Defence departments all across Europe are challenging industry to reduce development time and cost. More and more, the answers to these demands comes in the form of MIL-COTS products.
Consider the need for tactical intelligence in warfare. For the first time, technology is providing some ability for commanders to gain real-time insights and situational awareness 24/7. Tools such as unmanned aerial vehicles (UAVs) gather surveillance imagery that helps to find and neutralize insurgents and, perhaps equally important, identify those who legitimately occupy those areas.
Although the power requirements differ for each electronic device or system—fast delivery, lightweight, unique packaging, heat and noise management, low voltages, high currents, fast transient response, high efficiency—they all need MIL-COTS power.
UAVs, which have been characterized as the biggest change on the battlefield since the introduction of gunpowder, can handheld devices weighing about a pound or have a wingspan of 50 feet or more. They are designed to fly at altitudes from 2000 to 50,000 feet or higher; some can remain in the air for days. More importantly, though, from a power point of view, are the payloads they carry.
In the air, power solution(s) are dictated by the increasingly demanding requirements of the onboard electronics, which could include an onboard computer (e.g., for image processing, autopilot, data acquisition/analysis, control actuation), sensors (e.g., GPS receiver, gyroscopes, accelerometers), a transceiver, and cameras (e.g., infrared, thermal imagers, low-light TV cameras, video cameras).
Power requirements likely involve MIL-COTS 28Vdc input (MIL-STD-704) with an output of perhaps +5V (e.g., inertial sensors), +3.3Vdc (e.g., computers, GPS), and +12V (e.g., transmitters). Power could fall in the range of tens to hundreds of watts.
In general, whether a MIL-COTS UAV system is in the air or on the ground, reduced SWaP (size, weight, and power) and compute-intensive electronics are the order of the day. MIL applications, of course, must be rugged and able to withstand severe environments, including shock and vibration as well as very high and low temperatures (temperatures in Afghanistan, for example, can range from about 110ºF down to 50ºF below zero).
Power supplies must meet the requirements of the VR12 design guidelines, including response time, trim range, and the amount of permissible droop. For example, Intel’s new Core i7 processor is finding its way into many MIL-COTS applications. The Core i7 goes into sleep mode when there’s no processing needed; when it instantaneously wakes up, power must be there ready to go. Clearly, with such a processor, fast transient response from the power supply is absolutely essential.
New MIL-COTS power solutions are available to support such advanced technologies as those represented by UAVs and their ground systems—they’re small, lightweight, rugged, low noise, highly efficient, and provide fast dynamic response. Fitting into that category are power solutions based on the encapsulated V?I Chips, which have 1/16 and 1/32 brick footprints; weigh 0.5 ounces; and feature 95% efficiency, a -55ºC to 125ºC operating range, and a 1µs transient response (see the figure).
Military applications can also take advantage of the chips’ robustness, as they are able to withstand enormous amounts of shock. Ruggedised interconnect systems also help. Because the regulation and isolation are split into two devices, they can be physically located in different sections of the end use, distributing the thermal load more efficiently and allowing for weight distribution.
Keith Nardone is director of Business Development, Aerospace-Defence, Vicor Corporation