Alternating current motor control system with emergency control responsive to failure of power supply

Patent 5070290 Issued on December 3, 1991. Estimated Expiration Date:

March 13, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3829757

Inverter system
Patent #: 4445167
Issued on: 04/24/1984
Inventor: Okado

Controller for AC elevator
Patent #: 4661757
Issued on: 04/28/1987
Inventor: Hokari , et al.

Apparatus for controlling an elevator Patent #: 4678063
Issued on: 07/07/1987
Inventor: Kitaoka , et al.

Inventors

Assignee

Otis Elevator Company

Application

No. 314356 filed on 03/13/1989

US Classes:

318/758, With diverse operation187/288Control actuates mechanical braking means for power source

Examiners

Primary: Smith, David Jr.

International Class

H02P 003/26

Foreign Application Priority Data

1987-05-20 JP

Abstract

A control system for an alternating current motor, such as an elevator hoisting induction motor, in response to failure of power supply, such as service interruption, phase open and so forth, performs in a first emergency control mode and in a second emergency control mode. In the first emergency control mode operation, dynamic braking is used to decelerate the motor. On the other hand, in the second emergency mode, triggered while the motor is driven in regeneration mode to recirculate regenerated power to decelerate the motor, a mechanical brake is applied. During second emergency control mode operation, power supply condition is monitored to detect failure of the power supply for switching control mode from the second emergency control mode to the first emergency control mode. Switching from the second emergency control mode to the first emergency control mode assures synchroneous operation of an inverter and the motor after resumption of power supply to the motor in cases where the power failure is short in duration.