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:
Jul. 13, 1999
Filed:
Nov. 17, 1997
Yoriyuki Takekawa, Ohsato-gun, JP;
Zexel Corporation, Tokyo, JP;
Abstract
A device for driving a DC brushless motor by outputting commutation control signals based on voltages induced in the drive windings includes a position detection circuit having low-pass filter circuits that remove a chopping frequency component and have a phase lag of 60-90.degree. at maximum motor rotational speed, a rotational frequency computing section, and a phase correction amount computing section that effects a computation based on the rotational frequency computed by the rotational frequency computing section to set the commutation time point to produce a 30.degree. phase lag in a rotational speed range in which the phase lag falls in the range of 0.degree. to less than 30.degree. and to produce a 90.degree. phase lag in a rotational speed range in which the value of the phase lag falls in the range of 30-90.degree.. The device achieves high efficiency at optimum commutation timing in the high rotational speed region and suppresses vibration and noise in the low rotational speed region.