Abstract A method for calculating the mutual inductance of circular coils with parallel axes is presented by using the modified Bessel and modified Struve functions, which is obtained by the expansion expressions of the reciprocal distance in the cylindrical coordinates. The obtained expressions are further coped with the asymptotic expansions to facilitate the numerical calculations. The monotonicity of the modified Bessel and Struve functions is beneficial to the numerical evaluations of the improper integral, especially in the case of short thick coils or disk coils with large radial distance and small axial distance. The proposed method is several tens to hundreds times faster than the existing method using the oscillatory Bessel and Struve functions, with the same accuracy. Additionally, a closed-form solution of the mutual inductance for coplanar circular loops is given using the Gauss hypergeometric functions, and it is verified by numerical calculations.
Luo Yao. New Approach for the Mutual Inductance Calculations of the Circular Coils with Parallel Axes[J]. Transactions of China Electrotechnical Society, 2016, 31(2): 31-37.
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