Decoupling Control Scheme Bridging Frequency Tracking and DC Output Stabilizing for Wireless Charging System of Autonomous Underwater Vehicles

In harsh marine environments, small variations in parameters of the underwater wireless charging system would lead to system detuning and dynamic fluctuation of DC output, thereby reducing power transfer efficiency and output performance. To achieve maximum efficiency tracking and DC output stabilizing, a decoupling control scheme bridging frequency tracking and DC output stabilizing for the wireless charging system of autonomous underwater vehicles (AUVs) is proposed. To be specific, the primary side of the wireless charging system adopts adaptive frequency tracking control (AFTC) to ensure that the operating frequency can always work near the resonant frequency during the charging process of the lithium battery. The secondary side adopts double closed-loop control of voltage and current based on buck converter such that the DC output can be stabilized for efficiently charging of lithium battery. Experimental results show that the proposed decoupling control scheme can realize frequency tracking on the primary side while the lithium battery can be charged with constant current and constant voltage, under maximum efficiency.