Iterative Learning Control Algorithm for Feedforward Controller of EGR and VGT Systems in a CRDI Diesel Engine

The modern diesel engines equip the exhaust gas recirculation (EGR) system to suppress the NOx emissions. In addition, the variable geometric turbocharger (VGT) system is installed to improve the drivability and fuel efficiency. These EGR and VGT systems have cross-coupled behavior because they inte...

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Bibliographic Details
Published in:International journal of automotive technology 2018-06, Vol.19 (3), p.433-442
Main Authors: Min, Kyunghan, Sunwoo, Myoungho, Han, Manbae
Format: Article
Language:English
Subjects:
Actuators
Algorithms
Automotive Engineering
Control algorithms
Control theory
Controllers
Diesel engines
Engineering
Error reduction
Exhaust gases
Exhaust systems
Feedforward control
Gas flow
Low pass filters
Machine learning
Nitrogen oxides
Nonlinearity
Superchargers
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Summary:The modern diesel engines equip the exhaust gas recirculation (EGR) system to suppress the NOx emissions. In addition, the variable geometric turbocharger (VGT) system is installed to improve the drivability and fuel efficiency. These EGR and VGT systems have cross-coupled behavior because they interact with the intake and the exhaust manifolds. Furthermore, the turbocharger time delay, gas flow dynamics through EGR pipe cause the nonlinearity characteristics. These nonlinear multi-input-multi-output characteristics cause the degradation of control accuracy, especially during the transient condition. In order to improve the control accuracy, this study proposes an iterative learning control (ILC) algorithm for feedforward controller of EGR and VGT systems. The feedforward controller obtains the values about EGR and VGT actuators using the previous control results in predefined transient states. The ILC algorithm consists of a PD-type learning function and a low-pass filter. The control gains of learning function are determined to guarantee the convergence of learning results. In addition, the low-pass filter is designed for robustness against plant disturbance. The proposed control algorithm was validated by engine experiment which repeated predefined transient states. The error was reduced by 15 % according to the gain. As a result, the proposed algorithm is affordable for improving the transient control performance.
ISSN:1229-9138
1976-3832
DOI:10.1007/s12239-018-0042-z