Transmission Modeling for Optimization of Electric Powertrains

Sammanfattning: Over the last decade, the number of electric vehicles (EVs) on the world's roads has rapidly increased. Optimization of power consumption in electric powertrains will, therefore, lead to reduced energy usage in the road transport sector. EPOS, is a research project that aims to optimize EV powertrains, with the objectives to minimize cost and power consumption. As a part of the EPOS project, this thesis' purpose was to develop an optimization tool for the mechanical transmissions in EVs, with the objectives to minimize mass and power loss. The optimization tool is intended to run millions of times, therefore a target for execution time for the transmission optimizations was set. Models for component size and efficiency were initially created with a high level of detail, which was subsequently reduced in order to reach the target for execution time. Fixed values for design variables and an iteration based gear-set optimization model lead to successfully reaching the target, but solutions were less optimized. The xed variables' impact on the optimization result could be evaluated, by comparing the optimization solutions while varying the number of xed design variables. The optimal solution was determined with a scoring model, that compared the optimization objectives in terms of energy consumption. It was found that there was a signicant trade-o when minimizing mass and power loss. Prioritization in the trade-o was important when deciding on an optimal solution, in order to get the desired result. The nal conclusion of this thesis was that the detail of component models and the compromise between optimization objectives, have an important role in attaining the most optimal transmission design.