Method for controlling a hybrid ratio of a hybrid turbomachine

Abstract

The invention relates to a method (100) for controlling a hybridization rate of a hybrid turbomachine, the control method (100) comprising at least: - a step (102) of determining an electric torque control saturation, in particular based on a first static saturation law and a first dynamic saturation law, wherein the dynamic saturation law is defined in particular based on a target hybridization rate; - a step (103) of determining a fuel-flow control saturation; - a step (105) of determining an electric torque control and a fuel-flow control using a corrector, the corrector taking into account at least: - a difference between an engine speed to be reached and a current engine speed, - the electric torque control saturation, and - the fuel-flow control saturation, so as to obtain the target hybridization rate.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of turboengines for aeronautical applications, in particular to the field of hybrid turboengines. The present invention relates to a method for controlling the hybridization rate of a hybrid turboengine. The present invention also relates to a hybrid turboengine implementing the method for controlling the hybridization rate. Finally, the present invention also relates to an aircraft comprising a hybrid turboengine according to the present invention. BACKGROUND

[0002] Today, the hybridization of turboengines meets various needs, such as limiting exhaust gas temperature, distributing power withdrawal between different bodies (parts) of the turboengine, adjusting the engine operating line during engine transients, and optimizing stability.

[0003] Driving a hybrid turboengine is performed using multivariable closed loops, which take as input a speed trajectory command. These closed loops give as output a fuel flow command and an electric torque command for each motor in the turboengine.

[0004] A dual-rotor / bypass hybrid turboengine comprises a low-pressure motor connected to a low-pressure shaft and a high-pressure motor connected to a high-pressure shaft. In this case, the multivariable closed loops will have as output three commands:

[0005] - a fuel flow command,

[0006] - a low-pressure motor torque control, and

[0007] - a high-pressure electric torque command.

[0008] In automatic control, a system with a different number of input and output commands is called a rectangular system, in particular a MISO type system (i.e. "Multiple Input Single Output"), a SIMO type system (i.e. "Single Input Multiple Output") or a MIMO type system (i.e. "Multiple Input Multiple Output"). In other words, a single command must regulate at least two commands.

[0009] This arrangement is problematic because the system has only a single error rejection dynamic. Therefore, the distribution of the commands is fixed and it is not possible to change it dynamically.

[0010] By contrast, in a traditional automatic control problem, the goal is to obtain a square system with the same number of commands as the number of instructions. This arrangement makes it possible to influence two commands by changing two instructions.

[0011] In the case of a hybrid turbogenerator, the system equations make it possible to calculate the energy split between fuel flow and electric torque. When a speed increment is made, this can only be done using either the fuel flow or the electric torque, and is intrinsically linked to the machine sizing. In this case, the fuel flow and the electric torque will always maintain the same ratio in the corrector, and the hot / electric hybridization rate cannot be modified when the regulator is in use.

[0012] In other words, in a hybrid turbogenerator, according to the prior art, the hot / electric energy split remains constant over time and is set by the operating point of the engine and the design of the different components of the machine. If operating at a given speed, the split between fuel flow and electric torque is always the same.

[0013] However, this method for controlling a hybrid turbogenerator is not satisfactory because it does not allow the hybridization rate of the fuel flow / electric torque to be modified.

[0014] In particular, it is not possible to adapt the hybridization rate as a function of other operating parameters of the hybrid turbogenerator. For example, it is not possible to dynamically modulate the hybridization rate in response to the battery charge level or the complete or partial unavailability of the electrical power supply, in particular due to a fault. SUMMARY

[0015] The invention provides a solution to at least some of the problems discussed previously by a method for controlling the hybridization rate of fuel flow / electric torque in a hybrid turbogenerator. This is achieved by dynamically modifying the saturation of the commands, thereby obtaining a constraint on one of the energy sources and a compensation on the other.

[0016] To this end, a first aspect of the invention is a method for controlling the hybridization rate of a hybrid turbogenerator, the control method comprising at least:

[0017] o a step of determining the saturation of the electric torque command, in particular as a function of a static saturation law and a first dynamic saturation law, in which the dynamic saturation law is defined by a target hybridization rate;

[0018] o a step of determining the saturation of the fuel flow command;

[0019] o a step of determining the electric torque command and the fuel flow command using a corrector, the corrector taking into account at least:

[0020] o the difference between the engine speed to be reached and the current engine speed,

[0021] o saturation of the fuel flow command, and

[0022] o saturation of the fuel flow command,

[0023] so as to obtain a target hybridization rate.

[0024] As regards the "hybridization rate", it means the fuel flow rate / electric torque rate applied to the turbomachine.

[0025] As regards the "static saturation law", it means a criterion expressing the protective saturation of the fuel flow and electric torque commands.

[0026] As regards the "dynamic saturation law", it means a criterion related to the target hybridization rate.

[0027] More precisely, the static saturation is fixed since it is considered a priori in the definition of the regulator.

[0028] On the contrary, the dynamic saturation depends on parameters external to the regulator and thus cannot be considered in the definition of the regulator.

[0029] Within the scope of the invention, it is proposed to act dynamically, i.e. during the use of the turbomachine under regulation, on the saturation depending on thermodynamic parameters which are not strictly static.

[0030] As regards the "corrector" or "regulator", it means a control loop which produces an output parameter to be obtained in order to follow at least one instruction, such as the fuel flow command and the electric torque command applied to the hybrid turbomachine.

[0031] As regards the "current engine speed", it means the engine speed at the time of application of the control method according to the invention.

[0032] The control method according to the invention dynamically modifies the saturation, and thus the thermal / electric hybridization rate. In other words, the saturation is no longer considered only as a physical protection for the turbomachine and the electric machine. On the contrary, the saturation is over-constrained, thus reducing the use of one energy source with respect to the other. The corrector or regulator compensates for this reduction by increasing the energy source which is not over-constrained.

[0033] The over-constraint is achieved by means of the definition of a dynamic saturation law which allows to modify the proportion of electric torque in the hybridization rate. Thus, the dynamic saturation law is a method of constraining the saturation.

[0034] For example, the dynamic saturation law can be built using a fuzzy corrector, taking into account several engine parameters, in particular at least one electrical parameter and / or at least one engine parameter, to build saturation constraints to be applied to the regulator output command.

[0035] Within the scope of the invention, the saturations thus play a different role than in the prior art, which are set and only play a protective role.

[0036] In other words, the dynamic saturations of the control method according to the invention are non-linear, which leads to the regulator leaving the conventional operating mode. This is an additional constraint, since the stability of the correction network must be ensured when entering these saturations.

[0037] In the control problems of the prior art, the objective is always to have an instruction with the same number of commands as the number of commands, without trying to over-constrain the saturations, except for the purpose of physically protecting the machine.

[0038] Within the scope of the invention, the lack of instructions is made up by building an allocation between the commands using the saturation bias.

[0039] In addition to the machine-protective saturations representing static saturations, the control method according to the invention also builds dynamic saturations, which allow the energy to be allocated on the engine based on other needs than the protection needs. This dynamic saturation is located between the two ends of the static machine-protective saturations.

[0040] In addition to the features discussed in the preceding paragraphs, the control method according to one aspect of the invention can also have one or more additional features from among the following, which can be considered individually or according to any technically feasible combination:

[0041] - the dynamic saturation law includes an over-constraint of the electrical torque command protective saturation;

[0042] - the dynamic saturation law of the electrical torque command is built by a fuzzy controller, in particular taking into account at least one electrical parameter and one engine parameter;

[0043] - the electrical parameter is the charge level of a battery connected to an electric machine of the hybrid turbomachine, and / or the engine parameter is the exhaust gas temperature;

[0044] - the fuzzy controller uses linguistic parameters described by a Gaussian law and a "max-mean" type defuzzification method;

[0045] - the fuzzy controller uses linguistic parameters described by a non-Gaussian law and a "centroid" type method;

[0046] - the control method also comprises:

[0047] o a receiving step during which an instruction of engine speed to be reached is received;

[0048] o a difference determining step during which a difference between the engine speed to be reached and the current engine speed is determined;

[0049] - determining the electrical torque command saturation by selecting the minimum saturation between the static saturation and the dynamic saturation; and / or

[0050] - the dynamic saturation law is expressed by interpolation.

[0051] Another aspect of the application relates to a hybrid turbomachine, in particular a dual-rotor / bypass hybrid turbomachine with variable hybridization ratio, comprising the following elements:

[0052] o a propulsion system having a fuel flow command as input;

[0053] o an electric machine connected to the propulsion system and having an electrical torque command as input; and

[0054] o a computing device configured to determine the fuel flow command and the electrical torque command by implementing the method according to the first aspect of the application.

[0055] By virtue of implementing the hybridization ratio control method, the hybrid turbomachine according to the application can dynamically modify the fuel flow / electrical torque ratio.

[0056] The hybrid turbomachine according to one aspect of the application can have one or more supplementary features from among the following, which can be considered individually or according to any technically feasible combination:

[0057] o the hybrid turbomachine is a dual-rotor / bypass turbomachine;

[0058] o the propulsion system comprises a fan, a low-pressure shaft, a high-pressure compressor, a combustion chamber, a high-pressure shaft, a high-pressure turbine and a low-pressure turbine; and / or

[0059] o the electric machine comprises a low-pressure electric machine connected to the low-pressure shaft and a high-pressure electric machine connected to the high-pressure shaft. BRIEF DESCRIPTION OF DRAWINGS

[0060] The attached drawings illustrate the application by way of indication and do not limit the object of the application in any way.

[0061] [ Figure 1 is a schematic representation of a regulation method of the type according to the application;

[0062] [ Figure 2a multi-input single-output control map according to one embodiment of the application is shown;

[0063] [ Figure 3 an effect of hybrid rate management by command saturation according to one embodiment of the application is shown;

[0064] [ Figure 4 an example of fuzzy rules and linguistic parameters for constraining the hybrid level according to one embodiment of the application is shown;

[0065] [ Figure 5 and Figure 6 an injection and recuperation authorization law based on engine parameters and electrical parameters according to one embodiment of the application is shown respectively;

[0066] [ Figure 7 an example of power injection and recuperation constraint process as a function of input parameters is shown; and

[0067] [ Figure 8 a schematic representation of a hybrid turbomachine according to the application is shown. DETAILED DESCRIPTION

[0068] Unless otherwise indicated, identical elements appearing in different drawings have a single reference number.

[0069] Figure 1 A method 100 for controlling the hybrid rate of a hybrid turbomachine according to the application is schematically illustrated.

[0070] The control method 100 comprises a receiving step 101 during which an instruction of engine speed to be reached is received.

[0071] The control method 100 also comprises a step 102 of determining the degree of saturation of the electrical torque command, in which particularly the degree of saturation of the electrical torque command is determined according to a first static saturation law (SS) and a first dynamic saturation law (SD).

[0072] The first static saturation law SS represents a protective saturation of the electric machine.

[0073] In particular, the first dynamic saturation law SD is defined according to the target hybrid rate TH. Thus, the first dynamic saturation law SD is related to the target hybrid rate TH and can be defined according to several parameters of the turbomachine.

[0074] The control method 100 also comprises a step 103 of determining a fuel flow command saturation, in which a saturation of the fuel flow command is determined. According to one embodiment, the fuel flow command saturation is determined in particular according to a second static saturation law.

[0075] The second static saturation law represents a protective saturation of the internal combustion engine.

[0076] The control method 100 also comprises a step 104 of determining a difference, in which a difference between the engine speed to be reached determined in the receiving step 101 and the current engine speed at which the control method 100 is implemented is determined.

[0077] The control method 100 also comprises a step 105 of determining an electric torque and a fuel flow command, in which an electric torque command to be applied and a fuel flow electric torque command are determined.

[0078] The step 105 of determining an electric torque and a fuel flow command is performed by taking into account the difference between the engine speed to be reached and the current engine speed obtained in the step 104 of determining a difference, the electric torque command saturation obtained in the step 102 of determining an electric torque command saturation and the fuel flow command saturation obtained during the step 103 of determining a fuel flow command saturation.

[0079] The ability to modify the dynamic electric torque command saturation makes it possible to modify in real time the hybridization rate of the turbomachine.

[0080] According to the application, the step 102 of determining an electric torque command saturation and the step 103 of determining a fuel flow command saturation can be sequential, one after the other, or can be at least partially parallel, with one step being performed simultaneously with the other.

[0081] Figure 2 An example of a multi-input single-output type regulation map is shown, which allows the command to be modulated via saturation, according to one embodiment of the application. In other words, Figure 2 An example of the step 102 of determining an electric torque command saturation and the step 105 of determining an electric torque and a fuel flow command of the control method 100 according to the application is illustrated.

[0082] Figure 2 An example of how the dynamic saturation law SD is obtained as a function of the target hybridization rate TH is illustrated. The electric torque command saturation SE is calculated as the minimum saturation between the dynamic saturation SD and the static saturation SS.

[0083] The corrector CO or regulator CO uses the electrical torque saturation SE, the fuel flow command saturation SC and the difference between the engine speed to reach RA and the current engine speed RP to calculate the electrical torque command Cf and the fuel flow command Df applied to the hybrid turbomachine TMH.

[0084] The regulator CO also has as input the command difference corresponding to the difference between the linear command output from the regulator CO and the saturated command, i.e. the command actually injected as input to the hybrid turbomachine TMH.

[0085] The command difference prevents the regulator CO from continuing to increment a command that has reached its limit.

[0086] In order to enable the regulator CO command to be post-constrained with respect to the synthesis, the solution provided by the application consists in modulating the saturation of the command.

[0087] The regulator CO is designed to integrate the feedback of the saturated command, thus allowing the command to be adjusted to the actual saturation. The non-saturated command then compensates for the dynamics missing during the saturation process.

[0088] Figure 3 The effect of managing the hybridization rate by the command saturation is illustrated in the case of a dual-rotor / bypass hybrid turbomachine according to one embodiment of the application.

[0089] Figure 3 More particularly:

[0090] - the speed over time curve of the high-pressure body 301 of the turbomachine in response to the instruction 302;

[0091] - the fuel flow command 303 over time curve for different electrical torque command saturation values; and

[0092] - the electrical torque command 304 over time curve for different dynamic saturation values.

[0093] In other words, the electrical torque command 304 over time curve illustrates the effect of over-constraining the electrical torque command, thus reducing the proportion of electrical energy in the hybridization rate.

[0094] Notably, Figure 3 The regulator ensures the same dynamics for the speed monitoring in transient mode, but the hybridization rate is modified. Thus, the electrical torque is constrained, while the fuel flow plays a more important role in ensuring that the closed-loop dynamic target is met.

[0095] According to one embodiment, the dynamic saturation law of the electric torque command is built by a fuzzy controller or corrector. The fuzzy controller or corrector makes it possible to describe a set of rules for constraining the behavior to be adopted with respect to the target hybridization rate.

[0096] According to one embodiment of the application, the constraint management or dynamic saturation law is performed using a set of rules related to electrical parameters and engine parameters.

[0097] Figure 4 An example of fuzzy rules and linguistic parameters for hybridization level constraints according to one embodiment of the application is shown.

[0098] Thus, Figure 4 An example of a fuzzy controller or corrector built from the battery charge level and the exhaust gas temperature, also known by the acronym EGT, is illustrated.

[0099] In the case of a low battery, the fuzzy controller or corrector will try to limit the use of power injection, but will tend to use power recovery for charging.

[0100] In the case of a full battery, the controller or fuzzy corrector will tend to allow more power injection to limit the temperature rise, but if the battery charge is not high enough, it will limit the power injection related to this objective in order to focus on acceleration assistance.

[0101] If the engine temperature is very high, another rule will also limit the recovery for charging to an average level.

[0102] The linguistic parameters are described here according to Gaussian laws.

[0103] Figure 4 The example illustrated in the figure uses a "maximum of means" (MoM) defuzzification method to convert the linguistic values into numerical values.

[0104] By using a fuzzy controller or corrector, it is possible to promote certain usage modes of the turbo engine.

[0105] For example, during the deceleration phase, if the engine is old and less efficient, and the temperature is high, the fuel injection will be limited to protect the engine temperature.

[0106] Similarly, if the engine is cold and the battery is depleted, it will be considered to charge the battery to its maximum capacity.

[0107] If the engine is hot and the battery is depleted, it will be considered to charge the battery with limited power to avoid an excess of fuel in the combustion chamber, which leads to a too high temperature, which is an effect that is desired to be limited.

[0108] If the battery is charged during the acceleration phase, it will be considered to allow a high level of electric power assistance to the engine, which reduces fuel excess and extends the engine life.

[0109] Conversely, if the battery is depleted, it will be considered to ensure acceleration by fuel injection, since electric energy will not achieve the desired acceleration.

[0110] In other words, the fuzzy controller or corrector according to Figure 4 takes into account at least one electrical parameter and / or at least one engine parameter. In particular, the fuzzy controller or corrector according to Figure 4 takes as inputs the battery level, the exhaust gas temperature and the operating rules.

[0111] The battery level can be described using the Gaussian law or a straight line.

[0112] The operating rules are based on the fuel flow and electric torque saturation laws.

[0113] The inputs are associated with commands and are converted / translated by the fuzzy controller or corrector into mathematical laws.

[0114] The embodiment of the control method 100 using a fuzzy controller or corrector is particularly advantageous for users who do not have knowledge of automation but are familiar with the engine, for example thermodynamic specialists. The thermodynamic specialists will use states to describe the operation of the machine.

[0115] Figure 5 and Figure 6 show respectively an injection authorisation law and a withdrawal authorisation law based on engine parameters and electrical parameters according to one embodiment of the application.

[0116] Figure 5 The injection authorisation law based on the exhaust gas temperature and the battery level is illustrated. Figure 5 The injection authorisation law in Figure 4 is built using the fuzzy controller or corrector according to

[0117] Figure 5 It appears that when the battery is charged and the exhaust gas temperature is not too close to the limit value, the injection is promoted.

[0118] Figure 6 The drawdown authorisation law as a function of the exhaust gas temperature and the battery level is illustrated. Figure 6 The drawdown authorisation law in Figure 4 is built using the fuzzy controller or corrector shown in .

[0119] Figure 6 It is shown that the recovery is promoted when the battery is not full and the exhaust temperature is not too close to the limit value.

[0120] In another embodiment, the fuzzy controller or corrector uses linguistic parameters described by the non-Gaussian law and the "centroid" type method.

[0121] According to another embodiment, the dynamic saturation law is expressed by interpolation.

[0122] Figure 7 An example of the injection and power recovery constraint process as a function of the input parameters is shown.

[0123] More particularly, Figure 7 It is shown that:

[0124] - the variation process of the charge level 701 of the battery of the hybrid turbomachine;

[0125] - the variation process of the exhaust temperature 702;

[0126] - the variation process of the power injection authorization law 703 calculated using the fuzzy controller or corrector; and

[0127] - the variation process of the power recovery authorization law 704 calculated using the fuzzy controller or corrector.

[0128] Figure 8 A schematic representation of a dual-rotor / bypass type hybrid turbomachine 800 according to the illustrated example is illustrated, having a variable hybridization rate implementing the control method 100 of the hybridization rate according to the application.

[0129] The hybrid turbomachine 800 comprises a propulsion system comprising a fan 801, a low-pressure shaft, a high-pressure compressor 803, a combustion chamber 804, a high-pressure shaft, a high-pressure turbine 805 and a low-pressure turbine 806.

[0130] The hybrid turbomachine 800 also comprises a low-pressure electric machine 807 connected to the low-pressure shaft and a high-pressure electric machine 808 connected to the high-pressure shaft.

[0131] Furthermore, the low-pressure electric machine 807 and the high-pressure electric machine 808 are connected to the propulsion system.

[0132] Furthermore, the hybrid turbomachine 800 can comprise a reduction gear 802, in particular arranged between the fan 801 and the high-pressure compressor 803.

[0133] The hybrid turbomachine 800 also comprises a computing device configured to implement the control method 100 according to the application.

[0134] Such a computing device comprises for example a corrector or regulator for implementing a regulation loop. Moreover, the computing device can also comprise a controller for determining the saturation degree during the electric torque command saturation degree determination step 102 of the control method 100 according to the application.

[0135] According to one embodiment, the computing device of the hybrid turbomachine 800 can comprise a fuzzy controller or a corrector for determining a dynamic saturation law of the electric torque command.

[0136] The hybrid turbomachine 800 according to the application can vary the electric torque / fuel flow hybridization ratio by means of implementing the control method 100 according to the application.

[0137] The hybridization ratio of the hybrid turbomachine 800 according to the application can be determined as a function of electrical parameters and engine parameters. For example, the hybridization ratio can be determined by the charge level of the battery and the exhaust gas temperature.

Claims

1. A method (100) for controlling a hybrid rate of a hybrid turbomachine, the control method (100) comprising at least: - a step (102) of determining an electric torque command saturation degree according to a first static saturation law (SS) and a first dynamic saturation law (SD), the dynamic saturation law (SD) being defined in particular by a target hybrid rate (TH); - a step (103) of determining a fuel flow command saturation degree; - a step (105) of determining the electric torque command and the fuel flow command using a corrector (CO) taking into account at least: o a difference between a target engine speed (RA) and a current engine speed (RP), o the electric torque command saturation degree (SE), and o the fuel flow command saturation degree (SC), so as to obtain the target hybrid rate (TH).

2. The control method (100) according to the preceding claim, characterized in that The dynamic saturation law (SD) comprises an over-constraint on the electric torque command protective saturation degree.

3. The control method (100) according to one of the preceding claims, characterized in that The dynamic saturation law of the electric torque command is built by a fuzzy controller, in particular taking into account at least one electrical parameter and / or at least one engine parameter.

4. The control method (100) according to the preceding claim, characterized in that The electrical parameter is a charge level of a battery connected to an electric machine of the hybrid turbomachine, and / or the engine parameter is an exhaust gas temperature of the hybrid turbomachine.

5. The control method (100) according to claim 3 or 4, characterized in that, The fuzzy controller uses linguistic parameters described by a Gaussian law and a "max-mean" type defuzzification method.

6. The control method (100) according to claim 3 or 4, characterized in that The fuzzy controller uses linguistic parameters described by a non-Gaussian law and a "centroid" type method.

7. The control method (100) according to one of the preceding claims, characterized in that It comprises at least: - a receiving step (101) during which an instruction of a target engine speed is received; - a difference determining step (104) in which a difference between the target engine speed and a current engine speed is determined.

8. Control method (100) according to one of the preceding claims, characterized in that The electric torque command saturation degree is determined by selecting the smallest between the static saturation degree (SS) and the dynamic saturation degree (SD).

9. The control method (100) according to claim 1, characterized in that The dynamic saturation law (SD) is expressed by interpolation.

10. A hybrid turbomachine (800) with variable hybrid rate, comprising the following elements: - a propulsion system (801, 802, 803, 804, 805, 806) having a fuel flow command as input; - an electric machine (807, 808) connected to the propulsion system and having an electric torque command as input; and - a computing device configured to determine the fuel flow command and the electric torque command by implementing the control method (100) according to any one of the preceding claims.

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