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Abstract

The mutual inductance and the coupling coefficient for a couple of coils are usually described by simple parameters M and K respectively, instead of M₁₂, M₂₁ and k₁₂ and k₂₁. Many electric circuits theory books present at least a chapter about mutual inductance, in which a proof of M₁₂ = M₂₁ = M is usually described. Since most applications of M aim to transfer energy between coils, a coupling coefficient K is usually assumed without the rigorous analysis of k₁₂ and k₂₁. This paper presents an analysis of the mutual inductance between two coupled coils based on the linear magnetic circuit theory and a theoretical proof that it is not necessarily the case that k₁₂ = k₂₁ as many books assume. Finally, a practical experiment is presented to confirm the theoretical analysis.

Keywords

coupling coefficient magnetic circuits mutual inductance

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