| A battery electric vehicle uses a power battery as an energy source and uses a motor-driven method to replace traditional fuel vehicles.It can achieve pollution-free and zero emissions,and is close to or better than traditional internal combustion engines in terms of overall vehicle performance.Its driving range can meet the general driving needs.The battery electric vehicles currently used in daily life are mostly fixed speed ratio reducer devices,which have higher requirements for matching drive motors,need to provide a large reserve power and have poor efficiency during operation.Moreover,the key technical issues such as power battery and drive motor control have not yet been broken through,resulting in the short range of battery electric vehicles,safety,comfort,and high costs.These issues have not been fully resolved.One of the effective ways to improve the endurance of electric vehicles It is a reasonable matching and optimization of the battery electric vehicle power transmission system.This article takes a small logistics electric vehicle as the research object,studies the key content of its power system,optimizes the driveline speed ratio,shifts and other key contents,and builds a vehicle simulation test platform to analyze and verify each.The selection of key components and the rationality of the optimized design are as follows:First,basic structure and main key components of a battery electric vehicle are discussed;based on the theoretical knowledge of the vehicle,a mathematical model of the drive motor and the power battery is established,and the power transmission system is appropriately selected and calculated based on the vehicle performance parameters.The preliminary matching result of the vehicle matching parameters is obtained.Second,a battery electric vehicle model was built,including driver module,battery module,motor module,logical shift,and vehicle longitudinal dynamics module.By verifying the accuracy of the whole vehicle model under the typical cycle condition NEDC,it laid the foundation for the optimization and matching of the two schemes of power system parameters and the performance simulation of the car.Third,optimize the key components of the drive motor and the transmission ratio of the drive system in a battery electric vehicle,use the energy consumption of the entire vehicle as the target function,and the mileage requirements and power requirements of the vehicle as constraints,and use genetic algorithms to find the global optimal solution.Establish the power battery life model and seek the best series-parallel connection of the battery;through the simulation test,comparatively analyze the power and economy of the optimized single-speed reducer and the two-speed transmission,the optimized single-speed reducer and the two-speed transmission.The results show that the optimized single-speed reducer and two-speed transmission battery electric vehicle can reduce the energy consumption of the entire vehicle by about 27% and increase the driving range by 9.5% under the condition of meeting the power of the entire vehicle.Fourth,according to the performance requirements of the vehicle,determine the transmission scheme of the power train,draw the shift curve,and elaborate on the economic shift and power shift in more detail,and get the best economic shift curve and the best power shift curve.This research has important reference value for the design of matching and optimizing the key component parameters of the battery electric vehicle,the transmission ratio and the shifting law. |
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