Operation Range of Intermittent Velocity Control for Improving Top-Dead-Center Accuracy in Dual-Sided Free-Piston Engine Linear Generator

Abstract

A free-piston engine linear generator (FPEG) is constructed by combining a reciprocating internal combustion engine and a linear generator. FPEG is required to improve both the accuracy of the top-dead-center (TDC) positioning considering frequent combustion fluctuations and the reduction of power consumption. This paper confirms the influence of intermittent velocity control on power running suppression and TDC position deviation in a dual-cylinder FPEG. Intermittent velocity control is a simple method, which consists of repeatedly turning the speed control on and off. The experimental results of the glow engine indicate that this control suppresses power consumption and enables continuous combustion. The setting range for intermittent speed control, which continues operation only through regenerative operation, must be determined by considering the gain value. In addition, this paper explains the effects of the control range of intermittent velocity control on power generation efficiency, piston motion frequency, and TDC position deviation in the dual-cylinder FPEG. Increasing the range ratio of intermittent speed control improves power generation efficiency, but it also increases the standard deviation of TDC position.INDEX TERMS Free-piston engine, linear generator, generation control, speed control, and top-deadcenter