The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 07, 2008
Filed:
Dec. 16, 2004
Jeffrey A. Heydt, Longmont, CO (US);
James W. Dulaney, Jr., Shakopee, MN (US);
David R. Street, Allen, TX (US);
Nicholas Swezey, Bartlesville, OK (US);
Stuart Kevin Francis, Oklahoma City, OK (US);
Jeffrey A. Heydt, Longmont, CO (US);
James W. DuLaney, Jr., Shakopee, MN (US);
David R. Street, Allen, TX (US);
Nicholas Swezey, Bartlesville, OK (US);
Stuart Kevin Francis, Oklahoma City, OK (US);
Seagate Technology LLC, Scotts Valley, CA (US);
Abstract
Method and apparatus for controlling a brushless dc motor, such as the type used in a data storage device to rotate data storage media. A sequence of drive pulses is applied to rotate the motor. The sequence is switched from first to second motor commutation states at a time determined in relation to changes in elapsed time between successive pulses in the sequence. Each drive pulse has a duration established in relation to an inductance of the motor, and is separated from adjacent pulses by an intermediate delay of predetermined value. A peak elapsed time interval between successive pulses is identified, and the next commutation state is switched in at a selected time after the peak time interval. The sequence preferably accelerates the motor from rest to an intermediate velocity, after which back electromotive force (bemf) commutation is used to accelerate the motor to a final operational velocity.