按需功率匹配的重型车辆E-ECHPS节能机理与协调控制研究

For solving the critical problem of energy consumption and steering feel of the heavy-duty vehicles hydraulic power steering system (HPS), aiming to the coordination of energy-saving and steering maneuverability, a new electronically controlled hydraulic steering system (E-ECHPS) is proposed, which is characterized by an electromagnetic slipping clutch (ESC) to adjust the steering pump output power to achieve low-power and variable assisted force features. The corresponding assist characteristic curve for heavy-duty vehicles is created. Based on the ideology of on-demand power matching, the relationship between power supply, transmission and terminal components of E-ECHPS is established to reveal the coordination mechanism between energy-saving and maneuverability. According to the steering wheel angle/torque, vehicle speed and engine speed, the ESC current is controlled in nonlinear closed-loop. The adaptive fuzzy sliding mode control strategy for dynamic parameters on-line setting is investigated. Using the Lyapunov function, the adaptive rate of rule parameters is deduced, which enhances robust stability of control system. The agility of the E-ECHPS system is improved by the joint optimization of the structural and control parameters, and the system integrated design theory and optimization matching method are studied. The key components and prototypes of E-ECHPS are developed and tested. As the expectative results of this research project, compared with traditional HPS, E-ECHPS can save energy consumption more than 30% and improve handling and stability of heavy-duty vehicle significantly.

针对重型车辆液压助力转向系统（HPS）在能耗和转向路感方面存在的突出问题，从协调HPS的节能和转向操纵性出发，提出一种用电磁转差离合器（ESC）调节转向泵输出功率以实现低能耗及可变助力特性的新型电控液压转向系统（E-ECHPS），并创建重型车辆的理想转向助力特性；基于按需功率匹配思想，建立E-ECHPS中供能、输能和耗能元件之间的功率匹配关系，揭示E-ECHPS协调节能与操纵的机理；根据方向盘转角/转矩、车速和发动机转速对ESC电流进行非线性闭环控制，研究动态参数在线调节的自适应模糊滑模控制策略，基于李雅普诺夫函数演算规则参数的自适应率以增强控制系统的鲁棒稳定性；通过结构性能参数与控制参数的联合优化，提高系统的敏捷性；研究E-ECHPS系统的集成设计理论与优化匹配方法，研制E-ECHPS关键零部件和样机并进行试验验证，实现E-ECHPS比传统HPS节能30%以上、整车操纵稳定性显著提高。

针对重型车辆液压助力转向系统（HPS）存在的助力特性单一、无功损耗高的问题，构建了基于电磁转差离合器（ESC）的电控液压助力转向系统（E-ECHPS）；建立了ESC的电磁模型，通过分析ESC的电磁特性，对ESC进行了优化设计，推导了d-q坐标系下的ESC数学模型，通过仿真和试验得到了ESC的机械特性、输入-输出特性、励磁电流-输出特性等工作特性；为了提高ESC传递动力的效率，创新提出馈能型ESC的概念，发明了馈能型ESC的能量回收装置，设计了基于磁场定向原理的ESC馈能策略，试验结果显示ESC的能效提高了40.2%；首次通过实车试验获得了大客车驾驶员偏好的转向盘转矩，填补了该研究领域试验数据的空白，为了保证驾驶员在各车速下都具有良好的转向路感和手感，提出了基于驾驶员偏好转矩的负幂指数型助力特性设计方法；建立了E-ECHPS的能量流模型，分析了E-ECHPS节能机理，将E-ECHPS的按需功率匹配问题归纳为流量匹配、压力匹配、ESC转差损耗回收和功率匹配控制问题，提出了流量匹配和压力匹配方法，制定了E-ECHPS的按需功率匹配控制策略，进行了综合工况下HPS和E-ECHPS的能耗仿真，结果显示E-ECHPS的能耗相较于HPS降低了约30%；为了降低发动机转速波动、侧向力干扰等因素对控制精确性的影响，提出了基于自适应模糊滑模理论的E-ECHPS控制策略，仿真结果表明，自适应模糊滑模控制策略有利于提高车辆的操纵稳定性；研究了ESC的内转子转动惯量、电流和转差率等特征参数与响应时间的关系，仿真结果表明ESC转速响应时间随着内转子转动惯量的增加而显著增加，随着电流和转差率的增加而减小；根据系统压力、流量的匹配结果优化设计了E-ECHPS的机械系统、液压系统，搭建了E-ECHPS的整车试验系统，分别进行了原地转向、蛇形转向、中间位置操纵稳定性试验，试验结果显示，E-ECHPS车辆的低速转向轻便性提高了约16.9%，高速中间位置转向路感提高了约36.2%。本项目的研究成果为基于ESC的电控液压转向系统开发提供了设计理论和关键技术。