METHOD FOR CONTROLLING A TURBOMACHINE COMPRISING A GAS GENERATOR AND AN ELECTRIC MOTOR

Abstract

A method for controlling a turbomachine comprising including a fan positioned upstream of a gas generator. The turbomachine including an electric motor forming a torque injection device for a high-pressure rotary shaft, in which method a fuel flow setpoint for a combustion chamber and a torque setpoint (Tcons) for the electric motor (ME) are determined. The control method including the steps of determining (El) a hybridisation rate (TH) corresponding to the ratio of the power (Pe) consumed by the electric motor (ME) to the power generated by the high-pressure rotary shaft (P2), determining (E2) a torque threshold (Tseuil) from the hybridisation rate (TH), limiting (E3) the torque setpoint (Tcons) to the torque threshold (Tseuil) if the torque setpoint (Tcons) is higher than the torque threshold (Tseuil).

Claims

1. A method for controlling a turbomachine (100) comprising a fan (110) positioned upstream of a gas generator and delimiting a primary flux and a secondary flux, said gas generator being traversed by the primary flux and comprising a low-pressure compressor (111), a high-pressure compressor (112), a combustion chamber (113), a high-pressure turbine (114) and a low-pressure turbine (115), said low-pressure turbine (115) being connected to said low-pressure compressor by a low-pressure rotation shaft (121) and said high-pressure turbine (114) being connected to said high-pressure compressor (112) by a high-pressure rotation shaft (122), the turbomachine (100) comprising an electric motor (ME) forming a torque injection device on the high-pressure rotation shaft (122), a method in which a fuel flow rate setpoint (Qcons) in the combustion chamber (113) and a torque setpoint (Tcons) supplied to the electric motor (ME) are defined, the control method comprising the steps of: determining (E1) a hybridization rate (TH) corresponding to a power consumed (Pe) by the electric motor (ME) in relation to a power generated by the high-pressure rotation shaft (122), determining (E2) a torque threshold (Tseuil) from the hybridization rate (TH), and limiting (E3) the torque setpoint (Tcons) to the torque threshold (Tseuil) if the torque setpoint (Tcons) is greater than the torque threshold (Tseuil).

2. The control method according to claim 1, wherein the torque threshold (Tseuil) is determined according to the following law:
Tseuil=Tmax*A where A is a duty cycle determined from the hybridization rate (TH), and Tmax is a maximum torque setpoint for said electric motor (ME).

3. The control method according to claim 2, wherein the duty cycle (A) is determined from the hybridization rate (TH) according to an increasing law (L1, L2).

4. The control method according to claim 2, wherein the duty cycle (A) is equal to 1 above a predetermined hybridization threshold (STH).

5. The control method according to claim 3, wherein the law (L1) is linear up to a predetermined hybridization threshold (STH).

6. The control method according to claim 3, wherein the law (L1) is exponential up to a predetermined hybridization threshold (STH).

7. The control method according to claim 4, wherein the predetermined hybridization threshold (STH) is greater than 50%.

8. A computer program comprising instructions for executing the steps of the control method according to claim 1 when said program is executed by a computer of the (100).

9. An electronic control system (300) for the turbomachine (100) comprising a memory including instructions of the computer program according to claim 8.

10. A turbomachine (100) comprising an electronic control system (300) according to claim 9.

11. The control method according to claim 7, wherein the predetermined hybridization threshold (STH) is less than 70%.

Description

PRESENTATION OF THE FIGURES

[0026] The invention will be better understood on reading the following description, given by way of example, with reference to the following figures, given by way of non-limiting examples, wherein identical references are given to similar objects.

[0027] FIG. 1 is a schematic representation according to the prior art of the evolution of the low-pressure speed, the high-pressure speed, the fuel setpoint and the electrical consumption of the electric motor during acceleration of the turbomachine.

[0028] FIG. 2 is a schematic representation of the evolution of the electrical power consumed and the power developed by the high-pressure rotation shaft.

[0029] FIG. 3 is a schematic representation of a turbomachine according to the invention,

[0030] FIG. 4 is a schematic representation of the steps in a method for controlling a turbomachine according to an example of implementation in accordance with the invention.

[0031] FIG. 5 is a schematic representation of the evolution of the electrical power consumed, the power developed by the high-pressure rotation shaft and the hybridization rate.

[0032] FIG. 6 is a schematic representation of a linear law for determining a duty cycle in order to determine a torque threshold.

[0033] FIG. 7 is a schematic representation of the evolution of the low-pressure speed, the high-pressure speed, the fuel setpoint and the electrical consumption of the electric motor during an acceleration of the turbomachine over 9 seconds with a linear law according to [FIG. 6].

[0034] FIG. 8 is a schematic representation of the evolution of the low-pressure speed, the high-pressure speed, the fuel setpoint and the electrical consumption of the electric motor during an acceleration of the turbomachine over 4.5 seconds with a linear law according to [FIG. 6].

[0035] FIG. 9 is a schematic representation of an exponential law for determining a duty cycle in order to determine a torque threshold.

[0036] FIG. 10 is a schematic representation of the evolution of the low-pressure speed, the high-pressure speed, the fuel setpoint and the electric motor power consumption during an acceleration of the turbomachine over 4.5 seconds with an exponential law according to [FIG. 9],

[0037] FIG. 11 is a schematic representation of a system for controlling a turbomachine.

[0038] It should be noted that the figures set out the invention in detail in order to implement the invention, said figures of course being able to be used to better define the invention if necessary.

DETAILED DESCRIPTION OF THE INVENTION

[0039] With reference to [FIG. 3], a schematic representation of a turbomachine 100 of the dual-flow and two-spool turbojet engine for aircraft is shown. In a known way, the turbomachine 100 comprises, from upstream to downstream in the direction of gas flow, a fan 110, a low-pressure compressor 111, a high-pressure compressor 112, a combustion chamber 113 which receives a fuel flow rate setpoint Qcons, a high-pressure turbine 114, a low-pressure turbine 115 and a primary exhaust nozzle 116. The fan 110, the low-pressure compressor (or LP) 111 and the low-pressure turbine 115 are connected by a low-pressure rotation shaft 121 and together form a low-pressure body. The low-pressure rotation shaft 121 has a low-pressure speed N1.

[0040] The high-pressure compressor (or HP) 112 and the high-pressure turbine 114 are connected by a high-pressure rotation shaft 122 and together form a high-pressure body. The high-pressure rotation shaft 122 has a high-pressure speed N2.

[0041] The fan 110, which is driven by the low-pressure shaft 121, compresses the ingested air. This air is divided downstream of the fan 110 between a secondary air flux which is directed directly towards a secondary nozzle (not shown) through which it is ejected to contribute to the thrust provided by the turbomachine 100, and a so-called primary flux which enters the gas generator, formed by the low-pressure body and the high-pressure body, and is then ejected into the primary nozzle 116. In a known way, to modify the speed of the turbomachine 100, the pilot of the aircraft modifies the position of a control lever which makes it possible to modify the fuel flow rate setpoint Qcons in the combustion chamber 113.

[0042] With reference to [FIG. 3], the turbomachine 100 also comprises an electric motor ME configured to supply additional torque to the high-pressure rotation shaft 122. The operation of the turbomachine 100 comprises a control system 300 configured to obtain signals representing operating parameters PAR of the turbomachine 100 to determine a fuel flow rate setpoint Qcons and a torque setpoint Tcons for the electric motor ME. The operating parameters PAR of the turbomachine 100 may include, in particular, current measurements of the low-pressure speed N1, the high-pressure speed N2, the nozzle outlet temperature, the electrical power Pe consumed by the electric motor ME, the power generated by the high-pressure rotation shaft P2, pressure measurements, and so on.

[0043] With reference to [FIG. 4], the control system 300 is configured to implement a control method comprising the steps of: [0044] Determining E1 a hybridization rate TH corresponding to the power generated Pe by the electric motor ME in relation to the power generated by the high-pressure rotation shaft P2. [0045] Determining E2 a torque threshold Tseuil from the hybridization rate TH, [0046] Limiting E3 the torque setpoint Tcons to the torque threshold Tseuil if the torque setpoint Tcons is greater than the torque threshold Tseuil.

[0047] Thanks to the invention, the hybridization rate TH is taken into account to use the aircraft's electrical resources sparingly. The use of the electric motor ME is advantageously reduced when the degree of hybridization TH is low.

[0048] As illustrated in [FIG. 5] (which completes the [FIG. 2] previously presented), the hybridization rate TH drops significantly, in particular exponentially, when the turbomachine 100 is accelerated. Limiting the torque setpoint Tcons as a function of the degree of hybridization TH automatically reduces power consumption. This reduction is automatic and can be transposed to different turbomachines, regardless of a particular rotation speed.

[0049] The degree of hybridization TH is determined on the basis of operating parameters PAR of the turbomachine 100, in particular the power consumed Pe by the electric motor ME and the power generated P2 by the high-pressure rotation shaft 122. Determining the TH hybridization rate is quick and easy.

[0050] Preferably, the torque threshold Tseuil is determined according to the following law:

Tseuil=Tmax*A where: [0051] A is a duty cycle determined from the TH hybridization rate and [0052] Tmax is a maximum torque setpoint for said electric motor ME.

[0053] As shown in [FIG. 4], the duty cycle A is determined from the hybridization rate TH according to an increasing law L1, L2. So the higher the hybridization rate TH, the higher the duty cycle A. The electrical power Pe is thus consumed as a priority when it is significant in driving the high-pressure drive shaft 122 in rotation. This optimises the consumption of electric batteries.

[0054] The invention will be presented for a first linear law L1 and a second exponential law L2, but it goes without saying that the invention applies to other increasing laws.

[0055] As will be shown below, the duty cycle A is equal to 1 above a predetermined hybridization threshold STH in order to make maximum use of the electric motor ME when the hybridization rate TH is high. Such a predetermined hybridization threshold STH gives preference to the electric motor ME. Preferably, the predetermined hybridization threshold STH is greater than 50% so that the electrical input remains significant. This is preferably less than 70% to ensure maximum use of the electric motor ME at high hybridization rates TH. A predetermined hybridization threshold STH of 60% is then used as an example.

[0056] In a first example, with reference to [FIG. 6], the first law L1 is linear up to a predetermined hybridization threshold STH, in this case 60%, and then constant.

[0057] The duty cycle A increases between 0 and 1 for a hybridization rate TH of between 0% and 60%, then stagnates at 1. This allows us to determine a torque threshold Tseuil which is also increasing for the electric motor ME.

[0058] With reference to [FIG. 7], a schematic diagram shows the evolution of low-pressure speed N1, the high-pressure speed N2, the fuel setpoint Qcons and the electrical consumption of the electric motor Pe during an acceleration of the turbomachine over a time span of 9 seconds. A continuous line shows the low-pressure speed N1, the high-pressure speed N2, the fuel setpoint Qcons and the electrical consumption of the electric motor Pe according to the prior art (see [FIG. 1]). In [FIG. 7], a dashed line represents the electric motor power consumption Pe (L1), which is limited by the torque threshold Tseuil as a function of the first linear law L1.

[0059] It appears that the power consumption Pe is more linear, which limits wear and tear on the electrical machine ME. In addition, there is no over-consumption of electricity as in the prior art, which preserves the electrical resources on board the aircraft, such as batteries. Electric batteries of lower capacity can therefore be used.

[0060] With reference to [FIG. 8], the evolution of the low-pressure speed N1, the high-pressure speed N2, the fuel setpoint Qcons and the electrical consumption of the electric motor Pe during acceleration of the turbomachine over a time range of 4.5 seconds is shown schematically. For an acceleration over a reduced time range, the parameters of the turbomachine 100 are more impacted.

[0061] The solid line shows the values without the invention and the dashed line shows the values taking account of the torque threshold Tseuil as a function of the first linear law L1. There is an increase in the fuel setpoint Qcons (L1) (between t=29s and t=30.3s) with a gradual increase in the power consumption Pe. At time t=30.3s. the power consumption Pe falls due to the activation of the torque threshold Tseuil. The result is a slight drag on the high pressure speed N2 (L1), which cannot keep up with the set high pressure speed N2cons. The high pressure regime N2 (L1) was also exceeded at the end of acceleration at time t=33.6s.

[0062] To improve control performance while optimising power injection on the high-pressure rotation shaft 122, an L2 exponential law is recommended.

[0063] In this second example, with reference to [FIG. 9], the second law L2 is exponential up to a predetermined hybridization threshold STH, in this case 60%, and then constant.

[0064] The duty cycle A increases between 0 and 1 for a hybridization rate TH of between 0% and 60%, then stagnates at 1. This allows us to determine a torque threshold Tseuil which is also increasing for the electric motor ME.

[0065] With reference to [FIG. 10], the evolution of the low-pressure speed N1, the high-pressure speed N2, the fuel setpoint Qcons and the electrical consumption of the electric motor Pe during acceleration of the turbomachine 100 over a time range of 4.5 seconds is shown schematically. The dashed line in [FIG. 10] shows the electrical consumption of the electric motor Pe (L2), which is limited by the torque threshold Tseuil as a function of the second exponential law L2. The other parameters are only slightly affected by the second exponential law L2 (no dragging or overshooting). Regulation remains optimal.

[0066] As a result, Pe power consumption is more linear, which reduces wear and tear on the electrical machine ME. In addition, there is no over-consumption of electricity as in the prior art, which preserves the electrical resources on board the aircraft, such as batteries. The second exponential law L2 offers advantages for both normal accelerations (9 seconds) and rapid accelerations (4, 5 seconds). Control performance is maintained in all circumstances.

[0067] The invention also relates to a computer program comprising instructions for carrying out the steps of the control method when said program is executed by a computer. The invention also relates to the electronic control system 300 for the turbomachine 100 comprising a memory including computer program instructions.

[0068] An embodiment of an electronic control system 300 according to the invention is shown in [FIG. 11]. In this figure, the electronic control system 300 sends a torque setpoint Tcons and a fuel setpoint Qcons to the turbomachine 100, in particular to the electric motor ME and the combustion chamber 113. The turbomachine 100 transmits PAR operating parameters to the control system 300 as described above.

[0069] In this example, the control system 300 comprises a multivariable correction module 301 for determining gross torque setpoints Tcons* and fuel setpoints Qcons* from a speed setpoint (speed N1 or N2) and operating parameters PAR.

[0070] The control system 300 also comprises a fuel limiting module 302 which allows thermal limits (outlet temperature, etc.) to be imposed on the gross fuel setpoint Qcons* in order to determine the fuel setpoint Qcons to be supplied to the combustion chamber 113.

[0071] The control system 300 comprises: [0072] a module 41 for determining the degree of hybridization TH on the basis of operating parameters PAR, in particular the power consumed Pe by the electric motor ME in relation to the power generated by the high-pressure body P2. [0073] a module 42 for determining the duty cycle A from the hybridization rate TH on the basis of a law L1, L2, [0074] a module 43 for determining the torque threshold Tseuil from the duty cycle A and the predetermined maximum torque Tmax, [0075] a torque-limiting module 303 which allows torque limits to be imposed on the raw torque setpoint Tcons* in order to determine the torque setpoint Tcons to be supplied to the electric motor ME.

[0076] In this way, the torque setpoint Tcons will be limited to the torque threshold Tseuil if the torque setpoint Tcons is greater than the torque threshold Tseuil. The torque setpoint Tcons can therefore be saturated.

[0077] Thanks to the invention, the torque setpoint Tcons is determined to preserve the aircraft's electrical resources. Electrical power is only consumed when it is significant in the hybridization of resources consumed. Preserving electrical resources allows batteries to last longer, while reducing their cost and size.