Development of a simulation program to size electric vehicle powertrains

The main objective of this project is to develop a tool that allows the sizing, in terms of mechanical values (torque curve) and electric values (for battery and motor-controller), of powertrains for electric vehicles, given certain performance criteria. The second objective is to apply this tool to a specific case study. It is focused on the search for a modular powertrain solution for a range of vehicles of categories L3e, L6e and L7e. By modular is understood as physical compatibility (assembly compatibility) and technical compatibility (no performance limitations). Simulink, a tool of Matlab software, has been used to develop the sizing tool. It has been done by implementing a broad automotive and electric physical base, as well as different driving cycles to analyse vehicle’s performance. With this tool it is possible to define the main characteristics of electric powertrains: motor, motor-controller, fixed gear ratio and battery. A functional software for sizing electric powertrain has been developed successfully. With this tool it has been possible to size the electric powertrains of the case study vehicles. To size the case study powertrains, vehicles’ attributes and performance targets has been determined taking as reference type-approval regulations and an ad hoc market survey. Moreover, it has been developed a decision tree to make the decision about the modularity of the powertrains. The final decision about motor modularity for the case study has been to implement the same motor for the L3e and L6e vehicles, and a specific one for the L7e. However, this solution is not consolidated because it is needed an analysis done by an expert motor manufacturer, to obtain solutions technically and economically viable. It has been perceived that the requirements of performance and range are too ambitious for the type of vehicles of the case study (small dimensions) using low voltage batteries, since the required number of modules and the required current to be handled by the motor-controller are high: 6 modules for L3e vehicle, 9 modules for L6e and 11 modules for L7e, and current peaks up to 1111A (for L7e). Moreover, a methodology to obtain the motor maximum torque-speed curve has been described, so it is possible to compare the real motor curve with the one obtained by the sizing tool, with the aim of validating the software tool