Analysis Of Configuration Of Two-Mode EVT For Hybrid Electric Vehicle

Power-split hybrid vehicle has the advantages of series and parallel hybrid vehicle, it can decouple the speed and torque of engine and wheels, than achieve the function of continuous variable transmission. So it is called electronic variable transmission. According to the power-split ways, they can divided into three kinds of single-mode configurations: input-split, output-split, compound-split. If use two different single-mode can achieve dualmode configuration. Nowadays we use a mix of input-split and compound-split to achieve dual-mode configuration. Compared to single-mode configuration, dual-mode has a better workspace of engine and a better efficiency. But its configuration is complex and various, so it is more complex to analysis the configuration, to choose the configuration and to control the vehicle. Therefore in this paper will do some research about configuration analysis and configuration choose and control method. The main contents include:1. Analysis the existing dual-mode EVT configuration. Compare the similarities and differences of these configurations. Use lever analogy to analysis a configuration detailed. Include the speed and torque change of motor and engine, the function of four fixed ratios and how to achieve fixed ratios. In the end, analysis the working modes of the configuration.2. Mechanical point is one of the important parameters of power-split configurations. The size has a lot of influence of the performances of vehicle and it can help to choose the configurations. First, this paper analysis how mechanical point influence the vehicle performance. Then focus on how to solve the size of mechanical point. In the end, propose the configuration choose method based on mechanical point, this method can use to choose input-split, output-split, compound-split and daul-mode configurations.3. Power-split EVT configuration and AT configuration are made up by planetary gears. So this paper propose a dual-mode EVT configuration design process based on the design process of AT. Steps includes: 1.confirm the range of ratios, 2.confirm the size of mechanical points, 3.choose the configuration based on mechanical point, 4.add clutches to achieve fixed ratios, 5.simulink. Use the parameters of Prius to design a dual-mode configuration. Finally there are 2 dual-mode and 3 dual-mode plus 4 fixed ratios configurations meet the design requirements.4. Choose one dual-mode configuration achieved in part 3, then simulate. First, analysis the working modes of vehicle. Then analysis the control strategy and how to control the engine. Use the AMESIM to construct the whole vehicle model, then use Simulink to construct the control strategy model. Compare the simulation results with Prius’, and find that the power performance and fuel economy are better than Prius’. So it can have the conclusions that the configuration designed is suitably and dual-mode is better than single-mode configurations.In this paper, the configuration choose method, the dual-mode design process and control method improve the theory of dual-mode EVT. These theories can help to do some researches about hardware in loop and real vehicles.