System for controlling power sources in parallel with load estimation

Abstract

The invention relates to a control system for controlling an electrical system comprising a plurality of power sources, the control system comprising: a central controller (40) configured to generate a central setpoint (Pce) and to divide it into local setpoints (P) associated with the power sources; local controllers (311, 321, 331) in communication with the central controller (40), configured to: receive one of the local setpoints (P), implement droop control so as to generate a setpoint correction (Pco), generate an output setpoint (Pcs) on the basis of the received local setpoint (P) and the setpoint correction (Pco), and control one of the power sources using the output setpoint (Pcs); and the central controller (40) being configured to regulate the central setpoint (Pce) on the basis of signals representative of each output setpoint (Pcs).

Description

[0001] DESCRIPTION

[0002] TITLE: Parallel Power Source Control System with Load Estimation

[0003] TECHNICAL FIELD

[0004] This disclosure relates to the general field of power source control systems, and in particular voltage regulation when power sources are connected in parallel by a centralized controller.

[0005] STATE OF THE ART

[0006] 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 different countries. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0007] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain less energy-intensive and more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts, with the aim of improving the energy efficiency of aircraft.

[0008] Consequently, the Applicant is constantly working to reduce its climate impact by employing sustainable development methods and minimizing greenhouse gas emissions. This sustained research and development work focuses in particular on new generations of aircraft engines and the development of electric propulsion technologies.

[0009] An aircraft typically includes an electrical system powered by various sources and is propelled by a turbomachine. To improve the aircraft's energy efficiency, the turbomachine can be internally hybridized. This involves adding a hybrid electrical system that acts as an interface between the turbomachine's rotating shafts and the aircraft's electrical system. The hybrid electrical system aims to assist the turbomachine to optimize its operation by providing electrical assistance or drawing power from it. It must manage the power distribution between the turbomachine's high-pressure and low-pressure shafts, and in particular, limit the power drawn, while ensuring that all sources contribute to a sufficient supply of power to the aircraft's electrical system.

[0010] One proposed solution is an electrical system with multiple decentralized or local controllers. In this case, the low-pressure and high-pressure shafts are controlled independently and their voltage is regulated by controllers with non-zero steady-state error. However, proper power distribution depends heavily on the accuracy of the voltage measurements and the load level. Therefore, the bus voltage that is being regulated is significantly affected by local measurement errors.

[0011] A second proposed solution is a so-called "centralized" architecture, with a central controller that regulates the voltage of the electrical network and distributes power commands to the local controllers. The various electrical sources within an aircraft are distributed throughout the aircraft at varying distances from the central controller. Such a centralized architecture therefore does not allow for rapid communication between the local controllers, as the information transmission time on the communication buses depends on the distance.

[0012] In both centralized and decentralized architectures, regulating the voltage across the distribution bus requires the central controller to have access to a specific bus voltage value. Specifically, the central controller monitors the bus voltage to enable its regulation by the central controller or local controllers. Therefore, it is necessary to provide the central controller with a means of acquiring voltage measurements on the bus. However, communication between the central controller and the sensors used to acquire these measurements can be slow, potentially delaying the control system's response to a load change.

[0013] EXPOSED

[0014] One aim of the invention is therefore to provide a control system for an electrical system that can more quickly regulate the voltage of the electrical system's distribution bus in the event of a load impact on the bus. To this end, a control system is proposed for controlling an electrical system, the electrical system comprising a plurality of power sources connected in parallel to a distribution bus, the control system comprising:

[0015] • a central controller configured to: o generate a central setpoint and o divide the central setpoint into local setpoints respectively associated with the power sources,

[0016] • Local controllers communicating with the central controller, each local controller being configured to: o receive one of the local setpoints, o implement droop control from a reference parameter representing a local reference voltage and a measured voltage parameter representing a local measured voltage of the power source associated with the received local setpoint, so as to generate a setpoint correction, and o generate an output setpoint from the received local setpoint and the setpoint correction, o control one of the power sources using the output setpoint, wherein the central controller is configured to regulate the central setpoint from signals representative of each output setpoint, the regulation by the central controller being such that a sum of the local setpoints (P) received by the local controllers is equal to the sum of the output setpoints (P cs) generated by local controllers.

[0017] Each local controller can react quickly to a voltage excursion by attenuating it immediately after a load impact. Furthermore, generating local setpoints from signals representative of the loads taken from the power sources compensates for the steady-state error in the output setpoint caused by each individual local controller, without requiring the central controller to receive any additional information beyond what is already needed to regulate the power sources, including the output setpoints. This results in a control system that is responsive to load impacts and enables the regulation of the electrical system's bus voltage without steady-state error.

[0018] According to some embodiments, the central controller generates the central setpoint from signals representing loads taken from the power sources and from at least one of the following: • a voltage across the distribution bus measured or estimated from the local voltages measured from the power sources,

[0019] • information relating to a future opening of an electrical contactor on an aircraft or turbomachine,

[0020] • Information relating to a future connection or disconnection of an electrical load on the distribution bus,

[0021] • a direct measurement performed on an electrical charge.

[0022] In some embodiments, the central controller is further configured to:

[0023] - calculate an error correction power from the difference between the local setpoint and the output setpoint, and

[0024] - regulate the local setpoint by adding the error correction power to the local setpoint.

[0025] In some embodiments, the central controller is further configured to:

[0026] - calculate an error correction power from the difference between the local setpoint and the output setpoint, and

[0027] - convert the error correction power into an error correction voltage, and the drastic regulation is implemented from the reference parameter, the measured voltage parameter and the error correction voltage.

[0028] An electrical system is also proposed, comprising:

[0029] - a plurality of power sources connected in parallel to a distribution bus, and

[0030] - a control system as defined previously.

[0031] According to some embodiments, the local controllers are respectively associated with the power sources, and a current supplied by each power source depends on the output setpoint generated by the respective local controller.

[0032] Furthermore, a method is proposed for controlling an electrical system comprising power sources and a distribution bus to which the power sources are connected, the method being implemented by a control system comprising a central controller and local controllers associated respectively with the power sources, the method comprising the steps of: generation, by the central controller, of a central setpoint and division by the central controller of the central setpoint into a plurality of local setpoints respectively associated with the power sources, • reception, by each local controller, of one of the local setpoints,

[0033] • implementation, by each local controller, of a drastic control based on a reference parameter representing a local reference voltage and a measured voltage parameter representing a local measured voltage of the power source associated with the received local setpoint, so as to generate a setpoint correction,

[0034] • generation, by each local controller, of an output setpoint based on the received local setpoint and the setpoint correction,

[0035] • control, by each local controller, of the respective power source using the output setpoint,

[0036] • regulation, by the central controller, of the central setpoint from signals representative of the output setpoints.

[0037] DESCRIPTION OF THE FIGURES

[0038] Other features, purposes, and advantages will become apparent from the following description, which is purely illustrative and not exhaustive, and should be read in conjunction with the attached drawings on which:

[0039] [Fig. 1] schematically represents an aircraft;

[0040] [Fig. 2] schematically represents a turbomachine;

[0041] [Fig. 3] represents an electrical system of the aircraft, according to an embodiment comprising three power sources;

[0042] [Fig. 4] represents a control system for the electrical system of figure 3, according to a first embodiment;

[0043] [Fig. 5] represents a control system for the electrical system of figure 3, according to a second embodiment;

[0044] [Fig. 6] represents an error correction unit of the control system shown in Figure 5;

[0045] [Fig. 7] represents a control system for the electrical system of Figure 3, according to a third embodiment; [Fig. 8] represents a voltage regulation method for the distribution bus connecting the power sources of the electrical system.

[0046] Across all figures, similar elements bear identical references.

[0047] DETAILED DESCRIPTION

[0048] In this application, upstream and downstream are defined with respect to the normal flow direction of the gas through the turbomachine. Furthermore, the longitudinal axis X of the turbomachine is the axis of rotation of its rotor parts. The axial direction corresponds to the direction of the longitudinal axis X, and a radial direction is a direction perpendicular to and passing through this axis.

[0049] For illustrative purposes, Figure 1 represents an aircraft 100 comprising at least one propulsion unit 1, in this case two propulsion units 1. The propulsion units 1 are attached and fixed to the aircraft 100, for example each under a wing of the aircraft 100 as illustrated, or alternatively on the wing of the aircraft 100 or at the rear of the fuselage of the aircraft 100. The aircraft 100 is an airplane, but could alternatively be any other type of aircraft 100, for example a helicopter.

[0050] Description of the turbomachine

[0051] Figure 2 schematically represents a section of the propulsion unit 1 in a plane containing the longitudinal axis X. The propulsion unit 1 comprises the turbomachine 10 and a nacelle 20 surrounding the turbomachine 10.

[0052] The propulsion unit 1 is intended to be mounted on the aircraft 100. In this regard, the propulsion unit 1 may include a pylon (not shown) intended to connect the propulsion unit 1 to a part of the aircraft 100, transmitting the forces to the aircraft 100.

[0053] This disclosure is not limited to a twin-spool, twin-flow turbofan engine with direct fan drive 11 as illustrated. It extends more generally to various turbofan engine architectures, including unfaired turbofan engines, and other types of turbomachinery, which may have a different number of spools and / or flows.

[0054] This disclosure falls more generally within the context of the internal hybridization of the turbomachine 10, i.e. presenting an electrical system 3 in interface with the mechanical shafts of the turbomachine and the electrical network of the aircraft 100, as detailed later.

[0055] The turbomachine 10 comprises, from upstream to downstream in the direction of the gas flow, a blower 11, a compression section 16 comprising a low pressure compressor 161 and a high pressure compressor 162, a combustion chamber 14, an expansion section 15 comprising a high pressure turbine 152 and a low pressure turbine 151, and an exhaust casing.

[0056] Each of the low-pressure compressor 161, high-pressure compressor 162, high-pressure turbine 152, and low-pressure turbine 151 comprises a rotor portion and a stator portion, the rotor portion being capable of being driven in rotation relative to the stator portion about the longitudinal axis X. The blower 11, the rotor portion of the low-pressure compressor 161, and the rotor portion of the low-pressure turbine 151 are connected to each other by a low-pressure shaft 181 extending along the longitudinal axis X, thus forming a low-pressure body (LP body), which is a first rotating body. The rotor portion of the high-pressure compressor 162 and the rotor portion of the high-pressure turbine 152 are connected to each other by a high-pressure shaft 182 also extending along the longitudinal axis X, around the low-pressure shaft 181, thus forming a high-pressure body (HP body), which is a second rotating body.As can be seen in Figure 2, the compression section 16, the combustion chamber 1 and the expansion section 15 are surrounded by an engine casing 21, to which are connected the stator parts of the low pressure compressor 161, the high pressure compressor 162, the high pressure turbine 152 and the low pressure turbine 151. The engine casing 21 delimits a primary channel 13 allowing the flow of a primary gas stream A.

[0057] As explained previously, the longitudinal axis X defines the axis of rotation for the blower 11, the rotor parts of the compression section 16 and the rotor parts of the expansion section 15, in other words for the LP body and the HP body.

[0058] The nacelle 20 extends radially outside the turbomachine 10, around the longitudinal axis X, so as to surround the engine casing 21, and to define a secondary channel 12 allowing the flow of a secondary gas flow B.

[0059] The turbomachine 10 may also include at least one accessory gear box (AGB), typically housed in a cavity within the nacelle 20. The accessory gear box comprises a set of gears for rotating a plurality of shafts about their own axis, and accessories mounted on the plurality of shafts to derive useful mechanical power from their rotation. The gear set is itself driven by means of a radial drive shaft (RDS) connecting, possibly via a transfer case, the accessory gear box to at least one of the high-pressure (HP) and low-pressure (LP) units. For example, the radial drive shaft (not shown) may extend within a longitudinal cavity within an arm 17.In this way, mechanical power is likely to be taken from at least one of the high pressure body HP and the low pressure body BP to be delivered to at least one of the accessories via the accessory box.

[0060] Aircraft electrical system 100

[0061] As is known in itself, aircraft 100 comprises a plurality of electrical loads (or receivers) powered by electrical sources via an electrical network.

[0062] An electrical load is a device powered by electrical energy, usually direct current. It can be configured to transform the electrical energy that powers it into another form of energy, such as heat or mechanical energy.

[0063] Referring to Figure 3, the electrical loads can be divided into two categories. The first category of loads, Ch1, is external to the propulsion system 1. The electrical loads Ch1 specific to the aircraft 100 may include, for example, an electric motor, a heating and / or air conditioning system, or a compressor. These loads enable a number of functionalities, whether the aircraft is in flight or operating on the ground, such as pressurizing and / or illuminating the cabin of the aircraft 100, or operating the cockpit.

[0064] A second category of loads is internal to propulsion unit 1. Propulsion unit 1 includes the turbomachine 10, detailed above. The electrical loads Ch2 of the propulsion unit are loads of the turbomachine 10 (known as the "More Electric Engine" or MEE in English terminology). For example, the electrical loads of turbomachine Ch2 may include a starter, variable geometry components, or de-icing systems.

[0065] Multiple power sources allow electrical loads to be supplied with electrical energy, generally in the form of a continuous signal, typically a direct current voltage. On the one hand, the turbomachine 10 generally comprises two shafts, low-pressure 181 and high-pressure 182, which provide mechanical energy. Each shaft is associated with a generator motor that extracts mechanical energy from the associated shaft and converts it into electrical energy to supply the electrical grid.

[0066] On the other hand, aircraft 100 includes a plurality of electrical sources distributed throughout aircraft 100, for example an auxiliary power unit (APU), an electric battery, or a supercapacitor. These sources allow, in particular, for operation where the two shafts of the turbomachine 10 are assisted, but also for supplying various onboard systems on the ground (electrical voltage, pneumatic and hydraulic pressures, air conditioning) when the turbomachines 2 are stopped in order to save fuel, and during start-up.

[0067] The electrical network typically comprises a set of electrical conductors, typically a set of cables connecting the different electrical loads and sources, and busbars, for example a high-voltage direct current distribution bus.

[0068] Generally, generators that extract mechanical energy from shafts produce alternating current (AC). This AC is converted to direct current (DC) by an AC / DC converter. The electrical grid includes at least a portion of the network that carries direct current, as electrical loads are supplied with direct current.

[0069] Figure 3 illustrates an electrical system 3 distributed between the propulsion unit 1 and the aircraft 100 for supplying electrical power to the electrical loads of the aircraft Ch1 and / or the electrical loads of the turbomachine Ch2, typically by means of the direct current network.

[0070] The electrical system 3 makes it possible in particular to interface between the rotating bodies BP, HP of the turbomachine 10 and the electrical network of the aircraft 100. The electrical system is in particular configured to meet the electrical power requirements of the loads of the aircraft Ch1 and / or the turbomachine Ch2 by mechanically drawing power from the turbomachine 10, and to assist the start-up and / or the in-flight operation of the turbomachine 10 using electrical sources from the aircraft 100.

[0071] In the embodiment illustrated in Figure 3, the electrical system 3 comprises three electrical sources. The low-pressure body BP is connected to an AC generator 31, coupled to the accessory housing of the low-pressure shaft 181. The high-pressure body HP is connected to an AC generator 32, coupled to the accessory housing of the low-pressure shaft 182. The electrical system 3 also includes a DC power source 33, for example, a battery.

[0072] More generally, this disclosure extends to any multi-source electrical system, comprising one or more alternating current electrical sources and / or one or more direct current electrical sources. Notably, electrical system 3 may not include the direct current source 33.

[0073] The alternating current generator 31, 32 and the direct current source 33 can each independently belong to the turbomachine 10, i.e. be controlled at the same time as the turbomachine 10, or even be controlled by the turbomachine 10. Alternatively or complementaryly, the electrical sources 31, 32, 33 can belong to the aircraft 100, i.e. be controlled at the same time as the aircraft 100.

[0074] Preferably, each electrical source 31, 32, 33 is associated with a respective converter 310, 320, 330, that is, with an element configured to supply electrical power. For example, the alternating current generator 31, 32 is associated with an AC / DC converter 310, 320 enabling the supply of direct current.

[0075] The electrical system 3 includes a distribution bus 30, connected to at least one of the aircraft electrical load Ch1 and the turbomachine electrical load Ch2, preferably to both loads Ch1, Ch2.

[0076] Furthermore, each of the converters 310, 320, 330 is connected to the distribution bus 30.

[0077] The distribution bus 30 is configured to provide electrical power to the electrical load Ch1, Ch2 in the form of a continuous signal in order to meet the power requirements of the electrical load Ch1, Ch2.

[0078] In fact, at least one, if not each, of the converters 310, 320, 330 is configured to regulate the distribution bus 30 in voltage from an electrical power supplied by the respective electrical source 31, 32, 33. The number and type of converters 310, 320, 330 and of electrical sources 31, 32, 33 is, of course, not limiting.

[0079] In order for the elements connected to distribution bus 30, particularly the electrical loads Ch1 and Ch2, to function correctly, it is necessary to regulate the voltage of distribution bus 30. Even if V limits ma x and V mIf the voltage limits of the distribution bus 30 do not initially define constant electrical voltage values, particularly during the characteristic start-up time of the electrical system 3 or during the establishment of a steady state in the event of a power transient, it is common for these limits to subsequently define constant electrical voltage values, in order to guarantee the operational stability of the distribution bus 30 and the electrical system 3. Such a template can, for example, be defined in a standard relating to the quality of the electrical system 3 and / or the DC network, but also be defined by a specification of the aircraft 100 to which the electrical system 3 is connected, typically the requirements of the manufacturer of the aircraft 100 and / or the turbomachine 1 in which the electrical system 3 is integrated.

[0080] On the other hand, the voltage regulation of the distribution bus 30 must meet the power demands of the loads Ch1 and Ch2 connected to the distribution bus 30. Typically, when the amount of power drawn by at least one load Ch1 or Ch2 from the distribution bus 30 is greater than the amount of power injected into the distribution bus 30 by at least one converter 310, 320, or 330, the voltage of the distribution bus 30 decreases significantly. Conversely, when the amount of power injected by at least one converter 310, 320, or 330 into the distribution bus 30 is greater than the amount of power drawn from the distribution bus 30 by at least one load Ch1 or Ch2, the voltage of the distribution bus 30 increases. Thus, regulating the voltage of the distribution bus 30 not only ensures the safety of the electrical system 3 but also meets the power requirements of the loads Ch1 and Ch2.In other words, each of the converters 310, 320, 330 is configured to continuously adapt the power it injects or takes from the distribution bus 30, according to the voltage of the distribution bus 30, so as to meet exactly the power requirements of the loads Ch1, Ch2 connected to the distribution bus 30.

[0081] This injection or withdrawal of power from the distribution bus 30 by the converters 310, 320, 330 is made possible in particular by their connection to the electrical sources 31, 32, 33. In fact, at least one, if not each, of the alternating current generators 31, 32 is connected to a rotating body BP, HP, of the turbomachine 1 to allow an exchange of mechanical and / or electrical power between the rotating body BP, HP and the alternating current generator 31, 32, preferably to withdraw mechanical power from the rotating body BP, HP and transform it into electrical power, which electrical power is then delivered to the first converter 310 and / or the second converter 320 to be injected into the distribution bus 30. In the embodiment illustrated in Figure 3, the first alternating current generator 310 is connected to the body BP, while the second alternating current generator 320 is connected to the body HP.Since the electrical power supplied by the alternating current generators 31, 32 is in the form of an alternating signal, each of the first and second converters 310, 320 is configured to reversibly transform this alternating signal into a direct signal suitable for injection, and then for circulation, on the distribution bus 30.

[0082] Similarly, the DC power source 33 can deliver power in the form of a continuous signal to the third converter 330, which will still convert it, also reversibly, to shape it according to the constraints specific to the distribution bus 30, and then inject it onto the distribution bus 30.

[0083] Each, or at least one, of the alternating current generators 31, 32 can, for example, be a wound-rotor synchronous machine, typically comprising three stages (or "Variable Frequency Generator", VGF in Anglo-Saxon terminology), driven by at least one of the high-pressure shaft 182 and the low-pressure shaft 181 of the turbomachine 1, typically via the accessory gearbox. Other types of electrical machines are conceivable, such as, preferably, permanent-magnet synchronous machines (or "Permanent-Magnet Synchronous Machine Drives", PMSM in Anglo-Saxon terminology), which notably have the advantage of a lower mass, or such as induction machines (or "Induction machines" in Anglo-Saxon terminology) or variable reluctance machines.

[0084] The DC power source 33 may include a battery, a supercapacitor, a DC generator, and / or a fuel cell. The DC power source 33 allows, in particular, for relieving the rotating components BP, HP, or taking over their operation when, for example, the current draw required to meet the power needs of loads Ch1, Ch2 is too high. It also allows for the absorption of certain dynamics, such as sudden variations in the behavior of loads Ch1, Ch2.

[0085] The electrical system 3 includes a control system enabling the control of the electrical sources 31, 32, 33 connected in parallel on the distribution bus 30.

[0086] During operation, the electrical voltage within the distribution bus 30, or bus voltage Vdc, can vary around a given nominal value, or reference voltage V ref, for example, if an electrical load momentarily requires additional power or if a power source disconnects. Thus, the bus voltage Vdc must be regulated by the control system, which controls the power—or current—supplied by each power source 31, 32, 33 connected to the distribution bus 30. Figure 4 illustrates a control system architecture for the proposed power system. The control system comprises a central controller 40 and a plurality of local controllers 311, 321, 331. Each power converter 310, 320, 330 is connected to, or integrated with, a respective local controller.

[0087] The central controller 40 is configured to generate, at a center frequency Fc, local setpoints P respectively associated with the electrical sources 31, 32, 33. The center frequency Fc is limited by the bandwidth available in the communication buses linking the central controller 40 to the various local controllers 311, 321, 331. The electrical power sources 31, 32, 33 may be reversible or not.

[0088] More specifically, the central controller 40 is configured to generate a central power setpoint P ce , then to apply a power sharing function by means of a power sharing unit 42, so as to divide the central setpoint P ce in a plurality of local instructions P directed to the different power sources of the electrical system.

[0089] The bus voltage depends, in particular, on the changing power demands of loads Ch1 and Ch2 connected to the distribution bus 30. Typically, when a load Ch1 or Ch2 suddenly requires a significant amount of power to be drawn from the distribution bus 30, the voltage of the distribution bus 30 will drop sharply due to the response time of the electrical system 3 in supplying the necessary power to the distribution bus 30 to compensate for the power drawn. Similarly, when a load Ch1 or Ch2 suddenly sheds a significant amount of power from the distribution bus 30, the voltage of the distribution bus 30 will rise sharply due to the response time of the electrical system 3 in drawing the necessary power from the distribution bus 30 to compensate for this load shedding.Many Ch1, Ch2 loads, especially so-called "active" loads, typically a de-icing system, can exhibit this type of dynamic behavior, which can also vary during the different phases of flight.

[0090] Preferably, each electrical source 31, 32, 33 is associated with a local sensor configured to provide the associated local controller 311, 321, 331 with a local voltage measurement Vi, m es, specific to the power source considered. The local voltage measurement Vi, mes is typically close to the voltage across the bus terminals, but may not be equal to the distribution bus voltage 30, due to the impedance of the cables connecting the electrical sources 31, 32, 33 to the distribution bus 30. The control system further includes a central computer 4. The central computer 4 may, for example, be all or part of the system providing the interface between the aircraft cockpit 100 and the turbomachine 10 (or "Full Authority Digital Engine Control", FADEC, in Anglo-Saxon terminology), typically be the control unit of the turbomachine 10, ("Electronic Control Unit" or ECU in Anglo-Saxon terminology), integrated into the FADEC. The central computer 4 is connected to the control system, in this case to the power sharing unit 42. The central computer 4 can determine additional constraints to be respected by the electrical system 3 in order to meet the power requirements of the loads Ch1, Ch2.Thus, the central computer 4 can transmit to the power sharing unit 42 a plurality of respective thresholds associated with the electrical sources (called "setpoints" in English).

[0091] The central computer 4 can transmit a distribution instruction for the power taken from the rotating bodies BP, HP and the DC power source 33. The distribution instruction tells the central controller 40 how the total power to be taken from the turbomachine 10 to meet the requirements of the loads Ch1, Ch2 should be distributed between the rotating bodies BP, HP, and the DC power source 33, and can typically take the form of a percentage.

[0092] Figure 4 shows the control system in detail, according to a first embodiment. For clarity, only the local controller 311 associated with the high-pressure shaft is shown in detail; the local controllers 321 and 331 associated with the low-pressure shaft and the battery are represented by blocks. Naturally, the architecture shown for the local controller 311 can also be applied to one or both of the local controllers 321 and 331.

[0093] In general, the central controller 40, for example via the power sharing unit 42, transmits to each of the local controllers 311, 321, 331 a local setpoint P. Typically, the local setpoint P corresponds to a power, a torque or a current intensity, but can also be an electrical voltage.

[0094] The control system is configured to compensate for changes in voltage V <j cof the distribution bus 30 by the action of the converters 310, 320, 330, and in particular maintain the voltage of the distribution bus 30 within the limits allowing stable operation of the electrical system 3, between values ​​V m in and V ma x.

[0095] To achieve this, each local controller 311, 321, 331 is configured to generate, at a local frequency Fl, higher than the center frequency Fc, an output setpoint P cs based on the received local setpoint P. Preferably, the local frequency Fl is at least ten times greater than the center frequency Fc. Typically, the local frequency Fl is equal to 1 kHz, and the center frequency Fc is equal to 10 kHz.

[0096] Thus, each of the converters 310, 320, 330 receives the output command P from the respective local controller 311, 321, 331 cswhich is specific to it, and from which the converter 310, 320, 330 regulates the voltage of the distribution bus 30. The combination of the regulations of each converter 310, 320, 330 thus makes it possible to continuously follow the power requirements of the loads Ch1, Ch2.

[0097] Each local controller 311, 321, 331 is configured to control the associated electrical power source by implementing droop control, based on a droop gain associated with that power source. Droop control consists of allowing the measured local voltage Vi, m The voltage of the power source considered may vary slightly relative to the reference voltage Vi. ref, between a minimum and a maximum value. In what follows, the expression "drift control" should be interpreted as including the application to a signal, in particular within a drift unit 7 of the local controller 311, 321, 331, of a drift gain or coefficient, but without excluding the application of other signal processing steps subsequent to the application of the drift gain. The current intensity (or, equivalently, the power) exiting the drift unit 7 is proportional to the voltage drop seen by the power source, for example, following a load impact. The drift gain is notably applied by the local controller 311, 321, 331 to a difference between a measured voltage Vi, m es of the associated power source and a reference voltage Vi, ref for this same power source. Alternatively, the droop gain is applied by the local controller 311, 321, 331 to a difference between the squares of these values, namely Vi,mes 2 and Vi,ref 2 More generally, the drastic gain can be applied to any value allowing a comparison between the measured local voltage Vi, m es and the local reference voltage Vi, re f. The drowsiness regulation generates a setpoint correction P co that the local controller 311, 321, 331 adds to the local setpoint P sent by the central controller 40, so as to produce the output setpoint P cs The local controller 311, 321, 331 regulates the voltage of its associated electrical power source by means of this output setpoint P cs The instruction correction P co and the output instruction P csare of the same dimension as the associated local setpoint P: this can be a power, a current intensity, or possibly a mechanical torque or a voltage. During a load impact on the distribution bus 30, the drastic control implemented by the local controllers 311, 321, 331 ensures a high-frequency response to the disturbance.

[0098] Due to the voltage variation allowed by the drowsiness regulation, a non-zero error (called "steady-state error") is present in the output setpoint P cs of the local controller 311, 321, 331, including in stabilized mode following the load impact. The contribution of the local setpoint P sent by the central controller 40 to the output setpoint P cs This effectively cancels out this static error. Thus, the proposed control system allows for an adequate response from the electrical system at both high and low frequencies.

[0099] The central controller is also configured to observe output instructions P cs from the different sources of electrical power and to regulate the central setpoint P ce based on these exit instructions P cs . The central controller 40 includes for this purpose a load power estimator 50 which returns to the central controller 40 estimates of loads Ch1, Ch2 taken from the distribution bus 30.

[0100] The regulation performed by the central controller 40 is such that the sum of the local instructions P transmitted by the central controller 40 to the local controllers 311, 321, 331 is equal to the sum of the output instructions P cs generated by local controllers.

[0101] According to one embodiment, the sum of the load estimates Ch1, Ch2 generated by the load power estimator 50 corresponds to the sum of the output setpoints P csfrom the different power sources. Indeed, the output setpoints P cs at a given instant reflect the power required by the loads at a previous instant, due to the drastic regulation performed by the local controllers 311, 321, 331. One advantage of this configuration is that it allows the central controller 40 to establish the central setpoint P ce (and therefore the local instructions P) without requiring information relating to the voltage of the distribution bus 30, for example by a measurement taken by a sensor. Indeed, communication between such a sensor and the central controller 40 could delay the response of the central controller, and therefore of the control system, to a load impact.

[0102] In addition to the exit instructions P cs electrical power sources, other information can be taken into account by the load power estimator 50 in the calculation of the central setpoint P ceIn particular, when the electrical system is installed on board an aircraft, this information may include, but is not limited to: information relating to the bus voltage. Indeed, a drop in bus voltage represents a load demand, while an increase in bus voltage represents a load release; information from the aircraft's electrical cores, allowing for the anticipation of load releases due to the opening of an electrical contactor. This corresponds to a function known as ENMF (Electrical Network Management Function); information from the aircraft's electrical cores, allowing for the anticipation of load releases or demands due to the connection or disconnection of loads on the distribution bus.This corresponds to a function called ELMF (Electrical Load Management Function), information from the turbomachine's own electrical cores, allowing the anticipation of load releases due to the opening of an electrical contactor. This corresponds to a function called EENMF (Electrical Engine Network Management Function), information from the turbomachine's own electrical cores, allowing the anticipation of load releases or inrushes due to the connection or disconnection of loads on the distribution bus 30. This corresponds to a function called EELMF (Electrical Engine Load Management Function), direct measurements taken on certain loads Ch 1, Ch 2.

[0103] Information relating to ENMF, ELMF, EENMF and / or EELMF is particularly advantageous in that it allows us to anticipate a variation in load before it even takes place, these functions being themselves the cause of releases or calls for loads.

[0104] The load power estimator 50 can, in order to estimate load powers, implement several linear or nonlinear estimation / observation techniques based on signals representing the output setpoints, and possibly other information listed above. These estimation / observation techniques may include, but are not limited to:

[0105] UIO: Unknown Input Observer, DOB: Disturbance Observer or POB: Perturbation Observer, ESO: Extended State Observer

[0106] GESO: General Extended State Observer, SMO: Sliding Mode Observer, KF / EKF: Kalman Filter / Extended Kalman Filter

[0107] In some cases, local controllers 311, 321, 331 can introduce biases into the output P instructions cs , so that the central setpoint P ce generated by the central controller 40 is not equal to the sum of the output setpoints P cs . To overcome this problem, the control system may also include an error correction unit 51, which implements regulation based on local setpoints P.

[0108] According to certain embodiments, shown in Figure 5, the error correction unit 51 determines, for each local setpoint P, an error correction AP to be added to the local setpoint P based on the output setpoints P csOne embodiment of the error correction unit 51 is illustrated in Figure 6, in which each error correction AP is obtained by applying an error correction function to the difference between the local setpoint P and the output setpoint P cs of the associated power source. For example, when the control system includes three local controllers 311, 321, and 331 associated respectively with a low-pressure (LP) shaft of a turbomachine, a high-pressure (HP) shaft of the turbomachine, and a battery, the error correction AP311 for the high-pressure shaft is obtained from the difference between the local setpoint P311 for the high-pressure shaft and the output setpoint P cs ,3n for the high-pressure shaft; the AP321 error correction for the low-pressure shaft is obtained from the difference between the local setpoint P321 for the low-pressure shaft and the output setpoint P cs.32i for the low-pressure shaft; and the AP331 error correction for the battery is obtained from the difference between the local P331 setpoint for the battery and the output P setpoint cs .33i for the battery. Each AP error correction can, for example, be the difference between the local setpoint P and the output setpoint P cs associated.

[0109] According to another embodiment, illustrated in Figure 7, the central controller further comprises a conversion unit 52. The error correction unit 51 then generates, for each power source, an error correction power AP from the difference between the local setpoint P and the output setpoint P csassociated with this power source. Then, the conversion unit 52 converts each error correction power AP into an error correction voltage AV, so that the droop regulation is operated by the local controller 311 from: the reference parameter representing the local reference voltage Vi, re f, of the measured voltage parameter representative of the measured local voltage Vi, m es, and the AV error correction voltage

[0110] The proposed control system is suitable for a hybrid electrical system of a turbomachine, particularly an aircraft turbomachine, by satisfying power-sharing criteria between electrical sources. Applying drastic control at each source, due to the voltage variation it allows, prevents instability caused by the simultaneous response of each local controller to a load impact. Indeed, in an electrical system with multiple local controllers that generate a single local voltage setpoint for their respective power sources, a load impact triggers a simultaneous response from each local controller, which can either increase or decrease the bus voltage (VB). <j c beyond a reference value V re f (in English, this is referred to as "overshoot" or "undershoot"), generating an oscillatory behavior of the bus frequency V <j caround the reference value V re f. In addition, thanks to the possibility of predicting different values ​​of static gain K for the different local controllers 311, 321, 331, the proposed system advantageously allows great control of the sharing of power between the sources - it is thus possible to take more power from one source than from another, depending in particular on the flight phases of the aircraft.

[0111] Another advantage of the proposed system is that, thanks to the local controllers 311, 321, 331, it allows for regulation of the bus voltage V <j c even in the event of loss of the central controller 40.

[0112] Besides the fact that a power sharing between the different sources can advantageously be defined by means of the values ​​of the static coefficients K of each static unit 7, the static coefficients K must be chosen so that each power source can respond sufficiently quickly to the load impact, the response of the local controllers 311, 321, 331 being dominant over the response of the central controller 40 immediately after the load impact.

[0113] This application also relates to a method for regulating the voltage of a distribution bus linking power sources of an electrical system, illustrated in Figure 8. The method is implemented by the control system described above.

[0114] The central controller generates, taking into account the output instructions P cs , a central instruction P cewhich is then shared between the power sources by a power sharing unit 42 of the central controller 40, i.e., the power sharing unit 42 divides the central setpoint P ce in a plurality of local setpoints P, each associated with a power source. This power sharing is achieved through a power distribution setpoint C pp originating from the turbomachine control unit 10, or from another computer separate from the control unit, one function of this computer being to ensure power sharing between sources. The power sharing setpoint C pp is transmitted by the control unit or the computer to the power sharing unit 42 of the central controller 40.

[0115] Each local controller 311, 321, 331 receives one of the local instructions generated by the central controller 40, and implements a drowsiness regulation based on a parameter representative of the local reference voltage Vi, re f and a parameter representative of a measured local voltage Vi, m es of the power source associated with the received local setpoint (P), so as to generate a setpoint correction (P co ). The static regulation is implemented as explained previously.

[0116] Based on the local setpoint P received from the central controller 40 and the setpoint correction Pco, each local controller generates an output setpoint P cs by means of which it controls the power source associated with it. Finally, as soon as output commands P csThese signals were issued by the various local controllers 311, 321, 331; they are transmitted to the load power estimator 51 of the central controller 40, which regulates the central setpoint P ce based on the exit instructions P cs .

Claims

DEMANDS 1. Control system for controlling an electrical system, the electrical system comprising a plurality of power sources connected in parallel to a distribution bus (30), the control system comprising: • a central controller (40) configured to: o generate a central setpoint (P ce ) and to divide the central setpoint (P ce ) in local instructions (P) respectively associated with the power sources, • local controllers (311, 321, 331) in communication with the central controller (40), each local controller being configured to: o receive one of the local instructions (P), o implement a drastic control based on a reference parameter representing a local reference voltage (Vi, ref) and a measured voltage parameter representative of a measured local voltage (Vi,mes) of the power source associated with the received local setpoint (P), so as to generate a setpoint correction (P co ), and to generate an output instruction (P cs ) from the received local setpoint (P) and the setpoint correction (P co ), or to control one of the power sources using the output setpoint (Pcs), in which the central controller (40) is configured to regulate the central setpoint (P ce ) from signals representative of each output instruction (P cs ), the regulation by the central controller (40) being such that a sum of the local instructions (P) received by the local controllers (311, 321, 331) is equal to the sum of the output instructions (P cs ) generated by the local controllers (311, 321, 331).

2. Control system according to claim 1, wherein the central controller generates the central setpoint (P ce ) from signals representing loads taken from the power sources and at least one of the following: • a voltage across the terminals of the distribution bus (30) measured or estimated from the measured local voltages (Vi, m es) power sources, • information relating to a future opening of an electrical contactor on an aircraft or turbomachine, • information relating to a future connection or disconnection of an electrical load on the distribution bus (30), a direct measurement performed on an electrical charge.

3. A control system according to any one of claims 1 and 2, wherein the central controller is further configured to: - calculate an error correction power (AP) from the difference between the local setpoint (P) and the output setpoint (Pcs), and - regulate the local setpoint (P) by adding the error correction power (AP) to the local setpoint (P).

4. A control system according to any one of claims 1 and 2, wherein the central controller is further configured to: - calculate an error correction power (AP) from the difference between the local setpoint (P) and the output setpoint (Pcs), and - convert the error correction power (AP) into an error correction voltage (AV), and in which the drastic regulation is implemented from the reference parameter, the measured voltage parameter and the error correction voltage (AV).

5. Electrical system comprising: - a plurality of power sources connected in parallel to a distribution bus, and - a control system according to any one of claims 1 to 4.

6. Electrical system according to claim 5, wherein the local controllers are respectively associated with the power sources, and wherein a current supplied by each power source depends on the output setpoint (Pcs) generated by the respective local controller.

7. A method for controlling an electrical system comprising power sources and a distribution bus to which the power sources are connected, the method being implemented by a control system comprising a central controller (40) and local controllers (311, 321, 331) associated respectively with the power sources, the method comprising the steps of: • generation, by the central controller (40), of a central setpoint (P ce) and division by the central controller of the central setpoint (P ce ) in a plurality of local instructions (P) respectively associated with the power sources, • receipt, by each local controller (311, 321, 331), of one of the local instructions (P), • implementation, by each local controller, of a static regulation based on a reference parameter representative of a local reference voltage (Vi, re f) and a measured voltage parameter representative of a measured local voltage (Vi,mes) of the power source associated with the received local setpoint (P), so as to generate a setpoint correction (P co ), • generation, by each local controller (311, 321, 331), of an output setpoint (Pcs) from the received local setpoint (P) and the setpoint correction (P co ), • control, by each local controller (311, 321, 331), of the respective power source using the output setpoint (P cs ), • regulation, by the central controller (40), of the central setpoint (P ce ) from signals representative of the output instructions (P cs ).

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