【作者】 谢飞；

【导师】 张代胜； 苏荣；

【作者基本信息】 合肥工业大学 ， 车辆工程（专业学位）， 2021， 硕士

【摘要】 随着科技的进步,新能源与智能化成为了汽车行业在新时代的主题,电动汽车作为新能源汽车技术不断成熟的同时也可以作为智能化汽车的载体,因而受到了世界各国的重视。分布式驱动电动汽车相比于传统汽车,整车布置空间更大且整车控制更容易实现,但同时在转矩分配上也增加了电动汽车控制的自由度与复杂度,对整车转矩分配算法特别是转向时的转矩分配提出了更高的要求。本文针对分布式驱动电动汽车行驶时的不同工况下的转矩分配策略进行了研究。本文首先建立了整车的二自由度、七自由度整车动力学模型,为不同工况下分布式驱动电动汽车转矩分配提供了分析模型。而后基于驾驶员意图建立了马尔可夫预测模型,用于整车直行时的工况识别和转向时算法的优化。转向时,转矩分配以横向稳定性为控制目标,采用模型预测算法,并利用马尔可夫预测模型对该算法进行优化,制定了分布式驱动电动汽车转向时加速度变化条件下横摆稳定性的控制策略。直行时,以动力性和经济性为控制目标,利用马尔可夫模型来识别工况,分别制定了分布式驱动电动汽车匀速直行工况下和加速(减速)直行工况下转矩分配策略。本文采取了Matlab/Simulink与Car Sim联合仿真来验证不同工况下转矩分配策略,并以恒润科技制造的驾驶模拟器为对象,利用carmaker软件和Veri Stand软件搭建软件环境进行硬件在环实验验证仿真结果的有效性,结果如下:(1)转向工况下,基于模型预测的转矩分配策略使得分布式四轮驱动电动汽车最大横摆角速度跟踪误差和质心侧偏角误差控制在合理的范围内,改善了四轮的转矩分配,提高了整车在转向时的操作稳定性。(2)在加速(减速)直行工况下,前后轮驱动电机输出转矩的变化趋势、前后轮转矩分配系数的变化趋势都与整车加速度的变化趋势一致,且后轮总输出转矩一直大于前轮总输出转矩,降低了5.7%的附着率。更多还原

【Abstract】 With the progress of science and technology,new energy and intelligence have become the theme of the automotive industry in the new era.As the technology of new energy vehicles continues to mature,electric vehicles can also be used as the carrier of intelligent vehicles,so they have attracted the attention of all countries in the world.Compared with traditional vehicles,distributed drive electric vehicles have larger vehicle layout space and easier vehicle control,but at the same time,it also increases the degree of freedom and complexity of electric vehicle control in torque distribution,which puts forward higher requirements for vehicle torque distribution algorithm,especially the torque distribution in steering.In this paper,the torque distribution strategy of distributed drive electric vehicle under different driving conditions is studied.In this paper,two degree of freedom and seven degree of freedom vehicle dynamics models are established,which provide an analysis model for distributed drive electric vehicle torque distribution under different conditions.Then,based on the driver’s intention,a Markov prediction model is established to identify the vehicle working conditions in straight driving and optimize the steering algorithm.When steering,the torque distribution takes the lateral stability as the control objective,adopts the model prediction algorithm,and uses the Markov prediction model to optimize the algorithm,and formulates the control strategy of yaw stability under the condition of variable acceleration when the distributed drive electric vehicle steering.In straight driving,taking power performance and economy as control objectives,the Markov model is used to identify the driving conditions,and the torque distribution strategies of distributed drive electric vehicles under constant speed straight driving conditions and acceleration(deceleration)straight driving conditions are formulated respectively.This paper adopts MATLAB/Simulink and Car Sim joint simulate to verify the torque distribution strategy under different working conditions.Taking the driving simulator made by Hi Rain Technologies as the object,the software environment is built by using carmaker software and veristand software to carry out hardware in the loop experiments to verify the effectiveness of the simulation results(1)Under the steering condition,the torque distribution strategy based on model prediction makes the yaw rate tracking error and side slip angle error of the distributed four-wheel drive electric vehicle within a reasonable range,improves the torque distribution of the four wheels,and improves the operation stability of the whole vehicle during steering.(2)Under the condition of acceleration(deceleration)straight driving,the change trend of the output torque of the front and rear wheel drive motor and the change trend of the torque distribution coefficient of the front and rear wheels are consistent with the change trend of the vehicle acceleration.The total output torque of the rear wheel is always greater than that of the front wheel.The adhesion ratio is reduced by 5.7 %更多还原