电流比较仪多层小气隙磁屏蔽磁场的解析解

发布时间：2018-04-06 07:01

本文选题：电流比较仪　切入点：磁屏蔽　出处：《电工技术学报》2017年21期

【摘要】：磁屏蔽磁场的分析是实现高精度电流比较仪优化设计的关键,然而磁屏蔽气隙结构复杂,有限元法计算量大、计算精度难以满足要求。考虑磁屏蔽分层结构以及一次电流偏心和外部磁场干扰对磁场分布的影响,提出一个二维简化模型,利用极坐标系下Poisson方程解的正交函数展开式推导磁场的解析解,并利用有限元法验证解析解的正确性。通过二维解析模型与三维实际问题有限元计算结果的对比,发现两者具有简单的比例关系,且该比例关系不依赖于干扰源的位置,因此可用二维解析模型对三维实际磁屏蔽结构做出快速有效的评估。对坡莫合金的B-H曲线进行拟合,以线性近似下的磁场解析解为基础,利用安匝平衡时检测线圈的感应电压导出电流检测的误差估算公式,作为磁屏蔽效能分析的定量指标。对不同磁屏蔽结构的分析表明,双层结构比同样尺寸单层结构的屏蔽效能可提高近三个数量级。最后通过实验验证了解析表达式分析实际问题的有效性。
[Abstract]:The analysis of magnetic shielding magnetic field is the key to the optimization design of high precision current comparator. However, the structure of magnetic shielding air gap is complex, and the calculation cost of finite element method is large, so the calculation precision is difficult to meet the requirements.Considering the influence of the layered structure of magnetic shielding, the eccentricity of primary current and the interference of external magnetic field on the magnetic field distribution, a two-dimensional simplified model is proposed. The analytical solution of the magnetic field is derived by using the orthogonal function expansion of the solution of the Poisson equation in polar coordinate system.The correctness of the analytical solution is verified by finite element method.By comparing the results of the two-dimensional analytical model with the finite element method of three-dimensional practical problems, it is found that the two models have a simple proportional relationship, which does not depend on the location of the interference source.Therefore, a two-dimensional analytical model can be used to evaluate the real three-dimensional magnetic shielding structure quickly and effectively.The B-H curve of permalloy is fitted. Based on the analytical solution of magnetic field under linear approximation, the error estimation formula of current detection is derived from the inductive voltage of the detecting coil when the ampere-turn balance is used as a quantitative index for the analysis of magnetic shielding effectiveness.The analysis of different magnetic shielding structures shows that the shielding efficiency of double-layer structures is nearly three orders of magnitude higher than that of single-layer structures of the same size.Finally, the effectiveness of analytical expression analysis is verified by experiments.
【作者单位】：强电磁工程与新技术国家重点实验室(华中科技大学);中国电力科学研究院;
【基金】：国家电网公司纵向科技项目(JL-71-15-048) 湖北省非动力核技术协同创新中心资助
【分类号】：TM933.113

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