Hashimoto Kazuki, Okuda Takafumi, Hikihara Takashi
Department of Electrical Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan.
Rev Sci Instrum. 2020 Apr 1;91(4):044703. doi: 10.1063/1.5123774.
An investigation of air-core toroidal transformers has been undertaken to enable power converters to achieve megahertz operation. The characteristics of the air-core toroidal transformer govern the behaviors of the internal magnetic flux of the transformer. Understanding the behaviors at an above-megahertz level is a key issue in the design of the air-core toroidal transformer. This paper discusses the internal magnetic flux density distribution in the air-core toroidal transformer under high-frequency excitation. We propose a measurement method for the distribution and show the obtained results under a sinusoidal excitation with an amplitude of 1.5 A and a frequency of 1 MHz. The results reveal a non-uniform distribution in the tangential and normal directions. The cause of this non-uniformity was found to be the structure of the air-core toroidal transformer. In addition, the validity of the proposed measurement method was confirmed by comparing the experimentally obtained results with a numerical estimation using the Biot-Savart law. These results suggest that the proposed measurement method is capable of investigating the distributed characteristics of air-core toroidal transformers under megahertz excitation.
已对空心环形变压器展开研究，以使功率转换器能够实现兆赫兹级运行。空心环形变压器的特性决定了变压器内部磁通量的行为。了解兆赫兹以上频率水平下的行为是空心环形变压器设计中的关键问题。本文讨论了高频激励下空心环形变压器内部磁通密度的分布情况。我们提出了一种针对该分布的测量方法，并展示了在幅度为1.5 A、频率为1 MHz的正弦激励下所获得的结果。结果揭示了切向和法向方向上的非均匀分布。发现这种非均匀性的原因是空心环形变压器的结构。此外，通过将实验获得的结果与使用毕奥 - 萨伐尔定律的数值估计进行比较，证实了所提出测量方法的有效性。这些结果表明，所提出的测量方法能够研究兆赫兹激励下空心环形变压器的分布特性。
