FEA-based Optimal Design of the Radial Magnetic Bearings in Magnetic Suspended Hard Disk Drive

Magnetic suspended hard disk drive (MSHDD) is a novel concept of computer storage device in which conventional spindle bearings are substituted by magnetic bearings and other parts are kept unchanged to largely increase the rotating speed of the disks and actively control vibration of the disks. This paper presents the FEA-based optimization of a radial MB in a MSHDD test rig. The aim is to achieve maximum force in a limited space of the entire construction. The objective function is evaluated by static FEA-based 2D calculations. It includes the creation of the radial MB's FEA model, determination of the nonlinear solution of the magnetic scalar potential and the determination of force by Maxwell's stress tensor method. The optimization method and math model are presented with a detailed optimization flow. The optimization results and the geometry parameters' influence on the radial MB performance is concluded. Evaluated by magnetic field measurement data of the radial magnetic bearing, it is shown that FEA-based optimization achieved the maximum bearing force accurately and efficiently. The optimization has been performed with the FEA software-ANSYS EMAG