Pressure and flow based control of a turbocharged diesel engine air-path system equipped with dual-loop EGR and VGT

Abstract

This paper describes a pressure and flow based control method of diesel engine air-path systems equipped with dual-loop exhaust gas recirculation (EGR) and variable geometry turbine (VGT). For the control of dual-loop EGR systems, fraction states are usually controlled, but how to select the control outputs is still controversial. In this paper, considering availability and reliability of sensors, pressure and mass flow states are selected as control targets instead of fraction states. A robust nonlinear control method, input-output linearization is applied for the states of intake manifold pressure, exhaust manifold pressure, and fresh air mass flow rate in order to satisfy the target emissions. The control performance is verified by simulation based on the valid model of a heavy-duty 6000cc engine air-path.

Sliding Mode Control of Diesel Engine Air-path System With Dual-loop EGR and VGT Based on the Reduced-order Model

“…Besides, there exist three states to be controlled, i p , x p , and air W for satisfying the emission requirements [9]. Proper model-based control algorithm…”

“…HP EGR flow rate is modeled as (9) using an orifice equation. (9) In (9), HP PR is the pressure ratio across HP EGR flow and HP A the effective area of HP EGR flow determined by the valve position.…”

“…The model consisting of (12), (13), and (16) is a well-known 3rd order control-oriented model for the diesel engine with the single-loop EGR and VGT system validated in references [2,4,5]. The 5th-order model is designed by adding two dynamics (14) and (15) representing the properties of the LP EGR loop, to the 3rd-order model [9,10]. The 5th-order model is implemented under the following assumptions:…”

“…Hence, we need to select proper control states to be controlled for the combustion variables to satisfy the set-point requirements. In this paper, intake manifold pressure, exhaust manifold pressure, and fresh air flow rate are chosen as control states considering their physical importance in the operations of the air-path and availability of sensors [9,10]. This paper investigates the design of a model-based controller for the states, which is based on the 5th-order reduced model of the air-path.…”

“…To handle control problems of this highly coupled system, various model-based control methods of VGT and EGR systems have been investigated. Many studies have been conducted on the control of single-loop EGR systems [1]- [9] and a few studies on the control of dual-loop EGR systems, which is a relatively new research field.…”