Magnetic energy losses of SiFe sheets are determined by the standardized methods of single sheet tester (SST) or Epstein tester (ET). According to IEC standards, the total power consumption is measured in Watt-metric ways, and the portion that concerns the homogeneously magnetized region(s) is estimated on a nominal value $l_{m}$ of the so-called conventional effective magnetic path length (PL). A clear definition of PL is lacking—a suggestion being provided here. Standards express $l_{m}$ through the dependence between the magnetic field strength $H$ and the magnetization current. However, they apply the same value $l_{m}$ also for the determination of losses $P$ . From the viewpoint of physics, two PL quantities $l_{m},_{H}$ and $l_{m},_{P}$ would be preferable. The problematic is enhanced by the fact that the flux distribution within the magnetic circuit of a tester may change dynamically during the period of time, with induction changes $B(t)$ . This means that the physical PL $L$ is a function of time, according to a PL function $L$ [ $B(t)$ ]. Finally, dynamic changes in flux distributions prove to be distinctly influenced by hysteretic mechanisms which means that $L$ [ $B(t)$ ] exhibits loop character. The resulting complexity indicates that the concept of PL is not promising, if high accuracy of testing is demanded. However, for purposes of material comparisons, optimum PL values $L_{\mathrm {OPT}}$ may be suitable that are determined for individual material families. Analyses of instantaneous loss power values $p(t)$ indicate that energy dissipation is weak during high induction. Thus, determinations of $L_{\mathrm {OPT}}$ should be focussed on moderate induction. The ET is characterized by strong modifications of 3-D flux distributions which means that individual values $L_{\mathrm {OPT}}$ would be needed. On the other hand, the SST shows a clear design. For moderate induction, some energy dissipation is expected to occur within the yoke region. This indicates that $L_{\mathrm {OPT}}$ exceeds the conventional value of 450 mm, in weak ways.

中文翻译：

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能量损耗测试仪磁路长度的物理评估

SiFe 片的磁能损失由单片测试仪 (SST) 或爱泼斯坦测试仪 (ET) 的标准化方法确定。根据 IEC 标准，总功耗以瓦特为单位测量，涉及均匀磁化区域的部分按标称值估算 $l_{m}$ 所谓的常规有效磁路长度 (PL)。PL 缺乏明确的定义——这里提供了一个建议。标准快递 $l_{m}$ 通过磁场强度之间的依赖关系 $H$ 和磁化电流。但是，它们应用相同的值 $l_{m}$ 也用于确定损失 $P$ . 从物理学的角度来看，两个 PL 量 $l_{m},_{H}$ 和 $l_{m},_{P}$ 会更可取。测试仪磁路内的磁通分布可能会在一段时间内动态变化，随着感应的变化，这个问题变得更加严重 $B(t)$ . 这意味着物理 PL $L$ 是时间的函数，根据 PL 函数 $L$ [ $B(t)$ ]。最后，通量分布的动态变化被证明明显受到滞后机制的影响，这意味着 $L$ [ $B(t)$ ] 表现出循环特征。由此产生的复杂性表明，如果需要高精度的测试，PL 的概念是没有前途的。然而，出于材料比较的目的，最佳 PL 值 $L_{\mathrm {OPT}}$ 可能适用于个别材料族。瞬时损耗功率值分析 $p(t)$ 表明在高感应期间能量耗散较弱。因此，确定 $L_{\mathrm {OPT}}$ 应注重适度诱导。ET 的特点是 3-D 通量分布的强烈修改，这意味着单个值 $L_{\mathrm {OPT}}$ 将需要。另一方面，SST 显示出清晰的设计。对于中等感应，预计在轭区域内会发生一些能量耗散。这表明 $L_{\mathrm {OPT}}$ 以微弱的方式超过了 450 毫米的常规值。