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:
Jan. 02, 1979
Filed:
Aug. 30, 1977
Hitachi, Ltd., , JP;
Abstract
A control system for an a.c. motor having a polyphase primary winding (stator winding) and a corresponding polyphase secondary winding. The primary and the secondary windings are supplied with current from different frequency converters provided separately for each of the windings. The alternating currents flowing through the primary and the secondary windings are in opposite phase with each other. A position detector is provided for detecting the position of rotor of the a.c. motor. The magnitude of the primary current is controlled proportionally to a current reference signal in dependence on deviation of a speed feed-back signal from a speed reference signal, while the magnitude of the secondary current is controlled to a constant value. The phases of the primary and the secondary currents are controlled on the basis of the rotor position. The excitation frequencies for the primary and the secondary windings are set at a predetermined ratio between certain integers and a sum of these excitation frequencies is set to be equal to an angular frequency of rotating electrical angle of rotor.