Energy Balance-Based Dead Center Control of Free-Piston Engine Generator

Free-Piston Engine Generator (FPEG) is a novel power plant which is widely considered a promising technology for hybrid electric vehicles. This paper focuses on the precise Top Dead Center (TDC) control under combustion variations, and a motor thrust control strategy based on the energy balance principle is proposed. According to the operation measurements, the TDC of the current working cycle is predicted in real-time based on the quantitative analysis of the energy conversion flow, such that the negative effect caused by the combustion variation can be characterized. Then, the motor thrust is progressively adjusted during the working cycle based on the error between the predicted and the reference TDC. Finally, the simulation results show that the proposed control strategy can effectively realize the TDC control with high accuracy.