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:
Apr. 01, 2003
Filed:
Sep. 14, 2001
Yoshihito Kato, Tokyo, JP;
Kabushiki Kaisha Toshiba, Tokyo, JP;
Abstract
When the amount L of actual load change that is picked up from an external plant control device exceeds a reference level L* of load change amount per prescribed unit time that is pre-set to serve as an impact drop detection level, the d axis field current Id is suppressed to a prescribed limiting amount. The d axis voltage reference Vd* and hence the motor and armature voltage Eac are thereby suppressed exclusively during a prescribed field limiting period Td. A large potential difference (voltage margin) is thereby generated between the converter output voltage Vac and AC motor armature voltage Eac, thereby speeding up the rise of output current of the motor. Subsequent recovery of the motor speed after impact drop is speeded up by returning the voltage level to the original d axis voltage reference Vd*.