Title :
Characteristics of BEMF, cogging torque and UMF in a HDD spindle motor due to magnetization of PM
Author :
Kang, K.J. ; Jang, Gun Hee ; Sung, S.J.
Author_Institution :
PREM, Hanyang Univ., Seoul, South Korea
fDate :
Oct. 31 2012-Nov. 2 2012
Abstract :
This research mathematically derives the frequency components of back electromotive force (BEMF), cogging torque and unbalanced magnetic force (UMF) of a hard disk drives (HDD) spindle motor with 12 poles and 9 slots (12P9S) due to unevenly magnetized permanent magnet (PM). Only 3-multiple harmonics originated from uneven magnetization of PM introduces same frequency components to BEMF and slot-multiple harmonics to cogging torque, respectively. However, other harmonics of the uneven magnetization of PM except the 3-multiple harmonics introduce slot-multiple ±1 harmonics to UMF. The proposed mathematical equations are experimentally validated by comparing measured BEMF, cogging torque and UMF with measured surface flux density of PM.
Keywords :
disc drives; hard discs; magnetisation; micromotors; permanent magnets; torque; 3-multiple harmonics; BEMF; HDD spindle motor; PM; UMF; back electromotive force; cogging torque; hard disk drives; permanent magnet; slot multiple harmonics; surface flux density; unbalanced magnetic force; uneven magnetization; Density measurement; Frequency measurement; Magnetization; BEMF; UMF; cogging torque; magnetization;
Conference_Titel :
APMRC, 2012 Digest
Conference_Location :
Singapore
Print_ISBN :
978-1-4673-4734-1
