Performance analysis and demonstration of fuel cell/battery hybrid system for unmanned undersea vehicles

Fuel cells (FC) are expected to improve the endurance of unmanned undersea vehicles (UUVs). Hydrogen-oxygen fuel cells are commonly utilized undersea, which suffer from high cost and technical problems. However, virtually all commercial fuel cells are primarily designed for open spaces, which are inappropriate for undersea applications. Based on this, this paper proposes a hydrogen-air fuel cell/battery undersea hybrid system (FCBS), and evaluates the performance of the hybrid system to address issues. The UUV studied is a small modular UUV with an external diameter of 320 mm and a cruising power of 150 W–500 W. The calculation results show that the extended length of the UUV and the reduced dive depth can improve the endurance of FCBS system. Compared with FC system, the application of FCBS system can result in a growth of 22–34% in cruise time and an increasement of 36% in maximum range. However, this advantage does not apply at high velocities. In addition, there is an optimal velocity for the UUV to reach its maximum range, which is 1.2 m/s for FCBS system and 1.5 m/s for FC system. Finally, the experiment results prove the feasibility and reliability of the proposed scheme.