Research On System Simulation, Efficiency Optimization And Test Rig System Of A Series-Parallel HEV

Series-parallel hybrid electric vehicle(HEV) has complex system architecture and various operation modes because of the coupling and cooperation between internal combustion engine(ICE) and motor/generator. It combines the advantages of series type HEV and parallel type HEV, and better fuel economy is achieved. Researches and applications of series-parallel HEV are widely proceeding all over the world. TOYOTA is a pioneer and successful automotive in the R&D and mass production of series-parallel HEV. So, the Toyota Hybrid System(THS) has significant reference and resraech values. In this thesis, the vehicle modeling and simulation, system analysis and optimization and the test rig system for Toyota 2010 Prius are proposed.The key component of THS is the Electric Continuously Variable Transmission(ECVT), which is composed of MG1, MG2 and the planetary gear set. ECVT has the functions of both power splitting and stepless speed changing. First of all, this thesis analyzes the hybrid synergy drive system of 2010 Prius in detail, the system composition, components characterics, operation principles and operation modes are presented. Moreover, the definition and design method of the mixedness of series-parallel HEV are proposed.The dynamic vehicle simulation and control model is the foundation of researches on design, validation and optimization of the vehicle control and energy management strategies. The mathematical models of powertrain components, brake system, driveline and vehicle dynamics are analyzed firstly. The forward vehicle dynamic simulation and control mode is then established with Matlab/Simulink. The vehicle model is validated with specified control strategies and driving cycle. Results show that the model is feasible and effective, and has great flexibility and portability.The improvement of hybrid system efficiency has important significance on vehicle fuel economy. But it is difficult to evaluate the efficiency of series-parallel HEV because of its complicated operation conditions and energy management strategies. In this thesis, the operation conditions, power losses and efficiencies of the electric drive system at ECVT operation mode are quantitatively researched. Considering the problem of high loss, low efficiency of the electric drive system, an optimization method is proposed and validated.For better research on vehicle simulation model, hybrid system, vehicle control and enermanagement strategies of series-parallel HEV, a full power dynamic vehicle test rig system is proposed and established. The test rig has the functionalities of ICE and vehicle dynamics real-time simulation, “driver, powertrain and HCU”-in-the-loop simulation and HCU rapid prototyping capabilities. This test rig will play an important role in the R&D process of HEV.