University of Minnesota

Ke Li

Zongxuan Sun

Ali Sadighi

A free-piston ('FP') engine is a type of internal combustion engine with no crankshaft, so that its piston trajectory is no longer constrained by the mechanical linkage. FP engines have a high potential in terms of energy saving given their simple structure, high modularity and high efficiency, among other attributes. One of the technical barriers that affect FP engine technology is a lack of precise piston trajectory control. For example, the presence of a transient period after a single combustion event can prevent the engine from continuous firing. The present subject matter provides a control scheme that can utilize a reference and control signal shifting technique to modify the tracking error and the control signal to reduce the transient period.

Systems and methods for transient control of a free-piston engine

Motion control of a hydraulic free-piston engine is achieved in order to enable advanced combustions such as low temperature combustion. To accomplish this, an active controller acts as a virtual crankshaft, which causes a piston to follow a reference trajectory using energy from a storage element. Given the periodic nature of free-piston engine motion, an advanced controller of the present invention is preferably of robust repetitive type that is capable of tracking periodic reference signals.

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Minneapolis, MN, United States of America

Ke Li