A relatively direct method is expounded in this paper to prove the termwise differentiation of power series, and a simple method is expressed to calculate the Fouriercoefficient.
This paper selects the algorithm by quantifying the amplitude of the transform domain coefficient and uses this algorithm in the discrete Fourier domain and the discrete cosine domain.
The Fourier analysis method is applied to decompose the air-gap magnetic density into the basic wave and a series of harmonic and wave shape eigen coefficient of air-gap magnetic field are calculated.