Autonomous underwater vehicles (AUVs) are increasingly used for undersea exploration. The endurance of AUVs is limited by the onboard energy storage among which the battery systems dominate. Various underwater recharging methods are employed to increase the AUV range and autonomy. Currently, contact-based underwater recharging utilizes the wet-mate connector technology that requires a high-precision AUV docking, and is prone to electrical safety issues. To overcome these limitations, underwater wireless recharging techniques for AUVs have been explored in recent years. Wireless charging offers a safe and reliable method for autonomous power transfer between a charging station and a vehicle. This article reviews the state-of-the-art inductive wireless power transfer (IWPT) solutions for underwater applications and discusses the engineering challenges of the IWPT system design. Underwater environmental factors, such as seawater conductivity, temperature, pressure, water currents, and biofouling phenomenon, impose constraints on IWPT systems. A comprehensive review of AUV energy storage systems, docking methods, IWPT system control methods, and compensation networks is presented in this article. Based on the main operational and constructional principles, the AUV IWPT systems are categorized as loosely coupled transformers and resonant IWPT systems. Each of the categories is illustrated through their main design principles and implementations reported in the literature so far. Technical challenges, such as integration of IWPT system into an AUV hull, interoperability, alignment and retention issues, docking station sinking and stability, the design of pressure-tolerant charging electronics, data transfer, and the battery operation in the underwater environment are discussed in this article too. The article is concluded with the best practice overview of designing an IWPT system for AUVs.

中文翻译：

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自主水下航行器无线充电系统回顾

自主水下航行器 (AUV) 越来越多地用于海底勘探。AUV 的续航能力受到机载能量存储的限制，其中电池系统占主导地位。采用各种水下充电方法来增加 AUV 的航程和自主性。目前，接触式水下充电采用湿式连接器技术，需要高精度AUV对接，容易出现电气安全问题。为了克服这些限制，近年来已经探索了 AUV 的水下无线充电技术。无线充电为充电站和车辆之间的自主电力传输提供了一种安全可靠的方法。本文回顾了最先进的用于水下应用的感应式无线电力传输 (IWPT) 解决方案，并讨论了 IWPT 系统设计的工程挑战。海水电导率、温度、压力、水流和生物污垢现象等水下环境因素对 IWPT 系统施加了限制。本文全面回顾了 AUV 能量存储系统、对接方法、IWPT 系统控制方法和补偿网络。根据主要的操作和结构原理，AUV IWPT 系统分为松耦合变压器和谐振 IWPT 系统。每个类别都通过迄今为止文献中报道的主要设计原则和实现来说明。技术挑战，诸如将 IWPT 系统集成到 AUV 船体中、互操作性、对齐和保持问题、坞站下沉和稳定性、耐压充电电子设备的设计、数据传输和水下环境中的电池操作等，本文也讨论了. 本文最后总结了为 AUV 设计 IWPT 系统的最佳实践概述。