Roll Offset and Battery SOC Identification in Wireless Power Transfer System of Underwater Vehicles

Limited by finite self-contained energy resources, underwater vehicles are restricted in working range, depth and duration. Wireless power transfer (WPT) technology provides an effective solution for this bottleneck problem, enabling in-situ and real-time underwater energy replenishment. Due to roll motion, roll offset between underwater vehicles and energy base station disturbs system parameters and decreases system efficiency seriously. As an important index in judging charging progress and monitoring health state, battery state of charge (SOC) is difficult to predicted owing to poor communication ability of the system. Effected by serious eddy current effect in seawater, defining roll offset and battery SOC is not precise using traditional methods. Thus, this study proposes a data-driven method to recognize roll offset and battery SOC in wireless power transfer system with an improved equivalent circuit model considering eddy current effect. Experimental results show that the proposed method achieves high accuracy with an average error of 10% in parameters identification.