Unmanned Systems Technology 024 | Wingcopter 178 l 5G focus l UUVs insight l CES report l Stromkind KAT l Intelligent Energy fuel cell l Earthsense TerraSentia l Connectors focus l Advanced Engineering report

72 Dossier | Intelligent Energy fuel cell Power and control The cowling around the power electronics section is additively printed using a carbon fibre-impregnated nylon composite, for its strength-to-weight ratio and design flexibility. The power management module has three main parts: the control system, the battery management system and the power output management system. The control system is powered by an integrated circuit from STMicroelectronics that uses a 32-bit ARM processor core. “This controls various valves, stack thermal management, system safety, and manages data storage and transfer,” Kelly notes. On the rear of the 800 W module are four female connectors that interface with the control unit. On the top of the module is a debug port, for IE’s use only, which allows the company to test and validate the health of each unit before delivery. Underneath the debug port is a receptacle for communicating with the pressure regulator, which receives pressure measurements and also controls the solenoid valve. Under the pressure regulator’s data port is an interface port for connecting with the UAV’s flight controller. This outputs data including remaining fuel, hybrid battery voltage and the state of the system (whether it is initialised, outputting power or in standby mode). Error codes such as low fuel for a UAV in mid-flight are also delivered from here. “Those transmit in UART, the simplest format we could choose, to ease integration into whatever system the customer has,” Kelly adds. “And at the bottom is an SD card for logging performance data.” The battery management system monitors the cell voltage and temperature of the hybrid battery, and to safely control the discharging and recharging. The power output management system monitors and controls the voltage and current via the DC-DC converter, to ensure a regulated 25 V output. “It’s very difficult to make a fuel cell consistent and repeatable in all environments and in all applications, so this part of the power management system does that,” Kelly explains. “It means every time a user turns on this module they get the same power out, regardless of the ambient temperature or how much or little they know about fuel cells. “That’s essentially the overarching purpose of the entire power and control box, and one of the reasons we chose to put a DC-DC convertor in the unit.” The future In addition to the 800 W module aimed at UAVs up to 8 kg in weight, Ninan comments that Intelligent Energy has recently completed a new project towards an entirely new fuel cell specification (although details of it had not been released at the time of writing) in partnership with venture engineering company Productiv and UAV filming specialist BATCAM. The project targeted 20-25 kg UAVs that carry heavy filming equipment such as broadcast-quality cameras. With widening interest in the company’s UAV power technology, and an already significant range of vehicles and products powered by its systems, IE’s 800 W fuel cell module looks set to empower huge change across the unmanned world. February/March 2019 | Unmanned Systems Technology Intelligent Energy 800 W fuel cell Maximum continuous power: 800 W Maximum peak power: 1400 W Output voltage: 19.6-25.2 V Dimensions: 196 x 140 x 100 mm Weight: 930 g Operating environment temperature: 5-35 C Maximum altitude: 3000 m Storage temperature: -10 to +70 C System lifetime: 1000 hours Key suppliers Fuel cell: in-house Pressure regulator: Pressure-Tech Valves: The Lee Company Cooling fan motor: T-Motor Microcontroller: STMicroelectronics Battery: undisclosed Cabling: undisclosed Fuel tank: undisclosed Packaging: in-house Data sheet On one side of the power and control electronics section are four ports for debugging, pressure data, flight control data, and an SD card. On the other side are four additional connectors for the battery thermistor, power output, battery balance, and hybrid battery power input