Development of a Methodology for the Modelling of a BEV Powertrain in GT-SUITE

Simulation methods play a fundamental role in the development of electric powertrains to optimize vehicle performance, cost and streamline the control development. In this context, this study focuses on the development of a methodology for the evaluation of a battery electric vehicle (BEV) powertrain, by means of the CAE multi-physics simulation software GT-SUITE. First, the case study and the powertrain components are presented including battery pack, inverter with capacitor DC-Link and PM motor. Their function, the requested input data and the modelling criteria are discussed. Subsequently, an electrical-equivalent thermal model for the inverter is proposed, for the evaluation of the instantaneous junction temperature of the switches. Furthermore, the implementation of the Field-Oriented Control (FOC) is described, analysing also in detail the modulation technique for the switching command computation. The resulting powertrain model is then tested in both steady-state and transient conditions: with the steady-state simulation, the coupling of the battery pack and the inverter DC-link capacitors is analyzed, focusing on the frequency spectrum of the battery signals; meanwhile, the role of the transient simulation is to prove the validity of the control and to investigate the performance of each powertrain sub-system during various working conditions, such as driving test procedures. The generation of loss maps of the inverter is discussed, analysing the effect that different modulation techniques may have on the efficiency optimization of the system. Finally, to explore the validity of the model in evaluating different powertrain components, two alternative layouts of the three-phase inverter (two-legs and four-legs layout) are investigated. This comprehensive BEV powertrain model demonstrated to be a valuable tool for evaluating vehicle performance, developing control strategies and optimizing individual components.