Electric transit bus for variable grade terrain

Abstract

This paper overviews the design changes necessary to convert an AVS-22 electric bus to an in-vehicle component testbed. These changes include the addition of a data acquisition system and a modular control system that will be adaptable with changing components. The majority of this paper discusses the need for the bus to climb 25% grades, and how battery chemistry significantly affects hill climb performance. An equivalent capacity LI battery pack weighs 1620 kg less than the current LA battery pack. This corresponds to a reduction in required traction motor torque by 557 Nm and a peak power reduction of 132 kW. The weight reduction correlates to a reduction of the gear ratio by one, in the transmission. Therefore, the LI battery pack allows the bus to go up a 25% grade hill, without experiencing a significant drop in vehicle performance.