Effects of Noncharacteristic Harmonics on AC Losses of High-Temperature Superconducting Coils

Superconductivity is a remarkable state of matter exhibited by some materials, which is characterized by the vanishing of electrical resistivity at cryogenic temperatures, among other phenomena. However, the prospective economical viability of superconducting devices relies heavily on an efficient cooling system to remove the heat generated during operation. Although this would be meaningless in conventional devices, it occurs at cryogenic temperatures, impacting the efficiency and cost of the whole system. Thus, it is necessary to predict the losses of, e.g., superconducting coils in power systems. This article presents a study of ac losses in superconducting coils due to noncharacteristic current harmonics. These harmonic components are typical in electromechanical drives like the one presented in this article. A computational model of high-temperature superconducting coils and the numerical procedure used to solve the problem are described in this article. The contribution of the noncharacteristic harmonic components in these ac losses will be presented. These results, obtained by computational analysis, were validated in experimental tests that assessed the power dissipated due to triangular waveforms currents.