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:
Jan. 27, 1998
Filed:
Jun. 07, 1995
James Zweighaft, Boulder, CO (US);
Mark H Moyer, Arvada, CO (US);
Christopher Koerner, Longmont, CO (US);
Exabyte Corporation, Boulder, CO (US);
Abstract
A system and method is provided for controlling a brushless DC motor (100), the motor being of the type having a plurality of coils (25, 26, 27) and a switching amplifier coil driving circuit (25A, 26A, 27A) including a plurality of transistors (21, 22, 29, 30, 33, 34). Current application to the plurality of transistors is controlled to obtain, near a commutation point of the motor, a simultaneous rise in current applied to a first of the transistors and a fall in current applied to a second of the transistors. Controlling application of current to the plurality of transistors involves, for each of the transistors, generating a PWM gate drive signal by selectively switching between a nominal PWM signal and a constant signal. The selective switching is in response to a synthesized state signal, the synthesized state signal being generated to alternate variably between the two states in accordance with a desired ramping of current to the first and second transistors. In one embodiment, the control system is employed for a motor used to rotate a reel of a helical scan tape drive.