Commande d’un Convertisseur Multicellulaire pour une Application de Véhicule Électrique

Les convertisseurs à forte densité de puissance et à haut rendement deviennent de plus en plus intéressants dans l'industrie des véhicules électriques. Ce rapport de thèse présente un convertisseur multicellulaire parallèle CC-CC à haute densité de puissance et à haut rendement. Une topologie Buck à trois cellules connectées en parallèle et non-isolé a été choisie pour le convertisseur envisagé dans ce travail, est rendue nécessaire de par la caractéristique basse tension-fort courant des composants électroniques. Ce travail est consacré à la modélisation, la commande et à la supervision par simulation d'un convertisseur CC-CC multicellulaire associé en parallèle de type Buck pour une application de véhicule électrique. La mise en place de stratégies de commande sur ces architectures multicellulaires passe par une première étape de modélisation. Cette étape permet de retrouver les relations entre les variables à contrôler et les ordres de commande de toutes les cellules de commutation. Les stratégies appliquées dans ce projet, sont basées sur des approches non linéaires ainsi que sur la commande adaptative. Dans la deuxième partie de cette thèse, nous présentons l’implantation de ces stratégies dans l’environnement MATLAB®/ SIMULINK ™ afin de valider leur performance sur les convertisseurs multicellulaires parallèle pour une application de véhicule électrique. Après avoir testé le convertisseur, les résultats de simulation obtenus, ont été analysés sur la base du fonctionnement en régime permanent et dynamique, et ont démontré la supériorité de la topologie adoptée en termes d’efficacité énergétique par rapport aux convertisseurs conventionnels. Toutes les formes d'onde se sont avérées très proches de la théorie et des spécifications. L’association en parallèle des cellules de commutation a montré un rendement élevé et un bon partage du courant entre ses cellules. Un rendement d'environ 95% a été trouvé dans le mode de fonctionnement Buck, à la condition nominale. Ce convertisseur peut être utilisé dans un véhicule électrique pour interfacer des charges auxiliaires avec la batterie 12V

Control Strategies of DC–DC Converter in Fuel Cell Electric Vehicle

There is a significant need to research and develop a compatible controller for the DC–DC converter used in fuel cells electric vehicles (EVs). Research has shown that fuel cells (FC) EVs have the potential of providing a far more promising performance in comparison to conventional combustion engine vehicles. This study aims to present a universal sliding mode control (SMC) technique to control the DC bus voltage under varying load conditions. Additionally, this research will utilize improved DC–DC converter topologies to boost the output voltage of the FCs. A DC–DC converter with a properly incorporated control scheme can be utilized to regulate the DC bus voltage–. A conventional linear controller, like a PID controller, is not suitable to be used as a controller to regulate the output voltage in the proposed application. This is due to the nonlinearity of the converter. Furthermore, this thesis will explore the use of a secondary power source which will be utilized during the start–up and transient condition of the FCEV. However, in this instance, a simple boost converter can be used as a reference to step–up the fuel cell output voltage. In terms of application, an FCEV requires stepping –up of the voltage through the use of a high power DC–DC converter or chopper. A control scheme must be developed to adjust the DC bus or load voltage to meet the vehicle requirements as well as to improve the overall efficiency of the FCEV. A simple SMC structure can be utilized to handle these issues and stabilize the output voltage of the DC–DC converter to maintain and establish a constant DC–link voltage during the load variations. To address the aforementioned issues, this thesis presents a sliding mode control technique to control the DC bus voltage under varying load conditions using improved DC–DC converter topologies to boost and stabilize the output voltage of the FCs

Adaptive Output Feedback Control of Interleaved Parallel Boost Converters

International audienceThis paper addresses the problem of controlling interleaved dc-dc boost converters (IBC) associated to fuel cell (FC) energy generators. The FC-IBC association is powering a, possibly unknown and time-varying, load of resistance type. Furthermore, all IBC parallel cells are not equipped with current sensors. The control objective is twofold: (i) the IBC output voltage must be tightly regulated; (ii) the total current carried by the IBC must be equally shared between the different parallel branches. The complexity of the control problem lies in: (i) the system nonlinearity and instability of its zero-dynamics with respect to the output voltage; (ii) the load uncertainty; (iii) the inaccessibility to measurements of all currents. The instability of the output voltage zero-dynamics is coped by reformulating all control objectives in term of current regulation in the different converter cells. The resulting current regulation problem is dealt with by developing an adaptive output feedback controller. The latter includes a collection of adaptive current regulators and a battery of current estimators. The regulator parameter adaptation feature is used to compensate for the load uncertainty and variation. It is formally shown, using Lyapunov stability tools, that the proposed output feedback adaptive controller actually meets its objectives. This theoretical analysis is confirmed by numerical simulations showing that the controller enjoys additional robustness features

Adaptive Output Feedback Control of Interleaved Parallel Boost Converters Associated with Fuel Cell

International audienceThis article addresses the problem of controlling DC-DC interleaved boost converters associated to fuel cell energy generators. The fuel cell–interleaved boost converter association powers a possibly unknown and time-varying resistance load; furthermore, interleaved boost converter parallel cells are not equipped with current sensors. The control objective is twofold: (1) the interleaved boost converter output voltage must be tightly regulated and (2) the total current carried by the interleaved boost converter must be equally shared between the different parallel branches. The complexity of the control problem lies in (i) the system non-linearity and instability of system zero dynamics with respect to output voltage, (ii) load uncertainty, and (iii) inaccessibility to measurements of all currents. The instability of the output voltage zero dynamics is addressed by reformulating all control objectives in terms of current regulation in the different converter cells. The resulting current regulation problem is dealt with by developing an adaptive output feedback controller including a collection of adaptive current regulators and estimators. Parameter adaptation is used for compensation of load uncertainty. It is shown that the proposed output feedback adaptive controller meets its objectives. This theoretical analysis is confirmed by numerical simulations and experimental tests showing additional robustness features