Design and performance of a power train for mild-hybrid motorcycle prototype

Low weight and volume are the principal requirements for electric components in hybrid motorcycles, and the energy storage system (ESS) is the most important part that contributes to this issues. This paper deals with the choice of the best ESS and with the optimization of the hybrid power train in two-wheeled vehicles. A methodology of investigation is given in order to recognize all the data necessary to find the best technology and size for the ESS. The techniques adopted for the design of the electrical machine (EM) are also reported. Furthermore, simulations with finite elements (FE) and mathematical software, in order to predict the EM and the drive performances, are presented. Efficiency maps from FE simulations are also given. Different kind of ESSs are compared with the goal to choose the best solution balancing cost, volume and weight for a reference motorcycle. The whole power train has been practically realized and the new hybrid vehicle has been tested first in appositely test bench and also in a small private racetrack. The measured experimental results are presented.