Investigation of a high efficient Free Piston Linear Generator with variable Stroke and variable Compression Ratio A new Approach for Free Piston Engines

Abstract

Chemical energy can be converted to electricity with very high efficiencies by means of a free piston linear generator allowing a variable stroke and a variable compression ratio. Therefore online-downsizing in part-load is possible by reducing the stroke. As a result throttling, wall and friction losses are reduced. The paper describes the concept of the free piston linear generator, which is well suited for the HCCI-combustion process. It is expected that emissions and the fuel-consumption can be noticeable reduced. Calculations based on the NEDC indicate significant fuel savings for a mid-class car. Because of the non-existing mechanical coupling, cylinder cut-off can be realized very easily reducing the consumption of high power cars especially in urban drive cycles.The components linear generator and the gas spring have been built up and tested successfully. Examinations of the combustion process have begun on a fully variable electromagnetic valve-train test stand. A sophisticated adaptive control scheme is presented providing solid controls for the free-piston system. The paper describes the current status of the hardware development.

A Robust Generator–Harvester for Independent Sensor Systems

“…This mechanism, relative to a rotary engine with a crank mechanism, has only one or two pistons connected on a common shaft [26] and features precisely the controlled detonation and dynamics of the moving mass. A linear motor with free pistons uses the motion of a common shaft, on which a linear electric generator is mounted [40], or, alternatively, a hydraulic piston mounted on a common shaft is employed to generate hydraulic pressure by moving the piston. Only a limited number of authors [41] have hitherto simulated a setup to control a motor with a hydraulic pump.…”

Recent progress on performance and control of linear engine generator

“…In DLR, flat wires were used to obtain high space utilisation and good thermal conductivity, and this technology reduced the machine size by 33%. 99,114 An axial iron laminated along the circumferential direction for low eddy current loss was used. To reduce the mover mass, the mover was restricted to effective length only; therefore, the actual stator length was the total of the effective and stroke length of the mover, as shown in Figure 8(a).…”

“…This was achieved using the closed-loop control strategy for motoring and generating modes and improving the engine start-up and stable operation while decreasing the cycle-to-cycle variations. Graef et al 99 proposed a piston motion control strategy, where the piston position determines the valve, fuel injection and ignition timing and Ngwaka et al 50 used a similar approach of predefined piston positioning to achieve piston control and optimal valve and ignition timing for two and four strokes hydrogen-fuelled FP-LEG testing. A sinusoidal profile was used in the piston motion pre-set trajectory.…”

Design of a Linear Synchronous Generator and Examination of the Driving Range for a Free-Piston Engine Linear Generator System

“…Subsequently, the process of the design is as the follow. [1] Selection of the external dimensions of the LSG from the target of the output. [2] Selection of the pole pitch, number of poles, and slot combination.…”

“…However, environmental problems including air pollution and global warming that are caused by automotive vehicles continues to pose serious issues-although reduced by the increase of hybrid electrical vehicles (HEVs) are still serious. To solve this environmental issue, it is essential to develop a new power train and HEV system to improve the overall efficiency of automobiles (1)- (4) . Therefore, this study proposes an FPEG system.…”