Underwater low-power electromagnetic transducers with Central permanent magnet integration

High-efficiency electromagnetic transducers are crucial for enabling the self-sustained operation of underwater electromagnetic sound sources under power-constrained conditions as noted by Hao, Xie, and Ma [Proceedings of the 2019 Western China Acoustics Academic Conference, Guangzhou, China (November 5-9, 2019)]. This paper proposes a permanent magnet drive technology to enhance the electromechanical conversion efficiency of can-type electromagnetic transducers under low-power driving conditions. The can-type transducers consist of coils, an armature, and a cylindrical magnetic core with a central pillar, similar to the pot core proposed by Cui, Xu, Xu, and Shui [Electr. Eng. 101, 911-919 (2019)]. The proposed driving technology involves adding a permanent magnet to the central pillar to introduce a direct current excitation bias, thereby adjusting the static operating point and the electromechanical conversion efficiency of the transducer. In this paper, a theoretical model of the electromagnetic driving force is established, and finite element simulations show that adding a permanent magnet increases the electromechanical efficiency of can-type transducers from less than 1% to 84.43% under low-power conditions. Furthermore, prototypes of underwater can-type electromagnetic transducers with and without a permanent magnet at the core center were fabricated in this study. The experimental results confirmed that the permanent magnet drive technology significantly improves electromechanical conversion efficiency by adding a permanent magnet to the core center.