Researches On Dynamic Characteristics Of Hybrid Electric Tractor

Hybrid electric tractor(HET) is equipmented two power sources at the same time-thermodynamic (traditional diesel engine,this paper adopts ZS1100type) and power source (battery and motor,this paper adopts lead-acid battery and series DC motor).By making use of motor in tractor,which makes it possible that we can regulate flexiblely according to the actual condition and making the engine in comprehensive performance,so as to reduce oil consumption and emissions.This paper analyses the structure of adopted power coupler. Then analysis of its statics and dynamics,through the analysis of dynamics,calculation its kinetic energy and generalized force,finally according to the Lagrange equation to establiah the system differential equations;Building its simulation model and do the research on the characteristics of dynamics.The completed work and achieved results are generalized as follows:1. Analysis the reason of choosing the differential planetary gear train as power coupler of hybrid electric tractor and the advantages about planetary gear train. In this paper analysis of its kinematics、statics and dynamics,through the analysis of dynamics,calculation its kinetic energy and generalized force,finally according to the Lagrange equation to establiah the system differential equations, providing the theory reference for the follow-up work.2. In the software SimulationX, developing a system of hybrid tractor Simution system. Simulation analysis of dynamic characteristics starting,shifting,speed-up and speed-down and load mutation in three operation mode-engine working only,motor working only and hybrid mode and two different working conditions including plowing homework and road transport.The results of the study shows that:(1)Under3-different-mode, motor’s speed increases following motor’s votage increasing under starting moment,motor’s torque、motor’scurrent、driving wheel’s torque change one trend,fluctuating in the beginning moment and then tending to fixed value.The reason is motor’s torque、motor’scurrent、driving wheel’s torque is proportional to load torque,depending on the size of the load torque.(2) Engine’s torque、motor’s torque、motor’scurrent、driving wheel’s torque is proportional to load torque,depending on the size of the load torque.Engine’s torque increases firstly and then decreases with the increase of the speed, which is depend on the external characteristic of engine. Driving wheel’s speed increases following engine speed increasing,while motor’s speed remains constant.(3)Under3-different-mode,the change rule of engine’s torque、motor’s torque and motor’s current is consistent, chang following with gear changing, has no relationship with engine’s speed and motor’speed.In the shifting process, from one to six,engine’s speed approximately constant and there ia a big fluctuation in shift moment,this is because the shift instant need to overcome system inertial resistance. Engine’s torque increases following with gear increasing, driving wheel speed with the rise of gear and increase, drive rotary moment basic constant, which is decided by the applied load. The engine and drive rotary moment produced great fluctuation under shift moment, this is because shifting process needing to overcome the internal torque.3. Constructuring the test bench of hybrid electric tractor and developing measurement and control system on the basis of the LabVIEW and selecting the parametes of important component of the test bed. Building and debugging the test bed. Set the phase difference test on the filter, the sampling frequency, speed compensation, the initial phase difference,engine gear and the frequency of the sensor.4. Test research on dynamic characteristic of HET,the experimental research on three different driving modes(mode-engine working only,motor working only and hybrid mode),engine、motor、driving wheel’s speed and torqueand voltage and current of battery and motor in the procee of starting、shifting、speed up-down、add and subtract load,research shows that:(1)Start process of there modes,motor’s speed falls rapidly in starting moment,torque remains unchanged, the motor’s current increased rapidly,battery’s current also along with its change, battery’s votage drops slightly,which impacts engine torque lightly.(2)Mode-engine working only,engine’s speed keeps constantly in the process of shifting,its torque increases with wheel gear’s increasing, while the torque remains constantly.Under hybrid mode,engine’s speed producslarge-fluctuation and keep constant after a while. Motor’s speed rises with gear;Driving wheel’s speed rises along with gear increasing. The torque of engine, motor and driving wheel remains unchanged. Power’s voltage decrease with gear rising, motor’s voltage increases with the gear. The shitting rule of motor working only is similar with hybrid mode. (3) When the shift is constant,making its speed increases firstly and then decreases,the torque have the same change trend;The motor speed decreases with the increase of the engine speed,its torque remines unchanged;The voltage of battery and motor remains unchanged and the current of battery and motor decreases with the increase of the engine speed,which is consistant with motor speed.Through the research of this paper, it can provide support for the later experiment of the HETand the control system of the HET, it also provide support for doing reaserach on the characteristic of the HET and the degree of jerk. And this research is of important theoretical significance and practical value to the energy conservation and emissions reduction.