汽车电动助力转向回正控制研究

发布时间：2018-05-28 13:06

本文选题：电动助力转向系统 + 电机转速　；参考：《湖南大学》2016年硕士论文

【摘要】：近几年来,电动助力转向系统(Electric power steering system,EPS)由于具有节能、环保、主动安全性和良好的操纵稳定性等优势,在越来越多的汽车上成为标配;其控制模式已从最初的助力控制向回正控制、补偿控制、最大电流控制等综合模式发展,控制功能进一步加强。汽车行驶工况复杂,在不同附着系数路面上行驶时,转向回正力变化显著导致回正时出现回正不足或回正超调现象;这对汽车驾驶安全性和转向过程的操纵稳定性有重要影响。针对这种情况,论文选用齿轮助力式EPS作为研究对象,对EPS系统回正控制进行研究。为克服路面附着系数变化对车辆回正性能的影响,论文研究了基于回正力估计的回正控制。首先建立了电动助力转向系统模型,由车速和方向盘转角,确定期望回正力矩。其次采用变内阻、变反电动势系数的电机模型估计电机转速,并由估计的电机转速、电机电流,方向盘扭矩,估计车辆的回正力矩。最后以期望回正力矩与估计的回正力矩偏差为输入,对助力电机进行分段PID闭环控制,实现EPS回正力补偿。开发了EPS ECU,设计了EPS核心电路,电源电路,车速处理电路,电机驱动电路及CAN通信电路等。采用Carsim、Labview软件及转向系统实物搭建了EPS硬件在环仿真平台,并使用该平台,对本文提出的基于回正力估计的回正控制与基于方向盘转角的回正控制进行对比实验分析。实验结果表明,汽车在回正过程中,采用基于回正力估计的回正控制能在各种附着路面上快速准确回到中间位置,改善了汽车回正性能,提高了汽车驾驶安全性和转向操稳性。
[Abstract]:In recent years, electric power steering system (EPS) has become the standard in more and more cars because of its advantages of energy saving, environmental protection, active safety and good handling stability. The control mode has been developed from the initial power control to the integrated control such as return control, compensation control and maximum current control, and the control function has been further strengthened. When the vehicle is on the road with different adhesion coefficient, the change of steering return force leads to the phenomenon of insufficient return or overshoot, which has an important effect on the driving safety and steering stability of the vehicle. In this paper, gear assisted EPS is chosen as the research object to study the return control of EPS system. In order to overcome the influence of the change of road adhesion coefficient on the vehicle return performance, this paper studies the return control based on the return force estimation. First, the model of electric power steering system is established, and the expected return moment is determined by the speed and steering wheel angle. Secondly, the motor speed is estimated by the motor model with variable internal resistance and variable back EMF coefficient. The motor speed, motor current and steering wheel torque are estimated from the estimated motor speed, motor current and steering wheel torque. Finally, based on the bias between the expected and the estimated return torque, the piecewise PID closed-loop control is carried out for the auxiliary motor to realize the compensation of the EPS return force. EPS ECU is developed, and EPS core circuit, power supply circuit, speed processing circuit, motor drive circuit and CAN communication circuit are designed. The EPS hardware in loop simulation platform is built by using the Carsiman LabVIEW software and the steering system. By using this platform, a comparative experimental analysis is carried out between the return control based on the estimation of the return force and the return control based on the steering wheel angle. The experimental results show that the return control based on the back force estimation can quickly and accurately return to the middle position on various attached roads, improve the vehicle return performance, improve the driving safety and steering stability of the vehicle.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U463.4

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