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:
Dec. 28, 1999
Filed:
Jun. 29, 1998
Applicant:
Inventors:
Makoto Murase, Tokyo, JP;
Kazunari Mizuguchi, Tokyo, JP;
Toshio Tsubota, Tokyo, JP;
Tatsuo Nishizawa, Nagano, JP;
Assignee:
NEC Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H02P / ;
U.S. Cl.
CPC ...
318811 ; 318430 ; 318432 ; 318138 ; 318245 ; 318439 ; 318139 ; 318376 ; 318379 ; 318293 ; 318294 ;
Abstract
A drive current and a regenerative current are alternately applied to a motor during a PWM (pulse width modulation) time period. The regenerative current is produced by an electromagnetic induction of an armature and flows in the opposite direction as the drive current. Therefore, a rotating speed of the motor is reduced, so that a speed-reduction following characteristic for the motor is improved. By varying the duty factor, the lengths of time during which the drive current and the regenerative current are flowing can be controlled. Thus, the speed of the motor can be controlled.