October 1, 2006 Researchers at the ETH Chair for Power Electronics have developed an electrical generator that spins at a world record 500,000 revolutions per minute (RPM) and scientists are hopeful they can achieve twice this speed to touch the magical million rpm. The matchbox-sized motor generates the equivalent of 100 watts, including the power electronics interface, and has an efficiency of close to 95 percent. Powered by a gas turbine, one tankful of fuel drives the generator for about 10 hours at peak 100 watt performance. These ultra small gas turbines could replace conventional batteries as a mobile power source and have a range of potential applications, from dentistry where ever smaller holes could be drilled with ever higher rotation speed through to energy supply for mobile applications, such as portable heart-lung machines or artificial hearts. The little motors could also be used in turbo compressors, which condense gas mixtures or air.
In a next step, the team at ETH wants to create a propulsion system that can do a million revolutions per minute. This is not easily done. In order to achieve this goal the scientists will need special materials that can take the strain in the rotor. The current model is coated with titanium, which resists the extreme centrifugal forces. Individual components of the highly rotating power system. Highly compact electronics for the regulation (left), stator (centre) and rotor with mounted ball-bearings. The match neatly illustrates the size of the motor in its entirety.
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