Researchers at ETH Zürich’s Department of Power Electronics have developed an electrical drive system in cooperation with its industrial partners that can achieve more than 1,000,000 rpm. Up to now, industrially-deployed motors have normally reached 250,000 revolutions per minute.
|Top left: entire machine with stator and rotor. Bottom left: Rotor. Right: Power electronics. Click to enlarge. Source: ETH Zürich|
The new drive system generates an output of 100 watts and is barely bigger than a matchbox. The rotor construction has a titanium shell that is able to withstand extreme centrifugal forces and the ball bearings are optimized for extremely high speeds.
Conventionally, the higher the rotational speed, the more losses there are. But the researchers from ETH Zürich solved the problem with an especially low-loss stator. Ultra-thin copper wire is used for the windings which are inserted in a cylinder made of special iron previously unused for machines. In addition, the machine is fed by electronics specifically designed for such engine speeds.
The drive system was brought to fruition in collaboration with industry. The machine was manufactured by the German company, ATE GmbH, which specializes in the development of highly efficient electrical drives. The ball bearings came from the company, myonic, which is also based in Germany and has been manufacturing high precision miniature ball bearings for over 70 years. The construction of the whole system, the development of the electronics and the regulation of the drive system, however, was developed at ETH Zurich’s Department of Power Electronics.
Based upon the results of this research, Christof Zwyssig and Martin Bartholet, also a post-graduate in the same department, founded the spin-off company, Celeroton, in August 2008. The company will seek to provide ultra-high revolution electrical drive systems for different branches of industry and areas of application.
Celeroton is set to become a supplier for manufacturers of, for example, fast-spinning drill or milling machines. The trend towards increasingly smaller cell phones and other electrical appliances means that increasingly smaller holes have to be drilled for the electronics. This is only possible using a drive system that boasts a high rotational speed.