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Lower iron loss spindle motor stator design by using amorphous metal alloy

IP.com Disclosure Number: IPCOM000031476D
Publication Date: 2004-Sep-27
Document File: 2 page(s) / 13K

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Abstract

Disclosed is lower iron loss motor stator design by using amorphous metal alloy. A spindle motor with an amorphous steel stator will have high motor efficiency.

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HSJ820030077 Bob Martin/US/HGST@HGST Ungtae Kim, Stanley Y Wong, Andrew Hanlon

Lower iron loss spindle motor stator design by using amorphous metal alloy

  The total idle power consumption of a hard disk drive(HDD) spindle motor consists of windage loss, fluid dynamic bearing (FDB) friction loss, copper loss, and iron loss. Among them, iron loss is responsible for about 15% to 20% of the total power consumption at 10,000 RPM. The percentage may increase drastically if the spindle speed goes up over 15,000 RPM or higher. The stator is a very important component for an HDD spindle motor, associated with many aspects of motor performance ranging from motor efficiency to HDD spindle stack dynamics. Therefore, the design and manufacturing of a stator requires the state of art technology and optimization skills. However, the optimal design of a stator for lower iron loss is extremely difficult because there still remains a lot of unknown physics associated with it. Especially, in spindle motors used in HDDs, magnetic components are packed into a small volume even though they are manufactured typically with strong magnetic materials, leaving less room for optimization work.

This disclosure proposes a way to reduce the iron loss drastically by applying amorphous metals as the stator material to HDD spindle motors. Existing stator materials currently used for HDD spindle motors such as silicon steels, have excellent ferromagnetic properties, featuring high permeability and low hysteresis characteristics. However, these silicon steels still have some limitations in the application to HDD spindle motors with high efficiency. The main issue affecting motor efficiency is the losses. Reduction of losses increases the efficiency for given load conditions. Among electromagnetic losses, core loss components of electrical steels can generally be reduced by reduction in thickness (less eddy current); increasing resistivity of the stator material by higher silicon content (less eddy current); reduction in grain size (less eddy current); increasing the purity of the material (less hysteresis); and reduction in internal and surface strain (less hysteresis and eddy current), etc.. However, the silicon steels have some limitations in practicing the above mentioned manufacturing processes. Conventional silicon steel manufacturing processes can not still reduce the thickness to the lowest level possible, where iron loss is extre...