To address the narrow high-efficiency operating region and large efficiency fluctuation of underwater wireless power transfer(UWPT)systems under docking errors and ocean-current disturbances

a robust misalignment-tolerant array-type magnetic coupling mechanism based on bidirectional transmitter-receiver coupling-gradient compensation was proposed. According to the mapping relationship between the coupling coefficient and power transfer efficiency

a three-dimensional quantitative evaluation framework was established

consisting of the high-coupling-area coverage rate

coupling coefficient of variation

and efficiency coefficient of variation. On this basis

a double-layer staggered square transmitter array and an axially overlapped dual-receiver coil structure were designed

and the coupling and power transfer performances under hybrid lateral-rotational misalignment were verified through simulations and experiments. The results show that

at a transmission distance of 50 mm

the high-coupling-area coverage rate of the double-layer square transmitter array reaches 86.4%. After adopting the dual-receiver structure

the high-coupling-area coverage rate is increased to 100%

while the coupling coefficient of variation is reduced to 26.7%. At a rated power of 300 W

the power transfer efficiency remains above 87.3% over the tested misalignment range

and the efficiency coefficient of variation does not exceed 1.2%. The proposed method can significantly improve the positioning tolerance and power transfer stability of UWPT systems

and provides a design basis for efficient and reliable power supply for autonomous underwater equipment.