Abstract

Subject of the present work is the study, optimization, simulation and construction of a small axial flux coreless generator with permanent magnets for grid connected wind energy applications. An introduction is made on the principles of appropriate technology applications while also presenting the basic concepts of aerodynamics and turbine orientation that will be used.

The complete sizing process of a 3kW generator is presented, including the determination of the nominal operating conditions and the total set of dimensions of the generator. The dimensions of the coils and of the magnets are determined, as well as the total weight and cost of the generator.

According to the previous approach the design is optimized. The pole arc to pole pitch ratio and the ratio of the internal to the external diameter are optimized for lowest cost. Further more the factors of frequency and magnet thickness are examined. The optimized design is simulated and constructed. The generator is tested in the laboratory and the resulting measurements are compared to the simulation results.

Further on, the DC coupling of a similar locally manufactured small wind turbine is examined. Initially, the direct coupling of an 850W small wind turbine to batteries is simulated, and in continuation a series inductance is added for the improvement of the annual energy yield. The above arrangements are tested and measured in the laboratory and the results are compared with those of the simulation.

Finally, conclusions are drawn and proposals for improvements and further work are presented.

Keywords: appropriate technology, low cost, rural electrification, axial flux generators, permanent magnets, optimization, microgrids, AC coupling, DC coupling, direct battery connection, inductance connection, energy output enhancement.

Author: Giorgis Messinis / gmessinis@power.ece.ntua.gr

Responsible PhD: Kostas Latoufis / latoufis@power.ece.ntua.gr

Supervising Professor: Nikos Hatziargyriou / nh@power.ece.ntua.gr

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