Characterization of Belt Drive Systems in Hybrid Powertrains

The present work is intended to describe the concept and realization of a test rig for the characterization of the efficiency of front end accessory drives. The study is in particular addressed to those systems where the traditional alternator is replaced with a Belt Starter Generator (BSG). A BSG is an electric machine capable of working both as generator (to function as traditional alternator and regenerate energy during braking) and as motor (to start the engine and provide electric traction and boosting). The utilization of such device is among the solutions adopted by mild hybrid technologies that are addressed to the reduction of fuel consumption and pollutant emissions typical of ICEs by the application of electric machines. The introduction of a BSG into a belt drive system leads to strong variations of the belt tension due to the alternation of tight and slack span. The study of the efficiency of such system is crucial in defining the best operating strategy of mild hybrid systems comprising a Belt Drive System (BDS) equipped with a BSG.