Apparatus and method for controlling emergency operation in elevator system

• US 5,945,644 A
• Filed: 11/03/1997
• Issued: 08/31/1999
• Est. Priority Date: 11/04/1996
• Status: Expired due to Term

• Current Assignee: LG Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: LG Industrial Systems Co., Ltd (LG Corporation)
• Inventors: Jang, Cheol-Ho
• Primary Examiner(s): Nappi, Robert E.
• Application Number:
  US08/962,679
• Time in Patent Office: 666 Days
• Field of Search: 187/296, 187/293, 187/290, 187/391, 187/393
• US Class Current: 187/296
• CPC Class Codes: B66B 5/02 responsive to abnormal operating conditions

Abstract

An apparatus and method for controlling an emergency operation in an elevator system. The apparatus includes an inverter for inverting a direct voltage into alternating voltages and driving an induction motor with the alternating voltages, a current detector for detecting a current that flows through a first coil of the induction motor, a speed detector for detecting a speed of the induction motor and outputting phase signals, and a control circuit for receiving the current outputted from the current detector and the phase signals outputted from the speed detector and outputting a voltage command to the inverter. The apparatus and method shorten a rescue time by determining an elevator car driving direction by the use of the phase signals outputted form the speed detector during a driving interruption caused by an abnormal or emergency situation.

Claims

1. An apparatus for controlling an emergency operation in an elevator system, comprising:

an inverter for inverting a direct voltage into alternating voltages and driving an induction motor with the alternating voltages;

a current detector for detecting current that flows through the induction motor;

a speed detector for detecting a speed of the induction motor and outputting phase signals; and

a control circuit for receiving the current outputted from the current detector and the phase signals outputted from the speed detector, and outputting a voltage command to the inverter, the control circuit including,

a speed detection unit for receiving the phase signals outputted from the speed detector, and calculating an angular velocity of the induction motor;

a driving direction setting unit for receiving the phase signals outputted from the speed detector and the angular velocity from the speed detection unit, and determining a driving direction of an elevator car;

a speed command generator for receiving an output signal from the driving direction setting unit, and outputting a speed command;

a first subtractor for outputting a difference value between the speed command and the angular velocity;

a speed controller for amplifying the difference value outputted from the first subtractor, and outputting a current command for the induction motor;

a second subtractor for outputting a difference value between the current command and the current outputted from the current detector; and

a current controller for amplifying the difference value outputted from the second subtractor, and outputting the voltage command to the inverter.

6. The apparatus of claim 1, wherein the driving direction setting unit compares the phase signals to each other to determine whether a first phase signal of the phase signals is at a low level at the time of a falling edge of a second phase signal of the phase signals, and determines the driving direction of the elevator car based on this comparison result.

7. The apparatus of claim 1, wherein the driving direction setting unit compares the phase signals to each other to determine whether a first phase signal of the phase signals is at a high level at the time of a falling edge of a second phase signal of the phase signals, and determines the driving direction of the elevator car based on this comparison result.

2. A method for controlling an emergency operation in an elevator system, comprising the steps of:

first determining whether an elevator car is at a door zone of the elevator system for providing access to and from the elevator car;

second determining a driving direction of the elevator car in accordance with phase signals from a motor speed detector so that when the elevator car is at the door zone, the elevator door is opened, and otherwise, a brake of the elevator car is released;

third determining whether a count time is equal to or greater than a setting time, wherein the count time is counted from a time point at which the brake was released in said second determining step;

fourth determining whether an angular velocity of an induction motor for driving the elevator car is equal to or greater than a setting velocity, when the count time is greater than the setting time; and

maintaining a current elevator car direction determined after releasing the brake, when the angular velocity is equal to or greater than the setting velocity, and otherwise, changing the driving direction of the elevator car.

3. The method of claim 2, wherein the second determining step further comprises the steps of:

determining whether a first phase signal outputted from the motor speed detector is at a low level at the time of a falling edge of a second phase signal outputted from the motor speed detector; and

determining whether the first phase signal is at a high level at the time of the falling edge of the second phase signal.

4. The method of claim 3, wherein the step for determining whether the first phase signal is at a low level further comprises a step for driving the elevator car upwardly upon determining that the first phase signal is at a low level.

5. The method of claim 3, wherein the step for determining whether the first phase signal is at a high level further comprises a step for driving the elevator car downwardly upon determining that the first phase signal is at a high level.

8. An apparatus for controlling an emergency operation in an elevator system, the elevator system including a driving unit for driving an induction motor, the apparatus comprising:

a current detector for detecting current flowing through the induction motor;

a speed detector for detecting a speed of the induction motor and outputting phase signals based on this detection; and

a control circuit for controlling the driving unit based on the current detected by the current detector and based on the phase signals outputted from the speed detector, the control circuit including,

a driving direction setting unit for receiving the phase signals outputted from the speed detector, and determining a driving direction of an elevator car based on the phase signals.

a speed detection unit for receiving the phase signals outputted from the speed detector and calculating an angular velocity of the induction motor based on the phase signals,

a speed command generator for receiving an output signal from the driving direction setting unit and outputting a speed command based on the received output signal from the driving direction setting unit,

a first subtractor for outputting a difference between the speed command and the calculated angular velocity of the induction motor,

a speed controller for amplifying the difference outputted from the first subtractor and outputting a current command for the induction motor based on the amplified difference,

a second subtractor for outputting a difference between the current command and the current detected by the current detector, and

a current controller for amplifying the difference outputted from the second subtractor, generating a voltage command based on this amplified difference, and outputting the voltage command to the driving unit to control the driving unit.

9. The apparatus of claim 8, wherein the phase signals include first and second phase signals and the driving direction setting unit compared the first and second phase signals to each other to determine the driving direction of the elevator car.

10. The apparatus of claim 9, wherein the driving direction setting unit determines whether the first phase signal is at a low level at the time of a falling edge of the second phase signal, and drives the elevator car upwardly based on this determination.

11. The apparatus of claim 9, wherein the driving direction setting unit determines whether the first phase signal is at a high level at the time of a falling edge of the second phase signal, and drives the elevator car downwardly based on this determination.

12. A method for controlling an emergency operation in an elevator system, the elevator system including a driving unit for driving an induction motor, the method comprising:

detecting current flowing through the induction motor;

detecting a speed of the induction motor and outputting phase signals based on this speed detection; and

controlling the driving unit based on the current detected from said detecting step and based on the phase signals, said controlling step including,

determining, in a driving direction setting unit, a driving direction of an elevator car based on the phase signals,

calculating an angular velocity of the induction motor based on the phase signals,

receiving an output signal from the driving direction setting unit and outputting a speed command based on the received output signal from the driving direction setting unit,

calculating a first difference between the speed command and the calculated angular velocity of the induction motor,

amplifying the first difference calculated from said calculating step and outputting a current command for the induction motor based on the amplified difference,

calculating a second difference between the current command and the current detected from said detecting step,

amplifying the second difference,

generating a voltage command based on this amplified second difference, and

outputting the voltage command to the driving unit to control the driving unit.

13. The method of claim 12, wherein in said speed detecting step, the phase signals include first and second phase signals and in said determining step, the driving direction setting unit compares the first and second phase signals to each other to determine the driving direction of the elevator car.

14. The method of claim 13, wherein in said determining step, the driving direction setting unit determines whether the first phase signal is at a low level at the time of a falling edge of the second phase signal, and drives the elevator car upwardly based on this determination.

15. The method of claim 13, wherein in said determining step, the driving direction setting unit determines whether the first phase signal is at a high level at the time of a falling edge of the second phase signal, and drives the elevator car downwardly based on this determination.