Modeling And Simulation Of The Drivetrain Of Series Hybrid Electric Bus

The key to the program of hybrid electric bus to achieve the goal is to find the matching drivetrain. In this paper, the percept design, mathematics modeling, simulation analysis and results of the series hybrid drivetrain were described in detail.Firstly, based on the theory of hybrid electric vehicle (HEV), the series hybrid drivetrain is selected as the modeling object because it is especially adaptive to the city bus transportation. To find suitable components of the drivetrain, modern and future technologies of HEV were employed. The size of drivetrain components is approximately computed on the basis of the prototype of hybrid electric bus (HEB). And then, two solutions to the drivetrain were proposed.Secondly, the methodology and modeling issues of the drivetrain components were described by making reference to the model presented in some paper. Based on Matlab/Simulink modeling environment, the primary components are modularized and can run in the ADVISOR (Advanced Vehicle Simulator), a MATLAB simulation program developed by the U. S. Department of Energy's National Renewable Energy Lab. These ensure the utility and reliability of the model. During the simulation input step, the input of engine map and motor efficiency map are very difficult, so their solutions were given great emphasis. To improve the precision of the simulation, the advanced options of the ADVISOR(such as Grade test and Acceleration Test) were newly set up.In the next place, a simulate scheme is presented to simulate the HEB prototype and virtual drivetrain solutions. According to the scheme, the simulation analysis not only evaluates two hybrid control strategies ("Thermostat Control Strategy" and "power follower control strategy "), but also supplies the operation characteristic of the series hybrid drivetrain. These help to decide the final virtual drivetrain solution that its performance is approximately the same as the HEB prototype. At the same time, the rationality of the drivetrain of the HEB prototype was testified by the simulation result.Finally, the impact of key parameters to vehicle fuel economy was simulated in the sequence of technology addition pathway. The results show that compared to the conventional bus, the fuel economy of the series HEB can improve about 30% without reduction in its drive performance. This provides the strategy evidence for the optimization design of series HEB, which is extremely valuable in application.