Parametric analysis of axial flux wind generators focused on total harmonic distortion evaluation

A parametric analysis of axial flux disc machines (AFDMs) is performed in order to evaluate the total harmonic distortion (THD) of output voltage depending on the shape and size of permanent magnets. In renewable energy applications of AFDM (wind generators), THD is an important issue and the proposed simulation model can be used to predict the THD of the output voltage of a machine on the basis of key parameters. A simplified but reasonably accurate mathematical model has been developed to determine the equivalent circuit parameters of AFDMs of whatever configuration. The analytical model, validated by means of FEM and experimental data, allows extremely fast (almost instantaneous) calculations with an accuracy comparable with that of much slower and complex methods. Parametric analyses have been performed on an AFDM-12 - a machine with a stator and two rotors, and one coil per pole and per phase - with different shapes and sizes of permanent magnets. The harmonic content and THD of each configuration (with trapezoidal, triangular, rectangular and circular magnets) have been calculated and compared.