REACHING YOUR DESTINATION BY BUS IN A MORE ENVIRONMENTALLY AND CLIMATE-FRIENDLY WAY

How does the automatic start-stop system work in city buses?

All systems on the market have eliminated the conventional starter and replaced it with a starter generator, which is practically an electric motor (KSG = crankshaft starter generator or ISG = integrated starter generator, starter and alternator/generator are always one component). When pushing and braking, the system works as an alternator, when starting, it works as a starter (starter motor).

The starter generator is installed in the driveline between the engine and the gearbox and works in combination with starter and on-board batteries and increasingly with supercaps (capacitors). These can store and release high amounts of current extremely quickly; the electrical energy is stored here purely electrostatically. Combined with an intelligent self-learning battery energy management (BEM) that always uses the energy where it is most urgently needed.

To further optimise battery energy management, more and more GPS-based information is being integrated.

The BEM software also takes the route into account in terms of topography. A brief example: The bus compressor reports a need for energy and the compressed air supply for the brakes needs to be refilled. This information is not immediately implemented, however, and power from the batteries or capacitors is used for this purpose; the energy management system now delays the "execution of the command" for once. This is because a longer downhill stretch is coming up in a shorter distance. Only during the downhill run does the compressor start up and fill the compressed air supply. However, the energy for this often does not come from the batteries or capacitors, but directly from recuperation (=brake energy recovery). This protects the power storage units due to less cycling, because the charging and discharging processes can often be drastically reduced!