Efficiency estimation of one- and two-speed gear transmissions for the electric powertrain.

In the last decades, the automotive industry developed towards battery electric vehicles (BEVs) and this trend is expected to grow. Hence, it is necessary to focus on the EV powertrain for an efficient transmission of the power stored in the battery pack to the wheels of the vehicle. This thesis is organised in two parts. In the first one, an overall description of the EV powertrain, its main components, benefits and challenges is presented with specific details on the transmission’s state-of-the-art. Indeed, the researches’ attention is currently drawn by the possible introduction of a multi-speed gearbox in electric vehicles to enhance the economic and dynamic performances. Successively, the second section of the work centres on the development of a one-speed and a two-speed transmission models with the help of KISSsoft development tool. This software also introduces the efficiency computation of the designed layouts for several combinations of rotating speed and torque of the motor shaft, allowing the construction of the efficiency maps for the two solutions.