Power-Train Design and Performance of a Hybrid Motorcycle Prototype

This paper deals with the design of the power train for a hybrid electric motorcycle (HEM). The HEM power train is composed of an internal combustion engine coupled to a synchronous electric machine (EM). The EM is fed by a standard three-phase inverter connected to a high-voltage battery pack. Low weight and volume are the main requirements for HEMs, and the energy storage system (ESS) is the most critical part. Different kinds of ESSs are compared to choose the best solution balancing cost, volume, and weight. A methodology of investigation is proposed in order to recognize all the data necessary to find out the ESS. Moreover, the design choices adopted for the electric drive are reported. In order to predict EM, power converter, and battery pack performances, efficiency maps have been computed. The whole power train has been prototyped. Experimental tests of the HEM prototype on test bench and on a real racetrack are presented. All the experimental measurements highlight a significant performance enhancement of the new HEM with respect to the original one. The HEM acceleration time and top velocity have been improved without affecting too much the original motorcycle weight.