Model predictive air path control for a two-stage turbocharged spark-ignition engine with low pressure exhaust gas recirculation

Abstract

Innovative air path concepts for turbocharged spark-ignition engines with exhaust gas recirculation impose high demands on the control due to nonlinearities and cross-couplings. This contribution investigates the control of the air and exhaust gas recirculation paths of a two-stage turbocharged spark-ignition engine with low pressure exhaust gas recirculation. Using exhaust gas recirculation at high loads, the in-cylinder temperature can be lowered, reducing the knock tendency, while at the same time preventing the need for the enrichment of the air/fuel ratio. Air and exhaust gas recirculation paths are cross-coupled and show different delay times. To tackle these challenges, a data-based two-stage model predictive controller is proposed: The target selector accounts for the overactuated system structure, while the dynamic controller adjusts the charging pressure and exhaust gas recirculation rate. The prediction model setup is based on a small amount of dyno-run measurement data. To ensure real-time capability, the model is kept as simple as possible. This allows for fast turnaround times of the algorithm, while maintaining the necessary accuracy in steady-state and transient operation. This study focuses on a two-stage control concept based on a target selector for optimal stationary control inputs and the dynamic controller considering the dynamic behavior of the air and exhaust gas recirculation paths. Subsequently, the control concept for the two-stage turbocharged spark-ignition engine with low pressure exhaust gas recirculation is validated via experimental tests under real-driving conditions on an automotive test track, using a prototype test vehicle. Results show that boost pressure as well as exhaust gas recirculation rate setpoints are met without overshoot and control deviation with settling times being close to the boundaries set by the hardware.

A Hybrid Direct-Iterative Method for Solving KKT Linear Systems

“…Interior methods for nonlinear optimization [8,18,49,52] are essential in many areas of science and engineering. They are commonly used in model predictive control with applications to robotics [44], autonomous cars [53], aerial vehicles [22], combustion engines [23], and heating, ventilation and air-conditioning systems [26], to name a few. Interior methods are also used in public health policy strategy development [4,43], data fitting in physics [37], genome science [5,50], and many other areas.…”

Time-Optimal Low-Level Control and Gearshift Strategies for the Formula 1 Hybrid Electric Powertrain

“…However, all these approaches mainly rely on quasi-static system models and ignore the dynamic behavior of the internal combustion engine, e.g., the intake manifold or the turbocharger dynamics. To properly capture the engine dynamics, mean value engine models are usually formulated using nonlinear differential equations [31][32][33][34] and optimized offline [35][36][37][38][39][40] or online in a model predictive control fashion [41][42][43][44]. Recently, the air path of a forced-intake engine was modeled in a quasistatic manner as a basis for minimum fuel control [45,46].…”

A comparative study into the effects of pre and post catalyst exhaust gas recirculation on the onset of knock

“…There are a number of alternative strategies for controlling knock without the need for overfuelling and EGR is particularly prominent in this area. 1,2 The dilution effect of EGR can mitigate the risk of knocking combustion at high loads 3 whilst also providing fuel economy benefits at low load by reducing throttling losses. 4 Anticipated CO restrictions in the Euro 7 emissions regulations, alongside the real driving emissions (RDE) test protocols, have added to the pressure on OEMs to realise lambda one operation across the entire operating range of their engines.…”

“…There are a number of alternative strategies for controlling knock without the need for overfuelling and EGR is particularly prominent in this area. 1,2 The dilution effect of EGR can mitigate the risk of knocking combustion at high loads 3 whilst also providing fuel economy benefits at low load by reducing throttling losses. 4…”