Power Transfer Capacity Improvement of AUV IPT Systems via Impedance Transformation

Autonomous underwater vehicles (AUVs) are extensively utilized for underwater resource exploration, requiring inductive power transfer (IPT) systems with large output power to achieve quick charging. However, underwater positioning errors result in significant variations in the coupling coefficient of the IPT system. Moreover, AUVs employ diverse battery types and voltages, exacerbating the issue of decreased transferred power when the coupling coefficient and battery voltage are low, thereby prolonging the AUVs' charging time. To address this challenge, this paper proposes an impedance transformation method based on a π-network to improve power transfer capacity, which can also enhance the system efficiency under low battery voltage conditions. Firstly, the paper presents the proposed topology and analyzes its characteristics. Subsequently, the eddy current losses (ECL), zero-voltage switching (ZVS) condition, the parameters design of the π-network, and the power losses of the system are derived.Finally, a 5-kW prototype with a maximum DC-DC efficiency of 93.1% is built to validate the effectiveness of the proposed topology.