Parallel power source control system with load estimation

Abstract

This disclosure relates to a control system for an electrical system comprising a plurality of power sources. The control system comprises: a central controller (40) configured to generate a central setpoint (Pce) and 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 to generate a setpoint correction (Pco), and generate an output setpoint (Pcs) from the received local setpoint (P) and the setpoint correction (Pco), control one of the power sources using the output setpoint (Pcs); and the central controller (40) is configured to regulate the central setpoint (Pce) from signals representative of each output setpoint (Pcs). (Shortcut Figure: Fig. 4)

Description

Title of the invention: Control system for parallel power sources with load estimation. Technical field

[0001] This disclosure relates to the general field of electrical source control systems, and in particular voltage regulation when electrical sources are connected in parallel by a centralized controller. STATE OF THE ART

[0002] 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 operation, 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.

[0003] 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 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] 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 the use of electric technologies for propulsion.

[0005] An aircraft generally comprises an electrical network powered by various sources and is propelled by a turbomachine. In order to improve the aircraft's energy efficiency, it is possible to implement internal hybridization of the turbomachine. This involves adding a hybrid electrical system that forms an interface between the rotating mechanical shafts of the turbomachine and the aircraft's electrical network. The hybrid electrical system aims to assist the turbomachine in order to optimize its operation by providing assistance electrical or by drawing power. It must control the sharing of power between the high-pressure and low-pressure mechanical shafts of the turbomachine, and in particular limit the power drawn, ensuring that all sources provide a good supply to the aircraft's electrical network.

[0006] A first proposed solution is an electrical system with a plurality of decentralized or local controllers. In this case, the low-pressure shaft and the high-pressure shaft are controlled independently and are voltage-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. Thus, the bus voltage that one seeks to regulate is strongly affected by local measurement errors.

[0007] 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 present in an aircraft are distributed throughout it 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.

[0008] In both centralized and decentralized architectures, regulating the voltage across the distribution bus requires the central controller to have access to a value of this bus voltage. Specifically, the bus voltage is monitored by the central controller to enable its regulation by the central controller or local controllers. It is therefore necessary to provide for the acquisition of measurements on the voltage bus by the central controller. Here too, communication between the central controller and the sensors intended to acquire these measurements can be slow and delay the control system's response to a load impact. EXPOSE

[0009] One object of the invention is therefore to provide a control system for an electrical system that can more quickly regulate the voltage of the distribution bus of the electrical system in the event of a load impact on the bus.

[0010] 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: • a central controller configured to: • generate a central instruction and • divide the central setpoint into local setpoints, each associated with a specific power source. • local controllers communicating with the central controller, each local controller being configured to: • receive one of the local instructions, • implement 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, and • generate an output instruction from the received local instruction and the instruction correction, • control one of the power sources using the output setpoint,

[0011] wherein the central controller is configured to regulate the central setpoint from signals representative of each output setpoint.

[0012] 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 makes it possible to compensate for the steady-state error in the output setpoint due to each respective local controller, without requiring the central controller to receive additional information beyond that already necessary for regulating the power sources, including the output setpoints. This results in a control system that is responsive to a load impact and allows for the regulation of the electrical system's bus voltage without steady-state error.

[0013] 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 terminals, measured or estimated from local voltages measured from the 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, • a direct measurement performed on an electrical charge.

[0014] According to some embodiments, the central controller is further configured to:

[0015] - calculate an error correction power from the difference between the local instructions and exit instructions, and

[0016] - regulate the local setpoint by adding the error correction power to the local instructions.

[0017] According to some embodiments, the central controller is further configured to:

[0018] - calculate an error correction power from the difference between the local instructions and exit instructions, and

[0019] - convert the error correction power into an error correction voltage,

[0020] and the static regulation is implemented from the reference parameter, of the measured voltage parameter and error correction voltage.

[0021] An electrical system is further proposed comprising:

[0022] - a plurality of power sources connected in parallel to a bus of distribution, and

[0023] - a control system as defined above.

[0024] 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.

[0025] A method for controlling an electrical system comprising power sources and a distribution bus to which the power sources are connected is further proposed, 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, • receipt, by each local controller, of one of the local instructions, • 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, • generation, by each local controller, of an output setpoint based on the received local setpoint and the setpoint correction, • control, by each local controller, of the respective power source using the output setpoint, • regulation, by the central controller, of the central setpoint from signals representative of the output setpoints. DESCRIPTION OF THE FIGURES

[0026] Other features, purposes and advantages will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0027] [Fig.1] schematically represents an aircraft;

[0028] [Fig. 2] schematically represents a turbomachine;

[0029] [Fig.3] represents an electrical system of the aircraft, according to an embodiment comprising three power sources;

[0030] [Fig.4] represents a control system for the electrical system of the [Fig.3], according to a first embodiment;

[0031] [Fig.5] represents a control system for the electrical system of the [Fig.3], according to a second embodiment;

[0032] [Fig.6] represents an error correction unit of the control system shown in [Fig.5];

[0033] [Fig.7] represents a control system for the electrical system of the [Fig.3], according to a third embodiment;

[0034] [Fig.8] represents a method for regulating the voltage of the distribution bus linking the power sources of the electrical system.

[0035] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION

[0036] In the present 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.

[0037] By way of illustration, [Fig. 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.

[0038] Description of the turbomachine

[0039] Fig. 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.

[0040] The propulsion unit 1 is intended to be mounted on the aircraft 100. In this respect, the propulsion unit 1 may include a pylon (not shown) intended to connect the propulsion assembly 1 to a part of the aircraft 100, transmitting the forces to the aircraft 100.

[0041] This disclosure is not limited to a twin-spool, twin-flow turbojet with direct fan drive 11 as illustrated. It extends more generally to different turbojet architectures, including unfaired turbojets, and other types of turbomachinery, which may have a different number of bodies and / or flows.

[0042] The present 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.

[0043] 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.

[0044] 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 seen in the [Fig.2], the compression section 16, the combustion chamber 14 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 flow A.

[0045] 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.

[0046] 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.

[0047] The turbomachine 10 may also include at least one accessory gearbox (AGB), typically housed in a cavity within the nacelle 20. The accessory gearbox 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, optionally via a transfer case, the accessory gearbox to at least one of the high-pressure (HP) and low-pressure (LP) cylinders. For example, the power take-off shaft (not shown) can extend inside a longitudinal cavity formed within an arm 17.In this way, mechanical power is likely to be taken from at least one of the high-pressure (HP) and low-pressure (BP) bodies to be delivered to at least one of the accessories via the accessory box.

[0048] Aircraft electrical system 100

[0049] In a manner known per se, the aircraft 100 comprises a plurality of electrical loads (or receivers) powered by electrical sources via an electrical network.

[0050] An electric 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.

[0051] With reference to [Fig. 3], the electrical loads can be divided into two categories. A first category of loads Chl is external to the propulsion system 1. The electrical loads Chl specific to the aircraft 100 may include, by way of example, an electric motor, a heating and / or air conditioning system, or a compressor. They enable, in particular, a number of functionalities, whether the aircraft is in flight or in operation on the ground, such as pressurizing and / or illuminating the cabin of the aircraft 100, or operating the cockpit.

[0052] A second category of loads is internal to the propulsion unit 1. The propulsion unit 1 comprises the turbomachine 10, detailed above. The electrical loads Ch2 of the propulsion unit are loads of the turbomachine 10 (the "More Electric Engine" or MEE in Anglo-Saxon terminology). For example, the loads Electrical components of the Ch2 turbomachine may include a starter, variable geometries, or de-icing systems.

[0053] The plurality of electrical sources makes it possible to supply electrical loads with electrical energy, generally in the form of a continuous signal, typically a direct voltage.

[0054] On the one hand, the turbomachine 10 generally comprises two low-pressure shafts 181 and high-pressure shafts 182, which provide mechanical energy. Each shaft is associated with a generator motor allowing mechanical extraction from the associated shaft and conversion into electrical energy, in order to supply the electrical grid.

[0055] On the other hand, the aircraft 100 includes a plurality of electrical sources distributed throughout the 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.

[0056] The electrical network typically comprises a set of electrical conductors, typically a set of cables connecting the different electrical loads and the different sources, and bars, for example a high-voltage direct current distribution bus.

[0057] Generally, generator motors that extract mechanical energy from shafts produce alternating current. The alternating current is converted into direct current by an AC / DC converter. The electrical network includes at least a portion of a direct current network, with electrical loads being supplied with direct current.

[0058] Fig. 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 Chl and / or the electrical loads of the turbomachine Ch2, typically by means of the direct current network.

[0059] 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 Chl and / or the turbomachine Ch2 by mechanically drawing power from the turbomachine 10, and to assist the starting and / or in-flight operation of the turbomachine 10 using electrical sources from the aircraft 100.

[0060] In the embodiment illustrated in [Fig. 3], the electrical system 3 comprises three electrical sources. The low-pressure body BP is connected to an alternating current generator 31, coupled to the accessory housing of the low-pressure shaft 181. The high-pressure body HP is connected to an alternating current generator 32, coupled to the accessory housing of the low-pressure shaft 182. The electrical system 3 also comprises a direct current source 33, for example, a battery.

[0061] 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. In particular, electrical system 3 may not include the direct current source 33.

[0062] 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.

[0063] 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.

[0064] The electrical system 3 includes a distribution bus 30, connected to at least one of the aircraft electrical load Chl and the turbomachine electrical load Ch2, preferably to both loads Chl, Ch2.

[0065] Furthermore, each of the converters 310, 320, 330 is connected to the distribution bus 30.

[0066] The distribution bus 30 is configured to supply electrical power to the electrical load Chl, Ch2 in the form of a continuous signal in order in particular to meet the power requirements of the electrical load Chl, Ch2.

[0067] 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.

[0068] In order for the elements connected to the distribution bus 30, in particular the electrical loads Chl, Ch2, to function correctly, it is necessary to regulate the voltage of the distribution bus 30. Even if the Vmax and Vmin limits of the voltage of the distribution bus 30 do not define constant electrical voltage values ​​initially, particularly during the characteristic start-up time (or start-up) of the electrical system 3 or during the time of establishing a steady state in the event of a power transient, it is common for these limits to then define constant electrical voltage values, in order to guarantee the stability of operation 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.

[0069] Furthermore, the voltage regulation of the distribution bus 30 must be able to meet the power demands of the loads Chl, Ch2 connected to the distribution bus 30. Typically, when the amount of power drawn by at least one load Chl, 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, 330, the voltage of the distribution bus 30 decreases significantly. Conversely, when the amount of power injected by at least one converter 310, 320, 330 into the distribution bus 30 is greater than the amount of power drawn from the distribution bus 30 by at least one load Chl, Ch2, the voltage of the distribution bus 30 increases. Thus, regulating the voltage of the distribution bus 30 makes it possible, in addition to ensuring the safety of the electrical system 3, to meet the power requirements of the loads Chl, Ch2.In other words, each of the converters 310, 320, 330 is configured to continuously adapt the power it injects or draws 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 Chl, Ch2 connected to the distribution bus 30.

[0070] 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 onto the distribution bus 30. In the embodiment illustrated in [Fig. 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.

[0071] As 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.

[0072] Similarly, the DC power source 33 can deliver power in the form of a continuous signal to the third converter 330, which will nevertheless 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.

[0073] 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 have the particular advantage of having a lower mass, or such as induction machines (or "Induction machines" in Anglo-Saxon terminology) or variable reluctance machines.

[0074] The DC power source 33 may, for its part, comprise a battery, a supercapacitor, a DC generator, and / or a fuel cell. The DC power source 33 makes it possible, in particular, to relieve the rotating bodies BP, HP, or to take over their operation when, for example, the current draw required to meet the power needs of the loads Chl, Ch2 is too high, but it also makes it possible to absorb certain dynamics, such as sudden variations in the behavior of the loads Chl, Ch2.

[0075] The electrical system 3 includes a control system for controlling the electrical sources 31, 32, 33 connected in parallel on the distribution bus 30.

[0076] During operation, the electrical voltage within the distribution bus 30, or bus voltage Vdc, may vary around a given nominal value, or reference voltage Vref, for example, if an electrical load momentarily requires additional power or if an electrical source disconnects. Therefore, the bus voltage Vdc must be regulated by the control system that controls the power—or current—supplied by each electrical source 31, 32, 33 connected to the distribution bus 30.

[0077] Figure 4 illustrates a control system architecture for the proposed electrical 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.

[0078] 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.

[0079] More specifically, the central controller 40 is configured to generate a central power setpoint Pce, and then to apply a power sharing function by means of a power sharing unit 42, so as to divide the central setpoint Pce into a plurality of local setpoints P for the different power sources of the electrical system.

[0080] The bus voltage depends in particular on the changing power requirements of the loads Chl, Ch2 connected to the distribution bus 30. Typically, when a load Chl, 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 distribution bus 30 with the power needed to compensate for the power drawn. Similarly, when a load Chl, 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 Chl and Ch2 charges, particularly so-called "active" charges, typically a de-icing system, can exhibit this type of dynamic behavior, which can also vary during the different phases of flight.

[0081] Preferably, each power 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 Vimes, specific to the power source in question. The local voltage measurement Vimes 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 power sources 31, 32, 33 to the distribution bus 30.

[0082] 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"). The control unit (FADEC, in Anglo-Saxon terminology) typically serves as the control unit for 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, specifically the power sharing unit 42. The central computer 4 can determine additional constraints that the electrical system 3 must meet to fulfill the power requirements of loads C1, 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).

[0083] The central computer 4 can transmit a distribution instruction for the power taken between 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 Chl, 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.

[0084] 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 has been shown in detail; the local controllers 321 and 331 associated with the low-pressure shaft and the battery have been 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.

[0085] Generally, 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.

[0086] The control system is configured to compensate for changes in the Vdc voltage of the distribution bus 30 by the action of the converters 310, 320, 330, and in particular to maintain the voltage of the distribution bus 30 within the limits allowing stable operation of the electrical system 3, between values ​​Vmin and Vmax.

[0087] To do 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 Pcs from the received local setpoint P.

[0088] 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.

[0089] Thus, each of the converters 310, 320, 330 receives from the respective local controller 311, 321, 331 its own output command PCS, 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 Chl, Ch2.

[0090] 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 Vimes of the power source in question to vary slightly relative to the reference voltage Vef, between a minimum and a maximum value. In what follows, the expression "droop control" should be interpreted as including the application to a signal, particularly within a droop unit 7 of the local controller 311, 321, 331, of a droop gain or coefficient, but without excluding the application of other signal processing steps subsequent to the application of the droop gain.The current intensity (or, equivalently, the power) output from the droop unit 7 is proportional to the voltage drop seen by the power source, for example, following a load impact. The droop gain is applied by the local controller 311, 321, 331 to the difference between a measured voltage Vi>mes of the associated power source and a reference voltage Vi>ref for that same power source. Alternatively, the droop gain is applied by the local controller 311, 321, 331 to the difference between the squares of these values, namely Vi>mes² and Vi>ref². More generally, the droop gain can be applied to any value that allows a comparison between the measured local voltage Vi>mes and the reference local voltage V1>ref.The drastic control generates a setpoint correction Pco, which the local controller 311, 321, 331 adds to the local setpoint P sent by the central controller 40, thus producing the output setpoint Pcs. The local controller 311, 321, 331 regulates the voltage of its associated electrical power source using this output setpoint Pcs. The setpoint correction Pco and the output setpoint Pcs are of the same magnitude as the associated local setpoint P: it can be a power, a current, or possibly a mechanical torque or a voltage.

[0091] During a load impact on the distribution bus 30, the static regulation implemented by the local controllers 311, 321, 331 ensures a high-frequency response to the disturbance.

[0092] Due to the voltage variation permitted by the drastic control, a non-zero error (called "drastic error") is present in the output setpoint Pcs of the local controller 311, 321, 331, even in steady-state operation following load impact. The contribution of the local setpoint P sent by the central controller The 40 value in the output setpoint Pcs advantageously 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.

[0093] The central controller is further configured to observe the output setpoints Pcs from the various electrical power sources and to regulate the central setpoint Pce based on these output setpoints Pcs. For this purpose, the central controller 40 includes a load power estimator 50 which returns to the central controller 40 estimates of the loads Chl, Ch2 taken from the distribution bus 30.

[0094] According to one embodiment, the sum of the load estimates Chl, Ch2 generated by the load power estimator 50 corresponds to the sum of the output setpoints Pcs of the different power sources. Indeed, the output setpoints Pcs at a given instant reflect the power required by the loads at an earlier instant, due to the drastic regulation performed by the local controllers 311, 321, 331. An advantage of this configuration is that it allows the central controller 40 to establish the central setpoint Pce (and therefore the local setpoints P) without requiring information relating to the voltage of the distribution bus 30, for example, through a measurement taken by a sensor. In fact, 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.

[0095] In addition to the output setpoints Pcs of the electrical power sources, other information may be taken into account by the load power estimator 50 in the calculation of the central setpoint Pce. In 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 systems, allowing for the anticipation of charge 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 load demands due to the connection or disconnection of loads from the distribution bus 30. This corresponds to a function called ELMF ("Electrical Load Management Function"). - Information from the turbomachine's own electrical cores, allowing for the anticipation of charge releases due to the opening of an electrical contactor. This corresponds to a function called EENMF ("Electrical Engine Network Management Function"). - information from electrical cores specific to the turbomachine, allowing anticipation of load releases or load demands due to the connection or disconnection of loads from the distribution bus 30. This corresponds to a function called EELMF (“Electrical Engine Load Management Function”, or electrical engine load management function in French), - direct measurements carried out on certain Chl, Ch2 charges.

[0096] Information relating to ENMF, ELMF, EENMF and / or EELMF is particularly advantageous in that it allows one to anticipate a variation in load before it even takes place, these functions being themselves at the origin of releases or calls for loads.

[0097] The load power estimator 50 can, in order to estimate the load powers, implement several linear or nonlinear estimation / observation techniques based on signals representing the output setpoints, and possibly the other information listed above. These estimation / observation techniques may include, but are not limited to: - UIO: Unknown Input Observer - DOB: Disturbance Observer or POB: Perturbation Observer (perturbation observer), - ESO: Extended State Observer - GESO: General Extended State Observer - SMO: Sliding Mode Observer - KF / EKF: Kalman filter / extended Kalman filter

[0098] In some cases, the local controllers 311, 321, 331 may introduce biases in the output commands Pcs, such that the central command Pce generated by the central controller 40 is not equal to the sum of the output commands Pcs. To overcome this problem, the control system may further include an error correction unit 51, which implements regulation based on the local commands P.

[0099] According to certain embodiments, shown in [Fig. 5], the error correction unit 51 determines, for each local setpoint P, an error correction AP to be added to the local setpoint P from the output setpoints Pcs. One embodiment of the error correction unit 51 is illustrated in [Fig. 6], for which each error correction AP is obtained by applying a correction function error correction is based on the difference between the local setpoint P and the output setpoint Pcs of the associated power source. For example, when the control system includes three local controllers 311, 321, and 331 associated respectively with a BP shaft of a turbomachine, an HP shaft of the turbomachine, and a battery, the error correction AP3n for the high-pressure shaft is obtained from the difference between the local setpoint P3[i for the high-pressure shaft and the output setpoint PCSj3n for the high-pressure shaft; the error correction AP32i for the low-pressure shaft is obtained from the difference between the local setpoint P32i for the low-pressure shaft and the output setpoint PCSj32i for the low-pressure shaft; and the error correction AP33i for the battery is obtained from the difference between the local setpoint P33[ for the battery and the output setpoint PCSj33i for the battery.Each error correction AP can, for example, be the difference between the local setpoint P and the associated output setpoint Pcs.

[0100] According to another embodiment, illustrated in [Fig. 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 Pcs associated with that power source. Then, the conversion unit 52 converts each error correction power AP into an error correction voltage AV, so that the droop control is performed by the local controller 311 from: - of the reference parameter representing the local reference voltage Vijref - the measured voltage parameter representative of the measured local voltage Vi and vl, my 9 - of the AV error correction voltage

[0101] The proposed control system is suitable for a hybrid electrical system of a turbomachine, particularly an aircraft turbomachine, by allowing it to meet power sharing criteria between the electrical sources. The application of drastic control at the level of each source makes it possible, due to the voltage variation it allows for the source, to avoid instability due to the simultaneous response of each local controller to the load impact. Indeed, in the case where an electrical system includes several local controllers that generate a simple local voltage setpoint for their respective power sources, a load impact generates a simultaneous response from each local controller that can increase or decrease the bus voltage Vdc beyond a reference value Vref (this is referred to in English as "overshoot" or "undershoot"), generating an oscillatory behavior of the bus frequency Vdc around the reference value Vref. Furthermore, 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 on the flight phases of the aircraft in particular.

[0102] Another advantage of the proposed system is that, thanks to the local controllers 311, 321, 331, it allows regulation of the bus voltage Vdc even in the event of loss of the central controller 40.

[0103] 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.

[0104] This application further relates to a method for regulating the voltage of a distribution bus connecting power sources of an electrical system, illustrated in [Fig. 8]. The method is implemented by the control system described above.

[0105] The central controller generates, taking into account the output setpoints Pcs, a central setpoint Pce which is then shared among the power sources by a power sharing unit 42 of the central controller 40. That is to say, the power sharing unit 42 divides the central setpoint Pce into a plurality of local setpoints P, each associated with a power source. This power sharing is carried out by means of a power distribution setpoint Cpp 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 distribution setpoint Cpp is transmitted by the control unit or the computer to the power sharing unit 42 of the central controller 40.

[0106] Each local controller 311, 321, 331 receives one of the local setpoints generated by the central controller 40, and implements droop control based on a parameter representing the local reference voltage Vijref and a parameter representing a measured local voltage Vi>mes of the power source associated with the received local setpoint (P), so as to generate a setpoint correction (Pco). The droop control is implemented as explained previously.

[0107] Based on the local setpoint P received from the central controller 40 and the setpoint correction Pco, each local controller generates an output setpoint Pcs by means of which it controls its associated power source. Finally, from then on that output instructions Pcs have been issued by the different local controllers 311, 321, 331, these are transmitted to the load power estimator 51 of the central controller 40, which regulates the central setpoint Pce from the output instructions Pcs.

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: • generate a central setpoint (Pce) and • divide the central setpoint (Pce) into local setpoints (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: • receive one of the local setpoints (P), • implement drastic control based on a reference parameter representing a local reference voltage (Vi^f) and a measured voltage parameter representing a local measured voltage (Vi>mes) of the power source associated with the received local setpoint (P),so as to generate a setpoint correction (Pco), and • generate an output setpoint (Pcs) from the received local setpoint (P) and the setpoint correction (Pco), • control one of the power sources using the output setpoint (Pcs), wherein the central controller (40) is configured to regulate the central setpoint (Pœ) from signals representative of each output setpoint (Pcs).

2. Control system according to claim 1, wherein the central controller generates the central setpoint (Pœ) from representative load signals taken from the power sources and from at least one of: • a voltage across the distribution bus (30) measured or estimated from the measured local voltages (Vi>mes) of the power sources, • information relating to a future opening of an electrical contactor of an aircraft or turbomachine, • information relating to a future connection or disconnection of an electrical load on the distribution bus (30), • a direct measurement carried out on an electrical load.

3. 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. 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 wherein the droop control 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 process comprising the steps of: • generation, by the central controller (40), of a central setpoint (Pce) and division by the central controller of the central setpoint (Pce) into a plurality of local setpoints (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 drastic regulation based on a reference parameter representing a local reference voltage (V^f) and a measured voltage parameter representing a local measured voltage (Vi>mes) of the power source associated with the received local setpoint (P), so as to generate a setpoint correction (Pco), • generation, by each local controller (311, 321, 331), of an output setpoint (Pcs) from the received local setpoint (P) and the setpoint correction (Pco), • control, by each local controller (311, 321, 331), of the respective power source using the output setpoint (Pcs), • regulation, by the central controller (40), of the central setpoint (Pce) from signals representative of the output setpoints (Pcs).

Images