Integration of Battery Aging into the Energy Management of Hybrid Vehicles

Abstract

Hybrid electric vehicles use coordinated thermal and electrical power sources to reduce fuel consumption, but battery ageing progressively limits the electrical contribution to propulsion. This study integrates battery ageing into the energy management of a parallel hybrid electric vehicle controlled by an equivalent consumption minimisation strategy (ECMS). The strategy prioritises the battery as the principal power source and updates the equivalence factor using battery state-of-charge feedback. Battery ageing is represented through changes in capacity, internal resistance, and state of health, and its effect on energy management is evaluated through MATLAB/Simulink simulations. Two driving profiles are considered: the FTP-75 cycle and a class cycle derived from a set of driving cycles. For the FTP-75 cycle, the reported test duration and fuel economy are 2,500 s and 60%, respectively, with a new battery, compared with 400 s and 37% with an aged battery. For the class cycle, the corresponding values are 1,100 s and 43% for a new battery and 400 s and 19% for an aged battery. The simulations indicate that battery ageing reduces the duration of effective electric operation and increases reliance on the internal combustion engine as available electrical energy declines. Accordingly, incorporating battery ageing into ECMS-based energy management is necessary when evaluating fuel economy and electric-driving capability over the battery life cycle.