System Design And Analysis Of Electro-hydraulic Hybrid Drive System Of Battery Rail Vehicle

Rail transit has important social and economic benefits to social development.Rail vehicle is essential equipment in the construction and operation of rail transit,it can be used to vehicle traction and personnel,material transportation,etc.Traditional internal combustion engine rail vehicle have the disadvantages of low operating efficiency,serious pollution discharge,large working noise,and bad use environment.In the face of energy crisis and environmental protection issues,the driving system of rail vehicle is also driven by internal combustion engine drive to hybrid power drive.With the rapid development of electric drive technology and battery technology,the hybrid rail vehicle in transition stage began to evolve into battery rail vehicle.Battery rail vehicle has the advantages of no pollution emission,low running noise,and strong environmental friendliness.But there are disadvantages of large installed power,poor efficiency at low speeds,short battery mileage etc.In order to improve the shortcomings of battery rail vehicle,a new electro-hydraulic hybrid rail vehicle is proposed in this thesis.Firstly,the structure of the electro-hydraulic hybrid system are determined.According to the technical parameters and operating conditions of the rail vehicle,the main parameters of the drive system such as the power of the traction motor,the equivalent total displacement of the pump source,and the equivalent total displacement of the motor are calculated.Considering the complexity and economy,the structural scheme of the electro-hydraulic hybrid drive system for rail vehicle is determined,the driving system of a single rail vehicle is composed of two sets of electro-hydraulic hybrid driving system,a single set of electro-hydraulic hybrid driving system is used to drive a bogie.The battery is used as the main power source of the electro-hydraulic hybrid drive system,the energy released by the battery is converted into mechanical energy after transfering in turn by traction motor,hydrostatic transmission system and gearbox,and then drive the rail vehicle.Secondly,electro-hydraulic combined speed regulation is determined as the speed regulation strategy of the electro-hydraulic hybrid drive system for rail vehicle,the target vehicle speed is mainly matched by adjusting the displacement ratio of the variable pump and the variable motor,it can also matched by slight adjusting the speed of the motor when necessary.The experimental values of axial piston variable pump efficiency provided by REXROTH company are fitted by three order polynomial by Matlab cftool,and the function of the mechanical efficiency and the volume efficiency of the axial piston pump,relate to displacement ratio and the pressure difference,is obtained.According to the equivalent total displacement of the pump source of the electro-hydraulic hybrid drive system,four kinds of pump source schemes are designed,and the efficiency characteristics of the four schemes are compared and analyzed by AMESim software,and the optimal scheme is adopted as the pump source of the electro-hydraulic hybrid drive system.Then,the speed characteristic of the electro-hydraulic hybrid drive system is co-simulated with AMESim and Matlab/Simulink,the results show that the drive system can meet the maximum speed requirements of the rail vehicle.Then the simulation of the climbing ability of the drive system is carried out.The results show that the drive system can meet the maximum gradient requirements of the vehicle.Finally,the experimental platform is designed based on the existing conditions.Then the influence of different speed regulation schemes on the efficiency of the electro-hydraulic hybrid drive system is explored.The experimental results show that the test results show that increasing the displacement ratio of the pump and motor in the hydrostatic system can improve the overall efficiency of the drive system.