Magnetically Suspended Multipurpose Centrifuge.

Centrifuges operating in a field environment need to be compact, light weight rugged and reliable. Available centrifuges have reliability issues related to the robustness of the mechanisms supporting the centrifuge rotor. The mass imbalance introduced on the rotor by asymmetrically loaded tubes aggravates this problem considerably. Use of magnetic bearings with no rubbing surfaces is a viable solution to reduce wear and increase reliability. Combining the magnetic bearing into the structure of the drive motor is an innovative step forward in integrated design. Integration of magnetic bearings and drive motors is at the cutting edge of this technology. A design was developed and a model fabricated in this program to emulate the principle functions of a hematology centrifuge. The rotor of the centrifuge was successfully suspended using the magnetic fields developed by the drive motor stator. The drive is a pancake induction machine with 3-pole pairs arranged in three segments which allow a three-degree-of-freedom control. The program was successful in demonstrating the principle of operation of the combined magnetic suspension and motor drive. The progress made will allow a smooth extension of this technology to a commercial hematology centrifuge. The technology developed here is ideally suited for applications involving electrical drive systems and bearings.