Research On Modeling And Simulation Of The Coaxial Parallel Hybrid Power System Of The City Bus

The hybrid system has become one of research hotspots in automobile field. Energyconservation is the main objection of the power system’s design of hybrid electric vehicle(HEV).The power system is the core of the hybrid electric vehicle. The vehicle performanceis directly related to it. As the research object to the coaxial parallel hybrid power systemof gas-electric hybrid bus. The economy and enrgy conservation effect are researchedbased on analysis of the characteristics of the operating conditions and indicators of power.The simulation model of the vehicle and its main parts are established based onMATLAB/SIMULINK, including engine model, motor model, power-cell model,management strategy model, braking force distribution model, shift schedule model andthe vehicle resistance model etc. The simulation results show that the model can betterreflect the actual operating conditions of the hybrid bus.The finite-state machine theory of hybrid system is firstly introduced on analysis ofenergy flow. The management strategy is designed and model is established based onSIMULINK/STATEFLOW. Firstly regenerative braking strategy and energy distributingstrategy (fuzzy logic management strategy and the electric auxiliary management strategy)are established. Then the vehicle simulation model is let into the simulation interface. Intypical cycle conditions of china city bus, the performance of this power system iscompared to the tradition bus which has the same configuration. Finally, if an energyexpenditure method being used, simulation results show that there is about25%less gasconsumption than the tradition power system. This study provided guidance and referencefor further development of hybrid electric vehicle.