直流偏磁下叠片铁心磁致伸缩的实验测试与分析

Experimental Tests and Analysis of Magnetostrictive Behaviors in Laminated Cores at the Presence of DC Bias

电工钢片磁致伸缩效应是引起变压器铁心振动,并产生噪声的主要原因之一,直流偏磁的存在加剧了铁心的磁致伸缩形变。基于爱泼斯坦方圈装置开发了电工钢片叠片结构磁致伸缩特性测量系统,测量并分析了取向电工钢片叠片结构在不同直流偏磁磁场、磁化角度及磁化强度下磁致伸缩主应变大小和方向的变化情况,对比分析了单片电工钢片与其叠片结构磁致伸缩特性的差异,讨论了直流偏磁磁场对叠片结构磁致伸缩特性的影响,并建立了材料磁致伸缩特性数据库。基于上述测量数据,计算了直流偏磁下单相变压器铁心模型的磁致伸缩应变,并与实测值进行了对比验证,为直流偏磁下变压器铁心振动噪声的研究奠定基础。

Magnetostrictive phenomenon in electrical steel sheets is one of main reasons bring about the vibration of transformer cores and corresponding noise, and the presence of DC bias makes the magnetostrictive deformation serious. In this paper, the magnetostrictive measurement system for laminated configuration of electrical steel was developed based on Epstein frame setup. The magnitude and direction of the principal strain of magnetostriction of laminated configurations of grain-oriented electrical steel was measured and analyzed when applying several DC bias values, magnetization magnitudes and magnetization angles. The difference of magnetostrictive strain between a single sheet and laminated configuration was compared, and the influences of DC bias magnetic field on the magnetostrictive properties in the laminated configuration were discussed. A magnetostrictive property database about the material was built. Based on the database, the magnetostrictive strain in a single-phase transformer core was computed and verified with the experimental data, which provides a basis for the further research on the vibration and noise of transformer cores under DC bias.