Design Of Fuzzy Control Strategy Of Parallel Hybrid Electric Vehicle

In recent years, the shortage of oil supply and atmospheric environmentalproblems has increasingly attracted widespread attention. As the traditional fuelengine vehicles have exposed more and more problems, the development of newenergy vehicles has already become one of the future Trends which can promote thetransformation of the traditional auto industry. Hybrid electric vehicle is one of themost promising industrialized and marketed one in new energy vehicles, which showsgreat significance on the alleviation of energy crisis and air pollution. The vehiclecontrol strategy is the main component of hybrid electric vehicles, which can have areasonable control of energy between engine and motor and then effectively improvethe fuel economy of hybrid electric vehicles and reduce exhaust emissions. Therefore,this thesis conducts further research on some hot field of control strategy about hybridvehicles. That is the fuzzy control strategy of parallel hybrid electric vehicles.The thesis firstly gives a briefly discussion on the background and significanceof the research topic, and then shortly introduces the research status of controlstrategy on hybrid electric vehicles.Taking parallel hybrid electric vehicles as research objects, the thesis gives adetailed analysis on the modeling of the main modules, including dynamics model,engine model, wheel model, the main reducer model, the battery model, etc., and thenestablishes parallel hybrid electric vehicle models by using Matlab/Simulink as asimulation platform.On the basis of established parallel Hybrid electric vehicle model, the thesisproposes strategy of fuzzy logic control policy-driven mode, and designs aTwo-dimensional fuzzy controller which takes aggregate demand torque and batterySOC as input, engine torque as output. Then the thesis selects the CYC-NEDCdriving cycle for simulation on the fuzzy control strategy in ADVISOR, and thencompares the results with the logic threshold control strategy, which shows that fuzzylogic control strategy performances better in fuel economies and vehicle efficiency.Next, as to the difficulty of fuzzy strategy in the driving mode, the thesisrespectively uses different fuzzy controllers to impose the control based on double fuzzy strategy which uses both brake mode and drive mode. Then, we use ADVISORsoftware in the simulation experiment. Compared with fuzzy control strategy, theresult shows that double fuzzy control strategy can improve and enhance theperformance of the fuel economies and emissions effectively.On the basis of the above studies, the thesis presents an idea based on geneticalgorithms to modify the division of membership functions of double fuzzy controller,and then imposes simulation experiment in the condition of CYC-NEDC drivingcycle. Results show that the emission of HC, CO, NOx has reduced， the fuelconsumption has lowered, and the whole working efficiency of the motor hasimproved under the whole test cycle.