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Study On Energy Management Strategy For Mild Hybrid Electrical Vehicle With CVT

Posted on:2008-07-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:M H HuFull Text:PDF
GTID:1102360242971500Subject:Mechanical engineering
Abstract/Summary:PDF Full Text Request
CVT is an ideal transmission for vehicle owing to it's continuously varible ratio, so the powertrain of vehicle can get better matching with road load. For the same reason, if the hybrid electrical vehicle (HEV) is equiped with a CVT, engine could become working more efficiency, and motor could absorb more regeneration power. Then, HEV with CVT become an important researching branch.In this dissertation, considering characters of CVT, a series of technical researches on HEV equipped with CVT are carried out based on Chang'an mild HEV system. The main researches and conclusions are as followed.①Based on operating characters of the vehicle, the calculation methods of maximum power of the engine, rating power of the motor, rating voltage of the battery and CVT ratio range are presented. In order to obtain the minimum fuel consumption of mild HEV system under different drive cycles, the key parameters of the system are optimized.②After performing some experiments on the engine, Integrated Starter/Generator (ISG) motor ,CVT and NiMhH battery, numberical models of these key components are built by analyzing the test data. Energy efficiency model of the battery is proposed by theoretical deduction. And then,in order to improve energy efficiency of the battery during operation, the new cooling structure of the battery is designed by CFD simulation and validated by experiments. At last, by means of synthetically considering the effect of the viscosity of the lubricant on the power loss of CVT, the formulae of transmission efficiency is established. These reseaches provide theoritical foundation for the optimization of system efficiency of mild HEV with CVT.③Based on kinetic models of the vehicle under different operating modes, theoretic formula for the system efficiency of mild HEV with CVT is deduced. Then, synthetically considering characteristics of the key parts,such as engine, ISG motor, CVT and the battery, static control rules of the ISG motor torque and CVT ratio are optimized to maximize the system efficiency under different driving modes. At the same time, the static control rules of the ISG motor torque and CVT ratio are optimized to improve energy recovery rate under different braking modes. These researches provide theoretic foundation for the system energy management strategy of mild HEV with CVT. ④The working mode switch conditions and static power control strategy are proposed. Considering system dynamic fuel consumption and baterry life, the system dynamic optimization efficiency energy management strategy of the mild HEV to equip CVT is proposed. Finally, the mild HEV with CVT simulation is processed, and the new evaluating means of HEV fuel consumption is processed based on simulation results, which makes HEV fuel consumption estimate be close to actual value.⑤Test rig of mild HEV equipped with CVT is put up. Control system is developed by using Matlab/Simulink software and dSPACE real time workshop. Tests of idling stop, driving charge, driving discharge and regenerative brake are carried out. And system dynamic optimization efficiency energy management strategy of this dissertation is validated by experiments.As one of the major key techniques, energy management strategy plays an important role in the intellectual property of the HEV. The significance of the work in this dissertation lies in improving the domestic research and development of the HEV and promoting the industrialization of the HEV with self-owned intellectual property rights.
Keywords/Search Tags:Mild hybrid electric vehicle, Continuously variable transmission (CVT), Energy management strategy, Simulation, Test
PDF Full Text Request
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