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:
May. 15, 2007
Filed:
May. 06, 2004
Chia-feng Wu, Changhua County, TW;
Ching-sen Hsieh, Taoyuan County, TW;
Yueh-lung Huang, Miaoli, TW;
Ming-shi Tsai, Taoyuan County, TW;
Chia-feng Wu, Changhua County, TW;
Ching-sen Hsieh, Taoyuan County, TW;
Yueh-lung Huang, Miaoli, TW;
Ming-shi Tsai, Taoyuan County, TW;
Delta Electronics, Inc., Taoyuan County, TW;
Abstract
A fan speed control circuit includes a pulse width modulation (PWM) signal generating circuit, a driving circuit and a phase compensation unit. The PWM signal generating circuit generates a PWM control signal with a sequence of alternating on-time and off-time, and the driving circuit outputs a driving signal according to the PWM control signal to a fan motor. The phase compensation unit is connected to the fan motor for delaying or advancing the PWM control signal by a phase angle to synchronize the acting period of the back electromotive force formed by the magnetic flux variation with the off-time of the PWM control signal.