Jan. 10, 2000 WEST LAFAYETTE, Ind. -- Engineers are designing a new generation of automated warships that promise to reduce the size of naval crews by half, a welcome advancement in an era of shrinking U.S. military personnel.
"One goal is to build a ship that does not need any maintenance while at sea," says Scott Sudhoff, an associate professor at Purdue University's School of Electrical and Computer Engineering. "It's supposed to be highly robust so that, even if you take a missile hit, that ship could continue to fight its way into battle and continue with its mission without needing any maintenance until returning to port."
An important feature of the new naval vessels will be a system that automatically reroutes power around sections of a ship that are damaged in war, enabling the continued functioning of weapons, navigation and communication equipment. Congress recently approved research funding for the Energy Systems Analysis Consortium, led by engineers at Purdue and the University of Missouri-Rolla, to develop technologies critical to the system.
The U.S. Navy hopes to have the first "smart ships" in operation by the end of the decade.
Recent trends have made automated technologies especially necessary; the Navy has seen a 33 percent decrease in military personnel over the last decade and a significant reduction in experienced seamen.
The future warships will differ fundamentally from conventional vessels in that they will run on electric motors, and their power sources will not be connected directly to the propellers. Instead, the power source, such as a diesel or gas turbine engine, will drive a large electrical generator. The generator will, in turn, provide electricity for the motors that turn the propellers.
This sort of arrangement will offer far more flexibility for naval architects because the power source can be placed anywhere on the ship, instead of directly in line with the propellers.
In a conventional ship, the engines are continuously being throttled up and down to propel the vessel at different speeds. However, turbines connected to electrical generators can run at a constant speed, saving fuel, says Sudhoff, who, along with James Drewniak, an associate professor of electrical engineering at the University of Missouri, is heading the engineering consortium's work on the electric power and propulsion system.
The system will enable engineers and architects to design modular vessels consisting of several redundant "zones." If one zone gets severely damaged in an attack, automatic controls will instantaneously reroute the power to the rest of the ship.
However, one major challenge in building the next-generation ships is designing an electric power system that can be "automatically reconfigured" to compensate for damaged zones. The system is difficult to manage because of the myriad possible pathways over which electricity might have to be rerouted, the numerous pieces of equipment being switched on and off, and the ultra-high voltages and currents involved.
The voltage and current will be controlled by means of a method known as "power electronics," in which electricity is processed with semiconductor "converters." For example, if there is a drop in voltage leading to a particular piece of equipment, the voltage is converted automatically to its proper value so that the equipment is unaffected. But converting the power introduces instabilities to other parts of the system that must be fully anticipated and dealt with. Otherwise, the entire electrical system could fail, which would be catastrophic in battle.
Predicting the system's behavior under a multitude of conditions requires development of new mathematical testing techniques.
"Most people think you just plug something into the wall and it runs," Sudhoff says. "You can't do that with these devices. They have to be controlled with power electronics. Instead of five volts and miliamps, it's thousands of volts and thousands of amps.
"One of the big focuses of our research is finding the analytical tools to facilitate designs that can be proven to be stable over all operating conditions."
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