The French national railways company (SNCF) is involved in a new project called PLATHEE (energyefficient and environmentally friendly train platform) which aims at investigating and testing energyefficient and environmentally friendly traction systems. In particular, the design of a hybrid locomotive called LHyDIE has been started at 2005. This paper presents a new methodology for the hybrid electric vehicle design which exploits an energy management strategy based on a frequency approach. In particular, the design of the LHyDIE prototype and the energy management strategy implemented aboard are presented. The study mainly focuses on the battery and supercapacitor sizing taking account of the intrinsic energetic characteristics of these sources (i.e. energy and power densities, typical operating frequency) in the energy management strategy. The analysis of feasible configurations of the traction device determined in compliance with the battery stress, the system cost and the diesel oil consumption criteria and volume constraints is presented.

The French National Railways Company (SNCF) is interested in the design of a hybrid locomotive based on various storage devices (accumulator, flywheel, and ultracapacitor) and fed by a diesel generator. This paper particularly deals with the integration of a flywheel device as a storage element with a reduced-power diesel generator and accumulators on the hybrid locomotive. First, a power flow model of energy-storage elements (flywheel and accumulator) is developed to achieve the design of the whole traction system. Then, two energy-management strategies based on a frequency approach are proposed. The first strategy led us to a bad exploitation of the flywheel, whereas the second strategy provides an optimal sizing of the storage device. Finally, a comparative study of the proposed structure with a flywheel and the existing structure of the locomotive (diesel generator, accumulators, and ultracapacitors) is presented.

In this paper, the Integrated Optimal Design (IOD) approach for energetic system design is discussed. IOD aims at concurrently optimizing the architecture, the element sizing and the energy management in an energetic system. IOD leads to complex optimization problems (typically mixed variable problems with several constraints and multiple objectives) which can be solved with direct optimization methods. We illustrate the interest of this approach through the design of a hybrid environmentally friendly locomotive moved by four DC motors supplied by a diesel engine generator in association with electric storage elements (batteries and ultracapacitors).