Abstract
An improved axial-flux permanent-magnet (AFPM) generator has been built, as based on the ITDG/Piggott design for rural wind-electricity. The generator is characterized by electromechanical analysis, with parameters determined through curve fitting. The measured DC behaviour is explained by load-dependent rectifier transfer functions for voltage and current. Miscellaneous losses are parameterized in terms of a scaling law involving electrical load and shaft frequency. Two electrical configurations of the generator are characterized experimentally, i.e. (i) low-voltage star-parallel, and (ii) high-voltage star-series, with both ac and dc loads. Simulated system behaviour is determined by combining the electromechanical curves with the set of aerodynamic power curves obtained from modelling with blade element momentum theory. Using the blade geometry proposed by Piggott, the operational characteristics are satisfactory for charging 24 V batteries if the high-voltage configuration is used; i.e. no electronic load control is required. The complete wind system is an attractive low-cost method for remote wind-electric applications in low-speed (∼ 3 m/s) and medium-speed (∼ 5 m/s) wind sites.
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