Study On Electromechanical Hydraulic Energy Recovery And Reuse System Of Pure Electric Drive Excavator

With society’s increasing emphasis on environmental protection,a wide variety of widely used construction machinery is also facing the pressure of energy saving and emission reduction.As one of the most important construction machinery in engineering construction,hydraulic excavators have the problems of low energy utilization rate of the whole machine and a large amount of polluting gases and solid particles.The energy utilization rate of traditional hydraulic excavator is only 25%.Electric drive equipment using electric motors as the main power source has the advantages of low noise,high efficiency and zero emissions,and has received more and more attention in recent years.Most of the existing electrically driven hydraulic excavators adopt the hydraulic braking mode during boom lowering and rotary braking.Most of the hydraulic energy of the hydraulic system is converted into heat during the throttling process,which not only causes energy waste but also affects the life of the hydraulic system.Therefore,this article proposes an electrohydraulic energy recovery and reuse system based on the pure electric drive excavator system.The energy recovery unit,energy storage device and super capacitor energy storage system are developed.It can recover the energy recovery of the boom and the rotary movements,in improving the energy recovery in the process of the machine work.In this paper,the standard working conditions and the composite action process of the hydraulic excavator are analyzed at first,and the corresponding design scheme is proposed according to the working requirements of the energy recovery module and the energy storage module of the boom and the turntable.Integrating the design scheme of each module,the electromechanical hydraulic energy recovery and reuse system scheme of pure electric drive excavator is designed,and the working principle of each part is analyzed.Secondly,based on the energy recovery and reuse system designed in the previous paper,the theoretical analysis of the boom hydraulic cylinder and rotary motor is carried out and the mathematical model is built.The type selection and parameter matching of recovery pump/motor,accumulator,recovery motor and super capacitor are carried out.Thirdly,according to the hardware parameters of the ultracapacitor energy storage system,the parameters of the energy storage inductance and filter capacitor of bidirectional DC/DC are calculated.The double closed-loop control system of bidirectional DC/DC is designed by using average current method.Based on MATLAB/Simulink software,the compensator of bidirectional DC/DC control system is designed.Through calculation and fitting,the efficiency diagrams of bidirectional DC/DC and permanent magnet synchronous motor are obtained,and the oil leakage situation when the pump/motor is working is calculated.Finally,according to the above analysis,the simulation model of electromechanical hydraulic energy recovery and reuse system of pure electric drive mining is established in SimulationX,and the control strategy of the system is formulated.The system was simulated under the standard cycle condition,and its operating characteristics and energy consumption characteristics were analyzed.The efficiency of each component in the energy recovery process and the energy recovery efficiency of the whole machine were calculated.Under the same working condition,the energy consumption of the system is compared with that of the original electric drive excavator,hydraulic and electric energy recovery and reuse system of the nonenergy recovery system.The results show that the electro-hydraulic energy recovery and reuse system has a significant recovery effect,and the energy recovery efficiency is 72.11%,which can achieve 29.6% energy saving compared with the original system.