Philipp Elbert, Hans-Jörg Gisler, Prof Lino Guzzella
This project aims to minimise CO2 emissions of hybrid-electric buses used in public transport. In hybrid buses, the level of CO2 emissions greatly depends on the energy management system regulating the power split between the battery and the engine. Simulations show that a hybrid-electric bus with a good standard strategy emits 15-20% less CO2 than an equally sized diesel bus. However, the bus could potentially achieve savings of as much as 25-30%. So what is the problem with the standard strategy? The answer is that it cannot factor in future events, which leads to efficiency being compromised.
We have developed a new predictive strategy that uses a GNSS sensor to determine the exact position of the vehicle, which in turn allows us to factor in information on the elevation profile further ahead. This is possible, because buses used in public transport typically follow predefined routes. Simulations have shown that with our new predictive strategy hybrid busses would emit 25-30% less CO2 than a comparable diesel bus. Thus, our new predictive strategy helps cut CO2 emissions of hybrid-electric buses by 5-15%.