(per) Researchers at the ETH Chair for Power Electronics have developed a new electrical drive system. The mini-motor rotates at an astounding 500,000 revolutions per minute. This is a world record. Nevertheless, the scientists want to double this number.

The miniature motor, which is the size of a matchbox, including the power electronics interface, generates the equivalent of 100 watts of drive capacity. At up to 95 per cent, its efficiency factor is very high. The little motor can be powered by a gas turbine and the fuel is transported in a little tank. One tankful drives the generator for about 10 hours at a performance of 100 watts. At a lower performance of just 20 watts, for example, the fuel lasts correspondingly longer. The tank is very easy to fill.

Portable energy supply

These micro-gas turbines are used, above all, for mobile applications, such as energy supply for portable heart-lung machines or artificial hearts. The ultra small gas turbines could also replace conventional batteries as a mobile power source. Systems like this could be employed, among onther things in dentistry where ever smaller holes could be drilled with ever higher rotation speed. The little motors could also be used in turbo compressors, which condense gas mixtures or air.

The development continues however. 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.