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在带有废气再循环(EGR)和可变喷嘴涡轮增压器(VNT)的柴油发动机中,EGR与VNT工作过程中会出现相互之间的互扰。在发动机转速和喷油脉冲改变的瞬时状态下,设计和调整常规的PID控制器特别困难。针对这种情况提出了1种基于模型控制的瞬态和稳态控制系统。该控制系统在传统的PID控制基础上,利用空气动力学与传热学,优化并建立3个主要的控制模型,包括多输入多输出(MIMO)切换控制器,动态反馈器和干扰观测器。通过试验验证,EGR和VNT之间的干扰得到有效调节;在控制过程中,空气质量流量与进气歧管压力的响应延迟得到改善,并且NOx的排放量明显减少。
In diesel engines with exhaust gas recirculation (EGR) and variable nozzle turbocharger (VNT), mutual interference between EGR and VNT occurs during operation. It is particularly difficult to design and adjust conventional PID controllers at transient conditions where engine speed and fuel injection pulses change. Aiming at this situation, a transient and steady state control system based on model control is proposed. Based on the traditional PID control, the control system uses aerodynamics and heat transfer to optimize and establish three main control models, including multiple input multiple output (MIMO) switching controller, dynamic feedback and disturbance observer. Through experimental verification, the interference between EGR and VNT can be effectively adjusted. In the process of control, the response delay between air mass flow and intake manifold pressure is improved, and the NOx emission is obviously reduced.