Flywheel and supercapacitor peak power buffer technologies

Electric vehicles (EVs) are playing an increasing role in addressing the environmental burdens associated with personnel transport by offering an alternative to the IC engine vehicle that is free of exhaust emissions and is more energy efficient. However, because of the limited energy storage capability of current battery technologies, electric only vehicles cannot currently compete in terms of range between refuelling with their ICE counterparts. Improved overall vehicle efficiency and increased battery cycle life are key factors for the commercial success of an EV. The paper presents initial findings from a project whose aim is to re-evaluate the architecture of battery powered EV traction systems in the light of the latest developments in supercapacitor and flywheel peak power buffers, together with very high efficiency permanent magnet motor drives and power electronic converter. An objective being to improve both the range and cycle life available from a particular choice of battery through the use of an appropriate power and energy management system. In the search for the optimum system configuration, simulation plays an essential role in determining the energy requirements of a particular vehicle, in calculating the power train losses and performance, and in assessing the implication of a particular choice of component or control strategy. Therefore an initial phase of the research has been to develop a comprehensive suite of software macro models of the various traction system components and validate these through tests on state of the art components