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:
Sep. 27, 1988
Filed:
May. 20, 1987
Matti Kahkipuro, Hyvinkaa, FI;
Harri Hakala, Hyvinkaa, FI;
Kone Elevator GmbH, Baar, CH;
Abstract
A method for directing the power of a d.c. voltage source between a three-phase mains and a d.c. circuit, which comprises the steps of employing a diode bridge comprising a plurality of first diodes to rectify a three-phase mains voltage to a d.c. voltge when power is flowing from the three-phase mains to the d.c. circuit, converting the d.c. voltage to a three-phase a.c. voltage, when power is flowing from the d.c. circuit to the three-phase mains, by means of transistors in parallel with the diodes, employing control means for controlling the transistors, forming control voltages for the control means by a plurality of second diodes from the three-phase mains in such manner that each the transistor is conductive during the conduction time of the respective diode in parallel therewith, and shortening the conduction times of the transitors, in order to reduce the power circulating in the d.c. circuit, by connecting Zener diodes in series with respective ones of the transistors.