT Rbat

[0088] in generator convention with a current IBAT > 0 when the battery 125 supplies energy to the bus and the loads, with Eo the open-circuit voltage of the battery 125 and RBAT the internal resistance of the battery 125 for a given state of the latter, in other words typically a given state of SOC and / or SOH and / or temperature.

[0089] Thus, in order to allow the battery 125 to be recharged (IBAT < 0), the control system 115 drives the rectifier 116 so that it imposes a voltage UBUS greater than the open-circuit voltage Eo of the battery 125.

[0090] When the battery 125 is required to supply electrical power to the HVDC bus (IBAT > 0), the control system 115 drives the rectifier 116 so that it imposes a UBUS voltage lower than the open-circuit voltage Eo of the battery 125.

[0091] When no contribution from the battery 125 is desired to the electrical power delivered to the HVDC bus 130 and the battery 125 is to be maintained in the same state of charge (current IBAT = 0), the control system 115 drives the rectifier 116 so that it imposes a constant voltage UBUS, equal to the open-circuit voltage Eo of the battery, so as to maintain a zero current at the output of the battery 125.

[0092] Control of the DC voltage UBUs delivered by the rectifier 116 on the HVDC bus 130 thus makes it possible to control the charging or discharging current of the battery 125, and therefore to modulate the respective power contributions of the two generating elements 125, 110 to the propulsion of the aircraft.

[0093] Such control preferably involves closed-loop control of the battery current IBAT, since the open-circuit voltage Eo and internal resistance RBAT values ​​of the battery are difficult to access.

[0094] The control system 115 is typically configured to perform several of the following control functions, and advantageously all of the following functions:

[0095] - contribute to maintaining the rotational speed N2 of the turbomachine 112 in a allowed range between a lower stop N2_m1n and an upper stop N2_MAX;

[0096] - limit the electrical power PTgen delivered by the turbogenerator 110 at the output of the rectifier 116 to a value less than a threshold or maximum stop PTgen_max;

[0097] - limit the mechanical torque supplied by the TRQ turbomachine within a range between a minimum stop TRQM1N and a maximum stop TRQMAX;

[0098] - maintain a UBus bus voltage of the HVDC 130 bus within a limit lower UBus_min and an upper stop UBUs_max;

[0099] - maintain a battery current IBAT between a lower limit IBAt_min typically corresponding to a maximum current value during charging and which is strictly negative, and IBAT MAX corresponding to a maximum current value during discharging and which is strictly positive;

[0100] - ensure battery charging according to a current setting Ibat_ref typically generated by the BMS 126 electronic device.

[0101] To allow regulation of the aforementioned parameters, various means of measurement are provided.

[0102] Current measurement means 133, typically comprising a current sensor at the output of the rectifier 116, allow a measurement of the IDC current delivered on the HVDC bus 130 at the output of the rectifier 116 to be transmitted to the control system 115 of the rectifier 116.

[0103] Voltage measurement means 131, typically including a voltage sensor, are provided to transmit a measurement of the voltage UBUs of the HVDC bus 130 to the control system 115 of the rectifier 116. Current measurement means 129, typically including a current sensor, at the output of the battery 125, allow a measurement of the battery current IBAT to be transmitted to the control system 115 of the rectifier 116. Such means 129 may optionally be equipped with a current sensor at the battery 125 itself or at the output of the battery 125 on a portion of the circuit connected to the HVDC distribution network.

[0104] Current measurement means 119 for measuring the current in each phase of the generator 119 are also provided.

[0105] A rotational speed N2 of the turbine can be obtained by means of a speed sensor mounted on or near a power shaft of the turbomachine 112 while a torque measurement TRQ can be obtained by means of a torque meter installed on the output shaft of the turbomachine and a torque estimator integrated into the turbomachine control module 113.

[0106] A detailed example of an embodiment of a control system 115 of the active rectifier 116 enabling the aforementioned regulations to be carried out and the turbogenerator 110 and the battery 125 to be maintained within the various aforementioned operating limits is given in [Fig.3].

[0107] The control system 115 is equipped with a plurality of correction stages, in this particular embodiment ten stages, 80i, 802, 803, 804, 805, 806, 807, 808, 809, 8010, each configured to receive a measurement of a parameter and to, from a comparison between this measurement and a setpoint corresponding to a reference or to a stop, in other words a threshold not to be exceeded, establish an elementary instruction, here in particular homogeneous to a current, after passing through a corrector.

[0108] In this example, the elementary instructions IQREF_iBATREE, IqrEf_ibatmin, Iqrefjbatmax -, Iqref_n2min, Iqref_n2max, Iqref_trqmin, Iqref_trqmax, Iqref_ubusmin, Iqref_usbusmax, Iqref_ptgenmax produced at the output of the different stages, 80i, 802, 803, 804, 805, 806, 807, 808, 809, 80i0 are then transmitted to a logic module 85 for elementary setpoint selection, an example of which is given in [Fig.4].

[0109] This module 85 is configured to select a setpoint from among the aforementioned elementary setpoints, with Iqref ^(Iqrefjbatref or Iqrefjbatmin or IqrEf_ibatmax or IqREF_N2MIN OR IqREF_N2MAX °U IqreF_TRQMIN OR Iqref_trqmax, IqREF_UBUSMIN OR IqreF_USBUSMAX or Iqref_ptgenmax), and to output an output setpoint IQREF corresponding to the selected elementary setpoint. This selection is made based on the respective values ​​of the different elementary setpoints and a predetermined hierarchy that depends on the degree of importance, in other words, the priority, associated with the different control functions implemented by means of these different elementary setpoints. In this example embodiment, the selected elementary setpoint is a homogeneous setpoint for a current.The selected setpoint IQREF, produced at the output of module 85, then serves as the so-called "general" setpoint transmitted to a control module 99, which generates CMD control signals for the switching elements of the rectifier 116, typically in the form of PWM type signals.

[0110] Here in particular, the generator-rectifier assembly is controlled by means of a current output setpoint IQREF which corresponds to or is homogeneous with a quadrature component IQ of current IA, IB and Ic in the phases of the generator 114, resulting from a Park / Concordia transform (IA, IB and Ic) # (ID, Iq) in a rotating frame associated with the rotor of the generator 114, taking as convention IQ > 0 in generator operation.

[0111] The control module 99, which receives this IQRE F setpoint, can be specifically designed to determine an error from the difference between this vector component IQREF setpoint and a measured value established from phase current measurements IA, IB, Ic from generator 114, transformed into direct quantities ID and into quadrature IQ by Park transform, and to use controllers, for example of the proportional-integral type, to determine voltage setpoints from the error. The control module 99 is designed to determine the CMD switching commands of the rectifier switches from these voltage setpoints and, for example, after using an inverse Park transform. An example of vector control algorithms for a synchronous electric machine for The method for controlling a torque setpoint using Park's transformation is given in document EP2510612. Voltage measurements of bus UBus and N2 at the input of block 99 on [Fig.3] serve as control parameters for the inverter-electric motor assembly, with its 3 phase currents IA, IB and Ic.

[0112] In the embodiment illustrated in [Fig.3], each correction stage 80i, ..., 80io is here equipped with a comparator 82b 822, 823, 824, 825, 826, 827, 828, 829, 82i0 to establish a difference between a measured parameter and a reference or stop and a regulator or corrector 82b 822, 823, 824, 825, 826, 827, 828, 829, 8210 for example of the Proportional-Integral-Derivative (PID) type at the output of the comparator.

[0113] The elementary setpoint at the output of the correction stage 80i is the reference setpoint. Each elementary setpoint at the output of the different correction stages 802, 803, 804, 805, 806, 807, 808, 809, 80i0 represents a current value IQ which limits the reference setpoint so as not to exceed a corresponding lower or upper limit.

[0114] A first correction stage 80i is configured to receive a current setpoint IBAt _ Rude current.

[0115] The first correction stage 80i creates a closed loop for controlling the battery current IBAT to a setpoint IBAT REF, which corresponds to a battery charging current reference 125.

[0116] The first correction stage 80i is designed to maintain a battery charging current close to a reference. This stage 80i is configured to receive a battery current measurement IBAT, to determine, via comparator 82i, a difference between a reference setpoint Ibat_ref of battery current and the measured battery current IBAT, and to determine, at the output of a regulator 84i, an elementary reference setpoint of battery current Iqref_batref based on this difference. By convention, the charging current and the reference value IBAT_ref are negative. The reference setpoint IBAT_ref is derived here from the electronic BMS 126.

[0117] When the turbogenerator 110 is operating within a so-called "stabilized" operating range, far from the limits or operating stops that will be detailed later, and when the battery 125 has been used, for example, during a previous flight phase, the turbogenerator 110 can recharge the battery 125 by controlling, through appropriate control of the rectifier 116, the battery current to a setpoint IBAt_ref derived from and generated by the BMS device 126. This function is typically associated with a "LOW" priority level, and in particular the lowest among the priority levels to which the various correction stages and the different elementary setpoints at the output of these stages correspond.

[0118] A second correction stage 802 is provided to maintain the battery current above a minimum limit. This stage 802 is configured to receive a battery current measurement IBAT, to determine, via comparator 822, a difference between a minimum limit setpoint IBat_min for battery current and the measured battery current IBat, and to determine, at the output of a regulator 842, an elementary lower limit setpoint for battery current Iqref_Batmin based on this difference. Since the minimum limit value corresponds to a charging current value, this value is negative. The minimum limit IBat_min acts as a safety stop to prevent the battery from being recharged too abruptly, for example, during the capping of an overspeed following a rapid decrease in power demand.

[0119] A third correction stage 803 is configured to maintain the battery current below a maximum limit. This stage 803 is configured to receive a battery current measurement IBAT, to determine, via comparator 823, a difference between a maximum battery current limit setpoint IBAt_max and the measured battery current IBAt, and to determine, at the output of a regulator 842, an elementary upper battery current limit setpoint IqREf_Batmax based on this difference. The maximum battery current limit IBat_max corresponds to a safety limit that prevents excessively abrupt discharge of the battery, for example, during the clipping of a low-speed system following a rapid increase in power demand.

[0120] The correction stages 802>803 allow the current IBAT to be controlled and maintained within a range delimited by a lower limit IBAT_min of battery current and an upper limit IBAT_MAx of battery current. The respective outputs of the correction stages 802j 803 are, in this example, elementary quadrature current setpoints Iqref_Batmin and Iqref_Batmax-

[0121] To avoid damaging the 125 battery, the battery current IBAT is maintained between the values ​​IBAt_max during discharge and IIBAt_minI during charging. These limits are specific characteristics of the 125 battery.

[0122] A prolonged exceedance of these thresholds is likely to cause the battery 125 to be isolated from the HVDC bus 130 by the BMS device 126. This current regulation function IBAt is typically associated with a priority level referred to as "PRIORITY" and, in particular, with a priority level among the higher levels associated with the different regulation functions provided by the control system 115 of the rectifier 116.

[0123] A fourth correction stage 804 is provided to maintain a turbomachine speed N2 above a minimum stop N2m1n. This stage 804 is configured to receive a speed measurement of the turbomachine N2 and to determine via the comparator 824 a difference between a minimum speed stop setpoint of the turbomachine N2m1n and the speed measurement of the turbomachine N2, and to establish via the compensator 844 an elementary lower speed limitation setpoint of the turbomachine IqREf_n2min as a function of the difference received at the input of this controller 844. The stop N2m1n corresponds to an operating characteristic of the turbomachine to prevent a transient underspeed of the power shaft below a certain threshold, in particular during an excessively rapid load increase, from damaging it and / or requiring maintenance action.

[0124] A fifth correction stage 805 is provided to maintain the turbomachine speed N2 below a maximum limit. This stage 805 is configured to receive a turbomachine speed measurement N2 and to determine, via comparator 825, a difference between a maximum turbomachine speed limit setpoint N2M ax and the turbomachine speed measurement N2. It then establishes, via controller / corrector 845, an elementary upper speed limit setpoint IqREf_n2m ax based on the difference received at the input of this controller 845. The maximum turbomachine speed limit N2MAX corresponds to an operating characteristic of the turbomachine to prevent a transient overspeed of the power shaft above a certain threshold from damaging it and / or requiring maintenance.

[0125] The correction stages 804 and 805 implement closed control loops to protect the turbomachine against excursions below a lower speed stop N2m1n and above an upper speed stop N2MAX, particularly during rapid variations in power demand.

[0126] This N2 speed regulation function is associated with a priority level called "INTERMEDIATE", higher than the priority level "LOW".

[0127] The respective outputs of the correction stages 804 and 805 are in this example quadrature current setpoints IQREf_n2min and IQREf_n2max-

[0128] A sixth correction stage 806 is provided to maintain the turbomachine's mechanical torque above a minimum limit. This stage 806 receives a measurement of the turbomachine's mechanical torque TRQ and determines an elementary lower limit setpoint for the turbomachine's mechanical torque Iqref_trqmin based on the difference between a minimum limit setpoint for the turbomachine's mechanical torque TRQM1N and the current measurement of the turbomachine's mechanical torque TRQ.

[0129] A seventh correction stage 807 is provided to maintain the mechanical torque of the turbomachine below a maximum limit. This stage 807 is configured to receive a mechanical torque measurement from the turbomachine TRQ and to determine an elementary upper limit setpoint for the turbomachine's mechanical torque, Iqref_trqmax, based on the difference between a maximum limit setpoint for the turbomachine's mechanical torque TRQMAx and the measured torque TRQ. The sixth correction stage 806 and the seventh correction stage 807 are the closed-loop control circuits whose outputs respectively provide the setpoints Iqref_trqmin and Iqref_trqmax, which in this example correspond to a quadrature current.

[0130] A limitation of the TRQ torque to keep it below a TRQMAX stop is achieved by means of the correction stage 807 in order not to damage the mechanical transmission.

[0131] Similarly, a limitation of the torque TRQ to keep it above a minimum stop TRQM1N, typically of negative value in order to limit the torque generated in the motor quadrant by the generator on the turbomachine power shaft during operation with electrical power generated on the quasi-zero bus, is carried out here by means of stage 806.

[0132] This mechanical torque regulation function TRQ is associated with a priority level called "INTERMEDIATE", in any case higher than the priority level of the battery charging current regulation implemented using the correction stage 80i, and lower than the priority level of the battery current limiting function during charging and discharging.

[0133] An eighth correction stage 8O8 is provided for maintaining the bus voltage UBus above a minimum limit. This stage 8O8 is configured to receive a bus voltage measurement and to determine an elementary setpoint called the "lower bus voltage limit" Iqref_ubusmin based on the difference between a minimum bus voltage limit value UBus_min and the measured bus voltage UBus. Such a minimum bus voltage limit value UBus_min typically corresponds to a characteristic of a downstream electrical network and aircraft equipment connected to it. Below a certain voltage level, the inverters of the electric propulsion motors are likely to shut down.

[0134] A ninth correction stage 809 is provided for maintaining the bus voltage UBus below a maximum limit. This stage 809 is configured to receive a bus voltage measurement and to determine an elementary setpoint called the "upper bus voltage limit" Iqref_ubusmax based on the difference between a maximum bus voltage limit setpoint UBus_max and the measured bus voltage UBus. Such a minimum limit value UBus_max typically corresponds to a characteristic of a downstream electrical network and aircraft equipment connected to it. connected. Above a certain voltage level, the inverters of the electric propulsion motors are likely to shut down for safety reasons.

[0135] The eighth and ninth correction stages 808 and 809 implement closed-loop control of the minimum bus voltage limits UBus_min and maximum bus voltage limits UBus_MAX*

[0136] The respective outputs of the eighth and ninth correction stages 808 and 809 correspond in this example respectively to elementary quadrature current setpoints Iqref_usbusmin and Iqref_usbusmax-

[0137] The HVDC bus voltage 130 is thus maintained above the minimum limit UBus_min to prevent a current increase that could lead to excessive heating of the distribution cables and / or limit the performance of the electric propulsion motors. The HVDC bus voltage 130 is also maintained below the maximum limit UBus_max to prevent potential damage to the insulation of electrical equipment connected to the HVDC bus, particularly propulsion systems, to protect the battery cells 125, or to prevent reaching an overvoltage threshold corresponding to a safety threshold that could lead to a shutdown of the turbogenerator 110 or isolation of the battery 125 or the inverters of the propulsion motors integrated into the loads 140.

[0138] This UBUS bus voltage regulation function implemented using stages 808 and 809 is associated with a priority level called "PRIORITY", typically among the highest, and advantageously the highest, among the different priority levels of the regulation functions ensured by the control system 115 of the rectifier 116.

[0139] A tenth correction stage 80i0 is provided here to perform maximum power control supplied by the turbogenerator 110. This stage is configured to perform a feedback loop and maintain the electrical power of the turbogenerator 110 below a maximum limit PTgen_max0c. The correction stage 80i0 includes a multiplier 81 configured to receive the UBUS voltage from bus 130 and the bus current IDC at the output of the rectifier 116 and to determine a power PTgen equal to the product UBUS x IDc, this power PTGEN being compared to a limit setpoint PrGEN_MAx by means of the comparator 82i0, the difference between Ptgen_maxCI and PTgen being transmitted to the corrector 84i0. The 84i0 controller transmits at output an elementary electrical power limitation command of the turbogenerator IqREf_ptgenmax homogeneous to a quadrature current to the logic module 85 for elementary command selection.

[0140] This maximum power regulation function supplied by the turbogenerator 110 is associated with a priority level of “HIGH”.

[0141] Controlling the maximum electrical power PTGEN MAX deliverable by the turbogenerator 110 on the HVDC bus prevents damage to, or even a shutdown of, the turbogenerator 110 due to overheating of the generator 114 or a power module of the rectifier 116.

[0142] The control of the maximum electrical power of the turbogenerator 110 makes it possible to manage any temporary power supplements provided by the battery 125 during flight phases.

[0143] A particular example of the logic module 85 for elementary setpoint selection mentioned above is given in [Fig.4].

[0144] The logic module 85 has a chain of selection blocks, some of which use a "MAX" function and produce as output the one among its inputs that has the maximum value, and others use a "MIN" function and transmit as output the one among its inputs that has the minimum value.

[0145] Module 85 receives the various elementary instructions Iqrefjbatref, Iqrefjbatmin » IqREFJBATMAX» IqREF_N2MIN, IqREF_N2MAX, Iqref_trqmin, Iqref_trqmax, Iqref_ubusmin, Iqref.usbusmax, iQREF.PTGENMAxen output of the various correction stages 80i,..., 80i0. This module 85 is configured to, based on comparisons between the respective values ​​of said elementary instructions and a priority order associated with each of said correction stages 80i,..., 80i0, select and produce at output an elementary output instruction IQREF from among said elementary instructions.

[0146] This selected elementary setpoint then serves as the so-called "general" setpoint (IQRFF) from which the control block 99 develops the rectifier control signals typically in the form of PWM signals.

[0147] The module 85 is here formed of several selection blocks 90A, 90B, 90C, 90D, 90E arranged in cascade (from left to right in the figure) successively in increasing order of priority that we wish to give here to the different regulation functions implemented by the different correction stages 80i,..., 80i0 described previously.

[0148] In this particular embodiment, the correction stage 80i, which performs a closed-loop control of the battery current IBat to the setpoint IBAT_REF generated by the BMS 126 of battery 125, is the stage whose function is associated with the lowest priority. The battery charging current setpoint IBAt_ref is thus transmitted as input to a first 90A selection block located at one end of the cascaded series of blocks. This first 90A block also receives setpoints Iqref_trqmin and IQREF_TRQMAx issued at the output of the stage, respectively. correction 806, and the correction stage 807 relating to another function, of higher priority, in this example the control of the mechanical torque TRQ and its maintenance between a lower stop TRQM1N and an upper stop TRQMAx-

[0149] The first 90A selection block comprises a unit 94 performing a MAX function (i.e., a maximum value selection unit among its inputs), one output of which serves as an input to a unit 92 performing a MIN function (i.e., a minimum value selection unit among its inputs). The first 90A block returns as output the smaller of the two values: on the one hand, the elementary setpoint IQREF_TRQMAX for the upper mechanical torque limitation of the turbomachine, and on the other hand, the larger of the two values: on the one hand, the elementary setpoint IQREF_TRQMiN for the lower mechanical torque limitation of the turbomachine and the battery charging current setpoint Ibat_ref-

[0150] The output of the first block 90A is transmitted to a second block 90B, located after block 90A in the sequence of selection blocks. The second block 90B receives the elementary instructions IqREf_n2min, Iqref_n2max relating to a third function with a higher priority than those corresponding to the elementary instructions issued at the input of the preceding block 90A.

[0151] This third function here concerns the control of the transient speed excursions N2 of the turbomachine's power shaft, and its maintenance between a lower limit N2m1n and an upper limit N2MAx- The second selection block 90B is formed of a unit 92 performing a MIN function whose input is connected to an output of the previous block 90A and which selects the lowest value between this output and the lower speed limitation setpoint of the turbomachine lQREF_N2MiNet transmits this value to a unit 94 performing a MAX function which selects from among its inputs the highest one between those connected to the unit 92 and another input receiving the upper speed limitation setpoint of the turbomachine IqREf_n2max-

[0152] At the output of the second selection block 90B, a third selection block 90C receives the elementary setpoint Iqkef.ptgenmax relating to a fourth function, in this example the control of the maximum electrical power supplied by the turbogenerator, and its maintenance below a threshold or upper limit PTgen_max. This fourth function thus has, in this example, a higher priority than the first, second, and third functions mentioned above. The third selection block 90C is here formed by a unit 94 performing a MIN function to select its input having the highest value between an elementary setpoint from the preceding block 90B and the elementary setpoint IqRef_ptgenmax.

[0153] The fourth function, which here relates to the control of battery charge / discharge current limits, has a lower priority than a fifth function and a sixth function associated respectively, with elementary instructions Iqref_ibatmax,Iqref_ibatmin at the input of a fourth 90D selection block following the 90C block, and with elementary instructions IqREf_ubus max,Iqref_ubus min at the input of a fifth 90E selection block.

[0154] The fourth block 90D includes a unit 92 performing a MIN function between the elementary setpoint IqREf_ibatmin and the input of the previous block and a unit 94 performing a MAX function between the elementary setpoint Iqrefjbatmax, and the output of the unit 92.

[0155] The fifth and final 90E block in this sequence receives the elementary commands Iqref_ubusmin and Iqref_usbusmax, relating to the fifth function, which has the highest priority. In this example, the highest priority function is that concerning the control of the bus voltage and its maintenance between a lower limit Ubus_min and an upper limit UBus_max. The fifth 90E block selects between an elementary command transmitted by the preceding block and the Iqref_ubusmin and Iqref_usbusmax commands issued as inputs to the latter and relating to the fifth function. A 92 unit performing a MAX function selects the elementary command with the higher value between the elementary command IqREF_uBusMin and the command selected in the preceding block.A unit 94 performing a MIN function selects the elementary setpoint with the highest value between the elementary setpoint lQREF_uBusMAx and the output setpoint of the previous selection unit 92.

[0156] In the example described above, the control system 115 can be implemented at least in part by a computer system comprising a processing unit such as a microprocessor and at least one memory in which a computer program is stored, containing computer program instructions designed to be executed by the processing unit. Thus, the modules and stages described above can be implemented by means of a computer program in the form of software modules.

[0157] Alternatively, all or part of the modules and stages can be implemented in hardware form, i.e. in the form of an electronic circuit, for example micro-wired.

[0158] In an example of an embodiment as described above, the selected setpoint IQREF at the output of the selection module 85 corresponds to a quadrature vector component in the Park frame of the phase current electric generator.

[0159] As an alternative to control via such a current vector component, it is also possible to control the rectifier 116 with a DC rectifier voltage setpoint UBus_ref developed according to a principle analogous to that shown in [Fig. 3] and 4, the gains of the correction stages 84b... ,84i0 being adapted for develop elementary bus voltage setpoints at the output to comply with the various limits described, rather than elementary current setpoints IQ. However, control based on a current IQRFF has the advantage of faster regulation, in this case in particular less than 2 ms, and independent of certain system parameters such as the capacity of the HVDC bus 130, the voltage of the HVDC bus, the internal resistance of the battery 125. In addition, in the event of failure of sensor or means of measurement allowing to measure the UBUS voltage, the choice of a current control IQRFF makes it possible to keep operational almost all of the aforementioned regulation functions, in particular those allowing to regulate the parameters IBAF, TRQ, N2.

[0160] In the particular embodiment described above, the rectifier control system 115 comprises 10 correction stages 80i,..., 80i0. The control system is not necessarily limited to such a number of stages. It is therefore possible, for example, to add one or more additional control parameters or limits to be taken into account when developing the general IQRFF setpoint at the output of the selection module 95.

[0161] Thus, for example, the SOC of battery 125 can be taken into account in order to establish the IQRFF setpoint allowing the UBus- H bus voltage to be regulated. It is also possible to add a DC current limiting loop IDC at the rectifier output 116.

[0162] A regulation such as presented above applies equally to a turbogenerator in which the turbomachine drives an electric generator at the output of which a rectifier is provided, and to a turbogenerator formed of a turbomachine driving several electric generators in parallel through a gearbox.

[0163] It can also be applied to an electric generator formed of several independent three-phase stator windings, allowing to supply in parallel as many active rectifiers and HVDC buses.

[0164] Conventionally in a propulsion assembly according to the prior art, the control of the rotational speed N2 of the turbine, the limitation of the accelerations and decelerations of the turbomachine so as to keep them within its extinction and pumping limits is mainly achieved by the EECU control module 113 via the metering of the fuel injected into the combustion chamber.

[0165] In certain cases, particularly of a rotary-wing aircraft such as a helicopter where the inertia of the generator(s) driven by the turbomachine is much lower than that of a rotating assembly or when the turbomachine has a free turbine, this regulation may prove insufficient.

[0166] Furthermore, power demand variations in an electric propulsion system are significantly faster than in a conventional architecture solely equipped with a thermal engine. The combination of low driven inertia and rapid variations in propulsive power is likely to lead to larger instantaneous variations and excursions in N2 speed with a series electric hybrid propulsion architecture.

[0167] Now, to maintain the excursions of the speed N2 within a determined operating range, typically between 90% and 105% of the nominal speed of the turbine power shaft, one can, according to a particular embodiment, use the battery 125 connected to the HVDC bus 130 which serves as a buffer or electrical inertia.For this purpose, the charge and discharge of the battery 125 is controlled via the control system 115 of the rectifier 116 so that it transiently supplies energy to the HVDC bus 130 in order to prevent underspeed of the power shaft following a rapid increase in the demand for propulsive power exceeding the acceleration performance without pumping of the turbomachine, or conversely, transiently absorbs part of a surplus of energy supplied by the turbogenerator 110 in order to prevent overspeed of the power shaft during a rapid decrease in power demand exceeding the deceleration performance without shutdown of the turbomachine.

[0168] By rapid increase or decrease, we typically mean an increase or decrease of at least 200 kW / s.

[0169] Such a mode of operation is illustrated in figures 5A and 5B which respectively give curves C_PLOad,C_PTgen,C_PBat0' time evolution of powers and curves CSab, Caab of time evolution of rotation speed N2.

[0170] The power absorbed by the battery being initially zero (it is assumed that the latter is charged) and the electrical power PTgen supplied by the turbogenerator consequently equal to the power PLoad consumed by the propulsive loads, between instants tA and tB (acceleration phase) there occurs a rapid increase in the demand for power PLoad consumed by the propulsive loads according to a positive gradient exceeding the acceleration capacities without pumping of the turbomachine.

[0171] Assuming battery assistance (Caab curve representing a hybrid electric system operating according to the invention), the speed N2 of the power shaft begins to drop rapidly due to a power supply deficit from the turbogenerator 110, resulting in a decrease in the current setpoint ΔQREE_N2MiNen linked to the lower speed limit N2 of the power shaft (correction stage 844), and its inclusion in the limitation of the final current setpoint ΔQREE via the limiting block 90B. Due to the existence of a gain Due to the positive physical difference between the IQREF setpoint and the UBUS bus voltage, limiting the IQREF setpoint by a higher value results in the control system 115 driving the rectifier 116 to temporarily lower its UBUS output voltage, thereby discharging battery 125. After time tB, the power demand PloadSC stabilizes. As the power supplied by the turbogenerator PTgen gradually increases to the final demand Pload and the speed N2 reaches its setpoint, the control system 115 drives the rectifier 116 to increase its UBUS output voltage, thus recharging battery 125, and then restores the constant UBUS output voltage to maintain zero current at the output of battery 125.

[0172] Then, between times tc and tD (deceleration phase) a rapid decrease in the power demand PL0AD by the propulsive loads according to a negative gradient exceeding the deceleration capacities without extinction of the turbomachine.

[0173] Still assuming battery assistance (CaabX curve), the speed N2 of the power shaft begins to increase rapidly due to the inability of the turbogenerator 110 to reduce its power supply to the loads 140 sufficiently quickly. This leads to an increase in the current setpoint Iqref_n2m Axen, linked to the upper speed limit N2 of the power shaft (correction stage 845), and its inclusion in the limitation of the final current setpoint IQREF via the limiting block 90B. The limitation of the IQREF setpoint by a lower value results in the control system 115 driving the rectifier 116 to temporarily increase its output voltage UBUS in order to recharge the battery 125. After time tD, the power demand PloadSC stabilizes again.As the power supply from the PTgen turbogenerator gradually decreased to the level of the final PLoad demand and the speed N2 returned to its setpoint, the control system 115 controlled the rectifier 116 to reduce its UBUS output voltage in order to cause a charge of the battery 125 and then restored the constant UBUS output voltage in order to maintain a zero current at the output of the battery 125.

[0174] The power supplied by the PTgen turbogenerator (C_PTgen curve) has insufficient dynamics, limited by the laws protecting against pumping and extinction of the turbomachine.

[0175] In the event of the absence of battery assistance (CSab curve representing a system operating in a conventional manner), and taking into account the low overall inertia of the system driven by the free turbine, the evolution of the rotational speed N2 is such that it is likely to go below (underspeed) of a threshold N2 Min during acceleration and above (overspeed) of a threshold N2 Max during deceleration of a specified [N2 Min N2 Max] template.

[0176] In order not to limit the performance of the propulsion chain, it is planned here to control, via the control system 115 of the rectifier 116, the discharge and charge of the battery (C_PBat curve) so that the latter supplies or absorbs the power respectively deficient or excess, in order to limit the speed excursions N2 (Caab curve)- This advantageous operating mode, called "transient assistance", is obtained in particular thanks to the regulation loops implemented by the correction stages 804, 805 described previously.

[0177] Such an operating mode requires only brief use of the battery 125, typically lasting on the order of one to two seconds. The instantaneous peak powers involved can be on the order of several tens to a few hundred kW, with the energy supplied or absorbed by the battery 125 limited by the typically very brief nature of these operating modes.

[0178] Another possible mode of operation using a control system 115 of the rectifier 116 is illustrated in [Fig.6], to meet a high power demand from propellant loads.

[0179] Up to a certain instant tb, the power demand PLoad (CPLOad curve) of the propulsion loads, initially of a value Pi, increases but remains below the programmed maximum power limit PTgen_max. The control system 115 drives the rectifier 116 so as to maintain its output voltage UBus at a value such that the battery 125 produces zero output current while increasing the current delivered by the rectifier 116. The turbogenerator 110 then provides all of the PTgen power (CPTGen curve) on its own, and the power supplied by the battery PBAT (CPbat curve) is zero.

[0180] Then, from a time tb the demand for propulsive power increases beyond the programmed threshold PTgen_max.

[0181] Crossing this threshold results in a decrease in the current setpoint IqREf_p tgen MAxen linked to the upper limit of electrical power at the output of the rectifier 116 (correction stage 84i0), and its inclusion in the limitation of the final current setpoint IQREF via the limiting block 90C, provided that no other more restrictive limit applies. The limitation by upper value of the setpoint IQREF results in the control system 115 driving the rectifier 116 to lower its output voltage UBUs so that the battery 125 discharges while maintaining constant, typically by means of a proportional-integral control loop, the electrical power delivered by the rectifier 116. The battery 125, through appropriate control of the rectifier 116 implemented by system 115 then provides the additional power to the propulsive loads beyond the PTgen_max limit of the turbogenerator 110.

[0182] This advantageous operating mode is obtained in particular thanks to the regulation loop implemented by the correction stage 80i0 described above.

Claims

Demands

1. Device for a series-electric hybrid aircraft propulsion system, comprising: - an electric turbogenerator (110) comprising at least one turbomachine (112) and at least one generator (114) coupled to said turbomachine, - a storage battery (125), - an HVDC bus (130) coupled to said turbogenerator and to said battery (125), the turbogenerator (110) being connected to the HVDC bus (130) via an AC to DC rectifier (116) connected to phases of said at least one generator (114), said battery (125) being connected directly to the high-voltage direct current (HVDC) electrical network,the device further comprising a control system (115) for the rectifier (116) configured to control the rectifier (116) and manage the sharing of electrical power supplied on the HVDC bus (130) between said turbogenerator (110) and said battery (125) based on the setpoint control of at least the current (IBat) delivered by the battery (125), by modulating the output voltage (UBus) of the rectifier (116) via at least one control signal (CMD), in particular pulse-width modulation (PWM).

2. A device according to claim 1, wherein the control system (115) of the rectifier (116) comprises: - a plurality of correction stages (80i, ..., 80i0), each correction stage being equipped with a corrector (84b ..., 80i0) and being configured to receive a measurement of a rectifier output voltage regulation parameter (UBus) (116) from among a set of parameters such as a rectifier output current (IDC) (116), an HVDC bus voltage (UBUS), a turbomachine power shaft rotation speed (N2), a battery output current (IBAt), a turbomachine mechanical torque (TRQ), and to establish, from a comparison between this measurement of said regulation parameter and a reference or a limit not to be exceeded: an elementary setpoint, the respective elementary setpoints (Iqref_ibatref -, Iqrefjbatmin, IqREFJBATMAX, IqREF_N2MIN, IqREF_N2MAX, Iqref_trqmin, Iqref_trqmax, Iqrefjjbusmin, Iqrefjjsbusmax, Iqref_ptgenmax). at the respective outputs of said correction stages being all homogeneous to a current or all homogeneous to a voltage, - a logic module (85) for elementary setpoint selection configured to receive said elementary setpoints (Iqrefjbatref -, Iqrefjbatmin» IqREFJBATMAX, IqREF_N2MIN, IqREF_N2MAX, Iqref_trqmin, IqREF_TRQMAX, IqREFJJBUSMIN, IqREFJJSBUSMAX, IqREF_PTGENMAx) and to select, based on comparisons between respective values ​​of said elementary setpoints and a predetermined priority order associated with each of said correction stages, an elementary output setpoint from among said elementary setpoints, said selected elementary output setpoint serving as the so-called "general" setpoint (Iqref) from which said control signal (CMD) of the rectifier (116) is established.

3. Device according to claim 2, wherein said general control setpoint corresponds to a vector component (IQ) of phase currents (IA, IB, le) along a first axis of a rotating frame linked to a rotor of the generator (114).

4. Device according to any one of claims 2 or 3, wherein among said correction stages (80i, ..., 80i0) there is at least one or more correction stages or all of the correction stages among: - a first correction stage (80i) for controlling a battery current to a reference setpoint, configured to receive a battery current measurement (IBAt) and to determine an elementary reference battery current setpoint (Iqref_batmin) as a function of the difference between a reference battery current setpoint (IBAt_ref) and the battery current measurement (IBAT), - a second correction stage (802) for maintaining a battery current above a minimum stop,configured to receive a battery current measurement (IBAT) and to determine an elementary lower battery current limiting setpoint (Iqref_batmin) based on the difference between a minimum battery current stop setpoint (IBAT Min) and the battery current measurement (IBAT), - a third correction stage (803) to maintain a battery current below a maximum stop, configured to receive, a battery current measurement (IBat) and to determine an elementary upper battery current limiting setpoint (Iqref_batm ax) as a function of the difference between a maximum battery current stop setpoint (IBat_m ax) and the battery current measurement (IBAT), - a fourth correction stage (804) to maintain a turbomachine speed above a minimum stop, configured to receive a turbomachine speed measurement (N2) and to determine an elementary lower turbomachine speed limitation setpoint (Iqref_n2min) as a function of the difference between a minimum turbomachine speed stop value (N2m1n) and the turbomachine speed measurement (N2), - a fifth correction stage (805) to maintain a turbomachine speed below a maximum stop, configured to receive a turbomachine speed measurement (N2) and to determine an elementary upper turbomachine speed limitation setpoint (Iqref_n2max) as a function of the difference between a maximum turbomachine speed stop setpoint (N2max) and the turbomachine speed measurement (N2),- a sixth correction stage (806) to maintain the turbomachine's mechanical torque above a minimum stop, configured to receive a turbomachine mechanical torque measurement (TRQ) and to determine an elementary lower limit setpoint for the turbomachine's mechanical torque (Iqref_trqmin) as a function of the difference between a minimum stop setpoint for the turbomachine's mechanical torque (TRQM1N) and the current turbomachine mechanical torque measurement (TRQ), - a seventh correction stage (807) to maintain the turbomachine's mechanical torque below a maximum stop,configured to receive a turbomachine mechanical torque (TRQ) measurement and to determine an elementary upper limit setpoint for turbomachine mechanical torque (Iqref_trqmax) based on the difference between a minimum stop setpoint for turbomachine mechanical torque (TRQMAx) and the current turbomachine mechanical torque (TRQ) measurement; - an eighth correction stage (8O8) to maintain the HVDC bus voltage above a minimum stop, configured to receive, a bus voltage measurement (UBus) and to determine an elementary lower bus voltage limiting setpoint (Iqref_ubus_min) as a function of the difference between a minimum bus voltage stop setpoint (UBus_min) and the bus voltage measurement (UBUS), - a ninth correction stage (8O9) to maintain the HVDC bus voltage below a maximum stop and configured to receive a bus voltage measurement (UBUS) and to determine an elementary upper bus voltage limiting setpoint (Iqref_ubus_max) as a function of the difference between the bus voltage measurement (UBUS) and a maximum bus voltage stop setpoint (UBUS_max),- a tenth correction stage (80i0) to maintain an electrical power output of the rectifier below a maximum limit and configured to receive a bus voltage measurement (UBUS) and a bus current measurement (IDC) and to evaluate an electrical power measured at the rectifier output and to determine an elementary upper power limiting setpoint (Iqref_ptgenmax) as a function of the difference between the measured electrical power and a maximum power limit setpoint (Ptgenmax)-,

5. Device according to claim 4, wherein the first correction stage (801) is associated with a first priority level, and wherein the fourth and fifth correction stages (804,805) and / or sixth and seventh correction stages (806,807) are associated with a second priority level higher than the first priority level, the tenth correction stage (8010) being associated with a third priority level higher than the second priority level, the second and third correction stages (802,803) and / or eighth and ninth correction stages (808,809) being associated with a fourth priority level higher than the third priority level.

6. A device according to any one of claims 2 to 5, wherein the elementary setpoint selection logic module (85) (Iqrefjbatref → Iqrefjbatmin, IqREFJBATMAX, IqREF_N2MIN, IqREF_N2MAX, Iqref_trqmin, Iqref_trqmax, Iqrefjjbusmin, Iqrefjjsbusmax, Iqref_ptgenmax) comprises a plurality of selection blocks (90A, 90B, 90C, 90D, 90E), each comprising: - a minimum value selection unit (92) among its inputs arranged in series with a maximum value selection unit (94) among its inputs, Or - a minimum value selection unit (92; 94) among its inputs, Each of said selection blocks (90A, 90B, 90C, 90D, 90E) being configured to receive, among said elementary instructions, a given elementary instruction or a given pair of elementary instructions emanating from given correction stages among said correction stages receiving the same measurement of the same measurement parameter, said given elementary instruction or said given pair of elementary instructions being different from that(s) received by said other selection blocks, the selection blocks being arranged in a succession of cascaded blocks in an order depending on the order of priority to which the given correction stage(s) is or are associated, -a first block (90A) of said cascaded block series receiving as input an elementary instruction called the reference instruction (Iqref_ibatref) from among said elementary instructions, - a final block (90E) of said succession of cascaded blocks producing at output a setpoint said elementary output setpoint (Iqref) serving as a setpoint said "general" (Iqref), each of said other blocks receiving at input an elementary setpoint selected by a previous selection block of said plurality of selection blocks arranged in cascade, and producing, at output an elementary setpoint selected from its inputs and destined for a following block of said plurality of selection blocks.

7. 7. Device according to any one of the preceding claims, in which said turbomachine (112) is a free turbine.

8. Series hybrid electric propulsion aircraft comprising a device according to one of the preceding claims.

9. A method for controlling the turbogenerator (110) of a device as defined in claims 1 to 7, the HVDC bus (130) being coupled to at least one set of propulsion loads (140), comprising the following steps: - during an initial phase following the detection of an increase in demand for electrical power originating from said propulsion load assembly (140) and as long as an electrical power (PTgen) at the output of said rectifier (116) remains below a threshold, control the rectifier (116) so as to maintain its output voltage (UBus) at a value such that the current delivered by the battery (125) is controlled to a zero setpoint while increasing the current delivered by the rectifier (116) so that the turbogenerator (110) alone provides electrical power to the HVDC bus (130) in response to said increase, then, following detection of reaching an electrical power threshold (PTgen_max) at the output of rectifier (116) and a further increase in electrical power demand beyond said threshold from said propulsion load assembly (140), during a second phase,to control the rectifier (116) to lower its output voltage (UBus) so that the battery (125) discharges while maintaining constant and equal to the value of said threshold the power delivered by the rectifier (116) so that the turbogenerator (110) and the battery (125) jointly supply electrical power to the HVDC bus (130) in response to said new increase.

10. A method for controlling the turbogenerator (110) of a device as defined in any one of claims 1 to 7, the HVDC bus (130) being coupled to at least one set of propulsion loads (140), the method comprising the following steps: - following an increase in the electrical power demand from said set of loads (140) exceeding a no-pumping acceleration limit of the turbomachine (112) and causing a transient drop in speed (N2) of the power shaft of said turbomachine relative to its setpoint, controlling the rectifier (116) to temporarily lower its output voltage (UBUS) so as to cause a discharge of the battery (125), then, - following a stabilization of the electrical power demand from said set of loads, an increase in the electrical power delivered by said turbogenerator and a rise in the speed (N2) towards its setpoint,drive the rectifier (116) to increase its output voltage (UBUS) in order to charge the battery (125) and then restore the output voltage, (Ubus) constant so as to maintain a zero current at the output of the battery (125), and / or including the following steps: - following a decrease in the electrical power demand from said load set (140) exceeding a deceleration limit without shutdown of the turbomachine (112) and resulting in a transient increase in speed (N2) of the power shaft of said turbomachine relative to its setpoint, control the rectifier (116) to temporarily reduce its output voltage (UBus) in such a way as to recharge the battery (125), then, - following a stabilization of the demand for electrical power from said set of loads, a decrease in the electrical power delivered by said turbogenerator and a decrease in speed (N2) towards its setpoint, control the rectifier (116) to increase its output voltage (UBus) so as to charge the battery (125) then restore a constant output voltage (UBUs) so as to maintain a zero current at the output of the battery (125).

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