Design And Performance Research For Power Coupling System Of Plug-in Hybrid Electric Vehicle

With the rapid development of the automobile industry，china has to face up toincreasingly severe energy shortage and environmental pollution. Development ofelectric car can solve the energy and environmental problem of our country effectively.Since there is no breakthrough in key technology of fuel cell vehicle and pure electricvehicle, fuel-efficient ability of the traditional HEV is limited, Plug-in hybrid electricvehicle(PHEV), which has the advantage of the EV and HEV receive wide attention allover the world, become the most realistic electric vehicle.Power coupling system, which is the core technology of the HEV research, hasgreat impact on power performance, fuel economy and other performances. This paperintroduce the current situation and trend of the HEV’s power coupling system byanalyzing their advantages and disadvantages, and propose a plan of power couplingsystem with single motor and planetary mechanism. The main details in this paper areas follows:(1)The current situation of the development of the PHEV is expounded. Structureand characteristics of HEV is introduced. Operating principle of several typical powercoupling system is analyzed and EVT technology is the trend of power coupling systemis pointed out.(2) EVT structure at home and abroad always use two motors combined withsingle or multiple planetary mechanism. It is complicated in structure and hard tocontrol, so a simple scheme of power coupling system with single motor and singleplanetary mechanism is designed. Varieties of operation modes under different vehicledriving cycle conditions and coupling characteristics of different operation modes areanalyzed.(3)Take one type of Chang’An vehicle as research object, combing with the newtype power coupling system to design a new PHEV car. Based on national standard andcharacteristics of operation modes, the key parts of transmission system such as engine,motor, battery, planetary mechanism and so on are selected and matching.(4) According to structure of power coupling system and characteristics ofoperation modes, multi-logic thresholds control strategy has been proposed in order toimprove fuel economy and power performance. Engine operating region has beenoptimized; Factors which affect the charging and discharging efficency of the battery has been analyzed; Research of braking control strategy has been formulated; Statetransition flow chart between different operation modes has been determined.(5)The simulation models of vehicle transmission system are set in Matlab/Simulink, matching parameters and control strategy have been simulated. Thesimulating result shows that Power coupling system meets the power performancerequirement, the fuel economy are better than original vehicle.