Analysis of Eddy Current Losses in Wirelessly Charged Implantable Devices

The wireless power transfer (WPT) technique is extensively utilized for charging implantable medical devices. However, the presence of eddy currents in the metal casing significantly compromises power transfer performance, resulting in reduced efficiency and potential safety concerns for patients. To address this issue, a decoupled eddy current loss (ECL) model is derived, demonstrating that in a fully compensated WPT system, the total ECL is equivalent to the sum of the ECL contributions caused by the currents in each individual coil. Based on this principle, this paper proposes a decoupled measurement method to achieve a more accurate determination of ECL. Simulation and experimental results, conducted on a representative implantable device, validate the effectiveness of the proposed method and its potential to mitigate ECL.