EVT Configurations Design And Parameters Optimization Of Power-split Hybrid Electric Vehicle Based On Lever Analogy

With the development of economy, energy requirements from human keep increasing. China now is a developing country and needs more energy. Petrol is one of the most important energies used by human. However, petrol is primary energy and couldn't be renewable. It's necessary to save energy and reduce fuel consumption. The most important application of petrol is used as vehicles' fuel. So it's necessary to improve technology of vehicles to reduce fuel consumption of vehicles. And environment protection is becoming more important. Vehicle emission is one of the sources of air pollutant. Also, it's necessary to improve technology to reduce vehicles' emissions. Hybrid electric Vehicle(HEV), is one of the new energy vehicles. It can significantly improve fuel consumption and emissions of vehicles. Power-split HEVs have a good performance in fuel economy and emissions and are focus of HEVs' market. This dissertation is supported by the National Natural Science Foundation of China and studied the following contents about EVT configurations of power-split HEVs.(1)All possible EVT configurations of single and double PG set are analyzed based on lever analogy when configurations have the engine and two electric machines. Invalid or low efficiency configurations are excluded by mechanical point and speed or torque requirements of electric machines. Computer aided code is used for quickly screening a large amount of EVT configurations. Dynamic relationship of a EVT is analyzed by using lever analogy.(2)Engine, electric machine, battery and vehicle dynamic are modeled on MATLAB software. These models are prepared for the following simulation. Global energy management strategy--dynamic programming(DP) is used as vehicle control strategy in this paper. State and control variables of series, parallel and power-split are analyzed. The corresponding objective functions and constraints are set. The process and the principle of dynamic programming are explained.(3)Input-split EVT configurations are simulated by using DP algorithm on MATLAB. Fuel economy of all of EVT configurations are compared by using data fitting. The ratio of engine operating in high efficiency region is also considered. And the optimal EVT configuration is selected by fuel economy and the ratio of engine operating in high efficiency region. The parameters of the optimal EVT configuration are optimized.(4)The optimal configuration is simulated on NEDC, UDDS, HWFET and US06 cycles. The simulation results are analyzed. The characteristic and fuel economy of EVT configuration are analyzed. To validate the selected EVT configuration and optimization effect, the series and parallel HEVs, which have same basic parameters with power-split HEV, are simulated by using DP. The simulation results are compared with EVT configuration.Through above-mentioned research, this dissertation provides some theory basis for selection of EVT configurations and parameter optimization. It has a good effect on design and performance optimization of power-split HEVs.