New challenge: electromagnetic design of BLDC motors for high speed fluid film bearing spindles used in hard disk drives

It is a new challenge in the electromagnetic design of spindle motor when a hard disk drive is upgraded to a high speed one with either ball bearing or fluid film bearing. In this paper, detail discussion and analysis are made on the problems associated with converting low speed Brushless DC motor to high speed one used in fluid film bearing spindles. A design example is given for better understanding these problems. For a fixed form factor hard disk drive, the capacity of hard disk drive might be reduced unless high density medial and recording technique are used.