轮毂电动车转向工况的失稳边界分析及稳定性控制方法研究

发布时间：2018-05-11 16:47

本文选题：轮毂电动车 + 失稳边界　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：与传统集中式驱动方式相比,分布式驱动的轮毂电动车结构简单、四轮扭矩独立可控、节约能源,已经成为电动汽车研究重点和发展方向。对于转向工况,改善转向性能和提高稳定性是两大目标。目前主要通过直接横摆扭矩控制(DYC)协调四轮电机扭矩跟踪期望横摆,达到改善性能的目的。由于路面最大附着力的限制和轮胎的非线性特性,在很多极限工况下,车辆转向时极易发生严重侧滑导致失稳。另一方面,转向时,后驱比前驱具有更好的转向性能,但后驱的转向稳定性较差,易产生失稳现象。本文针对轮毂驱动电动车的前后轴扭矩分配的问题,分析车辆转向失稳的原因,和前后轴扭矩分配导致车辆失稳的边界,给出了基于前后轴扭矩分配的横摆稳定控制方法,实现改善转向性能和保障稳定性的目标。本文首先通过仿真,描述了前后轴扭矩分配对转向加速工况性能的改善和产生车辆失稳的现象。进而,结合车辆动力学模型,分析了车辆转向失稳的机理和主要原因。结合车辆失稳时的动力学特征,提出了一种确定失稳边界的方法。本文给出的方法利用车速、横摆率和侧向加速度信息,对车辆状态信息依赖较小,便于应用。基于给出的车辆失稳边界确定方法,本文提出了一种轮毂驱动电动车前后轴扭矩分配方法。该方法一方面充分利用各车轮的附着率,以提高车轮侧向力,达到提高转向性能的目的。同时,结合失稳边界,约束后轴扭矩分配比例,保证车辆转向的稳定性。最后,本文在前后轴扭矩分配的基础上进行了横摆稳定控制研究。为实现期望横摆率的跟踪,首先对期望横摆率的设计方法进行了分析,然后给出了一种横摆率跟踪模型预测控制(Model Predictive Control,MPC)控制器设计方法,硬件在环实验结果检验了本文方法的可行性。
[Abstract]:Compared with the traditional centralized drive mode, the distributed hub electric vehicle has the advantages of simple structure, independent and controllable four-wheel torque and energy saving, which has become the research focus and development direction of electric vehicle. For steering conditions, improving steering performance and stability are two major objectives. At present, the torque tracking of four wheel motor is coordinated by direct yaw torque control (DYC) to improve the performance. Due to the limitation of the maximum adhesion of the road surface and the nonlinear characteristics of the tire, it is easy for the vehicle to slip seriously and lead to instability under many extreme conditions. On the other hand, the back drive has better steering performance than the front drive, but the steering stability of the back drive is poor and the instability is easy to occur. In this paper, aiming at the problem of torque distribution in front and rear axle of electric vehicle driven by wheel hub, the causes of steering instability of vehicle and the boundary of vehicle instability caused by torque distribution of front and rear axle are analyzed, and the control method of yaw stability based on torque distribution of front and rear axle is given. Achieve the goal of improving steering performance and ensuring stability. In this paper, first of all, through simulation, the paper describes the improvement of the performance of steering acceleration and the phenomenon of vehicle instability caused by the torque distribution of the front and rear axle. Then, combined with vehicle dynamics model, the mechanism and main reasons of vehicle steering instability are analyzed. Based on the dynamic characteristics of vehicle instability, a method to determine the instability boundary is proposed. The method presented in this paper makes use of the information of vehicle speed, yaw rate and lateral acceleration, and has less dependence on vehicle state information, so it is easy to be applied. Based on the method of determining vehicle instability boundary, this paper presents a torque distribution method for front and rear axle of wheel-driven electric vehicle. On the one hand, the method makes full use of the adhesion rate of each wheel to increase the lateral force of the wheel and achieve the purpose of improving the steering performance. At the same time, combined with the instability boundary, the torque distribution ratio of rear axle is restricted to ensure the stability of vehicle steering. Finally, on the basis of torque distribution of front and rear shafts, the stability control of yaw is studied in this paper. In order to realize the tracking of the expected yaw rate, the design method of the desired yaw rate is analyzed at first, and then a design method of the model predictive control Predictive control MPC controller for the yaw rate tracking model is presented. The results of hardware in-loop experiments verify the feasibility of this method.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U469.72;TP273

【参考文献】