Research on the intermediate process of a free-piston linear generator from cold start-up to stable operation: Numerical model and experimental results

Feng, Huihua; Guo, Chendong; Jia, Boru; Zuo, Zhengxing; Guo, Yuyao; Roskilly, Anthony Paul

doi:10.1016/j.enconman.2016.05.068

Cited by 57 publications

(39 citation statements)

References 20 publications

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“…When the FPLG has two cylinders, the piston motion is mainly controlled by LEM during the starting process. Some studies focused on the starting process using position feedback or the constant-magnitude motoring force approach [37,[42][43][44][45]. In order to obtain a desired piston trajectory, the position error serves as a feedback variable to control the thrust force with appropriate value and direction [43].…”

Section: Atarting Methods Of Fplgsmentioning

confidence: 99%

A Review of the Design and Control of Free-Piston Linear Generator

et al. 2018

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The Free-piston linear generator (FPLG) is a novel energy converter which can generate electrical energy and is regarded as a potential technology for solving the restriction of the short driving range of electric vehicles. Getting rid of the crank and flywheel mechanism, FPLG obtains some advantages of a variable compression ratio, compact size, and highly-efficient power generation. Linear electric machine (LEM) design and piston motion control are two key technologies of FPLG. However, they are currently the main obstacles to the favorable performance of FPLG. LEM being used to drive the piston motion or generate electric energy is an integrated design including a motor/generator. Various types of LEMs are investigated, and suitable application scenarios based on advantages and disadvantages are discussed. The FPLG's controller is used to ensure stable operation and highly-efficient output. However, cycle-to-cycle variations of the combustion process and motor/generator switching make it difficult to improve the performance of the piston motion control. Comments on the advantages and disadvantages of different piston motion control methods are also given in this paper.The piston moves freely between TDC and bottom dead center (BDC), and its motion is determined by the resultant force that is acting upon it, including gas pressure force, electro-magnetic force, and rebound force [8][9][10]. The piston motion must be controlled by an electronic control system-an electronic crankshaft, which is an integrated control of combustion parameters or control variables of the LEM and rebound devices [5]. Moreover, there are cycle-to-cycle variations and periodic large disturbances during the combustion process. As a result, piston motion control is still the biggest challenge of FPLG [11]. Besides, LEM is not only used as a power output unit but also a control unit for adjusting the movement of the piston. For the FPLG, LEM requires high reliability, high precision, high efficiency, and so on. Various structures of LEM designed by many teams around the world have been investigated, but none of these meet all of the requirements due to the short stroke, high frequency, and high acceleration.In order to lucubrate the current existing problems, this paper reviews the key technologies of LEM design and FPLG motion control. Firstly, several basic structures of FPLG are introduced, and both their advantages and disadvantages are analyzed. Afterwards, according to the different types of structure, corresponding advantages and disadvantages of LEMs are presented. With respect to the existing LEMs, they are classified according to the different flux path and topology structures in the third section. Finally, different starting methods are introduced based on the FPLG's structure. In terms of power generation stage, piston motion control strategies are divided into three forms and introduced based on their control variables. They include three categories: active combustion parameters control, active LEM control, and the mixed cont...

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Section: Atarting Methods Of Fplgsmentioning

confidence: 99%

A Review of the Design and Control of Free-Piston Linear Generator

et al. 2018

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“…The free-piston diesel engine linear generator (FPDLG), as a novel energy conversion device, was researched, because of the background of low fuel consumption and stringent government emission legislation [1][2][3][4][5][6]. The FPDLG combines the free-piston diesel engines and the linear generator [7].…”

Section: Introductionmentioning

confidence: 99%

“…The FPDLG combines the free-piston diesel engines and the linear generator [7]. Its operation principle is that the high-temperature and high-pressure gas was produced after the heat-release process in the cylinder drives the mover (it combines the pistons and the generator moving magnet with connecting rod) to reciprocate, and the generator converts parts of the mover mechanical energy into electricity [2]. Without flywheel and crankshaft mechanism, so the FPDLG shows great differences with the conventional internal combustion engines (ICEs) in terms of the construction, operating performance, heatrelease char-acteristics, etc.…”

Section: Introductionmentioning

confidence: 99%

“…Zuo Zhengxing and Feng Huihua et al at Beijing Institute of Technology have designed two types of the FPLG, namely spark ignition FPLG and compression ignition FPLG [1,2,4,5,7]. They researched the operation characteristics and the control strategies of the FPLG by si-mulation results and experimental results [1,4]. According to the earlier results, it shown that because of the low running frequency of the FPLG, the two-stroke engine has poor ventilation quality, the prototype could not run continuously during the generating process.…”

Section: Introductionmentioning

confidence: 99%

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Effect of fuel injection characteristics on the performance of a free-piston diesel engine linear generator: CFD simulation and experimental results

Guo

Song

Feng

et al. 2018

Energy Conversion and Management

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“…Free-piston engine (FPE) technology is currently being explored by a number of research groups worldwide, including the authors' group [1][2][3][4][5][6][7][8]. A significant driving force is the automotive industry's increasing investment in hybrid-electric vehicle technology.…”

Section: Introductionmentioning

confidence: 99%

A Decoupled Design Parameter Analysis for Free-Piston Engine Generators

et al. 2017

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Abstract:The free-piston engine generator (FPEG) is a novel power generation device with an estimated brake efficiency (energy contained in the fuel that is transformed into useful work) of up to 46%, compared to the 25-35% reported in conventional reciprocating engines. This paper seeks to address a major challenge in the development of new and complex technologies-how do we effectively communicate and understand the influence of key design parameters on its operating performance? In this paper, the FPEG is described using a simple numerical model, a model which is reduced to a forced mass-spring vibration system under external excitation, enabling all the major input parameters to be decoupled. It proved that the engine piston position as a function of time and output power could be predicted directly from the input parameters with acceptable accuracy. The influence of the key FPEG design parameters on the piston oscillation characteristics and electric power output can be characterised with respect to one another and summarised. Key design parameters include piston mass, compression stroke length, piston cross sectional area, and electric load. Compared with previous and more complex numerical models, the presented methods can be used to simply describe the sensitivity of key design parameters on the FPEG performance. It will provide useful general guidance for the FPEG hardware design process.

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Research on the intermediate process of a free-piston linear generator from cold start-up to stable operation: Numerical model and experimental results

Cited by 57 publications

References 20 publications

A Review of the Design and Control of Free-Piston Linear Generator

A Review of the Design and Control of Free-Piston Linear Generator

Effect of fuel injection characteristics on the performance of a free-piston diesel engine linear generator: CFD simulation and experimental results

A Decoupled Design Parameter Analysis for Free-Piston Engine Generators

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