Study On Facing-Forward Simulation Of Electric Vehicle

The crisis of energy sources and pollution of the environments have brought rigorous challenge for the stable development of the automobile industry of the world. As the representative of the automobiles with new energy, the electric vehicle indicates the development direction for the automobile of the future. The research and application of the simulation technique in the electric vehicle design shorten the design period and save the research outlay. This paper discusses and researches the correlative contents on the facing-forward simulation of the electric vehicle and the task that is the sub-task of "simulation analysis system of multi-energy-source powertrain energy management" of the 863 electric vehicle important project presided by government.At the electric vehicle theoretical research stage, in order to choose the best vehicle structure, parts size and energy management strategy, we can set up the corresponding whole vehicle digital model and simulate the dynamics performance, fuel economy performance and exhaust emission performance, sequentially compare the merits and shortcomings of different designs which can be chosen.As the two most representative simulation structures of electric vehicle, both the facing-forward simulation and the facing-backward simulation have their own merits and shortcomings regardless of the modeling method or the simulation operation. By the comparison analyzing that integrates theory with example, this paper points out that the facing-backward simulation suits to be used at the primary design stage to guide the parts and control strategy choosing, but the facing-forward simulation is more suited to adjust and optimize the parts' parameters and control strategy to meet the application requirement of prototype vehicle at the late design stage.The development and application of simulation software play an important role as the basic platform of electric vehicle simulation research. Aiming at the demand of task research, task group developed a set of software called HEVSim for the hybrid electric vehicle simulation on the base of facing-forward simulation structure. This system provides a good environment for the design and optimization of the control strategy in the prototype vehicle.The unique component differentiation between the facing-forward simulationstructure and the facing-backward simulation structure is whether has a driver model. As the origination part of facing-forward simulation structure, the driver model sends control command to the controller directly. This paper introduces the modeling method of the driver model in detail. To the problem that real-time correct the difference between the demand vehicle speed of simulation and the acquire vehicle speed of simulation, this paper puts forward that use the conventional PI controller and the fuzzy logic controller to set up the driver model respectively. The corresponding modeling work is completed and the simulation has run in the HEVSim software. The simulation result shows the control effect of fuzzy logic controller is better than the PI controller's on the premise of achieving the demand of simulation.To the development of the controller of the new parallel hybrid electric vehicle EQ7200HEV related to our task, this paper presents the control strategy based on demand torque distribution. On the base of the optimal engine curve of steady state, the strategy distributes the work torque timely to the drive devices according to the driver's demand torque during the driving. At the same time, to the shortage of this control strategy, using fuzzy logic controller to substitute for the partial threshold judgments is presented and the membership function of some control variable in the fuzzy logic controller are optimized by genetic algorithm. Building the controller model with the developed control strategy and running it in the facing-forward simulation software HEVSim, the control effect satisfy the design requirement and the conclusion that facing-forward simulation is more convenient for the development and optimiza...