Control Of Auxiliary Starting System Of Electric Motor Driven By Hydraulic Pump

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.At present,two types of rail vehicle are widely used.The first type is an internal combustion rail vehicle driven by an internal combustion engine.Its transmission system is simple but its stability and efficiency of low speed condition is poor,and its harmful gas emissions will pollute the working environment.The second type is an electric rail vehicle driven by electric motor.Although it solve the problem of exhaust emission and noise of internal combustion rail vehicle,there are still some disadvantages such as high power configuration and short endurance mileage.In order to solve problems and disadvantages of two rail vehicles mentioned above,A novel electro-hydraulic rail vehicle is put forward.It uses three-phase asynchronous motor to drive and its speed is controlled by hydrostatic transmission technology.The three-phase asynchronous motor has been widely used in industrial and agricultural production due to its advantages such as simple structure,easy manufacture,stable operation and low price.However,three-phase asynchronous motor will generate high impact current when directly start-up.Impact current will cause a great impact on the power grid&motor and reduce their working performance and life.Meanwhile,large power consumption of motor will shorten the endurance mileage of power supply.In order to avoid the impact caused by the frequent start and stop of rail vehicle and prolong the endurance mileage,a novel auxiliary start-up system of the motor based on hydraulic control is proposed.In this thesis,the starting characteristics of two kinds of asynchronous motor are simulated and analyzed based on the MATLAB/Simulink simulation platform.Meanwhile,the experimental platform is built and experimental study was carried out on starting characteristics of two kinds of asynchronous motor.An auxiliary start-up system of electric motor is presented and its component parameters are analyzed based on simulation and experimental study.A Hydraulic Retarder System for rail vehicles is proposed and its component parameters and operating parameters are analyzed based on the AMESim simulation platform.The thesis mainly includes four parts:(1)the starting characteristics of two kinds of asynchronous motor are simulated and analyzed based on the MATLAB/Simulink simulation platform.The results show that both of two kinds of asynchronous motor will generate high impact current and power consumption when directly start-up.The starting current of the motor at different variable frequency starting time and at different initial speed are experimentally studied.The results show that the shorter the variable frequency starting time is,the higher the starting current is;the higher the initial speed is,the lower the starting current is.(2)An auxiliary start-up system of electric motor is presented and its component parameters are analyzed based on simulation.The results show that the displacement of hydraulic pump,gas precharge pressure,volume and hydraulic pressure of accumulator have certain influence on the speed characteristics of the system.(3)Test platform is built to test the influence of the accumulator pressure,volume and pressure on the characteristics of starting speed.The results show that gas precharge pressure,volume and hydraulic pressure of accumulator have certain influence on the speed characteristics of the system.(4)Based on long and steep downhill condition of rail vehicle,an energy recovery and retarder system is proposed.The system can not only be used to recover the energy,but also keep vehicle speed constant.The influence of the component parameters(displacement of hydraulic motor,gas precharge pressure,volume and hydraulic pressure of accumulator)and operating parameters(braking time,speed and slope)on the braking torque and energy recovery of the system is simulated and analyzed based on the AMESim platform.The results show that component parameters and operating parameters of the system have certain influence on the energy recovery and the braking torque.