Integrated design of a power module for hybrid powertrain

The world of traditional vehicles is moving towards an electrified landscape in which the internal combustion engine is flanked by an electric motor that acts as a support to it. A typical electric powertrain consists of a battery, an electric motor used to propel the car and a DC to AC inverter that transforms the DC voltage from the supply to the equivalent AC used to drive the electrical motor. The thesis work carried out is mainly focused on the analysis of a 48-V mild-hybrid vehicle with a P2-type powertrain configuration. Specifically, this thesis addresses the design and numerical validation of a DC-DC converter for the auxiliary loads installed on the vehicle. Therefore, the present work deals with the analog power design, simulations and building of a single power stage of a non-isolated synchronous step-down (buck) DC-DC converter topology, characterized by a nominal output power equal to 1.6 kW, capable of connecting the electrical car's system of 48-V to the standard 12-V battery system. As for the design of the different components that constitute the buck converter, the assigned project specifications necessary for the final development of the project were provided by ON Semiconductor. They also provided the datasheet of the power MOSFETs module to be adapted to the final model of the DC-DC converter, together with the working limits. Subsequently, a 3D CAD model of the latter was developed by means of the dimensions of each single component shown in the appropriate datasheets using SolidWorks®. Finally, thermal effects, i.e. heat dissipation of each individual component, were analyzed, also evaluating the overall power density of the envelope. A further purpose of this thesis project was to optimize the power module just described in terms of efficiency and also in terms of space in the circuit board according to pre-established project specifications by modifying certain parameters necessary for the calibration of the components. The overall project was developed using MATLAB®, Simulink® and in particular Simscape™ Toolbox environment for the electronic design. The COMSOL Multiphysics® simulation package was also used to verify the thermal behavior of the described system.