Analysis, Modeling And Simulation Of Power Flow For Hybrid Electric Vehicle With Dual-Planetary Gear

With the aggravation of environmental pollution and energy crisis, the development of new energy vehicles has become the focus of the world automotive industry. For the HEV(Hybrid Electric Vehicle) not only having good dynamics performance and mileage like traditional vehicle, but also having the advantages of less emissions, cleaning like electric vehicle, it has attracted an enormous amount of attention for researchers. Due to the compact structure, the vehicle speed and the engine speed can be decoupled at the same time, and the vehicle has more extensive working modes. For these reasons, the dual-planetary gear HEV has a good application prospect. However, because of the particular dynamic coupling mechanism in this dual-planetary gear HEV, the high power cycle will be happened if the parameter design is unreasonable. The vehicle efficiency would reduce for the power cycle. In this paper, the power flow's analysis, parameters matching and the modeling and simulation of the vehicle are carried out.Firstly, based on the power flow type of single planetary gear, a more detailed classification and description of the compound planetary mechanism is carried out. In this paper, the advantages and disadvantages of the compound planetary gear mechanism are analyzed, the reasons for the failure of the power flow splitting mechanism, such as noise, wear and transmission efficiency are expounded. Taking the power split mechanism dual planetary as an example, it describes the relationship between the type of power circulation mechanism and the planet row size parameter.Secondly, according to the status of the clutch, brakes and the dynamic components, the working modes of the dual-planetary gear hybrid vehicle is analyzed. The lever analogy is applied for analyzing kinematics of each model of dual-planetary gear hybrid vehicle, and the mathematical models are established. The general conditions for avoiding the generation of power cycle are determined, which provides the theoretical guidance for the selection of structural parameters of the dynamic coupling mechanism.Subsequently, according to hybrid vehicle's parameters, performance requirements and the general conditions for avoiding power cycle. The parameters of planetary gears are determined. Then it based on the dynamic performance index of the HEV in electric drive mode, compound drive mode, engine drive mode, choosing the best engine, battery, motor and other components.Finally, hybrid vehicle model is built in CRUISE, the simulation model is established in the MATLAB/Simulink. In the whole vehicle system, it finds that the hybrid electric vehicle meets the design objectives in the engine starting, climbing electric acceleration and pure electric mileage. In the NEDC driving, the engine is fixed at two operating points, the SOC(state of charge) also can be kept in a good range. It verified of the effectiveness of the design of a dual-planetary gear HEV and the control strategy.