Research On Load Extrapolation Method Of Hybrid Loader Motor

Hybrid loader has multiple power sources and replaces hydraulic torque converter with motor to drive,which effectively improves energy utilization and has good prospects for development.However,in terms of its study status,there are key problems that should be taken into concern.That is,how to consider the influence of motor control strategy for motor load extrapolation method and how to compile the load spectrum of hybrid loader motor.The paper is based on the National Science and Technology Support Project ?Research on the generic technology of energy conservation and emissions reduction of engineering machineries?(No.2015BAF07B01)and the National Natural Science Fund Project ?Extreme load estimation and intelligent extrapolation optimization of multi-power hybrid engineering vehicle in whole working condition?(No.51375202).This paper focuses on the above key technical problems.The main research contents and conclusions are given as follows:(1)The experimental prototype and motor control model are built,and the test scheme of motor load spectrum is also drawn up.The traditional loader is used as prototype and its key components are matched again according to the series hybrid structure.The rapid control prototype system DSPACE and the signal conversion module VCU_Link are applied to form the control system and data acquisition system of the experimental prototype.The total motor torque control strategy,the motor overload protection strategy and the motor torque optimization allocation strategy are made,which output the optimized motor torque based on driver' operation and also ensure the safety of motor.The load spectrum test scheme suited for hybrid loader motor is also made according to its operating characteristics.(2)The motor load data under typical conditions are tested and analyzed.Based on the load spectrum test scheme of hybrid loader motor,the motor load data are tested.The wavelet threshold de-noising method is used for motor load data to reduce their noise.The motor load data are divided according to the "V shape-6 section" features of wheel loader.The analysis results of motor load data in spading section show that the torque of single motor does not meet the thick tail distribution.However,the total motor torque in drive axle meets the thick tail distribution,and also has the characteristics of stationarity and ergodicity,which meets the preconditions of time-domain extrapolation method.(3)The POT model is built,and the total motor torque is extrapolated.To obtain the extrapolated load of single motor,the load extrapolation method which is composed of the POT model and the driving system co-simulation model is proposed.The POT model including threshold selection,function distribution,parameter estimation,test of goodness of fit and extrapolation result evaluation is built.The total motor torque is extrapolated by POT model.The extrapolated results show that POT model has a perfect extrapolation effect for the total motor torque.(4)The software MATLAB/Simulink and AMESim are used to build the driving system co-simulation model,and the extrapolated load of single motor is obtained through simulation.The dynamic model of hybrid loader driving system is built in AMESim.The motor control model is built in MATLAB/Simulink.By establishing a link between them,the driving system co-simulation model is obtained.Its rationality is verified by the graphic method and the correlation coefficient method.Taking the total motor torque after extrapolation as the load input of the driving system co-simulation model,the extrapolated load of single motor is obtained through simulation.The load extrapolation method which is composed of the POT model and the driving system co-simulation model effectively achieves the load extrapolation of hybrid loader motor.The extrapolated load of single motor can be used as essential data for reliability design of hybrid loader motor.