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:
Mar. 09, 2004
Filed:
Apr. 12, 2002
Jonathan C. Griffitts, Boulder, CO (US);
Mountain Engineering II, Inc., Longmont, CO (US);
Abstract
An electric system utilizes dynamic impedance changes in windings of an electric motor to measure/monitor mechanical position. The method employs a bridge amplifier to measure voltage at a center node or windings against a voltage derived from a reference network. When a winding of the motor is driven, the winding forms a voltage divider across the center node. Impedance changes in windings occur as rotor poles pass by stator poles. The center node voltage varies with these impedance changes in legs on either side; this variation with respect to the reference network corresponds to measurement of rotational position. These measurements provide position/velocity feedback to a servo controller as long as current runs through a winding. This position sensing also applies to controlling commutation for brushless DC motor. Impedance measurement use normal motor-drive current for excitation without additional sensing signals, extra “sense” windings, or external sensors.