By John Keller
Product Intelligence, 24 Feb. 2011. Aerospace and defense systems integrators increasingly are demanding digital power control in advanced electronics for a wide variety of reasons, among them ease of reconfigurability, flexibility and low costs of design, and the ability to prognosticate the status and life cycles of power-management components.
"We are seeing an expectation from our customers that we need to use digital control -- at least use a digital interface," explains Ernie Parker, director of technology development with the Crane Electronics Inc. Power Solutions segment in Redmond, Wash.
Digital power electronics control enables prognostication of components and batteries, Parker says -- for battery power levels, where a given battery is in its life cycle, and when power-management components are starting to behave in a way that indicate they are wearing out.
This kind of capability is important, particularly as military power electronics systems designers try to squeeze out every last bit of efficiency as possible in aerospace and defense electronics.
"Efficiency is the main factor for us," explains Dennis Kelemen, administrator of the Pico Electronics Inc. Power Products Division in Pelham, N.Y. "We make a small power converter, and are always looking for higher efficiency." One way to do this is to use digital control to make sure power-management components are working at top performance all the time. "High efficiency is the most important trend," Kelemen says.
Digital control also helps enable power systems designers to evolve their devices over time to meet their customers' changing requirements. "Sometimes the requirements from our customers are not really firm," explains Crane's Parker. "As they tailor their systems it is much easier to make changes and adapt with digital control, in-loop response, and in interface commands and signals."
In some of these ways, digital control in power electronics can aid reconfigurability and reduce development costs -- for the power electronics supplier as well as for the systems designer, he says.
Batteries represent a prime area for digital power management, even though adding digital control to batteries can increase up-front costs. When it comes to lithium-ion batteries for energy storage, digital control can enhance efficiency and safety. "Everything we are doing there is FPGA controlled," Parker says.
"These batteries are getting more expensive with the power-control electronics built-in, but our customers don't just want to replace batteries -- unless there is a need to." Today's batteries in aerospace and defense applications require indicators for the state of charge, the battery's state of health, and its state of life, Parker says.
State of charge indicates whether or not a battery has a full charge -- at least if it has enough power to fulfill its mission. State of health indicates if a battery is functioning properly and is operating at peak efficiency. State of life, meanwhile, indicates if a battery is wearing out and needs to be replaced.
"There is a lot of work going on in that area now," Parker says. "We are not there yet; the accuracy and integrity is not there for the aerospace and defense industry right now. The military and aerospace industry expects absolute accuracy for safety-critical applications, and the accuracy is not quite there yet."
The ability to prognosticate a device's state of charge, state of health, and state of life is not confined to batteries, Parker points out. "I really expect we will be seeing this expectation for prognostics expand beyond batteries to more complex power systems," he says. "Our customers need something that does not just indicate a fault, but rather something that is tending away from its norm so you can repair or replace it before it fails."
In other power electronics trends, systems integrators are increasing their requirements for radiation hardness, as well as device upscreening to ensure reliability in harsh operating environments, says Pico's Kelemen.
"We address different issues -- ground-benign, airborne, and space. This is a whole different level where we have to address environmental issues and do careful upscreening," Kelemen says. "There is no JAN standard for DC-DC converters, so it's important we can ensure that components are qualified for their operating environments."
Systems designers are asking for power components with the ability to resist the effects of radiation, "not only for space, but also for a few in-flight applications," Kelemen. "Aircraft today are flying higher and longer, with more exposure to radiation."
Absopulse Electronics Ltd.; Ottawa, Ontario; 613-836-3511; www.absopulse.com
Aeroflex Inc.; Plainview , N.Y.; 516-694-6700; www.aeroflex.com
AJ's Power Source Inc.; Land O Lakes, Fla.; 813-996-2583; www.ajpower.com
Analytic Systems; Delta, British Columbia; 604-496-9981; http://analyticsystems.com
Astrodyne Inc.; Mansfield, Mass.; 08-964-6300; www.astrodyne.com
Behlman Electronics Inc.; Hauppauge, N.Y.; 631-435-0410; www.behlmanpower.com
Comdel Inc.; Gloucester, Mass.; 978-282-0620; www.comdel.com
CUI Inc.; Tualatin, Ore.; 503-612-2300; www.cui.com
DRS Pivotal Power; Bedford, Nova Scotia; 902-835-7268; www.drspowersolutions.com
Electromech Inc.; Ramsey, N.J.; 201-934-3456; http://electromechinc.com
Energy Technologies Inc.; Mansfield, Ohio; 419-522-4444; www.ruggedsystems.com
Falcon Electric Inc.; Irwindale, Calif.; 626-962-7770; www.falconups.com
Gaia Converter Inc.; Saint Laurent, Quebec; 514-333-3169; www.gaia-converter.ca
HiTek Power Ltd.; Littlehampton, England; 011-44-1903-712400; www.hitekpower.com
International Rectifier; El Segundo, Calif.; 310-726-8000; www.irf.com
Interpoint, a Crane Co.; Redmond, Wash.; 425-882-3100; www.interpoint.com
ITT Power Solutions; West Springfield, Mass.; 413-263-6200; www.ittpowersolutions.com
Kepco Inc.; Flushing, N.Y.; 718-461-7000; www.kepcopower.com
Martek Power Abbott; Torance, Calif.; 310-202-8820; www.martekpower.com
MS Kennedy Corp.; Liverpool, N.Y.; 315-701-6751; www.mskennedy.com
Murata Power Solutions Inc.; Mansfield, Mass.; 508-339-3000; www.murata-ps.com
National Hybrid Inc.; Ronkonkoma, N.Y.; 631-981-2400; www.nationalhybrid.com
North Atlantic Industries; Bohemia, N.Y.; 631-567-1100; www.naii.com
Pduke Technology Inc.; Walnut, Calif.; 909-598-5000; www.pduke.com
Pico Electronics Inc.; Pelham, N.Y.; 914-738-1400 ; www.picoelectronics.com
Pioneer Magnetics; Santa Monica, Calif.; 310-829-6751; www.pioneermag.com
Power Solutions Inc.; Titusville, Fla.; 516-484-6689; www.powersolutions.com
Powerstax plc; Farnborough, England; +44 (0) 1252 407800,; www.powerstaxplc.com
Rantec Power Systems; Los Osos, Calif.; 805-596-6000 ; www.rantec.com
Schaefer Inc.; Ashland, Mass.; 508-881-7330; www.schaeferpower.com
Solitron Devices Inc.; West Palm Beach, Fla.; 561-848-4311; www.solitrondevices.com
SynQor; Boxborough, Mass.; 978-849-0600; www.synqor.com
TDK-Lambda; Neptune, N.J.; 732-922 9300; http://us.tdk-lambda.com/hp/
Teledyne Microelectronics; Los Angeles, Calif.; 310-822-8229; www.teledynemicro.com
Tracewell Systems; Westerville, Ohio; 614-846-6175; www.tracewellsystems.com
Transistor Devices Inc. (TDI Power); Hackettstown, N.J.; 908-850-5088; http://tdipower.com/
UltraVolt Inc.; Ronkonkoma, N.Y. ; 631-471-4444; www.ultravolt.com
Vicor Corp.; Andover, Mass.; 800-735-6200; www.vicr.com
Vishay Intertechnology Inc.; Malvern, Pa.; 610-644-1300; www.vishay.com
VPT Inc.; Blacksburg, Va.; 540-552-5000; www.vpt-inc.com
XP Power; Sunnyvale, Calif.; 408-732-7777; www.xppower.com