Implementation of an Energy Management Strategy for Hybrid Electric Vehicles Including Drivability Constraints

Abstract : The energy management strategy (EMS) of a Hybrid electric vehicle (HEV) is a supervisory control meant to steer power flows among the different energy sources of the powertrain. The EMS is designed for the purpose of reaching the maximum potential of a given powertrain architecture. Fuel consumption is not the only criterion to be considered for evaluating the global performance of an EMS, as the EMS also impacts other features such as drivability, through engine starts/stops and gear shifts. This paper proposes a general approach to include drivability constraints in the EMS of powertrains provided with discrete automated transmissions. As a first step, determinist dynamic programming (DDP) is used to compute the optimal solution of the resulting optimization problem. This optimal solution is then used to assess the performance of the proposed on-line strategy which is based on the Equivalent Consumption Minimization Strategy (ECMS). Finally, simulation results are completed by a discussion of experimental results, as the proposed on-line strategy has been implemented in a prototype vehicle designed at Renault and tested on a dynamometric bench.