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. 23, 1996
Filed:
Apr. 06, 1994
Thomas M McHugh, Farmington, CT (US);
David W Barrett, East Hartland, CT (US);
Edward E Ahigian, West Hartford, CT (US);
Jerome F Jaminet, South Windsor, CT (US);
Thomas He, Unionville, CT (US);
Richard E Peruggi, Glastonbury, CT (US);
Thomas M Kowalczyk, Farmington, CT (US);
Richard E Kulak, Bristol, CT (US);
Otis Elevator Company, Farmington, CT (US);
Abstract
An elevator car door is moved by a variable voltage, variable frequency linear induction motor which is driven open current loop to achieve a desired velocity profile indicated by an incremental linear encoder, with washed out proportional and integral gain. A magnetizing current insufficient to overcome the weight of the door is added in quadrature with the linear force current, and frequency is determined open loop in a predetermined fashion. Pulse width modulation voltage control signals are utilized to apply fixed voltages of correct polarity through a low pass three phase filter to the windings of the motor for correct intervals of time so as to synthesize desired sinusoidal winding currents. A boost of current is provided following each zero crossing of the sinusoidal winding currents to overcome lags therein. A ramp down of voltage avoids dropping the door at the end of door opening and door closing.