Examinator: Sebastien Gros, Inst för elektroteknik
Handledare: Anand Ganesan, Inst för elektroteknik
Opponenter: Filip Tagesson och Oskar Edholm
A common architecture for electric vehicles is to have electric machines on both the front and rear axle. This work is an attempt to derive an optimal torque split strategy between the two machines to reduce the overall energy consumption. A clutch is implemented on the front axle and its engagement is dynamically controlled to reduce the magnetic drag losses. As electric machine and inverter losses are also dependent on temperature, a power loss map based on torque, machine RPM and temperature is used. An upper temperature limit for both electric machine and inverter is also imposed for component protection. Thermal models for electric machine, inverter and coolant circuit are simplified using system identification and model order reduction approach. Dynamic programming is used to investigate the benefits of including thermal losses and to generate a benchmark solution for optimal torque split strategy. Further, an online controller is developed based on non-linear model predictive control. The controllers are verified in a high-fidelity simulation environment.
Keywords: Optimal torque-split control strategy, battery electric vehicles, thermal model of electric machines, system identification, model order reduction, co-simulation