Research On Construction And Control Strategies For Experimental Prototype Of Electric Drive Wheel Loader

With the implementation of "Made in China 2025",low-carbonization,informatization and intellectualization of wheel loaders has become a new direction.Electric drive technology is of great practical significance for energy saving and emission reduction of wheel loaders.It can make the engine mechanically be decoupled from the wheels and hydraulic pump,so the engine can always be operated in high efficient speed and torque region and the fuel economy of wheel loaders is improved.Moreover,the application of electronic control and bus technology provides the foundation for the electronic and intelligent development of wheel loaders.Compared to the traditional drive form,distributed drive as a new drive form dynamically controlling the driving force of front and rear axle/four wheels can reduce tire slippage during shoveling operations and enhance the power performance and fuel economy.So it is necessary to study and construct the experimental prototype of distributed and electric drive wheel loader to achieve the targets of low-carbonization and electrification.Combining with the national natural fund project(No.51375202)and Jilin province science and technology development program funded project(No.20160101285JC),the paper constructed experimental prototype of the front and rear axle independent and electric drive wheel loader based on dSPACE rapid control prototyping and studied its control strategies,of which the main contents are as follows.1.Classification and analysis of key technologies for electric drive wheel loadersAccording to the sources of power,the drive form of driving system and hydraulic pump,the electric drive wheel loaders were divided into different categories and each category's feature was analyzed.The key technologies were analyzed from three aspects,which clarified the importance of control technology for stable and efficient operation of wheel loaders.2.Overall layout of the prototypeTaking 18 type wheel loader as the study carrier,the power system design was determined.Combined with the overall layout requirements of wheel loaders,the overall layout of the prototype was completed from the aspects of mechanical structure,electrical and control systems.Based on the actual structure of the loader,the prototype was transformed to achieve the electric drive of the hydraulic pump and the front and rear axle.3.Drive/brake and fault diagnosis control strategiesAccording to the operating characteristics of wheel loaders,speed control strategy of the motor for driving hydraulic pump was formulated to reduce the power loss of the hydraulic system.A multi-mode drive control strategy for driving system was proposed to meet the dynamic and operational demand of the driver in different conditions.According to the working characteristics of the braking system,the braking energy recovery strategy was put forward.Based on the features of the distributed and electric drive technology and manmachine safety requirements,fault diagnosis and processing control strategy was proposed.4.Modeling and simulation analysisThe control model was established by MATLAB/Simulink,and the establishment of key modules was illustrated.The simulation model of driving control strategy was established,and the simulation of partial drive control strategy was completed.5.Prototype test and control strategy validationThrough bench and road tests,the executive parts run stably without any interference,so the design rationality of the overall layout was verified.Multi-mode drive/brake control was realized and the faults were processed quickly and effectively,which verified the feasibility of drive/brake and fault diagnosis and processing control strategies.The application of electric drive technology in wheel loaders was realized in the paper.The control system of the wheel loader was established,and the multi-mode control of the wheel loader was realized,which achieved the safe and stable operation of the wheel loader.This paper provided experimental platform support for the study of vertical and horizontal dynamic control technology and technical support for the study of low-carbonization,electrification and intellectualization technology of wheel loaders.