Abstract
This paper presents a comprehensive analytical model for dual rotor radial flux wind generators based on the equivalent magnetic circuit method. This model is developed to predict the flux densities of the inner and outer air gaps, flux densities of the rotor and stator yokes, back electromotive force (EMF), electromagnetic torque, cogging torque, and some other characteristics important for generator design. The 2D finite element method (FEM) is employed to verify the presented analytical model, fine-tune it, and validate the prediction precision. The results show that the errors between the proposed analytical model and the FEM results are less than 5% and even less than 1% for certain parameters, that is, the results obtained from the proposed analytical model match well the ones obtained from FEM analysis. Meanwhile, the working points at different temperatures are confirmed to exceed the knee point of the BH curve, which means that irreversible demagnetization does not occur. Finally, the optimization by FEM with the objective of fully using the inner space of the generator, decreasing the cogging torque, and reducing the total harmonic distortion (THD) of back EMF is performed.
Highlights
Wind power generation, as the most competitive and clean renewable energy technology, is attracting more and more attention all over the world
When using NdFeB magnets, the dual rotor permanent magnet (DRPM) machine can significantly improve the torque density and efficiency owing to the special structure of double rotors and dual air-gaps
A comprehensive analytical model for a dual rotor radial flux (DRRF) wind generator is developed based on equivalent magnetic circuit (EMC)
Summary
As the most competitive and clean renewable energy technology, is attracting more and more attention all over the world. When using NdFeB magnets, the dual rotor permanent magnet (DRPM) machine can significantly improve the torque density and efficiency owing to the special structure of double rotors and dual air-gaps. Dual rotor radial flux (DRRF) and dual rotor axial flux (DRAF) machines have similar torque density, torque-to-mass ratio, losses, and efficiency performance. This paper proposes a DRRF wind generator using ferrite magnets. Considering the fast performance of EMC and high accuracy of FEM, the analytical approach combining EMC and FEM should be a good compromise between simplicity and accuracy This approach is useful and effective in the preliminary design of an electrical machine. The elements of this analytical model are precisely calculated in cylindrical coordinates to achieve a high accuracy. The optimal split ratio of the inner and outer stator radius, the pole arc ratio of the inner and outer rotors, and the outer slot opening are determined
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