(19)
(11)EP 0 477 643 A3

(12)EUROPEAN PATENT APPLICATION

(88)Date of publication A3:
12.01.1994 Bulletin 1994/02

(43)Date of publication A2:
01.04.1992 Bulletin 1992/14

(21)Application number: 91115197.5

(22)Date of filing:  09.09.1991
(51)International Patent Classification (IPC)5H02M 1/08, H02P 5/22, H03K 17/725
(84)Designated Contracting States:
CH DE LI

(30)Priority: 28.09.1990 US 589860

(71)Applicant: OTIS ELEVATOR COMPANY
Farmington, CT 06032 (US)

(72)Inventors:
  • Ackermann, Bernd Ludwig
    W-1000 Berlin 27 (DE)
  • Herkel, Peter Leo
    W-1000 Berlin 65 (DE)

(74)Representative: Klunker . Schmitt-Nilson . Hirsch 
Winzererstrasse 106
80797 München
80797 München (DE)


(56)References cited: : 
  
      


    (54)Control of a discontinuous current by a thyristor rectifier with inductive load


    (57) 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.







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