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:
Mar. 04, 1997
Filed:
Sep. 27, 1994
Hidetoshi Umida, Tokyo, JP;
Fuji Electric Co., Ltd., Tokyo, JP;
Abstract
An apparatus for driving an AC motor at variable speeds facilitates arbitrary setting or adjustment of equivalent primary resistance of an AC motor. In one embodiment of the present invention, a reference AC voltage generator outputs reference AC voltage values for each phase of the AC motor, and signals derived from the reference voltage values are in turn used by a power converter to supply the AC motor with variable voltage and frequency. In this embodiment, two or more phase currents are fed back to, and subtracted from, the reference voltage values via a regulator. In another embodiment, an angular-frequency/biaxial-reference-voltage value generator generates a reference primary angular frequency value and biaxial reference voltage values of the AC motor in a rotating orthogonal coordinate system. In this embodiment, two or more of the AC motor's phase currents are fed back to, and subtracted from, the biaxial reference voltage values via a vector transformer and a regulator. The present invention not only avoids power loss associated with using resistors, but it also obviates manual, apparatus-by-apparatus adjustment of reference AC voltage values used to drive a given AC motor.