Modeling And Simulation Of Hybrid Electric Vehicle Transmission System

The demand for more environmentally friendly and fuel efficient vehicle has been increased in response to growing concerns on the clean environment and saving energy. In this context, the hybrid electric vehicle (HEV) has emerged as a viable solution to meet those requirements in short to midterm. Among many different hybrid modes, the three generally accepted classifications are series, parallel, series and parallel.The difference between different classifications of HEV is described in this paper and a parallel HEV transmission system mathematic model is build, which can be used when researching HEV structure and control strategy.Mathematic model in this paper is built by using MATLAB/SIMULINK, composed of CVT gearbox model, final drive model, wheel and axle model and so on. All those data used in modeling are from ADVISOR. In order to make this model can be used in common situation, all those parameters that describing the components' character are changeable. For example, ration 3 and 3.5 means two different final drives.Control strategy used in this paper is different from some others in regenerate control. Few control strategy used gearbox's ration control when the vehicle is regenerating. However, motor's efficiency in regenerating also should be controlled in order to make the best use of motor~[27], not for maximize the motor torque only. At the same time, of course, motor capacity, battery SOC and vehicle velocity are also considered.At the same time, control strategy "ECMS"~[35] is discussed in this paper, which is clearly recognized that the electrical energy and the fuel energy are not directly comparable, but an equivalence factor is needed. The equivalence between electrical energy and fuel energy is basically evaluated by considering average energy paths leading from the fuel to the storage of electrical energy.From the results of simulation, we can find that, the regenerative braking algorithm including the CVT ratio control provides improved SOC as much as 3 percent for commuter driving schedule.