Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1989-08-02
1990-06-05
Shoop, Jr., William M.
Electricity: motive power systems
Induction motor systems
Primary circuit control
318778, 318779, 318819, H02P 540
Patent
active
049320696
ABSTRACT:
An apparatus and method for automatic leveling of elevator cars by controlled DC plugging of AC induction motors. The invention utilizes, in a novel circuit and control arrangement, the external neutral connection of a Y-wound motor design to inject controlled direct current into the neutral to dynamically control the braking to a stop. The elevator car is thus more safely and accurately leveled at the desired floor than has heretofore been known in the art. A novel speed control method is also disclosed which compares and sums positive and negative DC signals and which switches to the motor braking mode at a desired time.
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Holtzinger Charles R.
Ralph George A.
Ip Paul
O'Connor Daniel J.
Shoop Jr. William M.
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