Parameters Matching And Optimization For Powertrain And Research On Automatic Shift Schedule Of Electric Vehicle

Electric vehicle can be designed as compact cars for the family、high-classcommercial cars、small trucks、city buses、road sweeping vehicles with energy savingand environmental protection.The power-train of the designed car designed in the paper is a tow-speed electricdrive axle composed of planetary transmission and the final drive, the electric vehiclescan use high output torque from low speed of motor to start or climbing in first gearand get a higher vehicle speed from high speed of motor in second gear.In the two-speed automatic transmission electric drive system, the torque of thedrive motor is determined by the maximum designed gradient, rotate speed isdetermined by the maximum speed of the vehicle, power is determined by themaximum speed of the vehicle and the maximum climbing power, the number ofbattery cells is determined by the peak power and input voltage of the motor, and thecapacity is determine by the driving range.According to the test cycle of Changsha, the expressions of specific energyconsumption and dynamic factor which associate with transmission ratio is establishedin the paper, putting the expressions separately as objective functions of optimization.Weighting factors based on the standard of improving the driving range while meetingthe power performance of the vehicle. A particle swarm optimization based onsimulated annealing is used in the paper, the optimization results show the climbinggradient meets the design requirement, the maximum speed does not change, but theacceleration time decreases and the driving range under tested cycle increased, theresults reached the optimal goal.When the SOC of the battery cells is less than0.291, the maximum continuousdischarge power of the battery cells cannot meet the constant output power of the drivemotor, the output torque and efficiency characteristics of the motor will change under alarge certain throttle. Therefore, the best power and energy shift schedule of theelectric vehicle are established according to these four parameters of the SOC, throttle,speed and acceleration of the vehicle.In this paper, the back simulation model supplement with a forward simulationmodel is established based on MATLAB/SIMULINK, the simulation results verifiedthe reasonable match parameters of dynamic system. The shift schedule model also established which ignored the complex motor control and battery control in the paper,which mean the speed and torque of the motor can automatically track and respond tothe objective value during the shifting, the simulation purpose is to verify thesuperiority of the automatic shift schedule. Compared with single parameter or twoparameters of automatic shift schedule, the simulation results from the best power andenergy shift schedule in the paper show smaller acceleration time and smalleracceleration energy consumption.