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Series hybrid electric vehicles have their wheels driven by an electric motor powered by a battery with an engine plant that cranks a generator unit to provide electric power to the battery and if necessary to the electric motor. They promise significant reductions in greenhouse gases without compromising driving performance. This year GM has launched the first mass produced series hybrid electric vehicle and other car manufacturer are to follow over the next decade. In recent years significant progress has been made in new battery techno logies, electric propulsion designs, and optimisation of power flow and control of the electric components to reduce the weight and cost. While these developments have been made successfully, little attention has been spent on improvement of the generator-set for series hybrid electric vehicles. Generally, a generator-set consists of a three-phase machine and a three-phase rectifier circuit. Conventional generator- sets suffer from significant voltage drops across the output of the rectifier circuit caused by current commutation, resulting from interaction between the machine inductances and the rectifier. Any voltage drop across the output of the rectifier circuit leads to an inefficient operation ofthe generator system. In this thesis, a new generator-set for the use in series hybrid electric vehicle applications is presented, whereby the voltage drop caused by commutation is eliminated. In a typical rectifier circuit the output voltage drop is proportional to the commutation time, which is a function of the value of the machine inductance. The novel topology operates in such a way that the commutation time becomes independent from the value of the machine inductance. This is achieved by eliminating the output de-link capacitors that are used in traditional rectifier circuits and transferring these capacitors within a new rectifier circuit. These embedded capacitors are charged and discharged simultaneously with two switches. The capacitors still have the function of electric storage but they also operate in resonance with the supply inductance.

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In this paper, three different system topologies for a high performance electric vehicle drive are compared to each other. Next to the classical three phase permanent magnet synchronous machine in different connection schemes, also one topology containing a six phase machine has been included into the study. Suitable inverter topologies are discussed as well as the design of the multiphase winding of the six phase machine. For each of the topologies under investigation, identical types of power semiconductor devices available on the market have been defined as well as an identical active volume of the inverter. The three system topologies (three phase single star machine with parallel inverters, three phase machine in H-bridge / six leg connection, six phase double star machine) have been compared to each other regarding their performance as well as their active short circuit and no-load characteristics. It has been shown by means of simulation that the six phase PSM structure offers some remarkable advantages with regard to its three phase counterparts which makes it adequate for high performance electric vehicle drive applications.:I. Introduction II. Inverter Topologies II.a) Three Phase, Single Star with Parallel Inverter (m3) II.b) Three Phase, H-bridge (m3h) II.c) Six Phase, Double Star (m6) III. Design of Electrical Machine IV. Simulation Results IV.a) Peak Performance IV.b) Induced Back-e.m.f. IV.c) Stationary Short Circuit Condition V. System Comparison VI. Conclusion

The purpose of the study is to analyze the energy use of battery electric vehicles (BEVs), to compare their energy usage with other different vehicle technologies, and ultimately to determine their suitability for recreational use. The possibility of applying such vehicles into South Africa’s game reserves is researched in terms of energy costs and evaluated. Calculations were made based on actual existing routes found in the Kruger National Park, and are presently used by tourists for sightseeing and to access the different camps within the park. Calculations were made on the forces acting on a vehicle driving through the different routes and terrains. These forces were then translated into fuel or energy consumption and subsequently into fuel and energy prices. The entire exercise was performed on alternative vehicle technologies in a hypothetical scenario. The calculations investigated the energy consumption and efficiency of a battery electric vehicle (BEV) and other vehicle technologies such as fuel cell electric vehicle (FCEV), hybrid electric vehicle (HEV), and lastly the internal combustion engine (ICEV) vehicle. It was found that the energy consumption of each vehicle technology revealed similar trends and ranking on most routes. However on certain routes, the energy usage difference amongst the different vehicle technologies became more pronounced. This can be attributed to the continuous demand of energy by the vehicle to maintain forward motion. It was found that in general, irrespective of the route profile, the route surface or its total distance, the highest energy efficiency is achieved by the battery electric vehicle (BEV), followed by the fuel cell electric vehicle (FCEV) and then by the combined hybrid electric vehicle (HEV) and lastly by the internal combustion engine (ICEV) vehicle. / Electrical Engineering / M. Tech. (Electrical Engineering)