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. 31, 1994
Filed:
Jul. 31, 1992
Scott W Cameron, Milpitas, CA (US);
SGS-Thomson Microelectronics, Inc., Carrollton, TX (US);
Abstract
A circuit and method for operating a polyphase dc motor of the type having a plurality of driving coils that are commutatively energized in a predetermined sequence to rotate a rotor has a zero crossing detector connected to determine when a back emf of a floating driving coil crosses zero. A generator for generating commutation sequence signals controls which of said driving coils are energized a delayed time after said zero crossing detector detects that a back emf of a floating driving coil has crossed zero. A mask circuit inhibits said zero crossing detector for a delayed time after a commutation change, in dependence upon an acceleration of the rotor. Also, a circuit is provided for adjusting the commutation delay time after a back emf of a floating one of said coils crosses zero, in dependence upon the acceleration of the rotor.