Operation Range of Generation Braking Force to Achieve High Efficiency Considering Combustion in a Free-Piston Engine Linear Generator System

Abstract

A linear generator system is expected to realize a highly efficient free-piston generation engine. The efficiency of the system mainly depends on the generation and thermal efficiencies of the engine. The generation efficiency decreases owing to a large braking force on the expansion stroke and a speed reduction at the ends of the stroke. This paper proposes generation control with resonance and output drop that improves the generation efficiency during the expansion stroke. When changing the amount of consumed fuel, the condition to maximize the electricity generation can be achieved by optimizing the ratio of the iron to copper losses. Furthermore, the proposed method improves the combustion performance of the engine by ensuring ideal speed at the combustion start position.

Generator Design Considering Mover Action to Improve Energy Conversion Efficiency in a Free-Piston Engine Generator

“…Energy flow is determined by solving the block diagram of Figure 3, which links three software. The mover action is obtained by solving Equation (1) using MATLAB-Simulink (The MathWorks, Inc., Natick, MA, USA), which contains the speci fications of the linear generator designed by JMAG-Designer (JSOL Corporation, Tokyo, Japan) and vector control [15,24]. The combustion thrust, considering the engine loss, is simulated using GT-SUITE (Gamma Technologies, LLC, Westmont, IL, USA).…”

“…A free-piston engine generation system (FPEG) recovers the combustion energy of the engine with a linear generator [10][11][12][13][14][15][16]. This system requires a highly efficient linear generator design, considering that almost the same combustion energy not randomly but repeatedly acts on the generator.…”

“…Delaying piston operation immediately after combustion can improve the engine thermal efficiency of the engine [25]. Extending the stroke with a single engine type using a spring suppresses the maximum braking force of the linear generator and reduces copper loss [15]. To maximize the energy conversion efficiencies of FPEGs, minimizing the engine and generator losses, the relevance of motor movement, engine efficiency, and generator efficiency need to be considered.…”

Improving the constant‐volume degree of combustion considering generatable range at low speed in a free‐piston engine linear generator system

“…In addition, it is possible to adjust the braking thrust by using the generation control with the linear generator and the inverter in the FPEG. The piston that is not fixed to the crank can have flexible action by the arbitrary braking thrust controlled with the inverter , as shown in Fig. .…”

“…Therefore, free‐piston engine linear generator systems (hereinafter, FPEG) have been attracting attention as the next power generation engine for onboard automobiles . The FPEG system consists of a free‐piston engine and a linear generator, which are reciprocating internal combustion engines.…”