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. 09, 1986
Filed:
Feb. 27, 1984
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H02P / ;
U.S. Cl.
CPC ...
318803 ; 318811 ; 318798 ;
Abstract
An AC motor such as an induction motor or a synchronous motor is driven by a PWM inverter. Turn-on of the PWM inverter is controlled by PWM pulse signals obtained as a result of comparison between voltage command signals (a modulation signal) and a carrier wave signal. The voltage command signals are obtained as a function of errors between current command signals and detected current signals. Ripples included in the voltage command signals are so suppressed as to be decreased as the rotation speed of the AC motor becomes lower. By so suppressing the ripples, the level of noise generated from the motor can be reduced especially when the motor operates in a low-speed rotation range.