Research on energy-saving characteristics of battery-powered electric-hydrostatic hydraulic hybrid rail vehicles

With the advantages of no emission and low noise, battery rail vehicles (BRVs) are widely used in the construction of subway, high-speed railway and so on. However, the problems of low energy efficiency and peak power shock of traction motor have severely restricted the application and promotion of BRVs. To address these problems, an electric-hydrostatic hydraulic hybrid powertrain (EH3) is designed in this paper. Friction braking (FB) is replaced by hydraulic regenerative braking (HRB) and the mode of recovered hydraulic energy coupled at the inlet of pump (ECIP) to assist acceleration is proposed. The energy conservation characteristics of recovery and coupling of hydraulic energy in EH3 powertrain are verified by simulation and laboratory test bench. The energy recovery efficiency of HRB is up to 50% and the new coupling modes can greatly reduce the consumption of electric power. The control strategy is designed to coordinate different working modes which are established based on the high-pressure accumulator (HPA) and the driving state parameters of BRVs. The simulation result shows that the energy consumption of the battery can be reduced by 17.32%. The EH3 powertrain has broad application prospects in realizing energy conservation, reducing peak motor power shock and improving the braking performance of BRVs. (C) 2020 Elsevier Ltd. All rights reserved.