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:
Dec. 16, 1986
Filed:
Aug. 19, 1985
Toshiaki Okuyama, Ibaraki, JP;
Hiroshi Nagase, Hitachi, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An induction motor is driven by a PWM inverter including switching elements such as gate turn-off thyristors of Graetz connection. Turn-on of the PWM inverter is controlled by PWM pulse signals generated from a pulse width modulator. The pulse width modulator includes comparators having a hysteresis characteristic which generate the PWM pulse signals on the basis of the magnitude and polarity of current errors between current command pattern signals and signals indicative of detected output currents of the PWM inverter. A signal generator generates an AC signal which is applied to the comparators so that the PWM pulse signals generated from the comparators act to increase the effective value of the neutral voltage of the output of the PWM inverter.