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. 07, 2004
Filed:
Jun. 27, 2003
Junnosuke Nakatsugawa, Hitachi, JP;
Hitoshi Ohura, Mito, JP;
Tsuyoshi Tanaka, Hitachi, JP;
Tunehiro Endo, Hitachiota, JP;
Yukio Kawabata, Hitachinaka, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
The present invention enables modulated wave signals having extremely small waveform distortion to be generated using a relatively simple circuit, and thereby it is possible to hold down vibrations and noise of a motor, which are attributable to torque ripples. In order to remove defects of the conventional techniques, the circuit generates a plurality of trapezoidal wave signals having at least two constant levels based on position sensing signals of magnetic pole of a motor, generates quasi-sinusoidal wave signals at a quasi-sinusoidal wave modulator based on the plurality of trapezoidal wave signals, and compares the quasi-sinusoidal wave signals with a carrier wave so as to perform PWM control of an inverter.