Power Performance Of Battery Hydraulic Hybrid Rail Engineering Vehicle

Developing urban rail transit has significant social benefits for alleviating urban traffic congestion and air pollution.Rail engineering vehicles are indispensable equipment in the process of construction,operation and maintenance of rail transit lines,which are used for vehicle traction,personnel and material transportation.The traditional internal combustion rail engineering vehicle not only has poor stability,low efficiency at low speed,and can't recover regenerative braking energy,but also emits harmful gases and operates with high noise.In recent years,with the development of electronics technology,especially the continuous improvement of the storage capacity and service life of batteries,rail engineering vehicles have begun to develop towards new energy.The battery rail engineering vehicle adopts motor traction and variable frequency speed regulation,which has the advantages of no pollution and zero emission,simple transmission chain and easy to realize stepless speed regulation.Although it solves the problems of serious energy consumption,emission pollution and noise of the internal combustion rail engineering vehicle,due to the inherent hard damage of electric traction system,the application status of battery rail engineering vehicle is not optimistic,and the main disadvantages are high installed power,large acceleration current impulse,low energy regenerative efficiency and short mileage.The hydraulic accumulator has high power density and can store and release energy in a short time with high energy recovery and reuse efficiency.Before the battery technology hasn't completely broken through the bottleneck,the electric hydraulic hybrid drive technology,emerged as a transitional period,is undoubtedly the best solution to solve the shortage of the battery rail vehicle.The electric hydraulic hybrid drive technology combines the advantages of the battery(high energy density)and the hydraulic accumulator(high power density).The instantaneous high power is released by the hydraulic accumulator to compensate for the shortage of power adaptability of the battery,so as to cut down the demand for peak power of the battery,and achieve the goal of reducing the installed power and impulse current and extending the mileage.This paper takes the battery rail engineering vehicle as the research object,and focuses on the following aspects.1.To solve the adverse influence of high current impulse caused by instantaneous acceleration large torque of battery rail engineering vehicle on battery cycle service life and vehicle mileage,a novel electric hydraulic hybrid powertrain is designed based on thetraditional hydrostatic transmission system(electric-hydrostatic hybrid powertrain).The energy saving mechanism and efficacy performances are described in detail,and the parameters of the hydraulic accumulator and hydraulic motor in the hydraulic energy storage system are also matched.2.Flow coupling and torque coupling are important ways to achieve power transfer of the electric hydraulic hybrid powertrain.Firstly,the power flow mathematical model of the electric hydraulic hybrid powertrain is established,and the key factors affecting the electric power in the hydraulic energy storage system are analyzed.Secondly,the influence of proportional flow valve discharge flow rate,proportional pressure reducing valve setting pressure and hydraulic motor displacement on the coupling performances of electric hydraulic power is investigated by means of simulation calculation combined with test.Finally,the experimental data is compared with the simulation results to verify the correctness of the simulation model and the credibility of the simulation results,and provide a reliable support for further research on the energy distribution of the rail energy vehicle under typical conditions.3.According to the driving characteristics of the battery rail engineering vehicle,the operating mode of the electric hydraulic hybrid powertrain is divided to guarantee that the electric traction system always works in an optimal state.Secondly,the dynamic coupling performances under different electric hydraulic power distribution ratios are explored based on typical working conditions,which lays the foundation for the development of the vehicle controller.4.Based on the previous analysis results of dynamic coupling under different electric hydraulic power distribution ratios,the optimization goal of the electric hydraulic hybrid powertrain is confirmed.The electric hydraulic hybrid acceleration strategy based on minimum power impulse is proposed accordingly,which can reasonably allocate the energy in real time according to the state parameters of electric hydraulic hybrid powertrain.Then,the AMESim-Simulink co-simulation platform is used to analyze the feasibility of the proposed electric hydraulic hybrid acceleration strategy.Finally,the effective of the electric hydraulic hybrid acceleration strategy based on the minimum power impulse for suppressing the discharge power of battery is further verified by experiment.