Electric Hybrid Bus Simulation and Optimisation
Christian Andersson 
External reviewer: Anders Malmqvist, ABB, Västerås 

The work presented here deals with evaluation and optimisation of the tractive system in hybrid electric buses. The work is based on analytical simulation models that are verified via measurements.
The main results of the work are:
· An optimised composition of the traction system topology, regarding the size of the different components in the drive train with respect to the performance and emission at a given drive cycle.
· A charging strategy taking into account a predicted drive cycle, the SOC of the batteries and the instantaneous tractive power.
· A transient emission measurement (TES) method for Internal Combustion Engines.

The simulation model concerns all the major power flow, vehicle speed, temperatures and Internal Combustion Engine (ICE) parameters of the busses. The model is verified through measurements on two hybrid buses in Malmö and Stockholm. The ICE models are verified through test bench driving, both by an external partner and by Lund University. The predicted drive cycle proposed here is based on position
measurements of the bus relative to the route. With the proposed changes in composition and charging strategy, one of the buses studied can reduce the battery weight with 60 %, the fuel consumption with 10 % and the size of the ICE with 60 %. As a part of the work with measurements on the busses some practical
experience of handling the vehicles have been gained, some of which are also presented in this report.