Residual Flux Density Measurement Method for Transformer Core Considering Relative Differential Permeability

摘要

The residual flux measurement is one of the difficulties in the transformer research field. This article presents a residual flux density ( ${B} _{mathrm {r}}$ ) measurement method considering the relative differential permeability ( $mu _{mathrm {rd}}$ ) of the core material. First, the basic relationship between $mu _{mathrm {rd}}$ and ${B} _{mathrm {r}}$ is analyzed on the basis of the magnetic domain theory. Then, combining the experimentally measured relationship between ${B} _{mathrm {r}}$ and $mu _{mathrm {rd}}$ , using $mu _{mathrm {rd}}$ as an intermediate variable, the relationship between ${B} _{mathrm {r}}$ and time constant is derived. Furthermore, a square iron core model is established by the finite-element method, and the empirical formula for calculating ${B} _{mathrm {r}}$ is was fit. Finally, the feasibility of this method and the accuracy of the proposed empirical formula are verified through experiments.