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Constrained Control of Free Piston Engine Generator based on Implicit Reference Governor

par Gong, Xun;Kolmanovsky, Ilya;Garone, Emanuele ;Zaseck, Kevin;Chen, Hong
Référence Science in China. Series F, Information Sciences
Publication Publié, 2019-11

Article révisé par les pairs

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Résumé :

The free piston engine generator (FPEG) is a novel power plant concept for series hybrid electric vehicles (HEV) that requires reliable control to regulate piston motion and guarantee safe operation during load transitions. This paper focuses on the control and constraint enforcement in a FPEG using a reference governor. A discrete, implicit, control oriented model describing the piston motion in a two-stroke twocylinder FPEG at the turnaround point is derived based on energy balance and a feedback controller is designed to track the desired turnaround position by regulating fuel. An implicit reference governor is developed to guarantee safe piston motion by managing the load transitions. The reference governor utilizes Newton’s method applied to an implicit nonlinear model for response prediction and a bisection search algorithm to enforce the constraints for all the future time instants by adjusting the reference command. Additionally, the error in applying one iteration of Newton’s method in predicting the response of the implicit nonlinear system is estimated and accounted for in constraint tightening to guarantee that constraints are robustly enforced. The simulation results show that the feedback control scheme incorporating the developed implicit reference governor can effectively enforce the prescribed constraints during load transition.