A Method to Reduce Eddy Current Loss of Underwater Wireless Power Transmission by Current Control

In recent years, wireless power transmission (WPT) technology based on magnetic resonance has been extensively studied. However, in contrast to that in the air, wireless power transmission in seawater medium will be accompanied by inevitable energy loss, that is, eddy current loss (ECL), which will increase with the frequency and coil current. In this article, an equivalent circuit model of the eddy current loss of underwater wireless power transmission is established, two methods to reduce the eddy current loss are proposed, and the optimal modulus ratio for the coil current of the dual-coil wireless power transmission system to reduce eddy current loss is calculated. Electromagnetic field (EMF) simulation software verifies the correctness of the two methods, and it is concluded that increasing the phase difference of the coil current or controlling the coil current ratio to ensure that the optimal modulus ratio is in a certain range can reduce the eddy current loss effectively and improve the energy transmission efficiency of the system by about 4~5%.