Research On Modeling And Simulation Of Four-wheel Drive Hybrid Electric Vehicle

Hybrid Electric Vehicles referred as HEV whose vehicle driving system composed of two or more single drive system. The vehicle driving torque provided by a single drive system alone or together based on actual vehicle driving state.HEV has two kinds of advantages compared with the traditional vehicle and electrical vehicle. The first one is that energy consumption and emissions performance of HEV are better than that of the internal combustion engine powered vehicles. The second one is that HEV’s mileage is far more than that of pure electric vehicles. So HEV is one of the development directions of today’s automotive. Because of its energy saving and low emission, HEV has had become a focus of research and development of automobile, and has already begun to be commercialized.This thesis took a four-wheel drive hybrid electric vehicle as the research object, which is based on the project between Tsinghua University and a Bus Company. Then it studied modeling and simulation of this hybrid electric vehicle, including the model building, offline simulation, rapid control prototype (RCP), automatic code generation, hardware in the loop simulation (HIL) and so on. The whole process was based on the "V" development model. Specifically as follows:(1) Established the simulation models of power-train components (including engine, motor, clutch, gearbox, vehicle), controller and driver in the Matlab/Simulink environment. Based on these models, it built the off-line simulation platform.(2) Designed the hybrid control strategy by modular design method according to the working mode and the method of torque distribution of the research object.(3) Obtained the simulation relevant parameters of the hybrid system by components bench scale test. Then it analyzed and calculated the vehicle’s dynamic performance and fuel economy on this offline simulation platform.(4) Developed a Rapid Control Prototype and a HIL system based on Veristand software and PXI hardware. By connecting the RCPs and the HILs, a real-time simulation platform is built. Furthermore, the designed control strategy is downloaded to the actual controller based on RTW automatic code generation technology. And the controller is tested on this real-time simulation platform.The performance of the HEV model can meet the functional requirements by verification both on off-line simulation and real-time simulation. The dynamic performance and fuel economic index can achieve the desired effect. And the methods could provide a reference for research on modeling and simulation of other hybrid systems.