Disk drive spindle motors and their controls

Disk drives require very high-precision spindle motors for fast and accurate access of data. As storage capacity and access rate increase, more demands are being made of spindle motors with respect to both electrical and mechanical performances. For error-free operations, spindle motors are required to comply with a host of requirements, such as run-outs, both axial and radial, acoustics, mechanical vibrations, electromagnetic interference, contamination, etc. Compliance to these requirements necessitate careful and novel design techniques and highly sophisticated manufacturing processes. This paper discusses various requirements and specific design issues (electromagnetic design, mechanical design, motor control) for the development of spindle motors suitable for different form-factor drives using permanent magnet brushless DC motors.