Skip to Main content Skip to Navigation
Theses

Analyse et commande de systèmes multivariables. Application à un turbopropulseur.

Abstract : In this Ph.D. thesis, we explore the different steps of designing a decentralized control applied on a turboprop engine.From the control point of view, the turboprop engine is a TITO (Two-Input Two-Output) process. The fuel flow is used to control the shaft power while the blade pitch angle is used to control the propeller speed. The turboprop presents important couplings between manipulated variables and controlled variables. When the fuel flow changes, the propeller speed is impacted. Similarly, when controlling the blade pitch angle to change the propeller speed to another level, the shaft power is affected, particularly during the transient states. The main objective of this research thesis is to design control laws for the turboprop. Beside technical specifications like response time and overshoot, couplings between loops have to be reduced as much as possible and control laws have to be robust to model uncertainties. For this industrial environment a decentralized strategy (with or without compensators) has been chosen. The decentralized strategy consists in designing monoloop controllers in order to drive the multivariable system. The decentralized strategy presents important benefits, such as flexibility as well as design simplicity, but is not efficient in presence of heavy couplings. In that case, it is possible to use compensators that reduce existing process interactions before designing the monoloop controllers.An important part of this work focuses on the development of these different strategies.The first step is the choice of the control structure, which strongly depends on the level of interaction. Despite the availability of different metrics - based on frequential responses, temporal responses, or Gramian – it is not easy to know which one is the most appropriate. Based on the analysis of couplings with different metrics, a procedure is proposed in order to choose the structure and the controllers design method.If the coupling analysis leads to adopt a decentralized strategy, the controllers can be designed using monoloop or multiloop methods. The first ones are simple but do not take couplings into account, whereas multiloop methods take specifically couplings into account but are more complicated. These tuning methods have been studied and recommendations have finally been made to choose the most appropriated method depending on the process and the requirements.In cases where the couplings analysis reveals a high couplings level, compensators can be associated with the decentralized strategy. The objectives of the compensators are to reduce couplings in the system and to facilitate the design of monoloop controllers. Several decoupling structures have been studied and compared. A decoupling procedure has then been proposed.These methodological studies have been applied to the turboprop engine. Following the coupling analysis, a decentralized strategy with decoupling has been chosen. After following the decoupling procedure and trying different solutions, the inverted decoupler has been adopted. Considering the dynamics of the system and the total decoupling provided by the inverted decoupler, PI controllers have been used and a monoloop tuning method has been chosen. In order to guarantee the desired performances over the whole flight envelope, control laws have been interpolated, using a gain scheduling technique. The structured singular value approach has then been used to demonstrate the robustness of the control laws with model uncertainties. Control laws have finally been implemented in the control software and simulation results have illustrated their good performances.
Document type :
Theses
Complete list of metadatas

Cited literature [175 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-02918193
Contributor : Abes Star :  Contact
Submitted on : Thursday, August 20, 2020 - 10:56:09 AM
Last modification on : Wednesday, October 14, 2020 - 3:57:05 AM

File

LE_BRUN_Christophe_These_VF.pd...
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-02918193, version 1

Citation

Christophe Le Brun. Analyse et commande de systèmes multivariables. Application à un turbopropulseur.. Autre. CentraleSupélec, 2015. Français. ⟨NNT : 2015CSUP0012⟩. ⟨tel-02918193⟩

Share

Metrics

Record views

47

Files downloads

59