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:
Sep. 20, 1994
Filed:
Sep. 24, 1993
Rolf Muller, St. Georgen, DE;
Papst Licensing GmbH, Spaichingen, DE;
Abstract
The stator winding of a brushless D.C. motor receives two current pulses per 360.degree.-el. of rotor rotation, each current pulse being furnished via a respective current path. Each current path contains at least one power transistor switch having conductive and non-conductive states. These states are determined by respective driver transistor switches; when the driver transistor switch is in a high-output-impedance state the respective power transistor switch is rendered conductive, but when in the low-output-impedance state it renders the power transistor switch non-conductive. In various ways disclosed herein measures are taken to prevent the power transistor switches of both current paths from being simultaneously conductive. This may be accomplished using inherent or discrete base-emitter capacitances so connected that a power transistor switch is switched off abruptly but switches-on only after the elapse of a predetermined delay. Alternatively, the Hall voltage produced by the motor's rotor-position-sensing Hall cell may be applied to comparators such that the power transistor switches are not even commanded to conduct except during respective periods each shorter than 180.degree.-el.