| Due to the energy crisis and environmental degradation,the requirement for automobile emissions is becoming stricter.This makes it extremely important to improve the technology for energy conservation and emission reduction.In the field of hybrid electric vehicle configuration,the designing methods are relatively limited.Most researches mainly focus on configuration topology and screening as well as parameter optimization,with a few studies combining configuration topology with functional requirements.These configurations are designed in terms of screening the range of which is limited to certain kinds and fail to lead a fundamental guide to the design of configuration.The research of this subject starts with the fuel-saving principle of hybrid electric vehicles,analyzes the characteristics of basic schemes of speed coupling and torque coupling,studies the configuration reconstruction,configuration topology,and parameter optimization methods,and establishes a systematic hybrid configuration design method.Based on the researching goals and ideas above,the contents of this article are arranged as follows:The first part is a analysis of speed and torque coupling basic scheme.The fuelsaving mechanism of the hybrid electric vehicle takes advantage of an electric motor to adjust the engine operating point.And there are two basic ways----speed adjustment and torque adjustment----with the former being speed decoupling and the latter torque decoupling.In the analysis of speed coupling,the objective of the research is the basic speed coupling scheme of a single planetary row.Six basic speed coupling schemes can be obtained through different ways of connecting the power source to/with the planetary row.And an analysis of speed decoupling capability,torque amplification capability and electrical power characteristic is conducted based on the six schemes.Torque coupling analysis divides the basic torque coupling schemes into two categories based on whether the motor gear ratio and the engine gear ratio are coupled.Each category takes full considerations to engine gear and motor gear so as to produce a variety of basic torque coupling schemes based on which an analysis of torque decoupling capability and torque amplification capability is conducted.In the first part a relatively effective basic speed decoupling scheme is obtained.However,this scheme is far from enough to deal with the complicated industrial situation,which makes the second part,a reconfiguration based on the speed and torque decoupling scheme,necessary.The second part includes four sections: configuration reconstruction,configuration topology,parameter optimization,and configuration multi-angle evaluation.The reconfiguration is reconstructed based on speed-coupling basic scheme and the torque-coupling basic scheme,distinguished by single motor and duel motors,and focused on the speed decoupling,torque decoupling and the transmission.Since clutch is not involved the reconfiguration cannot meet every end of modes of pure electric,pure engine,hybrid drive,brake energy recovery and parking charging.Therefore,a design of configuration topology is necessary.A specific research on the design of configuration topology attempts to satisfy basic functional requirements and to improve efficiency.In order to have a specific evaluation of efficiency,main parameters should be clarified.Multi-goals parameter optimization(dynamic and economic)is performed on the configuration parameters.In order to obtain the most optimized reconfiguration with best comprehensive performance,a multi-angle evaluation method is established.The configuration is evaluated from three angles: dynamic,economic and working condition adaptability,and comprehensively the best-performed configuration will be selected.This part combines part 1 with part 2 to work out a hybrid-drive system so as to affirm the validity of works above.First,a proper basic scheme is obtained through analysis of speed decoupling capability,torque decoupling capability,torque amplification capacity and electronic power.Second,single motor reconfiguration is carried out based on the basic scheme,including speed coupling + transmission,torque coupling + transmission,and speed coupling + torque coupling.The configuration topology aimed to meet the demands of working modes.Third,a multi-goals optimization from the perspective of dynamic and economic parameters is achieved.Finally,the best option,the S-4,is determined by multi-angle evaluations.In the last part,dynamic/economical simulation verification compares the dynamic and economical of S-4 and THS(Toyota Hybrid System).The simulation of dynamics aims at the maximum driving torque of the wheel.The detailed analytical comparison between S-4 and THS in respect of the output torque of the wheels and the acceleration process clearly demonstrates that the dynamic performance of S-4 is much better than THS in that the 100 km acceleration time of the former is 6.69 s,decreasing by 6.81 s compared with the latter.Economical simulation takes WLTC as the backward simulation input and DP as the control strategy.A comparison of electric power loss and the distribution of engine operating points between S-4 and THS leads to a conclusion that the electric power loss of S-4 is less than THS,and that the ability of adjusting the engine operating point of THS exceeds S-4.The fuel consumption of the two turns out to be little different: S-4 is 1.2% more than THS. |
