Fuel cell charging system with air breathing capability, autonomous underwater vehicle (AUV) system including same, and method of use

An autonomous underwater vehicle (AUV) 100, comprising:

• an onboard computing system 150 comprising a processor, the computing system 150 comprising instructions executable by the processor to provide a system manager module 160;
• a power system 120 configured to provide electric power to operating units of the AUV;
• the power system 120 comprising a power generation subsystem 122 in electrical communication with a power storage subsystem 124, the power system 120 configured to operate in a charging cycle;
• the power generation subsystem 122 comprising a fuel cell charging system 130, the fuel cell charging system 130 comprising an air breathing subsystem 140 changeable between an open condition and closed condition, in the open condition the air breathing subsystem 140 in open communication with atmospheric air when the AUV 100 is located at the ocean surface, the air breathing subsystem 140 comprising intake air passed into the AUV 100 from the external atmosphere, in the closed condition the air breathing subsystem 140 closed to prevent intake air from passing into the AUV 100 from the external atmosphere;
• the fuel cell charging system 130 comprising an onboard supply of hydrogen gas 182 delivered to a fuel cell 132;
• the fuel cell 132 receiving the intake air, the fuel cell 132 receiving the hydrogen gas, the fuel cell 132 configured to perform fuel cell process operation with the oxygen in the intake air and with the hydrogen gas, the fuel cell process operation generating electric energy and waste water output from the fuel cell 132;
• the power storage subsystem 124 comprising a chargeable battery subsystem 136 configured to store electric energy output from the fuel cell 132;
• and
• the system manager module 160 configured to control the AUV 100 to ascend to the surface from submerged operation to perform a charging period of the charging cycle, the system manager module 160 configured to control the AUV 100 to descend from the surface to submerged operation to perform a discharging period to power operations of the AUV 100,
• hydrogen storage 182 volume independent of oxygen storage.

A method 400 of use of an autonomous underwater vehicle (AUV) including a fuel cell charging system having an air breathing subsystem taking intake air from the external atmosphere, a supply of compressed hydrogen in onboard storage tanks, the intake air and hydrogen supplied to an air-breathing PEMFC housed in a water-tight AUV hull structure, the PEMFC operable to produce electric energy for operating the AUV, the PEMFC generating waste water, the power generation subsystem comprising a water removal system for discharging the waste water offboard, the fuel cell charging system having a power storage subsystem including a chargeable battery subsystem in communication with a battery management subsystem, said method 400 comprising:

• providing 404, by an onboard computing system, a system manager configured for controlling the fuel cell charging system;
• determining 408, by the system manager, when the AUV will submerge;
• stopping 412, by the system manager, the PEMFC from charging the chargeable battery subsystem, when the AUV is to submerge;
• first closing 416, by the system manager, an air intake valve connected to an air intake snorkel of the air breathing subsystem;
• second closing 420, by the system manager, the water removal system;
• first switching 424, by the system manager, the battery management subsystem and chargeable battery subsystem to output mode from charging mode;
• detecting 428, by the system manager, that the AUV has surfaced;
• starting 432, by the system manager module, operation of the PEMFC charging system;
• first opening 436, by the system manager, the intake valve connected to the snorkel;
• second opening 440, by the system manager, the waste water exhaust valve;
• and
• second switching 444, by the system manager, power output generated by operation of the PEMFC to charging the chargeable battery subsystem.

A method 300 of use of an autonomous underwater vehicle (AUV) including a fuel cell charging system, the fuel cell charging system including a power generation subsystem having an air breathing subsystem taking intake air from the external atmosphere, a supply of compressed hydrogen in onboard storage tanks, an air-breathing PEMFC housed in a water-tight AUV hull structure, the PEMFC receiving the intake air and hydrogen, the PEMFC operable to produce electric energy for operating the AUV, the PEMFC generating waste water, the power generation subsystem comprising a water removal system for discharging the waste water offboard, the fuel cell charging system having a power storage subsystem including a chargeable battery subsystem in electric current communication with the power generation subsystem to receive electric energy to charge the chargeable battery subsystem, the chargeable battery subsystem in communication with a battery management subsystem operable to control charging and discharging of the chargeable battery subsystem, said method 300 comprising:

• operating, by an onboard computing system comprising a processor, a system manager configured for controlling the fuel cell charging system;
• comparing 304, by the system manager, stored energy level relative to a predetermined minimum threshold, for the chargeable battery subsystem;
• surfacing 308 the AUV to the ocean surface from a submerged location, by the system manager, when the stored energy level has met the predetermined minimum threshold for the chargeable battery subsystem;
• initiating 312, by the system manager, charging operation by the fuel cell charging system when the predetermined minimum threshold is met when the AUV is located at the ocean surface;
• first opening 316, by the system manager, the air breathing subsystem by opening an air intake valve thereof to intake atmospheric air to pass as intake air into the air breathing PEMFC;
• second opening 320, by the system manager, the hydrogen supply subsystem by opening a hydrogen supply valve to enable hydrogen gas to pass into and react in the PEMFC to generate electric energy supplied to the power storage subsystem in electrical communication with the PEMFC, to charge the chargeable battery subsystem;
• third opening 324, by the system manager, the water removal system by opening a waste water exhaust valve to enable discharge of waste water from the water removal system;
• charging 328, by the system manager, the chargeable battery subsystem by controlling operation of the PEMFC to generate electrical energy supplied to the chargeable battery subsystem;
• ending 332, by the system manager, charging of the chargeable battery subsystem by disrupting supply of electric energy to the chargeable battery subsystem;
• first closing 336, by the system manager, the air breathing subsystem by closing an air intake valve, to discontinue intaking and passing of intake air into the air breathing PEMFC;
• second closing 340, by the system manager, the hydrogen supply subsystem by closing a hydrogen supply valve to prevent hydrogen gas from passing into the PEMFC, to stop operation of the PEMFC;
• and
• third closing 344, by the system manager, the water removal system by closing the waste water exhaust valve to stop discharge of waste water from the water removal system and prevent backflow entry of foreign water inside the AUV hull structure.