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:
Aug. 18, 1981
Filed:
Feb. 07, 1979
Hiroshi Narita, Katsuta, JP;
Michimasa Horiuchi, Katsuta, JP;
Masahiko Ibamoto, Katsuta, JP;
Hideaki Rokutan, Katsuta, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A motor control apparatus to supply current from a D-C source to an electric motor has a thyristor chopper circuit, the duty factor of which is controlled depending on a current instruction signal. The thyristor chopper circuit is provided between the terminals of the D-C source in series with an electric motor, and has main and auxiliary thyristors. A series connection of a capacitor and a reactor, forming commutating elements, is connected across the auxiliary thyristor and oscillates to generate a pulse of current through a forward diode in order to turn off the main thyristor when the auxiliary thyristor is turned on. In addition, a saturable current transformer having first, second and third windings is provided. Through the first winding chopper current flows, and the second winding operates as the reactance of the commutating elements. The third winding is provided within the closed circuit formed when the chopper circuit is blocked, and causes current across the secondary winding to charge the capacitor of said chopper circuit.