In high-temperature superconducting (HTS) power devices, the presence of iron cores changes the magnetic field profile around the HTS coil windings, potentially affecting their AC loss characteristics. AC loss measurements for HTS coil windings coupled with an iron core using the electrical method can lead to a significant error, owing to the indirect estimation of the iron core loss through using a copper test coil. To investigate the cause of the experimental error and the influence of an iron core on coil AC losses, transport AC losses of REBCO double pancake coil (DPC) assemblies coupled with an iron cylinder were measured. A 40-turn 1DPC and an 80-turn 2DPC assembly wound with 4 mm SuperPower wire were employed in the measurements. To ensure the same iron core loss using the HTS coil assembly and the copper coil, 2D finite element method simulations were conducted iteratively to design the iron core and the copper coil to get the same local magnetic field distributions in the designed iron core for the two cases. The main cause of the error is due to the difference in local magnetic flux densities in the iron core generated by the HTS coil assembly and the copper coil even when the ampere-turns of the coils are identical. We showed that the simulation-guided measurement method can assure accurate AC loss measurement in the HTS coil assemblies coupled with iron cores. Compared with the AC losses in the 1DPC and 2DPC coil assemblies without the iron cylinder, the presence of the iron cylinder significantly increases the coil losses. Frequency dependence is observed in the coil AC losses of the 1DPC and 2DPC assemblies when coupled with the iron cylinder. This is due to the eddy current induced in the iron cylinder generating a magnetic field, which influences the coil AC loss.

中文翻译：

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REBCO 线圈组件与铁筒耦合的交流损耗实验研究

在高温超导 (HTS) 功率器件中，铁芯的存在会改变 HTS 线圈绕组周围的磁场分布，从而可能影响其交流损耗特性。由于通过使用铜测试线圈间接估计铁芯损耗，因此使用电气方法测量与铁芯耦合的高温超导线圈绕组的交流损耗可能会导致显着误差。为了研究实验误差的原因以及铁芯对线圈交流损耗的影响，测量了与铁圆筒耦合的 REBCO 双扁平线圈 (DPC) 组件的传输交流损耗。测量中采用了用 4 mm SuperPower 线缠绕的 40 匝 1DPC 和 80 匝 2DPC 组件。为了确保使用高温超导线圈组件和铜线圈具有相同的铁芯损耗，迭代地进行二维有限元方法模拟来设计铁芯和铜线圈，以在设计的铁芯中获得相同的局部磁场分布。案例。造成误差的主要原因是，即使线圈的安匝数相同，高温超导线圈组件和铜线圈在铁芯中产生的局部磁通密度也存在差异。我们表明，仿真引导的测量方法可以确保与铁芯耦合的高温超导线圈组件中的交流损耗的精确测量。与没有铁筒的1DPC和2DPC线圈组件中的交流损耗相比，铁筒的存在显着增加了线圈损耗。当与铁圆筒耦合时，1DPC 和 2DPC 组件的线圈交流损耗与频率相关。这是由于铁筒内感应出的涡流产生磁场，影响线圈交流损耗。