Toufik Azib

An Innovative Control Strategy of a Single Converter for Hybrid Fuel Cell/Supercapacitor Power Source

In this paper, an innovative control strategy for hybrid power sources dedicated to automotive applications is detailed. First, an analysis of classical hybrid architectures using fuel cell (FC)/supercapacitors is presented. Then, an analysis of load requirements for automotive applications is proposed. A new control strategy of a single converter, based on a cascaded control loop with a decoupling strategy in the frequency domain, is fully explained. Finally, experimental results on a Ballard proton exchange membrane FC are presented to illustrate the effectiveness of the proposed method.

Saturation Management of a Controlled Fuel-Cell/Ultracapacitor Hybrid Vehicle

In this paper, a new control strategy, including saturation management of hybrid fuel-cell (FC)/ultracapacitor (UC) power sources, is described. First, an analysis of hybrid architectures using an FC and UCs for automotive applications is presented. Next, the model and the control strategy are described using energetic macroscopic representation (EMR). The main improvement over classical control strategies of such systems is to take into account saturation management with a dynamic reconfiguration of the energy management strategy (EMS). It includes the regenerative breaking in high state of charge (SOC) of the UC and the supply of a full power demand in low SOC of the UC. Finally, experimental results with small-scale devices show the effectiveness of the proposed control strategy using saturation management.

Structure and control strategy for a parallel hybrid fuel cell/supercapacitors power source

In this paper, two control strategies for two parallel hybrid fuel cell/supercapacitors power source are described. First, different hybrid architectures using fuel cells for automotive applications are analyzed. Two parallel hybrid configurations are more precisely detailed and their control strategies are explained. Then, experimental validations using a Nexa Ballard PEM-FC as main source and BOOSTCAP Maxwell supercapacitors as auxiliary source are presented to illustrate the effectiveness of the proposed control strategies.

Supercapacitors for power assistance in hybrid power source with fuel cell

This paper deals with the use of supercapacitors as ancillary power supply in transport applications powered by a PEM fuel cell. These applications are known for strong transient power demand which makes supercapacitors a relevant choice. The aim of this association and its associated power management is to guarantee load requirements as well as to minimize fuel consumption and to ensures that each component constraint is satisfied (lifetime, reliability, high efficiency, …). The designed strategy uses a cascade control allowing a frequency decomposition of the power demand cycle: supercapacitors supply the high band of the load power frequency spectrum whereas low frequencies are provided by the fuel cell which contributes to the longterm autonomy. An experimental 1 kW power test bench has been designed to illustrate the effectiveness of the proposed method. Experimental results are presented demonstrating that this approach provides improvements in terms of a significant energy savings when ancillary power supply is implemented.

Sliding mode control and simulation of a hybrid Fuel-Cell Ultracapacitor power system

This paper deals with a robust control strategy for modern distributed generation systems made up of hybrid PEM (proton exchange membrane) Fuel Cell (FC) and Ultracapacitors (UCs) power system. Particularly, for future fuel cell a vehicle application is presented. Given the constraint of the FC dynamics and the complexity of the energy management, a second order sliding mode control (SMC) strategy is designed to improve the robustness and the performance of the system. This control strategy, based on frequency decomposition of the load specifications, uses a cascaded closed loop control. It takes into account the slow dynamics of FC and the state of charge (SOC) of the UCs. FC output power is determined according to the low frequency (LF) load requirement and the UC SOC. UCs value is determined according to the high frequency (HF) load requirement. Therefore, two voltage control loops are designed. The DC bus voltage is regulated by the UCs source using a classical proportional integrator (PI) controller. The UCs SOC voltage is regulated by the FC source using a sliding mode (SM) controller, which improves the global performance of the controlled system. An analysis of the simulation results is conducted using Matlab/Simulink software in order to verify the effectiveness of the proposed control strategy. It confirms that the developed model and its control strategy exhibit excellent performance.

Interconnection and damping assignment passivity-based control of a fuel cell system

This paper presents the design of a non-linear controller for an energy hybridization structure involving a hydrogen fuel cell with supercapacitors for applications with high instantaneous dynamic power. The design of the controller is based on the interconnection and damping assignment - passivity based control, and compared with a standard controller strategy based on proportional-integral controller. The stability properties, the number of degree of freedom and performances of both controllers are discussed.

Control strategy with saturation management of a fuel cell/ultracapacitors hybrid vehicule

In this paper, a new control strategy including saturation management of hybrid fuel cell/ultracapacitors power source is described. First, an analysis of hybrid architectures using fuel cells and ultracapacitors for automotive applications is presented. Then, a two-converter parallel configuration is more precisely detailed. The model and the control strategy are described using the Energetic Macroscopic Representation (EMR). So, the main originality of this paper is based on the consideration of the systems limits. This leads to a very complete Energy Management Strategy, which has been evaluated and validated in simulation.

A new on-line state-of-health monitoring technique dedicated to PEM fuel cell

This paper is in the scope of fuel cell robust control. As a matter of fact, reliability and lifetime are the two major key points for fuel cell commercialization, especially as far as proton exchange membrane technology is concerned. To bring about these essential properties, the system designer needs to build a robust control law based on a suitable and on-line state of health knowledge. For this latter diagnosis purpose, we describe a new on-line impedance spectroscopy which gets accurate data while still allowing load monitoring.

Optimization of a power electronic structure for hybrid Fuel Cell/Ultracapacitors vehicle

This paper deals with the optimization of a parallel hybrid Fuel Cell (FC)/ Ultracapacitors (UCs) power source for automotive applications. The aim of this hybridization and its control are to fulfil the load requirements as well as to comply with the component constraints (high efficiency, reduced weight and cost, etc.). First, a classical hybrid architecture using FC/UCs and a two-converter structure is presented. After that, power requirements for automotive applications are analyzed, and the load power demands for the FC/UCs sources are deduced. Secondly, the model-based design approach is used for the optimization, and a selection of the main components to be optimized is presented. Thus, the simulation model and the control strategy are detailed. This model has been validated experimentally. Finally, an optimization algorithm is designed using Parallel Computing and the Genetic Algorithm toolbox of Matlab/Simulink. The retained criterion is based on the reduction of the total volume of the system.

Design methodology with optimization of an interleaved buck converter for automotive application

This paper presents a design methodology applied to interleaved converters. This methodology is based on a multi-physic optimisation. The number of cells is used as a key parameter to formalise this approach with analytical models established to offer compromise needed between the computation time and results accuracy. The proposed methodology is applied to an interleaved buck converter for automotive application considering electric, volume, efficiency and thermal constraints. It allows to find the optimal converter architecture by searching the optimal number of cells and adequate active and passive components selected from a manufacturer data base. The methodology is drawn up to remove the risk of feasibility of a converter configuration considering several design specifications.