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. 07, 1982
Filed:
Dec. 01, 1980
Fujitsu Fanuc Limited, Tokyo, JP;
Abstract
Disclosed is a DC motor drive circuit adapted to prevent thyristor commutation failure when a thyristor-controlled three-phase full-wave reversible bridge undergoes a transition in operating mode from a power inversion mode to a power rectification mode. The drive circuit includes a thyristor-controlled three-phase full-wave reversible bridge whose firing phase is controlled in accordance with a speed deviation between the actual speed of a DC motor and a command speed, polarity discrimination means for discriminating the polarity of the speed deviation, firing phase narrowing means operable in the power inversion mode to narrow the thyristor firing phase down to a minimum firing phase due to a reversal in the polarity of the speed deviation, detection means for detecting an intermittence in armature current, and blocking means for blocking firing of the three-phase thyristor-controlled inverter for a prescribed period of time when the intermittence of the armature current has been detected, the operation mode of the inverter being changed over from the power inversion mode to the power rectification mode after the lapse of said prescribed time period.