EGR涡轮增压柴油机的进气未燃空气质量分数估计

Unburned Air Mass Fraction Estimation for Model-Based EGR Turbocharged Diesel Engine Unburned Air Mass Fraction Estimation

为解决车用EGR涡轮增压柴油机进气未燃空气质量分数无法直接测量的问题,提出了一种估计未燃空气质量分数的方法.在构建高压回路EGR涡轮增压柴油机动态模型的基础上,设计了EGR流量的高增益观测器,为进气歧管未燃空气质量分数的准确估计奠定基础;基于进排气歧管未燃空气质量分数的动态方程,设计了柴油机未燃空气质量分数的全维状态观测器,并基于李雅普诺夫稳定性理论,对设计的观测器进行了稳定性分析.分析结果表明,设计的观测器是一渐近稳定系统,可以用于对未燃空气质量分数进行估计.利用GT-Power仿真数据以及试验数据对设计的EGR流量观测器和未燃空气质量分数观测器进行验证.结果表明,设计的观测器能够对参数进行准确估计,估计误差在3%以内,满足柴油机控制系统的需求.

Intake unburned air mass fraction cannot be directly measured on production EGR turbocharged diesel engine. To deal with this problem, an innovative unburned air mass fraction estimation method for EGR turbocharged diesel engine was proposed in this paper, laying the foundation for the diesel air path control based on intake unburned air mass fraction. A dynamic model of the high pressure EGR turbocharged diesel engine was developed, and the EGR flow high gain observer was designed based on the dynamic model, to lay the foundation for the accurate estimation of the unburned air mass fraction. Based on the dynamic equations of the unburned air mass fraction in the intake and exhaust manifold, the full dimension state observer of the unburned air mass fraction was designed. The convergence stability of the observer was proved through a Lyapunov analysis. The results show that the observer can meet the stability requirements. It can be used for estimating the unburned air mass fraction. The EGR flow observer and the unburned air mass fraction observer were verified also using the GT-Power simulation data and the experimental data. The results show that the designed observers can accurately estimate the parameters, and the estimation error less than 3%, which meet the demand of diesel engine control system.