New system to help hybrid and electric cars keep their cool

Washington, September 23 (ANI): Researchers at Purdue University have created a new system to cool high-power electronics in electric and hybrid cars, aircraft, computers and other devices.

Indiana's 21st Century Research and Technology Fund provided funding to Purdue and Delphi Corp. in Kokomo, Ind., to help commercialize the advanced cooling system using microchannels for electronic components in hybrid and electric cars.

The new type of cooling system will be used to prevent overheating of devices called insulated gate bipolar transistors, high-power switching transistors used in hybrid and electric vehicles.

The chips are required to drive electric motors, switching large amounts of power from the battery pack to electrical coils needed to accelerate a vehicle from zero to 60 mph in 10 seconds or less.

The devices also are needed for "regenerative braking," in which the electric motors serve as generators to brake the vehicle, generating power to recharge the battery pack; to convert electrical current to run accessories in the vehicle; and to convert alternating current to direct current to charge the battery from a plug-in line.

The high-power devices produce about four times as much heat as a conventional computer chip.

The researchers studied a "dielectric liquid," a fluid that doesn't conduct electricity, which allows it to be used directly in circuits without causing electrical shorts.

"We have finally made sense of boiling in small-scale channels and now have a nice understanding of the physics," said Suresh Garimella, the R. Eugene and Susie E. Goodson Professor of Mechanical Engineering at Purdue University.

Researchers used special test chips fabricated by Delphi that are about a half-inch on each side and contain 25 temperature sensors.

"Right under each of these sensors is a little heater, so we can adjust the amount of heat we apply to specific locations on the chip and simulate what happens in a real chip," said Garimella.

The microchannels are etched directly on top of the silicon chips.

Because both the channels and the chip are made of silicon, there is no dramatic difference in expansion from heating, which allows chips to be stacked on top of each other with the cooling channels between each chip.

This stacking makes it possible to create more compact systems, since the chips do not have to be laid out horizontally on a circuit board as they ordinarily would.

The cooling systems are being developed to cool the electronic controls in aircraft, military systems and for other applications. (ANI)