Unmanned Systems Technology 022 | XOcean XO-450 l Radar systems l Space vehicles insight l Small Robot l BMPower FCPS l Prismatic HALE UAV l InterDrone 2018 show report l UpVision l Navigation systems

60 but he points out that that comes with a much higher price tag, so an open- cathode cell is more appropriate to an affordable system. But the main advantage of the open-cathode system, he says, is the weight of it, in comparison with a closed-cathode one. Ivanenko says, “The BMPower system has a lower price than the available ‘aerospace’ systems. This advantage is achieved by simplifying the design and reducing the number of auxiliary subsystems, such as feed pumps, radiators, humidifiers and so on. We also reduce the cost of production through the use of new technologies: for instance, we refused to use expensive membranes.” In the 1000 FCPS the hydrogen supply runs from the cylinder in which it is stored to a gas connector next to the cell module. This has a central component with electronically governed valves that control the admission of hydrogen from the pressure regulator on the remote cylinder. The gas connector sends hydrogen to one side of the unit, which has its own regulator valve. On the other side is an additional discharge valve that opens briefly every 30 s to allow the escape of what is described by Ivanenko as “ballast gases”. It can be seen that on one outer wall of the module a tube projects from each side: that is where the gas connector feeds the hydrogen and the discharge valve operates. On another outer wall of the unit (around the corner from the hydrogen inputs) is the electrical output. That takes the form of a pair of copper prongs, one projecting from each end, which provide the electrical power take- off points. Sensors measure the amount of hydrogen left in the cylinder, the running temperature of each cell and so on. The system’s electronic control unit takes the form of a separate box that is normally installed to one side of the module. Likewise, the buffer battery is remotely located. Inside the 1000 At the heart of each PEM fuel cell is a very thin membrane, which has to keep the hydrogen and air separate while letting protons pass rapidly through and blocking the passage of electrons. The membrane is often made from DuPont’s Nafion, since it offers the desired qualities. Ivanenko says, “We can use Nafion for the membrane but we are developing alternative approaches as well. We have already tested all the membranes from well-known manufacturers, and now we are doing tests with Russian and Chinese companies that have just entered the market. “We are looking to switch from an industrially manufactured membrane like a Nafion one to creating the membrane from liquid dispersion directly onto the electrode – direct membrane deposition technology. We are switching from a conventional membrane to this new technology.” Any membrane needs to be coated with a catalyst that is normally carbon black with a small amount of platinum. Ivanenko says, “Although we are now using a different approach, we do use platinum on carbon black for the catalyst. We are now depositing the catalyst on the electrodes [diffusion layers] instead of on a membrane. “This approach is more compatible with our new technology of ‘direct membrane deposition’ from liquid dispersion to gas diffusion layers.” The fuel processing system within the BMPower 1000 FCPS The system has a lower price than the available ‘aerospace’ systems, which is achieved by simplifying the design and reducing the number of subsystems October/November 2018 | Unmanned Systems Technology