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The papers in this special section focus on advanced vehicle power propulsion systems. Electrification f vehicles is one of the major trends in current research and development. In coming years, answers regarding more electric-based propulsion systems for a smooth and decided transition into more efficient and environmentally sensitive propulsion systems are required. Researches and developments should respond to these challenges by investigating more advanced energy storage, power propulsion and energy conversion systems in order to ensure better energy performance, reduced operating cost, and higher lifetime of the next generation of electric vehicles.

In this paper the hybridization of a small passenger car equipped with a Continuously Variable Transmission (CVT) is investigated. Designing a hybrid drive train is a multi-objective design problem. The main design objectives are fuel consumption, emissions, and performance. However, it is difficult to find a global optimal integral design solution due to the interdependence of design choices (parameters) regarding the drive train topology, component sizes, component technologies, and the control strategy, and the unknown sensitivity of the design objectives to the design parameters. In this work a parametric optimization procedure is presented in solving the design problem, where the main design objective is fuel consumption. The effects of parameter variation on the fuel consumption have been investigated. Furthermore, a reduced hybrid drive train model is introduced with which the effects of design parameter variation is studied very quickly and with an average error of less than 1.6%.

In the near future, a significant increase in electric power consumption in vehicles is expected. To limit the associated increase in fuel consumption and exhaust emissions, smart strategies for the generation, storage/retrieval, distribution, and consumption of electric power will be used. Inspired by the research on energy management for hybrid electric vehicles (HEVs), this paper presents an extensive study on controlling the vehicular electric power system to reduce the fuel use and emissions, by generating and storing electrical energy only at the most suitable moments. For this purpose, both off-line optimization methods using knowledge of the driving pattern and on-line implementable ones are developed and tested in a simulation environment. Results show a reduction in fuel use of 2%, even without a prediction of the driving cycle being used. Simultaneously, even larger reductions of the emissions are obtained. The strategies can also be applied to a mild HEV with an integrated starter alternator (ISA), without modifications, or to other types of HEVs with slight changes in the formulation.