Optimizing Hybrid Powertrains for Light Duty Commercial Vehicles

<div class="section abstract"><div class="htmlview paragraph">Battery electric vehicles (BEVs) are well-suited for many passenger vehicle applications, but high cost, short range, and long recharging times have limited their growth in commercial vehicle markets. These constraints can be eliminated with plug-in hybrid electric vehicles (PHEVs) which combine many benefits of BEVs with those of conventional vehicles. In this study, research was conducted to determine the optimal hybrid electric powertrain system for a Class 3, light duty commercial vehicle. The key technologies used in this hybrid powertrain include engine downsizing, P3 architecture hybridization, and active thermal management of aftertreatment. A vehicle cost of ownership analysis was conducted to determine the economic viability, a very important consideration for commercial vehicles. Several combinations of E-motor and battery pack sizes were evaluated during the cost analysis and the best possible configuration was determined. The resulting vehicle powertrain demonstrated ~60% reduction in CO<sub>2</sub> over the World Harmonized Light Duty Transient Cycle (WLTC) and Federal Transient Procedure (FTP75) test cycles compared to the baseline internal combustion engine (ICE) vehicle. The NO<sub>X</sub> emissions were also evaluated during those test cycles, and the test results indicated that intermittent engine operation associated with Plug-in Hybrid Electric Vehicle (PHEV) operation, can result in higher NO<sub>X</sub> emissions. Advanced aftertreatment thermal management strategies are required to reduce NO<sub>X</sub> emissions in PHEVs. Finally, an exhaust heater was used to reduce tailpipe (TP) NO<sub>X</sub> emissions, and a pathway for even lower NO<sub>X</sub> emissions is identified.</div></div>