Energy solutions for vehicular systems: Introduction

FCEV are a promising alternative clean propulsion that no pollutants are emitted [1] . This type of vehicles exploits the advantages of  PEMFC which  have several advantages such as:  high efficiency, low-temperature operation and are clean functioning [2]. Among  these characteristics, the PEMFC remains  an excellent technology  for  vehicular systems [3].

Thanks to the different advantages of fuel cell  systems, especially a Proton Exchange Membrane (PEM) which presents the best candidate and  a very efficient solution especially in vehicle applications. However, a PEMFC have a slow dynamic response which keeps it from responding quickly. Besides,  the integration of auxiliary energy source guarantee to overcome these problems and provide high efficiency.

For this reason, many researchers  were oriented towards using at least one additional storage energy working with fuel cell  in order to guarantee power production  for power train during transient phases and  in order to minimize of  hydrogen  consumption. These power sources  present very effective solutions  in solving the dependence of fuel cell power generation on different driving cycle and  allows  the main energy source to have more flexible and reliable working performance.

Therefore, an Energy Management Approach (EMA) is always needed for electric vehicle powered with different  energy source  in order to manage the energy flow from different  sources to supply the motor. The importance of using an efficient EMA resides in providing enough to cover the power load demand during the different driving phases. This latter must be always developed in a way that ensures that  the fuel consumption of the main energy source as low as possible.

The present work consists in integrating a second energy storage device into a power train in terms to guarantee a power  production  and minimizing  the fuel consumption. This auxiliary source chosen is a supercapacitor. In this study, in order to guarantee an optimized operation of the system a proposed control strategy is implemented  to manage the flow of energy between the different sources and in order to limit the use of the  fuel and  benefit as much as possible the storage element.

This paper gives, in Section II, a modeling of the main and a secondary power sources separately: the PEMFC and the Maxwell supercapacitor. Next, we presents in Section III,the control strategy description for the energy storage device converters. Finally, we developed an management strategy in order to reduce the hydrogen consumption of main source.

PEM fuel cell/SC electric vehicle configuration: The studied system in our work  is composed of a hybrid energy source feeding an power train  system as shown in Fig. I.1. The hybrid configuration includes a PEMFC  and a backup power system composed by a storage device which is a  bank of supercapacitor. Energy flow in this system is managed by an Energy Management System (EMS) which is developed  in order to control the different sources and the power train  system through the different static converters. The detailed controls structure and the proposed energy management algorithmwill be  treated ad  demonstrated in our work.