TURBOMACHINE SYSTEM COMPRISING A MEANS FOR CONTROLLING TURBOMACHINE FLOW RATES, PRESSURE AND TEMPERATURES, VEHICLE, METHOD AND PROGRAM BASED ON SUCH A SYSTEM

Abstract

The invention relates to a two- or more-stage turbomachinery system for a motor vehicle, comprising compressors (C1, C2), turbines (T2, T1), and generators (G2, G1); two combustion chambers (CC1, CC2); a flow cooler (IC) connected to the first compressor (C1) and the second compressor (C2); and a recuperator-type heat exchanger (E1). The turbomachinery system further comprises: a means for controlling the airflow (Qair) entering the first compressor as a function of the rotational speed of the first electric generator (G2); and / or a means for controlling a first pressure (P2) downstream of the first compressor (C1) as a function of the rotational speed of the second electric generator (G1). The invention also relates to a vehicle, a method, and a program based on such a system. Figure 1

Description

Title of the invention: TURBOMACHINE SYSTEM COMPRISING A MEANS FOR CONTROLLING TURBOMACHINE FLOW RATES, PRESSURE AND TEMPERATURES, VEHICLE, METHOD AND PROGRAM BASED ON SUCH A SYSTEM

[0001] The invention relates to the field of motor vehicles comprising a turbogenerator, and more particularly to methods of controlling such turbogenerators.

[0002] Currently, range extender systems are based essentially on a supercharging stage implementing a compressor, a combustion chamber and a turbine like the system from Delta Cosworth.

[0003] The generator architecture based on Delta Cosworth's electrified turbogenerators does not incorporate a device on the turbine to manage post-compressor pressure. It is a fixed-geometry turbine. Consequently, the actuators are limited to the amount of fuel injected, the amount of heat produced by Joule heating with the electrical resistance in the electrified catalyst, and the rotational speed of the electric machine of the electrified turbogenerator.

[0004] The system under development at the applicant is based on a two-stage supercharging system made with two electrified turbogenerators, each having a variable geometry turbine, as well as two catalytic combustion chambers, illustrated in [Fig. 1]. This system therefore has two catalysts, one of which is electrified and positioned upstream of the low-pressure turbine.

[0005] Within the framework of the invention, the way of linking the measurable quantities and the controllable quantities is done according to the following relationships: - the air flow rate: = f ( memhp ) ; - the pressure after the low pressure compressor: A ~ a,EM-Lp); - the pressure after the high-pressure compressor: P3 = f (VGTHP ); - the pressure after the high-pressure turbine: P^ = f( VGTLP); - the temperature in the combustion chamber is TchLp - f ( QW^p); - the temperature in the combustion chamber is TchHP — f ( QinjHp ).

[0006] The measurable quantities (P2, P3, P4, TchHP, TchLP and Qair) are linked to the respective corresponding controllable quantities (^em-hp^ mem-lp, VGThp, VGTlp, Qinj LP' Qinj-HP

[0007] Thanks to this method, we obtained a control structure allowing us to retrieve the operating points at various points in the architecture.

[0008] These operating points are derived from a theoretical thermodynamic analysis of the two-stage cycle. Our control model architecture allows us to reach these reference points. These points are attainable within the limits of the approximations made by the theoretical model of the two-stage system.

[0009] The prior art control strategy can be circumvented by choosing other quantities allowing to establish a way to control the two-stage system by correctly choosing the observable quantities necessary for controlling this autonomy extender.

[0010] This workaround could be achieved by controlling it using specific parameters.

[0011] An objective of the present invention is to provide a solution for controlling an electrified turbocharger by means of control parameters.

[0012] To achieve this objective, the invention proposes a turbomachine system for a motor vehicle, comprising: - a first turbocharger comprising a first compressor, a first turbine and a first electric generator; - a second turbocharger comprising a second compressor, a second turbine and a second electric generator; - two combustion chambers; - a flow cooler connected to the first compressor and the second compressor; - a heat exchanger connected to the second compressor and a first combustion chamber, itself connected to the second turbine, the second combustion chamber being connected to both turbines, the system being configured to implement a fluid flow from the first compressor to the cooler, to the second compressor, to the heat exchanger, to the first combustion chamber, to the second turbine, to the second combustion chamber, to the first turbine, and back to the heat exchanger, the turbomachine system further comprising: - a means of controlling the airflow entering the first compressor as a function of the rotational speed of the first electric generator; and / or - a means of controlling a first pressure downstream of the first compressor as a function of the rotation speed of the second electric generator.

[0013] Advantageously, the control architecture according to the invention, with the correct coupling between the measurable and controllable quantities, makes it possible to control the extender of autonomy, within its capabilities, so as to reach the reference values ​​for the air flow rate (Qair), pressures (P2, P3, P4), and combustion chamber temperatures (TchHp, TchLP). Furthermore, controlling these parameters (air flow rate Qair, pressures P2, P3, P4, and combustion chamber temperatures TchHP, TchLP) makes it possible to achieve a regenerative electrical power output for each generator.

[0014] Preferably, the second turbine is a variable-geometry turbine, and the turbomachine system further includes a means for controlling the rotation of the second turbine, and a means for controlling a second pressure downstream of the second compressor as a function of the opening of the second turbine.

[0015] The turbine opening represents, for example, a percentage of the turbine blade opening, or an arbitrary signal, or a voltage or current for controlling the blade actuators.

[0016] This makes it possible to propose a means of controlling said pressure.

[0017] Preferably, the first turbine is a variable geometry turbine, and the turbomachine system further includes a means for controlling the rotation of the first turbine, and a means for piloting a third pressure downstream of the second turbine as a function of the opening of the first turbine.

[0018] This makes it possible to propose a means of controlling said pressure.

[0019] Preferably, the turbomachine system further includes a means for controlling a quantity of fluid injected into the first or second combustion chamber, and a means for controlling the temperature of said combustion chamber as a function of said quantity of fluid injected.

[0020] This makes it possible to propose a means of controlling the temperature of said combustion chamber.

[0021] Preferably, the turbomachine system further comprises at least one intermediate turbocharger including an intermediate compressor between the first compressor and the second compressor, an intermediate turbine between the first turbine and the second turbine, an intermediate electric generator, said intermediate turbocharger forming at least one intermediate stage, and the second turbocharger forming a final stage, each intermediate stage comprising an intermediate combustion chamber between the successive turbines; and a cooler between the successive compressors, characterized in that it further comprises a means for controlling the inlet pressure of an intermediate stage as a function of the rotational speed of the turbine of the following stage.

[0022] This makes it possible to propose a means of controlling the pressure at the inlet and outlet of each stage of a system with three or more pressure levels.

[0023] The invention further relates to a motor vehicle comprising a turbomachine system according to the invention.

[0024] Another object of the invention relates to a method for controlling a turbomachine system according to the invention, characterized in that it comprises: - a step to control the airflow entering the first compressor as a function of the rotational speed of the first electric generator (G2), and / or - a pressure control step downstream of the first compressor based on the rotational speed of the second electric generator. In the case of a multi-stage system, this step is performed based on the rotational speed of the electric generator of the next stage.

[0025] Preferably, the control method further includes a step of controlling the pressure at the inlet of a stage as a function of the rotational speed of the turbine of the following stage.

[0026] The invention further relates to a computer program comprising program code instructions for executing the steps of the control method according to the invention, when said program is running on a computer.

[0027] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures, in which: - [Fig.l] schematically illustrates a two-stage turbomachine system architecture according to the invention; - [Fig.2] schematically illustrates a turbomachine system architecture according to the invention, with more than two stages.

[0028] The invention relates to a turbomachine system for a motor vehicle. The system comprises two turbochargers: the first turbocharger comprises a first compressor Cl, referred to as low pressure, a first turbine T2, referred to as low pressure, and a first electric generator G2; the second turbocharger comprises a second compressor C2, referred to as high pressure, a second turbine T1, referred to as high pressure, and a second electric generator Gl.

[0029] The turbochargers can be mounted on separate Al, A2 shafts as illustrated in the figures; or be mounted on the same shaft.

[0030] The system further comprises two combustion chambers CCI, CC2, and a flow cooler IC connected to the first compressor Cl and the second compressor C2.

[0031] The system further comprises a heat exchanger El connected to the second compressor C2 and the first combustion chamber CCI. The first combustion chamber CCI is connected to the second turbine TL. The second combustion chamber CC2 is connected to both turbines.

[0032] The system is configured to implement a fluid flow Fl from the first compressor Cl to the cooler IC, to the second compressor C2, to the heat exchanger El, to the first combustion chamber CCI, to the second turbine Tl, to the second combustion chamber CC2, to the first turbine T2, again to the heat exchanger El.

[0033] Control architectures can take a simplified form or more elaborate forms, for example, disturbance rejection. This two-stage turbogenerator architecture is a non-linear system with coupled phenomena. Some of the multiple interactions between quantities (measurable or not) and control quantities can be treated in the control section as disturbances.

[0034] One could, for example, adopt control structures having complex forms treating these interactions as a disturbance, the regulation of which could be done by rejecting this disturbance in the control system implemented.

[0035] When the two-stage system is made more complex with a second stage, the controls can follow the architecture described in [Fig.1].

[0036] The following relationships show how measurable quantities are linked to controllable quantities: - the air flow rate: Q . = f (WEMa,) ; - the pressure after the high pressure compressor: P3- f ( VGTHP); - the temperature in the combustion chamber is jCch( I. - f ( &nJLP) ; - the temperature in the combustion chamber is Tchffl) - f ( &nj ) ; - the pressure after the low pressure compressor: Pi = f{; - the pressure after the high pressure turbine: Pi = f ( VGTLP).

[0037] This choice was made by proceeding through successive steps of increasing complexity between a single-stage turbogenerator and a two-stage turbogenerator. These relationships are obtained after maintaining the basic structure established with a single turbocharger, namely the control of the air flow by the speed of the electric machine of the high-pressure section: — f ( ), the pressure between The high-pressure compressor and the high-pressure turbine are controlled by the variable geometry turbine opening / position control VGTHP; P3 = f ( VGTHP ). The temperatures of the catalytic chambers being controlled respectively by the quantities injected upstream of these chambers: T^.^ f Ç&njjjp) and Tch^= f(QinjLp ), we deduce the remaining possible associations to link the remaining measurable and controllable quantities .P^- f( <üem-lp) and P4 = f ( VGTLP ).

[0038] However, this architecture can easily be circumvented. This circumvention is the subject of the present patent application. It is possible to retain control of the Air flow rate by the speed of an electric machine of an electrified turbocharger. Here, the new relationship for this control is: - f ( Wemu.) : this is indeed the machine of the electrified low-pressure turbocharger which is chosen for airflow management.

[0039] Thus, according to the invention, the turbomachine system further includes a means of controlling the air flow (Qair) entering the first compressor as a function of the rotation speed of the first electric generator (G2).

[0040] In the context of a two-stage turbogenerator, we implement temperature control in the combustion chambers. Thus, the temperatures of the catalytic chambers remain controlled respectively by the quantities injected upstream of these chambers: TchHP = / ( QmjHp ) and TChLP = / ( QinjLP ) •

[0041] Furthermore, the pressures P3 and P4 appear difficult to control other than by the two variable geometry turbines. Therefore, we implement the following relationships between these pressures and the controllable quantities: P3 = f(VGTHP) and I\ = f(VGTLP).

[0042] As a result of these choices, the pressure between the two compressors is controlled by the rotational speed of the electric machine of the HP turbocharger:

[0043] The pressure after the low-pressure compressor: P2 = f ( (Cem-hp)

[0044] Thus, according to the invention, the turbomachine system further includes a means of controlling the pressure downstream of the first compressor as a function of the rotation speed of the second electric generator (Gl).

[0045] The "low level" architecture of the control structure of the two-stage turbogenerator allows several operating points to be determined.

[0046] These operating points are derived from a theoretical thermodynamic analysis of the two-stage cycle (see more). Our control model architecture allows us to reach these reference points. These points are attainable within the limits of the approximations made by the theoretical model of the two-stage system.

[0047] With this method, in which the air flow is controlled by the low-pressure electric machine, the pressure P3 is controlled by the high-pressure variable-geometry turbine, and the temperature of the high-pressure combustion chamber is controlled by the quantity injected upstream of it, as many stages as necessary could be controlled. This is illustrated here with 3 stages ([Fig. 2]).

[0048] With the approach of the invention, the link between measurable quantities and controllable quantities is easily determined. The choice made is as follows:

[0049] The air flow rate is a function of the rotational speed of the lowest pressure electrified turbocharger: = f( ) = f( "h ). For each pressure between the We choose to control the lower pressure compressor and the higher pressure compressor in the following way: V ne[l, nb étages-1] : P itin =

[0050] For each pressure difference between the highest and lowest pressure turbines, we choose to control it as follows: [V n nb stages] :P = f(VGTn)^cp , — p , . P 'mjtb floor — * number of floors — ■* out / tb floor With ■ P stage ■> the outlet pressure of the highest pressure compressor stage; and - P outjib stage, the pressure at the inlet of the highest pressure turbine, that is to say, the pressure at the outlet of the highest pressure combustion chamber.

[0051] The temperature in the combustion chamber is Tehn = f(Qinjn).

[0052] The interest of the invention lies in the simplification of the association between controllable quantities and measurable quantities.

[0053] The invention further relates to a method of controlling a turbomachine system implementing the means described above.

[0054] The method includes a step of controlling the air flow Qair as a function of the rotation speed of the first electric generator G2.

[0055] The method further includes a step of controlling the pressure downstream of the first compressor as a function of the rotation speed of the second electric generator Gl.

[0056] In the case of multi-stage systems, the control method may further include a step of controlling the inlet pressure of a stage as a function of the rotational speed of the turbine of the next stage.

Claims

Demands

1. Turbomachinery system of a motor vehicle, comprising: - a first turbocharger comprising a first compressor (Cl), a first turbine (T2) and a first electric generator (G2); - a second turbocharger comprising a second compressor (C2), a second turbine (T1) and a second electric generator (G1); - two combustion chambers (CCI, CC2); - a flow cooler (IC) connected to the first compressor (Cl) and the second compressor (C2);- a heat exchanger (El) connected to the second compressor (C2) and to a first combustion chamber (CCI), itself connected to the second turbine (Tl), the second combustion chamber (CC2) being connected to both turbines, the system being configured to implement a fluid flow (Fl) from the first compressor (Cl) to the cooler (IC), to the second compressor (C2), to the heat exchanger (El), to the first combustion chamber (CCI), to the second turbine (Tl), to the second combustion chamber (CC2), to the first turbine (T2), again to the heat exchanger (El), the turbomachine system further comprising - a means for controlling the air flow (Qair) entering the first compressor as a function of the rotational speed of the first electric generator (G2);and / or - a means of controlling a first pressure (P2) downstream of the first compressor (Cl) as a function of the rotation speed of the second electric generator (Gl).;

2. Turbomachine system according to claim 1, wherein the second turbine (Tl) is a variable geometry turbine, characterized in that it further comprises a means for controlling the rotation of the second turbine (Tl), and a means for piloting a second pressure (P3) downstream of the second compressor (C2) as a function of the opening of the second turbine (Tl).

3. A turbomachine system according to any one of claims 1 to 2, wherein the first turbine (T2) is a variable geometry turbine, characterized in that it further comprises a a means of controlling the rotation of the first turbine (T2), and a means of piloting a third pressure (P4) downstream of the second turbine (T1) as a function of the opening of the first turbine (T2).

4. Turbomachine system according to any one of claims 1 to 3, characterized in that it further comprises a means for controlling a quantity of injected fluid (Qinj Hp, Qinj lp) in the first (CCI) or the second combustion chamber (CC2), and a means for controlling the temperature (Tch) of said combustion chamber (CCI, CC2) as a function of said quantity of injected fluid (Qinj_Hp, ​​Qinj-Lp).

5. Turbomachine system according to any one of claims 1 to 4, characterized in that it further comprises at least one intermediate turbocharger comprising an intermediate compressor (IC) between the first compressor (C1) and the second compressor (C2), an intermediate turbine (IT) between the first turbine (T2) and the second turbine (T1), an intermediate electric generator (IG), said intermediate turbocharger forming at least one intermediate stage, and the second turbocharger forming a final stage, each intermediate stage comprising an intermediate combustion chamber (ICC) between the successive turbines (T2, T1); and a cooler (ICC) between the successive compressors (C1, C2), characterized in that it further comprises a means for controlling the inlet pressure of a stage as a function of the rotational speed of the turbine of the following stage.

6. Motor vehicle comprising a turbomachine system according to any one of claims 1 to 5.

7. A method for controlling a turbomachine system according to any one of claims 1 to 5, characterized in that it comprises: - a step of controlling the air flow rate (Q,,,,) entering the first compressor as a function of the rotational speed of the first electric generator (G2), and / or - a step of controlling the pressure downstream of the first compressor as a function of the rotation speed of the second electric generator (Gl).

8. Control method according to claim 7 taken in its connection with claim 4, characterized in that it further comprises a step of controlling the pressure at the inlet of an intermediate stage as a function of the rotational speed of the turbine of the following stage.

9. Computer program comprising program code instructions for performing the steps of the control process according to any one of claims 7 to 8, when said program is running on a computer.

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