Design, modeling and control of micro internal combustion swing engine (MICSE) systems

A micro internal combustion swing engine (MICSE) is a rotationally oscillating freepiston engine in which combustion occurs in four chambers separated by a single rotating swing-arm. Mechanical-to-electrical power conversion is realized via a shaft-coupled inductive alternator outside the combustion chamber. A MICSE based power system is a very promising solution to palm-sized portable power applications.;The focus of this work is design, modeling, and control of the MICSE system. Proper design of the clearance gap for dynamic sealing is critical to ensure continuous engine operation and obtain specified thermal efficiency. A finite element heat transfer model is developed to characterize the gap size changes due to differential thermal expansions of engine core parts. Design solutions have been developed and successfully experimented on a prototype engine. Petri-net based hybrid modeling concept is applied to the MICSE application. The models developed with this concept describe the hybrid nature of a MICSE, including two types of engine subsystems (continuous time and discrete event based), in an independent but integrated manner. The developed hybrid models are validated using experimental data. These models provide a deep understanding of engine dynamics due to the impacts of spark and valve timing, and facilitate the development of control strategies and algorithms. Challenges for developing MICSE control systems come both from the free-piston nature of a MICSE and real-time micro controller realization. Due to the lack of crankshaft and the small system size, the time domain is identified more suitable for control than the crank angle domain in the MICSE application. A crankshaftless engine timing control concept was proposed and implemented. Experimental results have demonstrated the crankshaftless control is an accurate, reliable, cost-effective and space-saving approach to realize the MICSE timing. Extremum seeking is applied to realize the optimal control of spark timing for a two stroke MICSE system. Closed loop control of the spark timing and exhaust valve timing is designed to maintain the MICSE voltage/speed output at a constant level under load fluctuations. Conclusions and future work are presented at the end of this dissertation.