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The paper explores the design implications of accommodating the engine start function in a large variable frequency starter-generator. Using data from an existing 225kVA starter-generator the trade off between the stator current, which impacts the size and rating of the start inverter, and the field current, which affects the size, rating, and complexity of the excitation system is explored. The suitability of a 3-phase AC main exciter is assessed as a direct replacement for the conventional main exciter. An optimization of the 3-phase configuration is presented, aimed at achieving minimum input VA to the exciter for a given field excitation requirement during start. Results from this prototype start excitation system indicate high levels of field current are possible from a design which could be retrofitted within the mechanical envelope of the conventional exciter.

The alleviation of environmental problems associated with personal, public and commercial transport in urban areas has become an important issue for both policy makers and the automotive industry. Future legislation in Europe and the USA is expected to introduce strict limits in vehicle emissions, and both electric and hybrid vehicles are considered to be strong contenders for meeting low / zero emissions targets. As a result, research into electrically driven powertrains, which have similar performance attributes as ICE (Internal Combustion Engine) vehicles, has led to the development of electrically actuated wheel technologies, with increasing attention being focused on research into novel antilock braking / traction control (ABS / TCS) strategies. This paper describes a comparison of traction control schemes using real - time observer based estimates of μ-slip characteristics.