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. 14, 2000
Filed:
Feb. 09, 1999
Otis Elevator Company, Farmington, CT (US);
Abstract
Each torque-producing phase current of a multi-phase motor is passed through a filter which includes an R/C shunt to ground and a series, current-compensated choke. Each choke has a winding in series with each phase so that the net current generated by phase currents in the windings is zero, and therefore the net flux generated by phase currents in the highly permeable core of the choke is zero at all times. However, there is significant inductive reactance created by the non-counterbalanced motor leakage currents, which prevent leakage currents from circulating through the motor. Thus, torque-producing motor currents can accurately be measured for feedback, without pollution from leakage currents. LEM current transducers allow use of small, proportional currents in the measuring and suppress inter-phase coupling.