Hybrid Engine Motor Systems

A hybrid engine motor system is an approach to combine different types of engines in one vehicle, to reach an energy efficiency gain in comparison to traditional engines. Usually a combustion engine is combined with an electric drive [1]. The whole drive system is called power-train, which is optimized in order to access the advantages of both engine types. The electrical drive can provide power at zero pollution in certain cases and enables higher fuel efficiency of the combustion engine. Therefore such hybrid systems use methods like regenerative braking, which is using the kinetic energy while braking to reload the battery, or start-stop mechanisms, to automatically stop the combustion engine while the car is standing still and restart the engine when it is needed. To sum this up, the benefit of hybrid cars is “to operate the combustion engine in more suitable regimes with better fuel combustion conditions” [2]. There are different construction methods for hybrid engines, varying in the way the two engines are working together. Figure 1 shows three possible schemas of a hybrid drive powertrain, including a construction in series, in parallel and a combined construction [2]:

Figure 1: Series hybrid drive (l), parallel hybrid drive (m) and combined switched hybrid drive (r) [2]

The role of ICT in the context of hybrid motor systems is to enable the optimization of design and control of these systems. Information technology therefore provides tools for offline planning and simulation of motor systems, that allow the calculation of the parameters providing maximum efficiency of the motor system [1]. Beside offline optimization, hybrid motor systems have to be controlled online to adjust the workload of both engine types. This function is fulfilled by built-in computer systems as well [3]. A study in 2008 came to the conclusion that a hybrid engined car had a reduced fuel consumption by about 13,6 percent in comparison to the same type of car powered by a traditional combustion engine [2]. The fuel-saving potential of hybrid cars can therefore be assumed to be environmentally relevant, but rather low. The hybrid engine technology is particularly efficient for delivery vehicles and buses, where frequent stops are necessary, rather than long-distance road travel [4]. This statement is based on the fact, that the hybrid technology is characterized by producing electricity from recovering breaking energy, which is used to reload the battery for the electric engine. In general the environmental benefits of hybrid motor systems compared to traditional commercial cars are:

• reduced greenhouse gas emissions, due to increased energy and fuel efficiency, 
• a lower noise level at idle and slow speeds, due to the use of the electrical drive, and 
• reduced fine dust emissions, which is an essential environmental factor, especially in cities.

In comparison to hybrid cars the positive environmental impact of completely electric powered vehicles would be more substantial. An immediate benefit of electric cars is that there are no fine-dust emissions arising from these engines. But the electricity needed for powering electric cars primarily is still generated by fossil fuel power plants. Therefore greenhouse gas emissions savings can only be achieved by reloading electric cars from renewable sources of energy. One promising concept are Smart Grids, which enable the efficient integration of small-scale power generators based on renewable sources of energy [5]. Smart Grids could also supply charging stations as well as simplified charge billing, by logging in to the owner’s account when a vehicle is plugged into the grid. Additionally, the batteries of electric cars could be used as distributed power storage in Smart Grids [4]. By this electric vehicles could help balancing the energy on the electrical grid, a concept that is called vehicle to grid [5]. This approach could be especially beneficial in peak times.

References

[1] A. Kleimaier and D. Schroeder. Hybrid cars, optimization and control. In Industrial Technology, 2004. IEEE ICIT ’04. 2004 IEEE International Conference on, volume 2, pages 1084 – 1089 Vol. 2, dec. 2004.

[2] Z. Cerovsky and P. Mindl. Hybrid electric cars, combustion engine driven cars and their impact on environment. In Power Electronics, Electrical Drives, Automation and Motion, 2008. SPEEDAM 2008. International Symposium on, pages 739 –743, june 2008.

[3] B. Tomlinson. Greening through IT - Information Technology for Environmental Sustainability. The MIT Press, 2010.

[4] B. Metz. Controlling climate change. Cambridge University Press, 2010.

[5] U.S. Department of Energy. What is the smart grid? http://www.smartgrid.gov/the_smart_grid. Accessed: 2013-02-12.