On Design and Analysis of a Novel Transverse Flux Generator for Direct-driven Wind Application

This thesis deals with the analysis of a permanent magnet synchronous generator suited for direct-drivenwind turbines inmegawatt class. The higher specific torque and power density of a transverse flux permanent magnet machine in comparison to conventional radial-flux machines make it a promising solution for direct-driven wind turbine generators. The novel transverse flux generator investigated in this work would allow a better utilization of the available nacelle space due to its more compact construction. The major part of the thesis deals with the finite element analysis and analytical calculations of transverse flux generators. The computations are performed for single units of the basic transverse flux topology (BTFM) and the one utilizing iron bridges (IBTFM). As the selection of the pole length in a transverse flux machine affects the pole-to-pole flux leakage and thus its performance, the topologies have been analyzed with respect to the varying dimensions in the direction of movement. The topologies utilizing IBTFM have been found to be superior to the BTFM with respect to the flux linkage (by 110%) and utilization of the magnets (by 84%). The machines with longest magnets gave the largest flux linkage, while machines with short magnets should be preferred for better magnet utilization. The four sets of dimensions have been selected for a dynamic finite element analysis. The power factor is evaluated for the topologies with the varying dimensions in the peripheral plane in static finite element analysis. The performance of the topologies with the best power factor in the studied range (0.62 in the BTFM and 0.57 in the IBTFM), as well as the topologies that give the highest power factor to magnet volume ratio, is compared with the dynamic simulations.The electromagnetic and cogging forces of the transverse-flux generator are estimated. The IBTFM is superior to the BTFM with respect to the force production, where the three-phase electromagnetic force is twice as large as in the BTFM. The force ripples of the three-phase electromagnetic force are found to be insignificant in both topologies. An analytical procedure based on the results from the finite element simulations is applied for evaluation of the transverse flux generators with different shapes and topologies. The effectiveness of each topology is investigated based on the estimation of the torque production in a certain nacelle volume. A toroidal generator with the iron-bridge topology is the most compact alternativefor a wind turbine as it has the highest torque-per-volume ratio. Furthermore, the analyticalmodel, including evaluation of the synchronous inductance, is developed and compared with the results obtained in the threedimensional finite element analysis. Themodel provides a good agreement for the studied set of dimensions.

[1]  J. Soulard,et al.  Transverse Flux Machines for Sustainable Development - Road Transportation and Power Generation , 2007, 2007 7th International Conference on Power Electronics and Drive Systems.

[2]  Maxime R. Dubois,et al.  A new design method for the clawpole transverse flux machine. Application to the machine no-load flux optimization. Part II: Optimization aspects , 2010, The XIX International Conference on Electrical Machines - ICEM 2010.

[3]  J. Davenport.  Editor , 1960 .

[4]  H. R. Bolton,et al.  Linear motors with transverse flux , 1971 .

[5]  Chandur Sadarangani.  Transverse flux linear machine with a tubular translator construction , 2006 .

[6]  S. M. Abu Sharkh,et al.  The problem of power factor in VRPM (transverse-flux) machines , 1997 .

[7]  G. Henneberger,et al.  Development of a new transverse flux motor , 1997 .

[8]  D. H. Kang,et al.  Analysis and optimal design of transverse flux linear motor with PM excitation for railway traction , 2003 .

[9]  T.A. Lipo,et al.  TORUS concept machines: pre-prototyping design assessment for two major topologies , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[10]  Anders Grauers,et al.  Design of Direct-driven Permanent-magnet Generators for Wind Turbines , 1996 .

[11]  Alija Cosic,et al.  Analysis of a novel Transversal Flux Machine with a tubular cross-section for Free Piston Energy Converter application , 2010 .

[12]  Henk Polinder,et al.  Basic Operation Principles and Electrical Conversion Systems of Wind Turbines , 2005 .

[13]  Thomas Ackermann,et al.  Wind Power in Power Systems , 2005 .

[14]  Vaclav Smil,et al.  Energy at the Crossroads: Global Perspectives and Uncertainties , 2005 .

[15]  Yung-Kang Robert Chin.  A Permanent Magnet Traction Motor for Electric Forklifts : Design and Iron Loss Analysis with Experimental Verifications , 2006 .

[16]  E. Spooner,et al.  TORUS' : a slotless, toroidal-stator, permanent-magnet generator , 1992 .

[17]  Jacek F. Gieras,et al.  Axial Flux Permanent Magnet Brushless Machines , 2005 .

[18]  Hans-Peter Nee,et al.  Design Steps towards a High Power Factor Transverse Flux Machine , 2001 .

[19]  Maxime R. Dubois,et al.  A new design method for the clawpole transverse flux machine. Application to the machine no-load flux optimization. Part I: Accurate magnetic model with error compensation , 2010, The XIX International Conference on Electrical Machines - ICEM 2010.

[20]  Peethamparam Anpalahan.  Design of transverse flux machines using analytical calculationsafinite element Analysis , 2001 .

[21]  Hans Schütz.  Transverse flux machines , 2010 .

[22]  Samir Kouro,et al.  Unidimensional Modulation Technique for Cascaded Multilevel Converters , 2009, IEEE Transactions on Industrial Electronics.

[23]  Thomas M. Jahns,et al.  Pulsating torque minimization techniques for permanent magnet AC motor drives-a review , 1996, IEEE Trans. Ind. Electron..

[24]  H. Weh.  New Permanent Magnet Excited Synchronous Machine with High Efficiency at Low Speeds , 1988 .

[25]  Freddy Magnussen.  On design and analysis of synchronous permanent magnet machines for field-weakening operation in hybrid electric vehicles , 2004 .

[26]  Juliette Soulard,et al.  Parametric study of a transverse flux wind generator at no-load using three-dimensional finite element analysis , 2009, 2009 International Conference on Electrical Machines and Systems.

[27]  Maxime R. Dubois,et al.  Optimized Permanent Magnet Generator Topologies for Direct-Drive Wind Turbines , 2004 .

[28]  Jacek F. Gieras,et al.  Permanent magnet motor technology : design and applications , 1996 .

[29]  Heyun Lin,et al.  Magnetic field analysis of a novel flux switching transverse flux permanent magnet wind generator with 3-D FEM , 2009, 2009 International Conference on Power Electronics and Drive Systems (PEDS).

[30]  H. Polinder,et al.  Comparison of direct-drive and geared generator concepts for wind turbines , 2005, IEEE International Conference on Electric Machines and Drives, 2005..

[31]  Dmitry Svechkarenko.  On analytical modeling and design of a novel transverse flux generator for offshore wind turbines , 2007 .

[32]  B. J. Chalmers,et al.  An axial-flux permanent-magnet generator for a gearless wind energy system , 1999 .

[33]  W. M. Arshad.  A Low-Leakage Linear Transverse-Flux Machine for a Free-Piston Generator , 2003 .

[34]  Design of the Zephyros Z 72 wind turbine with emphasis on the direct drive PM generator , 2004 .