Analytical modeling of air-gap field distributions in permanent magnet embedded salient pole wind generator

A simple magnetic circuit method (MCM) is developed for analytical calculation of the air-gap magnetic flux density waveform of a permanent magnet embedded salient pole wind generator (PMESPWG), which can consider the saturation in the side frame and the upper core of its pole shoe. In the MCM, the magnetic circuit is divided into a series of sub-circuits according to the flux paths to cope with different lengths of air-gap and different saturation levels of the pole shoe upper core. In order to evaluate the validity of the proposed method, air-gap flux densities of a 3.3 MW machine prototype are calculated and validated by the finite-element method (FEM) results. By utilizing the developed MCM, the air-gap flux distribution of the PMESPWG is optimized to obtain the maximum fundamental and minimum total harmonic distortion.