After more than 100 years of combustion engine use for vehicle propulsion, a most relevant and slightly provocative question is: why is there so much interest now in hybrid vehicles development? The answer is multi-faceted, however there are basically three main arguments for the revitalized interest: less CO2-emissions and significantly lower fuel consumptions; improved driving dynamics and comfort through a second energy converter which for a limited time can deliver increased driving torque and/or acceleration; and last but certainly not least, the development of hybrid vehicles act as an intermediate and necessary stage in the on-going development towards fully electrical vehicles. Development of hybrid vehicles faces many new technical challenges; a number of components in the drive-train need more space and add weight to the vehicle, the battery is a particularly demanding device. Furthermore, customers require that a hybrid vehicle, despite its increased complexity, should have the same performance, reliability and cost profile as a conventional one. This certainly puts heavy demands on the vehicle development. Improved battery technology, better electric motors and power electronics are necessary, requiring optimization of vehicle aerodynamics and thermal management. Three concepts are common in discussions on hybrid and electrical vehicles: energy management, road vehicle aerodynamics, and thermal management. Many times this terminology is ambiguous and may create miss-understandings and even incorrect interpretations. In the paper these concepts are defined, sorted out and discussed. Main focus of the paper is on the use of vehicle aerodynamics and thermal management on hybrid and electrical vehicles. A brief history of hybrid vehicles, starting with one of the first hybrid cars that was built back in 1899 by Ferdinand Porsche, is given as an introduction. This vehicle was the System Lohner-Porsche Mixte, and used a gasoline engine to supply power to an electric motor which in turn drove the front wheels. From the historical archive, milestones are elucidated and analysed from today's environmental perspective. The historical part finishes with a discussion based on the ever-increasing environmental awareness; and that the Toyota Prius (for example) may be in for some stiff competition. To increase the relevance of motor sport for production car design a number of new regulations were introduced for the 2014 season. Specifically for F1 a massive fuel consumption challenge, 100 kg/h fuel flow limit and a maximum fuel allocation of 100 kg, was introduced. To meet these conditions new power units were developed due to a fundamentally different rulebook. This means the return of turbo-charging and a massive increase in potency of the hybrid system. Hence, the F1 cars for 2014 may be categorized as hybrid electrical vehicles since they combine a conventional internal combustion engine with an electrical propulsion system, and may be considered as the most energy-efficient vehicles of today. In this context, the energy recovery systems such as KERS (Kinetic Energy Recovery System), MGU (Motor Generator Unit) and recuperative braking are all used to the limit and in the paper these devices are reviewed and discussed. In a similar way as for passenger and race cars there is a potential of introducing hybrids for medium and heavy trucks. Benefits from a second energy converter in the next generation of trucks are illustrated, and possibilities opened by hybrid propulsion in new vehicle architectures are summarized and discussed. Lithium-ion batteries show strong dependence on their operating temperatures, too low temperature will limit the energy efficiency, while a too high will accelerate the aging of the battery. Hence, the maintenance of good operating temperature (climate control) of the battery storage is of utmost importance for the functioning of hybrid and electrical vehicles. A number of important factors, such as the temperature of the ambient-air, engine, electrical motors and load cycles of the vehicle interact and must be controlled in order to optimize drive range and battery aging. Advanced models for the description of the different systems and their interaction are needed.


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