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:
Apr. 27, 1993
Filed:
Aug. 27, 1991
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
When a sensorless and brushless DC motor is started, the rotor having a magnet is positioned by first exciting one pair of motor coils and then exciting another pair motor coils. The excitation of the motor coils is repeated until the rotor stops vibrating. Further, the positions of the magnetic poles of the rotor are detected by comparing the back electromotive force produced in each motor coil with the voltage generated in common to all motor coils. The rotation speed of the rotor is acquired from both the positions of the magnetic poles and the one cycle period of a signal representing the position of the rotor. A suitable delay time corresponding to the acquired rotation speed is determined, and the excitation phases are switched in accordance with the suitable delay time.