Power electronics designs trending smaller and more efficient
Designers of power electronics components for the military market say business is steady, but they continue to be challenged to increase efficiencies while simultaneously shrinking component size. Meanwhile, in the space arena there is a move toward digital devices.
Procurement strategies in the defense world are embracing more open architectures and a greater use of COTS designs in new electronic systems and legacy upgrades. New Department of Defense (DoD) program requirements are also pushing for lower Size, Weight, Power, and Cost or SWaP-C.
Designing low-power systems is trickier than ever as military systems integrate high-energy commercial processors and components.
“Managing power is not a glamorous endeavor, but is essential as military electronics designers continue to add capability to platforms not originally designed to handle the energy that modern electronics expend,” says Bud Jewett, Director of Business Development and Company Relationships at Crane Aerospace & Electronics in Lynnwood, WA. “Every design is unique with unique requirements for packaging, size, and weight.
“Military customers are looking for smaller, lighter, more efficient power devices with a lower total cost of ownership,” Jewett continues.
There is a push from DoD customers for higher efficiency as well as a requirement for wider input voltage ranges and smaller sizes, says Kai Johnstad, Product Marketing Manager for Vicor in Andover, MA. “The usual things,” he adds.
On the application side, the big push is toward unmanned systems, Johnstad continues. In the unmanned market, the demand for smaller power supplies is quite strong as platforms such as small Unmanned Aerial Vehicles (UAVs) continue to shrink, requiring unique size requirements for electronic components, he adds.
“More efficient power supplies also are going to be necessary for high energy producing applications such as high-powered jammers for long-range communications and directed energy weapons,” Jewett says.
Custom versus COTS
“Many of the capability upgrades for existing military systems require unique size and weight considerations, which creates opportunities for designers of custom power solutions such as Crane,” Jewett says. “The various form factor and weight requirements are not conducive to an off-the-shelf, one-size-fits-all solution.”
Regarding custom versus COTS, a lot of those decisions depend on the expertise and comfort level of the customer, says Vicor’s Johnstad. The primes have more expertise in design and will typically purchase modules they can design into their systems.
Weight can be just as important as form factor, because many platforms have weight thresholds that cannot be exceeded, Jewett says. Meeting these requirements is challenging because military designs often do not factor in the power conversion considerations until later in the design process, he adds.
In an ideal world, the power design of a system would be laid out first, but that does not happen. Therefore, more customization is needed. If it is done at the last minute, designs become limited as to how much power can be saved.
Whether or not a customer needs a more complicated custom design or a COTS solution really depends on the expertise of the in-house system integrator, Johnstad says.
Many times, customization consists of ruggedizing brick-based designs, Johnstad says.
For more on custom designs by Crane and Vicor, visit at www.craneae.com and www.vicorpower.com.
A COTS product offered by Vicor is the MIL-COTS VI BRICK filter as a compact DC front-end module, either as stand-alone or integrated with the 28 V MIL-COTS PRM, which provides EMI filtering and transient protection, according to a Vicor release (Figure 1). The device meets conducted emission/conducted susceptibility per MIL-STD-461E and input transient surges per MIL-STD-704 or MIL-STD-1275.
Also on the COTS side, engineers at VPT Inc. released a new DC-DC converter for use in commercial avionics, military avionics, and other high-reliability power systems. The DVAB Series eliminates cross-regulation errors and has tightly controlled line and load regulation errors enabled by the use of two independent control loops, according to a company release.
VPT’s avionics “customers demand long-term reliability with extremely tight performance metrics,” says Michael J. Bosmann, Senior VP of VPT. For more information, visit www.vpt-inc.com.
Emerson Network Power’s rugged small digital control devices are also getting design wins in commercial avionics and in-flight entertainment systems, says Shreek Raivadera, Marketing Communications manager at Emerson Network Power in Leicester, U.K. The IFE systems generate a phenomenal amount of power, he adds.
Emerson mostly focuses on the commercial market, but is looking to expand in the military and sees these devices as ideal for military applications such as radar and sonar as well as ground-based Command, Control, Communications, Computers, Intelligence Surveillance, and Reconnaissance (C4ISR) applications, Raivadera continues. The products have yet to go through an official mil-standard testing process, but internal testing shows they can handle the extreme requirements, Raivadera says. For more information, visit www.emersonnetworkpower.com.
Power electronics for space
Smaller size and lower weight requirements are also driving designs of power integrated circuits for space. Designers in this market segment also are seeing greater demand for digitization and standardization across different platforms.
The most common trends in the military space market are standardization, TOR compliance, improved performance, and increased demand for digital devices, says Fred Farris, Vice President of Sales and Marketing for International Rectifier’s (IR’s) HiRel Products in El Segundo, CA.
“Customers are interested in standardizing across platforms and payloads to reduce development time and cost, and this standardization is being flowed down to components and power supplies they purchase,” Farris says.
Regarding TOR compliance, Farris says, “Many if not most of the military space programs today are requiring compliance to the TOR – reliability requirements for government space contracts that involve design, development, and test of spacecraft bus, payload, and launch vehicles.
The demand for digital devices also “is expected to climb as the needs for digital and signal processors onboard a spacecraft continue to rise,” he continues. “Other performance trends see bus voltages continuing to increase while efficiency demands on power electronics increase as well.”
One of International Rectifier’s latest digital space power products is the GH Series of radiation-hardened (rad-hard) DC-DC converters (Figure 2). These devices are designed for onboard spacecraft applications with a mission life as long as 15 years. The series is targeted for designs that use new digital signal processors and FPGA technologies that require a supply voltage as low as 1.0 V. Other features include 18 V to 40 V input range, a Total Ionization Dose (TID) of more than 100 kilorads, and a weight of less than 110 g, according to an IR release. For more information, visit.
(Click graphic to zoom)
VPX power solutions in demand
Board designers continue to see more requirements for ruggedization of power components and are also seeing more demand for VPX-related power supplies.
Over the past several years, there has been a demand for 3U CompactPCI power supplies, says Lou Garofolo, Product Manager at the Power Supply division of North Atlantic Industries in Bohemia, NY. North Atlantic has addressed this demand with their 55LQ and 55MQ product lines. “Most recently, we have seen the trend toward higher-density VPX power supplies that are designed per VITA standards – such as form factor, pinouts, and signaling. We are addressing this through our line of 3U and 6U VPX products with either DC or AC inputs.”
“In the military, conduction-cooled power supply market, our customers are typically looking for fully integrated power solutions that include built-in EMI filtering and input transient protection, which require output power ride-through during severe input power transients that take place on military platforms,” Garofolo says. “Today’s smaller, lighter systems require high-efficiency power supplies in the highest power density possible.”
Another trend Garofolo says he sees is for “intelligent power supplies, which can either report status through discrete signals or through detailed reporting via communication buses such as I2C. Common requirements are for monitoring and/or reporting of input status, output voltage, output current, and temperature monitoring/shutdown. Along with intelligence, there are very often requirements for features such as inhibit/enable, current share, and holdup time.
North Atlantic’s VPX product is the VPX55-3 (Figure 3), a high power density 3U VPX power supply with a +28 Vdc input and 6 outputs (per VPX) at a total output power of 300 W. The conduction-cooled device meets MIL-STD 461 EMI requirements when used with additional system filtering. For more information, visit.