Impacts of WLTP Test Procedure on Fuel Consumption Estimation of Common Electrified Powertrains

The new European test procedure, called the worldwide harmonized light vehicle test procedure (WLTP), deviates in some details from the current NEDC-based test which will have an impact on the determination of the official EU fuel consumption values for the new vehicles. The adaptation to the WLTP faces automakers with new challenges for meeting the stringent EU fuel consumption and CO2 emissions standards. This paper investigates the main changes that the new test implies to a mid-size sedan electrified vehicle design and quantifies their impact on the vehicles fuel economy. Three common electrified powertrain architectures including series, parallel P2, and powersplit are studied. A Pontryagin’s Minimum Principle (PMP) optimization-based energy management control strategy is developed to evaluate the energy consumption of the electrified vehicles in both charge-depleting (CD) and charge-sustaining (CS) modes. The results show that across different electrified vehicle architectures, the vehicles’ fuel economy using the WLTP cycle in CS mode substantially decreases compared to the NEDC cycle. Moreover, in CD mode, the battery needs to deliver more power in WLTP cycle compared to the NEDC to meet electric-only range requirement.