Energy management strategy design and fuel consumption analysis for a parallel hydraulic hybrid vehicle

In this paper, the energy saving benefits of a parallel hydraulic hybrid vehicle (PHHV) are investigated. The vehicle powertrain components such as engine, hydraulic pump/motor (HPM) and accumulator are modelled to demonstrate the PHHV powertrain working principle. The optimal fuel economy of the PHHV is obtained by dynamic programming (DP) optimisation. Based on the DP optimisation results, a practical rule based energy management strategy (EMS) is designed with which the PHHV fuel economy in real application is investigated, including gear shift schedule and regenerative braking control strategy. Through simulation under a selected urban driving condition, PHHV achieves fuel consumption reduction by 27.5% compared to the conventional engine driven vehicle, which proves that the PHHV achieves significant energy saving benefits. PHHV consumes only 1.5% more fuel with the rule based EMS than the DP optimisation, indicating the effectiveness and practicality of the rule based EMS in urban driving conditions.