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:
Jul. 25, 1989
Filed:
Jul. 05, 1988
Tooru Tanahashi, Inazawa, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
An apparatus for controlling an alternating current (A.C.) powered elevator includes a converter for converting A.C. power from A.C. power sources into direct current (D.C.) power and an inverter for converting the D.C. power into A.C. power of variable voltage and variable frequency. The converted A.C. power drives an induction motor to operate an elevator cage. The apparatus calculates a current command value from a speed command value and the speed of the motor and compares the current command value with the output current of the inverter. The apparatus further includes a conversion switch which produces an exciting current component switching command when operated and computing means for receiving the speed command value, a speed signal, and the exciting current component switching command and for calculating the current command value.