World’s First Commercialized Hydrogen-Fuel Cell Powers Drones for Humanitarian Missions

Doosan Mobility Innovation (DMI) is delivering humanitarian relief to remote locations using drones powered by its innovative energy-dense hydrogen-fuel cells. With two hours of flight time, the drones have transported masks and emergency supplies between the U.S. Virgin Islands and have delivered medical AEDs to the top of Mt. Hallasan (6,388 feet), the tallest mountain in South Korea, located on Jeju Island. This technology paves the way for developing mobile robots with extended range and load capacity.

DMI drones delivered emergency medical supplies to the Virgin Islands. A hydrogen-fuel–cell power pack made this possible by enabling over two hours of UAV flight time; 4× longer than most battery-powered drones.

Additional uses for the DMI extended-range drones have been in commercial applications in which longer flight times have enabled the monitoring of vast solar farms, such as Korea’s largest solar energy plant in Solasido, Haenam. When performing the same mission using a battery-powered drone, more than six battery replacements were required.

Solar panel inspection is achieved with far greater efficiency and speed by DMI drones. Using a hydrogen-fuel–cell drone equipped with a common camera and a thermographic camera, the image of a power plant on a site of about 20 MW was obtained by just two automatic grid flights. When performing the same mission using a battery-powered drone, more than six battery replacements are required.

High-density power design to optimize power pack performance

Developing a hydrogen-fuel cell for mobile devices requires overall technological innovation from materials science to full system-level design optimization. The key to mobility is miniaturization, increasing efficiency and lowering system weight. Moreover, high energy output and durability should be incorporated for a long, stable flight. Therefore, it is necessary to reduce the weight of the stack, configure a powertrain with high power density, and simplify the design of the overall power pack, including peripheral components, to fully optimize the system.

Core to these design goals are the architecture and implementation of the system’s power delivery network (PDN). The DP30 power pack has two main powertrains that supply power to the drone’s rotors and to the controller for the two stacks. Because of the wide range and variable output voltage of the DP30 power pack, from 40 to 74 V, the powertrains were designed to ensure a tightly regulated 48-V, 12-A output to the rotor motors of the drone, plus a 12-V, 8-A output to the stack controller board and fans.

Energy density comparison: hydrogen fuel cell versus lithium power

To achieve high efficiency and high energy density in the PDN, DMI selected Vicor PRM buck-boost regulators and a ZVS buck regulator. The PRMs support the up-to-74-V open-circuit voltage (OCV) of the hydrogen-fuel–cell stack and perform a stable voltage regulation to 48 V, as shown in Figure 5.

Structure of hydrogen-fuel–cell power pack

In the drone’s rotor-side PDN, two PRM buck-boost regulators (PRM48AF480T400A00) are configured in parallel to supply the 12 A required by the rotors. The PDN for the digital controller board in the stack uses a lower-power PRM (PRM48AH480T200A00), followed by a 48- to 12-V ZVS buck regulator (PI3546-00-LGIZ).

Figure 5: To achieve high efficiency and high energy density, Vicor PRM buck-boost regulators and a ZVS buck regulator were used. The PRMs support the up-to-74-V open-circuit voltage of the hydrogen-fuel–cell stack and perform a stable voltage regulation to 48 V.

Diversification of product lines by power capacity

Apart from the 2.6-kW DP30 power pack currently being produced, DMI plans to diversify product lines by power capacity. The company is expected to develop products with various capacities, ranging from the 1.5-kW hydrogen-fuel–cell power pack that is scheduled to be released next year to a 10-kW one, and to launch corresponding drones suitable for each power pack.

The Vicor modular approach to power enables scalability to support such diverse product lines. This also allows DMI to focus on solving other engineering problems, such as stack structure changes, powertrain and peripheral components, and the heat-dissipation method, all of which arise from the expansion of power capacity. With Vicor, DMI is better able to pursue its main objectives: to increase durability and stability, as well as achieve the miniaturization and lightening of fuel cells with high energy density.