Modellazione e verifica sperimentale di un controllo di un powertrain elettrico: pacco batteria, inverter, motore brushless SPM = Modeling and experimental validation of an electric powertrain control: battery pack, inverter, brushless motor SPM

Modeling and experimental validation of an electric powertrain control: battery pack, inverter, brushless motor SPM In recent years, the need to reduce CO2 emissions and to save on fossil fuels has become part of society and everyone's life, developing a radical change in various areas, especially in transports. For these reasons, Electro-mobility (e-mobility) is one of the most adopted solution by carmakers, which however collide with the need to simulate the electric vehicles behaviour, first of all with regard to the electromechanical aspects. In order to deepen this need, it was assembled an electric prototype and it was studied the validation process of the electric powertrain model. This thesis concerns the revamping of an electric vehicle called Mulotipo made up by IEHV research group of Politecnico di Torino. This vehicle was not working because of the low voltage of the battery pack and the absence of the inverter and electric motor parameters. At the beginning it was made a benchmark of many commercial inverters to be used on the new electric powertrain of Mulotipo, considering only the inverters with nominal voltage and nominal current compatible with the other elements of the powertrain. The choice was made by evaluating the right operational voltages compatible with electric motor and the battery pack, and also the economic advantage of being already in possession of the inverter. Therefore, the inverter chosen was the Sevcon Gen 4 Size 6 already present in the laboratory of the Beond company. Similar assessments have been considered for the motor choice, so it has been chosen a SPM Brushless motor already in possession of the Beond company. Different methodology was used to make the battery pack; because of other battery pack commissions it has been decided to make a battery pack compatible with the other powertrain elements chosen and even compatible with one battery pack commissioned. Once the components have been decided, a powertrain model was elaborated on Simulink to simulate the behaviour of the entire vehicle made up by the selected powertrain. First it has been elaborated a time continuous model and then it has been implemented a discrete time model taking into account the real behaviour of a real time inverter control, because of the presence of the time discretization made up by the microcontroller. This second type of model was more realistic evaluating real control problems like speed feedback, rotor position discretization, actuation delay and additional noise on the electrical and mechanical quantities. It has built some structural parts to adapt the existing chassis to the new powertrain components. It has also been machined the tripods to have the right measure in order to achieve the right mechanical coupling between transmission and wheels. Afterwards it has been assembled a 16 series cells, 48 nominal voltage battery pack with passive BMS, interlock routine, 2 contactors and a precharge relay, to supply the vehicle. Once the assembly was completed, it was proceeded to the validation tests; to have the right moment of inertia seen by the motor, it was obtained the weight of the vehicle using 4 balances, one per wheel. It has been proceeded on creating a real driving cycle with a real time test, using Etas as the capture tool for currents and voltages; subsequently the same driving cycle has been simulated on Matlab to validate the model.