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:
May. 11, 1999
Filed:
Aug. 21, 1997
Seiko Epson Corporation, Tokyo, JP;
Abstract
In a radial gap type brushless DC motor having a motor structure for generating a starting torque and lowering rotational speed fluctuation by forming either one of a pair of upper and lower (right and left) claw poles to have a smaller interval in the circumferential direction with respect to the other claw pole, shifting the position of the upper or lower claw poles toward the rotating direction of the rotor from the middle position of the other claw pole and claw pole, and setting a ratio (a/p) of the claw pole width a and the pole pitch p, a ratio (b/a) of the claw pole width a and the claw pole width b, and a ratio (c/d) of the claw pole pitch c and the claw pole pitch d to fall in a prescribed range, a method for driving a motor forms the generated torque cycle of a cogging torque generated between a permanent magnet rotor (2) and a stator into large and small torque waves, and switches the current of a coil (12) at a high peak of absolute quantity or in the vicinity thereof among a plurality of positive peaks of the cogging torque. Further, a method for driving a motor wherein the coil current is switched at a position where the excited torque generated by the coil current becomes zero or in its vicinity. And, a method for driving a motor wherein the coil current is switched in a vicinity of a positive peak of the cogging torque and giving a no-current passing period when switching the coil current.