Abstract
A long-term operation test of a specially developed electric bus has been performed as part of a project organized by the Japanese Ministry of the Environment. The following information related to the inductive power supply (IPS) system was obtained. (1) One practical issue of the IPS system is misalignment between the transmitting coil and receiving coil when the vehicle is parked outside the optimum position. After measuring and evaluating this issue over a period of five months using the developed mini bus, it was found that misalignment tended to be greater in the longitudinal direction than the lateral direction. After the driver became fully accustomed to parking the mini bus, the evaluation found that the maximum misalignment was approximately 6.5 cm. (2) The degree of misalignment measured in the test had virtually no adverse effect on the efficiency of the adopted IPS system (86% when the coils are aligned directly opposite each other). (3) The feasibility of moderating the system performance was examined, principally to help reduce costs. Specifically, a new system design theory was proposed that moderated the design requirement for the reduction in the coupling coefficient that occurs when misalignment increases. After studying and adopting the proposed method, it was found that, even with a large moderation in coupling coefficient performance, it could be possible to realize a system with only a comparatively small drop in efficiency.
