Research On Automatic Idle Speed Control System Of Load Adapting For Pure Electric-Driven Construction Machinery

High energy consumption,poor emissions,noise and other issues have been the important factors to hinder the development of the construction machinery.The engine's efficiency has been improved,while the hybrid energy-saving technologies were used.While the construction machinery driven by the pure electric power system,which is simply modified,has not given full play to the advantage of high efficiency of the pure electric driven system.Therefore,in order to reach the full potential of the construction machinery driven by the pure electric,it is important to study the pure electric driving which is suitable for the complicated operating conditions and working types of the construction machinery,which is of great theoretical and practical significance for the development of pure electric drive construction machinery.The pure electric driving construction machinery is studied in this paper.The key technologies include the compound modes of the pure electric driving,power matching based on variable speed,energy storage management,coordinated control of the whole machine and the new automatic idle speed control(AISC)technologies.The power compound modes driven by the pure electric are explored.The principle and structure of the AISC system are introduced.The mathematical model of the AISC is set up and the parameters are designed and optimized.The control strategy which gives consideration to both control performance and energy saving is proposed.This provides a practical and efficient AISC method for pure electric driving construction machinery,and can provide key technologies for other pure electric drive construction machineries,and design basis for the next generation of energy-saving construction machinery products.The main framework of this dissertation is organized as follows.In Chapter 1,the background and significance of energy saving of the construction machinery are introduced.The energy saving technologies of the traditional construction machinery driven by ICE are summarized.The main reasons for the low efficiency of the traditional construction machinery are analyzed.The latest development and research of the pure electric driving construction machineryare summarized.The reason that the motor drive technology used in other fields can't be directly transplanted to the construction machinery are analyzed.The research status of the AISC is presented in detail.And finally the primary research contents of this dissertation are summarized.In Chapter 2,in order to lay the foundation for the research of key technologies of follow-up pure electric-driven engineering machinery,the performance characteristics of the existing energy storage components and the motors are analyzed.Nine kinds of compound modes of the pure electric driving for the construction machinery are put forward.The structure characteristics of pure electric construction machinery,which uses a multiple energy to substitute for a single energy,multi-motor to substitute for an ICE,variable speed of motors to substitute for variable displacement of pumps,are analyzed.A new scheme of pure electric driving hydraulic excavator system is presented.the energy consumption of ISC is discussed.The load pressure adapted AISC system based on the variable speed of motor and hydraulic accumulator which is used as the auxiliary driving is put forward.The basic structure and working principle of the AISC system are analyzed.In Chapter 3,the mathematical model of the speed control of the actuators of the new AISC system is established and the control characteristics are compared and analyzed.The key parameters,such as the power motor,the hydraulic pump and the hydraulic accumulator,are optimized and the idle speed is chosen.The AMESim-MATLAB/Simulink co-simulation model is established.The influence of the hydraulic accumulator and the composite control algorithm on the response of the system are compared.And the influences of the matching of the control performance of the system between the pre-charge pressure and the rated volume of the hydraulic accumulator,the system piping volume with the motor response characteristics on the control performance of the system are studied.In Chapter 4,a new AISC division rules and control strategy are proposed.The control performance is the main considerations of the first level AISC.And based on this,the maximum load pressure adaptation control strategy and the compensation for the differential pressure optimization strategy are put forward.The energy saving is the concerns of the second level AISC,and the minimum energy consumption controlstrategy of the whole machine is proposed.When the AISC is switched off,to achieve the rapid recovery of the target speed,the global positive flow control strategy based on the variable speed is put forwards.The simulation model is used to verify the feasibility of the proposed control strategies.In Chapter 5,a test rig was constructed to study the energy saving and control performance of the proposed AISC system.The results show that the division rules of the novel control modes are feasible and the proposed control system can achieve a better performance than the conventional one when the idle speed is switched off.The energy saving efficiency of the proposed system can reach 67% approximately.The proposed AISC system has the better performance and the higher energy saving efficiency.In Chapter 6,the main conclusions and achievements are summarized.The innovation points are presented.And the future research outlooks are suggested.