Research On The Plug-in Hybrid Power System Of The Bus

Hybrid electric vehicle(HEV),as a transitional vehicle in the process of vehicle electrification,has the advantages of good economy,strong endurance and low emission.At present,plug-in HEV has become the mainstream product of HEV in the market.In this paper,a new plug-in hybrid electric system with auxiliary box for a domestic bus is proposed.The device consists of a main box and a sub-box.There are two power input shafts and a middle shaft in the sub-box.The power input shafts of the main gearbox are connected with an engine,and the power output shafts extend into the sub-gearbox and act as the first input shafts of the sub-box.The end of the second input shaft of the sub-box is connected with a driving motor.The first input shaft of the sub-box and the output shaft of the sub-box realize three gears coupling of the sub-gearbox,and the second input shaft of the sub-box and the output shaft of the sub-box realize three motor gears coupling.The matching of transmission ratio and the design of transmission structure are completed based on the research vehicle.The ADVISOR software is used to redevelop the parallel hybrid model.The dynamic and fuel economy are simulated under the modified NEDC and UDDS conditions.The pure electric mode is simulated under the urban condition of NEDC test cycle.The simulation results show that the fuel consumption can be saved 22.75% under the modified NEDC mode and 18.25% under the UDDS mode.Under pure electric mode,the driving distance is 51.2km in the range of power battery power set,which meets the design requirements.A hybrid power system model is established by using AMEsim simulation software,and five representative shifting processes are selected for simulation.The simulation results show that the new hybrid structure can realize no power interruption in the shift process and has good shift quality.