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:
Jun. 13, 2000
Filed:
May. 11, 1999
Shinichi Ishii, Saitama, JP;
Hirokazu Tajima, Tokyo, JP;
Fuji Electric Co., Ltd., Kawasaki, JP;
Abstract
A control apparatus for an induction motor includes a current detector for detecting the current of the induction motor; a first coordinate transformer for resolving the current into an exciting current component and a load current component; a slip value calculator for calculating a slip angular frequency of the induction motor based on the load current component; a correction value calculator for calculating a correction value for the slip angular frequency of the induction motor in response to the change of the exciting current component; a multiplier for correcting the slip angular frequency by using the correction value calculated in the correction value calculator; an adder for calculating a reference primary angular frequency based on the corrected slip angular frequency; a voltage vector calculator for calculating a reference voltage value based on the reference primary angular frequency; and a second coordinate transformer for feeding the calculated reference voltage value to the inverter. The control apparatus keeps the rotating speed of the induction motor at a predetermined value when the slip frequency change occurs due to temperature rise in the induction motor.