The Bearingless 2-Level Motor

Several processes in chemical, pharmaceutical, biotechnology and semiconductor industry require contactless levitation and rotation through a hermetically closed chamber wall. This paper presents a novel concept that combines crucial advantages such as high acceleration capability, large air gap and a compact motor setup. The basic idea is to separate a homopolar bearing unit axially from a multipolar drive unit on two different height levels. Hence, the proposed concept is denominated as "bearingless 2-level motor". In this paper, the bearing and drive functionalities are explained in detail and design guidelines are given based on analytic equations and electromagnetic 3D simulations. Furthermore, the influence of non-idealities such as saturation and coupling effects are evaluated and included in the design. Finally, measurements on an experimental prototype exemplify the design considerations and prove the excellent performance of the new concept.