Optimal control of an integrated energy and thermal management system for electrified powertrains

This paper proposes an integrated energy and thermal management system (IETMS) to quantify the influence of a cold-start on the fuel-saving potential and the gain of utilizing waste heat recovery (WHR) technologies on the ultimate fuel saving of a plug-in hybrid electric vehicle with cabin heating. A cold-start indicates a low engine temperature, which increases the frictional power loss, resulting in excess fuel consumption. A dual source WHR (DSWHR) system harvests waste heat from exhaust gases and the recovered power is temporarily stored into the battery and can be retrieved when needed. Furthermore, it recuperates waste energy from a continuously variable transmission and an electric machine including power electronics to increase the heating performance of a heat pump, which reduces the load on the battery. For a known driving cycle, New European Driving Cycle, the IETMS aims to maximize the fuel efficiency. Numerical results demonstrate that a cold-start has a remarkable impact on the fuel-saving potential, 7.1%, yet a small influence on the optimization strategy. The DSWHR system shows a significant improvement on the ultimate fuel saving, up to 13.1%, from which insights into the design of WHR technologies can be drawn.