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The depletion of the world oil reserves is a major problem facing the world community today. The number of years that oil resources can support our energy needs depends on its proven reserves, new discovery and cumulative consumption. As more countries evolve from developing nations into industrialized societies, the number of vehicles on the road skyrockets. This drastically increasing number of cars on the road is one of the main causes of the rapid depletion of the world oil resources. It also impacts the environment in the form of acid rain, global warming and increased concentrations of ozone near the surface of the earth. This basically leaves two alternatives, stipend the growth of industry or reduce the fuel usage of our vehicles. Recession is not very enjoyable, therefore great efforts are being made to improve the fuel efficiency of modern vehicles, but due to the physical characteristics of internal combustion engines, there is an efficiency limit.

Currently, almost all the activities in the development of new generation of vehicles are focused on fuel cell powered vehicles (FCVs) and hybrid electric vehicles (HEVs). However, there are still uncertainties as to which provides the maximum benefits in terms of performance, energy savings and impact on the environment. This paper compares the performance and parameter characteristics of FCVs and HEVs with a view towards an objective assessment of the relative performance of these vehicles. In particular, this paper reviews major characteristics of FCVs as zero or ultra-low emission vehicles (ZEV/ULEVs), their presumed high efficiency and potential for using alternative fuels, while also considering their limited performance at high power demands.

New dc to dc converter topologies are presented which are suitable for high density high power supplies. Topological variations of the basic inverse dual converter (IDC) circuit such as the transformer coupled, the multiphase and the multipulse derivation of the single phase IDC have been analysed and some simulation results have been presented. It has been shown in a recent publication [1] that the single phase IDC offers a buck-boost operation over wide range without transformer, bidirectional power flow, and complementary commutation of the switches. The topologies examined in this paper have additional features such as lower device and component stresses, and smaller filter requirements, resulting in smaller size and weight. Some performance and possible applications are also examined. Finally the IDCs for serial and parallel power distribution, and ac tapping of the IDC are discussed.

Electric power generation and conditioning have experienced revolutionary development over the past two decades. Furthermore, new materials such as high energy magnets and high temperature superconductors are either available or on the horizon. Our work is based on the promise that new technologies are an important driver of new power system concepts and architectures. This observation is born out by the historical evolution of power systems both in terrestrial and aerospace applications. This paper will introduce new approaches to designing space power systems by using several new technologies.

Two parallel HEV control concepts: ‘thermostat’ and ‘power split’ are compared in this paper. To achieve a substantial improvement in fuel economy, the ‘thermostat’ or ‘on/off’ control technique intended to improve the fuel efficiency of a series HEV has been adopted and designed for parallel HEV. Among different ‘power split’ concepts developed for parallel hybrids only the ‘electrically assist’ algorithm is considered in this paper. These two control concepts are compared for three parallel HEV architectures: pre-transmission, post-transmission and continuous variable transmission hybrids. The comparison study also includes the effect of hybridization factor-the ratio of the electric power to the total propulsion power. The matrices of comparison are level of performance, energy consumption and exhaust emissions. The SAE J1711 partial charge test procedure is followed.