ECE: Electrical & Computer Engineering
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Research: Electronics

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Page 24 - Magnetic ArmorA power electronics team has developed high-voltage, distributed-power technology so a standard military vehicle battery can provide enough instantaneous energy for electromagnetic armor to repel an incoming projectile. The high-performance system dramatically reduces weight and thickness of the vehicle armor and enhances survivability and mobility.

The technology, developed at the Center for Power Electronics Systems (CPES), passed U.S. Army Research Laboratory testing and is undergoing vehicle testing.

Electromagnetic armor uses an intense electrical discharge to create a powerful, pulsed magnetic field on the intercepting plate to destroy incoming projectiles. Using a pulsed power system, the CPES technology converts 24V battery input to charge the armor to 10 kV, which is more than 410 times higher than the input. The system takes five to 10 seconds to recharge the armor for respective events. In each charging cycle, 100 kJ of energy is delivered in a two-stage step-up. First, front-end converters boost voltage to 600 V, then load converters raise the voltage to 10 kV.

The front-end converters use a high-frequency, soft-switching technique and a newly developed, amorphous magnetic material. Power density is 45W/cubic inch with 91.3 percent efficiency and the switching frequency of 200 kHz is two to four times higher than state-of-the-art. The amorphous material helps cut the magnetic size by 80 percent of conventional transformers. The load converter also achieves greater than 90 percent efficiency and 35 W/cubic-inch power density. CPES Director Fred Lee served as lead on the project.

Jason Lai’s team at the Future Energy Electronics Center (FEEC) has developed a highly efficient converter that takes the unpredictable, slow DC output of solid oxide fuel cells and produces the high-quality, high-power AC voltage needed by household and business devices. The converter boosts net power output and helps downsize both the fuel cell stack and its supporting electronics. The development is a significant step toward the U.S. Department of Energy (DOE) goal of 40-60 percent overall fuel cell efficiency at a cost of $400/kW by 2010.

The FEEC technology converts 22 V to 400 V at 97 percent efficiency, while reducing 120 Hz ripple current to 2 percent—eliminating the need for the costly, bulky capacitors or additional converters that are customarily used.

The research was funded by DOE’s Solid State Energy Conversion Alliance (SECA) Program. SECA studies indicate that each 1 percent improvement in inverter efficiency can reduce fuel cell stack costs by $5-$10 per kW.

Photograph of test tubesPhotograph of glowing test tubesKathleen Meehan’s team is working with materials, environmental, and life scientists to develop robust optical bio-sensors for studying living cells. Goals are real-life monitoring of cell response to drugs, viruses, and chemicals, plus identifying intracellular pathways via functionalized probes. The probes are semiconductor quantum dots tailored to detect chemicals through the attachment of biochemical ligands to their surfaces. Photos: CdSe quantum dots in aqueous suspension. Dot diameter influences color.

Page 25 - CircuitBradley Fellow Douglas Sterk developed a technique that allows the integration of three transformers and two inductors onto a single magnetic core, outperforming standard technology that requires one core for each transformer and inductor. His prototype power supply (shown above) increases the load current more than 30 percent above today’s state-of-the-art eighth brick power supplies. With more power delivered in a smaller package, Sterk’s converter can replace more expensive quarter brick converters used by today’s telecommunications devices.