Functional model of BSG 48V for new Diesel MHEV application

In these years the reduction of gases and pollutants released in the air is one of the most important and discussed topic. The transports are one of the major responsible of CO2 emitted with related climate change. Automotive industries and car producers, like Stellantis Group, are pushing the development of new technologies and innovative propulsion systems: in the recent years the number of electric vehicles is quickly increased, and thanks to the continuous research for electrification of motors, a large CO2 reduction could be achieved. The progress in electric drives, has been gradually improved and it’s started with hybrid electric vehicles (HEVs), through the integration of internal combustion engine with the electric motor. During the past few years also full electric vehicles (BEVs) and plug-in electric vehicles (PHEVs) have been designed and produced. An initial introduction on these used electric architectures and on the different layouts is reported: the configuration P0, usually called Belt Starter Generator (BSG), is discussed in detail. The main objective of this thesis is to create a functional model of BSG 48 V for new Diesel Mild hybrid electric vehicles and the study of electric 48V network: in this configuration, the electric motor is always connected to the Internal combustion engine through the drive belt. Starting from the analysis of BSG structure, the study of electrical environment and its 48 V components allows to build a Simscape modelling of Belt Starter Generator and 48 V network. The Belt Starter Generator with electric 48 V net model has been simulated using Matlab and Simscape in different operative conditions, considering standard operating points and the fault situation: results of electrical and mechanical response have been analysed. The proposed model, designed for Stellantis, will be necessary to simulate and perform some different tests on the BSG system, to analyse the outputs and the interactions with other components. In the second part, numerical and graphical approaches are used with the aim to evaluate the damage of support axial bearings of BSG 48 V. From the data results of some mission profiles tests on the bearings, time histories of stressed mechanical components are extracted in order to consider torque, velocity of rotation and the rotating moment histogram (RMH). The RMH is used to compute the fatigue damage of bearings. Different mission profiles have been elaborated to assess many operating points, taking into account the motoring phase and the regeneration phase of the BSG. The activities allow to get a model for electrical stress analysis and a mechanical damage evaluation, that are useful for supporting development phases and properly define the validation profile for the electrical architecture and sub-components.