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This paper aims at the modeling and performance simulation of a heavy-duty parallel diesel-hybrid transit bus over a variety of different drive cycles. Based on the simulation results, a comparative analysis is performed on the overall drive train efficiencies for the various driving patterns. The simulations are performed for 7 different driving patterns, which show varying results from the point of view of overall percentage drive train efficiency and performance parameters, such as acceleration and tail pipe emissions. Thus, through the studies conducted in this paper, the main goal is to evaluate the potential of the parallel diesel-hybrid transit bus under investigation. In addition, a critical parameter of the developed hybrid bus is the regenerative energy recovery. It is a well-known fact for hybrid electric vehicles (HEVs) that the regenerative energy recovery potential is primarily dependent on its driving pattern.

This paper focuses on the effects of ultra-capacitors as a component of energy storage in hybrid electric vehicles (HEV). The main energy source in a hybrid vehicle is the battery. HEVs with battery sources are presently fairly effective; however, major drawbacks include the cost and size of such batteries. The purpose of this paper is to demonstrate that the addition of ultra-capacitors as a component of the energy storage system can reduce these drawbacks significantly by reducing the size of batteries required to drive the vehicle. To integrate ultra-capacitors into hybrid vehicles, the ADvanced VehIcle SimulatOR (ADVISOR) was used. The vehicle used to conduct this study was the 2004 Jeep Liberty sport utility vehicle (SUV). To simplify the analysis process, the conventional Jeep Liberty was modeled in ADVISOR to resemble the actual performance specifications of the SUV currently in the market.

Intensifying demands for higher fuel economy from one hand and environmental concerns from the other are driving advanced automotive power systems to be more electric. As a result, automotive electrical systems with higher capacity and more complexity are needed to cope with this expanding electrification trend. As different electrical applications and loads are being introduced in automobiles, multi-converter intensive power electronic systems are emerging as the next generation of the advanced automotive electrical systems. In fact, power electronic converters and electric motor drives are inevitable parts of more electric automotive power systems. When power electronic converters and electric motor drives are tightly regulated to improve system performance and efficiency, they present negative impedance characteristics of constant power loads to the entire automotive electrical system. This destabilizing effect may cause system instability.