This content is not included in your SAE MOBILUS subscription, or you are not logged in.
The Free Piston Linear Generator - Development of an Innovative, Compact, Highly Efficient Range-Extender Module
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 08, 2013 by SAE International in United States
Annotation ability available
The present paper introduces the Free Piston Linear Generator (FPLG) - a compact electricity generation unit, which is being developed at the German Aerospace Center (DLR). It is designed as a free-piston combustion engine with integrated linear generator. This combination allows for highly efficient conversion of the chemical energy stored in a fuel to electrical energy.
By combining a two stroke combustion chamber, a linear alternator and an adjustable gas spring the engine design results in a compact package. In comparison to conventional combustion engines, additional degrees of freedom are available for controlling the combustion process. In this context efficiency advantages are expected due to the missing mechanical link to a crank which leads to flexibility in terms of stroke and compression ratio.
Applied as a range-extender-unit, the system provides additional electric energy to electric vehicles in case of discharged batteries. In addition to this automotive application, the FPLG can be used as an auxiliary power unit for example in aircrafts as well as in decentralized combined heat and power plants (CHP).
A step-by-step development strategy leading to the first overall FPLG system has been pursued. In the past years, the DLR has developed and experimentally verified several demonstrator prototypes for all necessary subsystems. Development systems comprising of several of the subsystems and (in some cases) of an auxiliary hydraulic actuator have been investigated.
Free piston specific challenges have to be addressed, e.g. increased requirements concerning steadiness of the combustion process. In addition to the hardware development, active control of piston motion is a major technological challenge. Model based algorithms for this purpose have been developed and implemented on a real time system. Applied to one of the development systems, their performance is evaluated in experiments.
CitationKock, F., Haag, J., and Friedrich, H., "The Free Piston Linear Generator - Development of an Innovative, Compact, Highly Efficient Range-Extender Module," SAE Technical Paper 2013-01-1727, 2013, https://doi.org/10.4271/2013-01-1727.
- German Federal Government's National Electromobility Development Plan, Press Release Federal Ministry of Economics and Technology
- Pohl , S.-E. , Gräf , M. Dynamic Simulation of a Free-Piston Linear Alternator in Modelica Proceedings of the 4 th international Modelica Conference 2005
- Pohl , S.-E. Der Freikolbenlineargenerator - Theoretische Betrachtungen des Gesamtsystems und experimentelle Untersuchungen zum Teilsystem der Gasfeder PhD Thesis Hamburg, Germany 2007
- Kock , F. , Ferrari , C. Flatness-Based High Frequency Control of a Hydraulic Actuator Journal of Dynamic Systems, Measurement, and Control March 2012 134
- Rinderknecht , F. The linear generator as integral component of an energy converter for electric vehicles European All-Wheel Drive Congress Graz 2011
- Rinderknecht , F. , Herzog , H.-G. Adaptation and optimization of a linear generator for a hybrid vehicle concept Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition 2010 Shenzhen China
- Rinderknecht , F. Entwicklung und Untersuchung eines Lineargenerators für ein Hybridfahrzeug PhD Thesis Technical University of Munich 2012
- Haag , J. , Ferrari , C. , Starcke , J. , Stöhr , M. et al. Numerical and Experimental Investigation of In-Cylinder Flow in a Loop-Scavenged Two-Stroke Free Piston Engine SAE Technical Paper 2012-32-0114 2012 10.4271/2012-32-0114
- Lindgarde , O. Method and System for Controlling a Free-Piston Energy Converter Patent, US 7,721,686 B2 2010
- Dunne , J. F. Dynamic Modelling and Control of Semifree-Piston Motion in a Rotary Diesel Generator Concept Journal of Dynamic Systems, Measurement and Control 2010
- Aichlmayr , H. T. Design Considerations, Modeling, and Analysis of Micro-Homogeneous Charge Compression Ignition Combustion Free Piston Engines PhD Thesis University of Minnesota
- Carter , D. and Wechner , E. The Free Piston Power Pack: Sustainable Power for Hybrid Electric Vehicles SAE Technical Paper 2003-01-3277 2003 10.4271/2003-01-3277
- Wang , J. Howe , D. A linear permanent magnet generator for a free-piston energy converter 2005 IEEE International Electric Machines and Drives Conference (IEMDC)
- Atkinson , C. , Petreanu , S. , Clark , N. , Atkinson , R. et al. Numerical Simulation of a Two-Stroke Linear Engine-Alternator Combination SAE Technical Paper 1999-01-0921 1999 10.4271/1999-01-0921
- Ferrari , C. Entwicklung und Untersuchung eines Freikolbenlineargeneratorsystems unter besonderer Berücksichtigung des verbrennungsmotorischen Teilsystems mit Hilfe eines neuartigen vollvariablen Prüfstands PhD Thesis Stuttgart, Germany 2012