Optimal Design of Permanent Magnet Bearings with Application to the HeartQuestTM Ventricular Assist Device

Closed-form design equations for magnetic bearings are desirable for design optimization of sophisticated electrical mechanical systems such as artificial hearts. We develop asymptotic approximations to force and stiffness characteristics of magnetic bearings formed from concentric permanent magnet rings having rectangular cross sections. The equations are well adapted to spreadsheets and facilitate an efficient numerical optimization process. The method was applied to the development of the HeartQuestTM VAD (ventricular assist device), which achieved remarkable compactness and stable operation.