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:
Nov. 09, 1993
Filed:
Dec. 20, 1991
Bernd L Ackermann, Berlin, DE;
Peter L Herkel, Berlin, DE;
Otis Elevator Company, Farmington, CT (US);
Abstract
For controlling the current in an inductive load, the gate current used to fire thyristors in a rectifier is controlled to reach zero at exactly the same time, within a given half-wave, as the current in the inductive load which receives the voltage from the rectifier, keeping gate voltage on as long as thyristor current is on. A discontinuous thyristor converter current signal is detected and used to generate an enable signal in conjunction with a thyristor gate voltage. The enable signal, in synchronism with a power supply line voltage, provides a pair of channeling signals which then, depending upon whether the field current is positive or negative, activate the gate voltages of the thyristors such that the gate voltages end exactly at that time, within a given half-wave, where the generator field current becomes discontinuous.