Sensitivity analysis of vehicle performance to transmission parameters in parallel HEVs with dynamic programming optimization

It is well known that hybrid electric vehicles (HEVs) have fewer requirements to transmission due to the favorable performance of electric motor for traction. However, multi-gear transmission with more gears is still beneficial in improving acceleration and fuel economy performance of the vehicles than one with fewer gears, even not as much as in conventional vehicles. On the other hand, use of multi-gear transmission with more gears inevitably adds complexity to vehicle structure and control, consequently resulting in high cost. In this paper, the sensitivity of vehicle performance to transmission gears for a parallel HEV has been analyzed by using SOC based Dynamic Programming. The results generated in this paper provide helpful guidance for HEV design.