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. 05, 2001
Filed:
Nov. 05, 1999
Satoshi Kusaka, Tokyo, JP;
Shunichi Kondoh, Tokyo, JP;
Other;
Abstract
An object is to realize acoustic noise reduction under a wide range of rotating speeds and together with PWM control. A signal (VCTL,) is generated as a trapezoidal wave repeatedly rising and falling in each given electrical angle section extending before and after the current-supply pattern is switched in accordance with the electrical angle of a rotor of a motor, and a signal (VCTL,) is generated in the opposite phase. A control circuit (,) appropriately selects among the signals (VCTL,and VCTL,) and a given signal (SCTL) and inputs them to comparators (,to,). The comparators (,to,) compare the input signals with a carrier signal (B,) provided as a triangular wave. Switch elements for controlling the current-supply pattern to the motor turn on/off on the basis of output signals (C,to C,) from the comparators (,to,). As a result, the current-supply pattern is switched softly by PWM control in the electrical angle section mentioned above.