High Power Bearingless Slice Motor (3-4kW) For Bearingless Canned Pumps

In the manufacturing industry many processes involve chemical liquids. There are processes like etching, stripping, cleaning or polishing involving aggressive liquid chemicals. Depen-ding on the process all kinds of acid, organic solvents and bases are used and have to be pumped through the fabrication tools. In these wet processes, pumps are one of the most critical parts. Especially in the semiconductor industry the quality of the processes highly depends on the purity of the chemicals. There-fore process pumps have to fulfill high require-ments on chemical resistance, purity and reliability, which pneumatically driven bellows or diaphragm pumps satisfy. However, these pumps have considerable disadvantages such as: pulsating flow, mechanical wear, short life time and low energy efficiency. Bearingless centrifugal pump systems can be the solution for these problems. In this paper a new 3-phase bearingless permanent magnet slice motor is presented. This bearingless slice motor has a mechanical power of up to 4kW and is used in a centrifugal pump application. A typical appli-cation area for this power range is the semi-conductor and the chemical industry. In delivery applications high purity pump systems with an operating flow of up to 150l/min and an operating pressure of 4,5bar are required. Such an operating point assumes a mechanical drive power of about 3 – 4kW. This deve-lopment has been done in close collaboration with the company Levitronix in Switzerland.