An innovative concept for short-distance electricity-powered public transport vehicles developed by German researchers will be introduced at the International Motor Show in Frankfurt.
The project aims to prove that, despite the currently high costs of batteries, the battery-based electric drives could be profitable even with the current state of the technology development.
“Energy efficiency of an electric bus can be increased by an adequate selection of components already,” said Martin Gießler, Head of the demonstrator development project at the Karlsruhe Institute of Technology.
The characteristics of short-distance travel – including frequent acceleration and braking, as well as high utilisation rate – make the electric power trains a favourable solution for use in cities.
“Of course, an anticipatory operation and recuperation strategy plays an important role,” Gießler said. Recuperation allows converting energy released during braking back into electrical energy that could be used to power the vehicle.
The demonstrator contains a drive train with a high-torque electric motor, a high-voltage network, a battery management system, and a novel modular battery system with lithium-ion cells.
The drive's low-torque engine of the is supplying a high driving torque for the vehicle. The engine is connected directly with the differential gear of the rear axle. It decreases the gear reduction to be implemented and, hence, ensures a high efficiency of torque transmission.
The battery system consists of flat modules that can be stacked to reach the dimensions and electric characteristics desired. Various spaces in the different types of vehicles can be used for accommodating the energy storage system. The battery management system and drive control developed for the KIT demonstrator allow for driving operation taking into account the current performance limits of the system and its components.