A Binary Controller to Ensure Engine Peak Efficiency for a Parallel Hybrid Electric Car

The fuel efficiency of the hybrid electric vehicle (HEV) highly relies on the engine efficiency. This paper proposes a particular powertrain configuration on a small hybrid electric racing car where the engine is only allowed to operate with peak efficiency. An online binary controller, accordingly, is developed based on dynamic programming (DP) to control the engine on/off status and the torques from the electric motors (EMs) to ensure the HEV can successfully complete the drive mission with minimal fuel consumption. For comparison, the paper also develops an optimal powertrain controller of the same HEV with the normal usage of the engine, i.e., the engine operates at any feasible point of the 2D fuel efficiency map. The simulation results show that this binary controller can improve roughly 13% on fuel efficiency compared with the general engine case.