中文摘要：

根据分布式驱动电动汽车前轮独立驱动的特点和拓扑结构,分析了其实现差动助力转向的可行性,并提出了差动助力转向闭环控制方法。基于纵向车速和转向盘转角确定了参考转向盘力矩,以它为控制目标设计了差动助力转向闭环控制策略,以改善车辆的转向性能。针对特定工况下电机输出转矩饱和的情况设计了遇限削弱积分变参数PI控制算法和回正识别策略与控制算法,保证在低速时转向盘能快速回到中间位置,而在高速时能提供一定的阻尼,以减小转向盘回正超调。实车试验结果表明：设计的控制算法可为驾驶员提供随车速而变的转向助力,从而减小转向盘力矩,改善车辆的转向轻便性;同时,能准确地判断回正状态,跟踪转向盘力矩参考值,显著改善回正工况车辆响应。

英文摘要：

Based on the features and topology structure of front wheel independent drive in a distributed drive electric vehicle, its feasibility of implementing diflerential assisted steering is analyzed and a closed-loop con-trol scheme for differential assisted steering is proposed. Based on longitudinal speed and steering wheel angle, the reference steering wheel torque is determined, and with which as control target the closed-loop control strategy for differential assisted steering is devised to improve the steering performance of vehicle. A varying parameter PI control algorithm with anti-windup integral and aligning recognition strategy and control algorithm are devised for the situa-tion of motor output torque saturation in specific condition to ensure the steering wheel returning to central position in low speed while providing certain damping in high speed for reducing the overshoot of steering wheel return. The re-sults of real vehicle test indicate that the control algorithm can provide assisted steering force varying with vehicle speeds and hence reduce steering wheel torque and improve the steering handiness of vehicle. Meanwhile it can also accurately judge the state of aligning,make steering torque follow its reference value and significantly enhance vehi-cle responsibility in aligning condition.