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.