Performance optimization of mild hybrid passenger vehicle by dual control strategy for city driving cycle

Abstract

The automobile industry is facing challenges owing to stringent emission regulations and adaptation to the evolving technologies. The launched hybrid vehicles are facing challenges regarding the cost-fuel benefit trade-off as well as the complexity in packaging the E-Machine between Internal Combustion Engine (ICE) and transmission system. The P3 hybrid configuration with AMT system is a way to achieve better drivability and fuel benefit. This paper focuses on development of Dual Control Strategy (DCS) for performance improvement in retrofitted 48 V P3 hybrid AMT vehicle. The DCS is developed based on rule based approach and Adaptive-Equivalent fuel Consumption Minimization Strategy (A-ECMS). The proposed control strategy includes decision making of mode shift between electric and ICE mode, optimal torque distribution between ICE and E-machine, equivalence cost factor computation with kinetic energy at the wheel and drivability consistency subjective to system limits during E-Creep, E-Launch and mode shift. The overall energy transfer efficiency to the wheels is improved by considering the global constraint, State of Charge (SOC) difference and the local constraint of 48 V battery, E-Machine and ICE. The 48 V P3 hybrid AMT vehicle with DCS can provide 10 kW power during torque assist or electric drive and −12 kW during recuperation or ICE mode, which results an elevated real time fuel economy by 66.7% and promises a improved driving performance in Bangalore city Driving Cycle (BDC).