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In this study, the series hybrid electric system is recommended as suitable power systems of the motor vehicles in urban area. It is important for this system to improve the comprehensive energy efficiency when components are combined, and to evaluate it appropriately. In this report, the technique to grasp energy loss in detail that occurs when electric power flows complicatedly in the series hybrid power system has been examined and the energy efficiency of the series hybrid power system on urban driving has also been evaluated.

The cordierite filter has been widely studied because of it's inherent, high capacities in the collection efficiency and heat-resistance. During the regeneration process of a cordierite filter, failure of ignition or incomplete burning propagation occurs, and additionally melts or cracks develop sometimes. In this study, the problems stated above are considered from a new standpoint, and a regeneration method that does not strictly depend on accumulated soot quantity is discussed. A filter made of SiC (Silicon carbide) possesses the requisite electric resistance and it's possible to heat it uniformly by using electricity. Accumulated soot can be uniformly incinerated not by burning propagation but by simultaneous ignition and burning of all accumulated soot. Silicon carbide has a higher resistance to heat than cordierite. Therefore, a self-heating filter made of SiC makes it possible to regenerate the filter in a wider range of accumulated soot.

The purpose of this study is to examine a proper power system for a miniature vehicle called as “Commuter-car” that is expected to be used for commutation or shopping in urban areas. Before starting experiments, an investigation of actual commutation driving was made. It was found that the driving distance was generally short and that start-stop frequency was high at commutation driving in urban areas. As a result of this driving investigation, it was educed to introduce an electric motor traction method into commuter-cars. First, a small generator was added to a conventional electric vehicle (EV) to convert it into a series hybrid vehicle. The running range of this vehicle was confirmed experimentally to be extended much more than the base EV in transient driving. Therefore, it was judged that series hybrid system is reasonable to be applied to commuter-cars.