Unified Model and Transition Phenomenon of AC Copper Loss Considering Temperature and Frequency

The existing methods of alternating Current(AC) copper loss primarily focus on analyzing the influence of either frequency or temperature on loss. The variation of copper loss under the coupled effects of temperature and frequency has not been studied. To address this issue, a unified model of AC copper loss considering temperature and frequency is proposed. The transition phenomenon of AC copper loss is discovered during the derivation process of the unified model. As the temperature increases, the direct current(DC) copper loss rises while the skin effect is suppressed. The combined influence of these factors leads to a nonlinear transition phenomenon in AC copper loss. Take a single-phase transformer as an example, a three dimensional finite element model(3D FEM) is established to better simulate the actual winding paths. Subsequently, an experimental platform is constructed, and experimental is conducted for both square and circular winding. Then, the accuracy of the unified model is validated through 3D FEM and experimental, with an error of less than 10.6%. Meanwhile, the transition phenomenon in AC copper loss is observed during both the finite element and experimental. The unified model provides a novel approach for power evaluation of high density electromagnetic components. And the transition phenomenon of AC copper loss offers new ideas for selecting optimal operating points.