The control of a free-piston engine generator. Part 1: Fundamental analyses

Mikalsen, R.; Roskilly, Anthony Paul

doi:10.1016/j.apenergy.2009.06.036

Cited by 151 publications

(59 citation statements)

References 10 publications

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“…To start the free piston engine, electrical power is supplied to the linear electric machine to drive the translator oscillate, operating the linear electric machine as a motor. 3,9,10 In most cases, however, the drive force is not big enough to start free piston engine in one stroke. Then, an oscillation starting approach is proposed, which has been accepted in most FPLA concepts currently.…”

Section: Introductionmentioning

confidence: 99%

“…1,2 The free piston engine can optimize the combustion process with the advantage of the variable compression ratio, leading to higher part-load efficiency and possible multi-fuel operation. 1,3 Since the linear package contains fewer moving parts compared with conventional crankshaft machine, the FPLA has the advantages including lower friction loss, higher reliability, lower cost, and more durability. [4][5][6][7] It is a simpler and more efficient energy conversion device compared with the conventional crankshaft internal combustion engine.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Parameters matching requirements for diesel free piston linear alternator start-up

Zuo

Feng

et al. 2015

Advances in Mechanical Engineering

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It is important to identify the relationship between the starting requirements and the structure parameters of the diesel free piston linear alternator on the structural design stage. In this article, the forces applied on the moving part during the starting process are analyzed, and an oscillation model is established. The numerical simulation results of the oscillation model are presented, and the energy-transfer mechanism is analyzed. Then, the oscillation model is simplified by utilizing the energy balance theory. Expressions of the achieved starting frequency and required starting force are derived and the effects of different design variables on them are investigated. The results show that the achieved compression ratio is determined by the energy balance between the friction consumption and the energy supplied by the starting force. The starting frequency achieved and starting force required are associated with the cylinder bore, the moving mass, and effective stroke of the engine, which can be applied to the matching design and optimization of the prototype.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Parameters matching requirements for diesel free piston linear alternator start-up

Zuo

Feng

et al. 2015

Advances in Mechanical Engineering

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“…The combustion fluctuation results in the variation of the expansion force, and hence leads to cycle-to-cycle variations of the motion states of the free-piston. Once the piston cannot reach the top dead center (TDC) position, the combustion of the following cycles will be insufficient, which will thereby cause unstable operation [6]. The proposed decoupling design process can be divided into three phases:…”

Section: Introductionmentioning

confidence: 99%

Decoupling Design and Verification of a Free-Piston Linear Generator

et al. 2016

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This paper proposes a decoupling design approach for a free-piston linear generator (FPLG) constituted of three key components, including a combustion chamber, a linear generator and a gas spring serving as rebounding device. The approach is based on the distribution of the system power and efficiency, which provides a theoretical design method from the viewpoint of the overall power and efficiency demands. The energy flow and conversion processes of the FPLG are analyzed, and the power and efficiency demands of the thermal-mechanical and mechanical-electrical energy conversion are confirmed. The energy and efficiency distributions of the expansion and compression strokes within a single stable operation cycle are analyzed and determined. Detailed design methodologies of crucial geometric dimensions and operational parameters of each key component are described. The feasibility of the proposed decoupling design approach is validated through several design examples with different output power.

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“…With the benefits of simple structure and easy realization, currentstroke and current-voltage double closed-loop control strategies [19][20][21][22] are employed in traditional free-piston power generating system, which ignored the d-q axis current coupling problem. Current feedback decoupling control strategy is investigated to realize the d-q axis current full coupling of motor control system.…”

Section: Introductionmentioning

confidence: 99%

Research on Control Strategy of Free-Piston Stirling Power Generating System

et al. 2017

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Abstract:As a clean and fuel adaptive alternative power plant, the Stirling power generating system has drawn attention of experts and scholars in the energy field. In practical application, the instability of free-piston Stirling power generating system caused by abrupt load change is an inevitable problem. Thus, methods to improve the output frequency response and stability of the free-piston Stirling power generating system are necessary. The model of free-piston Stirling power generating system is built by isothermal analysis firstly, and the initial control strategy based on given voltage system is put forward. To further improve the performance of power system, a current feedback decoupling control strategy is proposed, and the mathematical model is established. The influence of full decoupled quadrature-direct (d-q) axis currents is analyzed with respect to the output voltage adjusting time and fluctuation amplitude under the variations of piston displacement and output load. The simulation results show that the system performance is significantly improved, but the dynamic regulation lags caused by the decoupled current control still exist. To solve this problem and improve the performance of decoupled-state feedback current control that relies on parameter accuracy, internal model control based on sliding mode (IMC-SM) current decoupling control strategy is proposed, the system model is established, and then the performance of voltage ripple in generating mode is improved. Finally, the test bench is built, and the steady state and transient voltage control performances are tested. The feasibility and priority of the control strategy is verified by experiment and simulation results.

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The control of a free-piston engine generator. Part 1: Fundamental analyses

Cited by 151 publications

References 10 publications

Parameters matching requirements for diesel free piston linear alternator start-up

Parameters matching requirements for diesel free piston linear alternator start-up

Decoupling Design and Verification of a Free-Piston Linear Generator

Research on Control Strategy of Free-Piston Stirling Power Generating System

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