The Design And Research Of HET’s Power System

Tractor as an important agricultural machinery, has complex diverse workingprojects and changeable harsh operating environment. Because the engine workingpoints are bad and the engine’s power can not be taken full advantage of, thetraditional tractor power system has caused serious energy waste and bad emission.Since the motor is added onto the hybrid system, the engine working area can beoptimized to improve the energy efficiency, and with the the dual pressures of globalenergy crisis and severe environmental pollution being faced, the research that thehybrid technology can be applied to tractor to constitute a hybrid electric tractor(simply, HET) power system is a important way to improve fuel economy and reduceexhaust emission for tractor.Based on the analysis of structures, working principles, working models,advantages and disadvantages of the three hybrid systems, a biaxial parallel hybridpower system which is suitable for tractor has been proposed; taking DFH1804tractoras the study object, according to the requirement of tractor’s various working projectson traction, tractive power and something else, and referring to DFH1804tractor’swhole parameters, the types and parameters of the engine, electric motor, batteries,power coupling mechanism, transmission and other components of HET’s powersystem have been chosen and designed; the output characteristics models of the engineand motor selected have been established by using their test data and their controlmethods have been analyzed; combined with the tractor’s various working modes, thetheoretical tractive characteristics curves of DFH1804tractor have been drawn, thetractive characteristics of tractor has been analyzed theoretically; and the ideal drivecharacteristics field of HET’s power system has been proposed; according to theengine and motor coordinating working principle of the parallel hybrid system andtractor’s working project types, the coordinate matching control methods and itsimplemented methods of the three working modes of HET’s power system have been formulated. By using the existing results of tractor performance research and Matlabprogramming, the theoretical tractive characteristic curves of HET’s power systemhave been drawn and analytically compared with DFH1804tractor’s; the powerperformance evaluation: the traction power utilization, has been proposed, by usingwhich the power performance of DFH1804tractor and HET have been comparativelyanalysed; the results show that HET’power system surpasses DFH1804tractor’s ontraction performance and power performance.