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Research on power coupling characteristics and acceleration strategy of electro-hydrostatic hydraulic hybrid power system

Aiming at the adverse effect of the peak power of the electric motor of the battery-powered rail vehicles on the battery life and the driving range when starting or accelerating, a new type of electro-hydrostatic hydraulic hybrid powertrain is designed. This article proposes a novel power form that assists the vehicle to start or accelerate through two power coupling methods: torque coupling circuit and flow rate coupling circuit which have good power performance and energy-saving performance. A mathematical model for power coupling of hybrid power system is constructed, and the effects of key parameters of the system and different power coupling ratios on electric power consumption and power coupling characteristics are studied. Based on the simulation and test platform, the power coupling characteristics of the electro-hydrostatic hydraulic hybrid powertrain are simulated and experimentally researched. The results show that compared with the traditional electro-hydrostatic series system, the novel electro-hydrostatic hydraulic hybrid powertrain can effectively avoid the impact of electric motor power and reduce the power consumption. Based on the characteristics of power coupling, the acceleration strategy of minimum peak power is studied to control the key components of the power coupling process. Simulation and experimental results show that under the control of the new acceleration strategy, the electro-hydrostatic hydraulic hybrid powertrain has good electro-hydraulic power coupling characteristics. The electric power of the power system is greatly reduced during acceleration, which has better energy-saving characteristics and value for engineering applications.