Apparatus and method for controlling operation of elevator in power failure

• US 6,315,081 B1
• Filed: 12/15/1999
• Issued: 11/13/2001
• Est. Priority Date: 12/15/1998
• Status: Expired due to Term

• Current Assignee: LG Otis Elevator Company
• Original Assignee: LG Industrial Systems Co., Ltd (LG Corporation)
• Inventors: Yeo, Hwan Je
• Primary Examiner(s): SALATA, ANTHONY J
• Application Number:
  US09/461,768
• Time in Patent Office: 699 Days
• Field of Search: 187/290, 187/293, 187/295, 187/296, 318/779, 318/781, 318/782, 318/799-815, 307/64, 307/66
• US Class Current: 187/290
• CPC Class Codes: B66B 1/285 with the use of a speed pattern generator
• CPC Class Codes: B66B 5/02 responsive to abnormal operating conditions
• CPC Class Codes: B66B 5/027 to permit passengers to leave an elevator car in case of failure, e.g. moving the car to a reference floor or unlocking the door

Abstract

An apparatus for controlling an operation of an elevator includes a power supply unit for detecting whether the main power supply was supplied including a charger and for outputting a predetermined control signal, an operation control unit for receiving the control signal from the direct current power supply unit and a demand control signal inputted by a user and for outputting a speed control signal and a load compensation signal so as to control the elevator system, a power consumption detector for computing a power consumption of the alternating current motor, a speed limiter for limiting a speed of the motor upon receipt of the alternating current motor speed signal from the speed detector and the power consumption of the motor computed by the power consumption detector, and a speed control unit for controlling a rotational speed of the alternating current motor upon receipt of the load compensation signal and the control signal from the speed limiter. By having such construction, the discharge amount of a charged power supply is minimized when an elevator is operated on the charged power supply in an emergency and an over current is prevented.

Claims

1. An apparatus for controlling the operation of an elevator when a power failure occurs in an elevator system which includes a main alternating current power source for supplying AC power to the system, a converter for converting the AC power from the power source to direct current, a first inverter for inverting the direct current to alternating current according to a pulse width modulated signal, a first pulse width modulator for providing a pulse width modulated signal to control a switching of the inverter, an alternating current motor driven at a speed corresponding to the alternating current output from the inverter, a pulse generator for generating a pulse signal according to a rotational speed of the motor, and a speed detector for detecting a speed of the motor depending on the pulse signal from the pulse generator, the apparatus comprising:

a direct current power supply unit including a power failure detector for detecting a power failure of the main power source, a battery for charging a voltage from the power source in normal state or supplying charged voltage when a power failure is detected depending on the output from the power failure detector, a second inverter for inverting a direct current from the battery into an alternating current, a second pulse width modulator for providing a pulse width modulated signal to control switching of the second inverter and a transformer for boosting output voltage from the second inverter;

an operation control unit for receiving a power failure detecting signal from the power failure detector and receiving a call signal or destination selection signal from a hall call or a car call of the elevator system and outputting a speed control signal and a load compensation signal so as to control the elevator system;

a power consumption detector for computing a power consumption of the motor;

a speed limiter for limiting a speed of the motor depending on the motor speed signal from the speed detector and the power consumption of the motor computer by the power consumption detector; and

a speed control unit for controlling a rotational speed of the motor upon receipt of the load compensation signal and the control signal from the speed limiter.

2. The apparatus according to claim 1, wherein the power consumption detector computes the power consumption of the motor depending on the detected speed of the motor and a torque current of the motor.

3. The apparatus according to claim 1, wherein the power consumption detector detects that the motor is consuming the power if the computed power consumption of the alternating current motor is of a positive (+) value, and detects that the motor is generating a power if the computed power consumption of the motor is of a negative (−

) value.

4. The apparatus according to claim 1, wherein the speed limiter subtracts a speed command from the motor speed signal so that the power consumption of the alternating current motor does not exceed the maximum capacity of the power supply unit.

5. A method of controlling the operation of an elevator when a power failure occurs in an elevator system which includes a main alternating current power source for supplying AC current to the system, a converter for converting the AC current from the power source to direct current, a first inverter for inverting the direct current into an alternating current according to a pulse width modulated signal;

a first pulse width modulator for providing a pulse width modulated signal to control switching of the inverter, an alternating current motor driven at a speed corresponding to the alternating current output from the inverter, a pulse alternate generator for generating a pulse signal according to a rotational speed of the motor, and a speed detector for detecting a speed of the motor depending on the pulse signal from the pulse generator, the method comprising the steps of;

detecting a power failure of the main power source with a power failure detector, charging a voltage from the power source in a normal state or supplying charged voltage when a power failure is detected with a battery depending on the output from the power failure detector, inverting a direct current from the battery into an alternating current with a second inverter, providing a pulse width modulated signal with a second pulse width modulator to control switching of the second inverter and boosting output voltage from the second inverter with a transformer;

receiving a power failure detecting signal from the power failure detector and receiving a call signal or destination selection signal from a hall call or a car call of the elevator system and outputting a speed control signal and a load compensation signal so as to control the elevator system with an operation control unit;

computing a power consumption of the motor with a power consumption detector;

limiting a speed of the motor depending on the motor speed signal from the speed detector and the power consumption of the motor computed by the power consumption detector with a speed limiter; and

controlling a rotational speed of the motor upon receipt of the load compensation signal and the control signal from the speed limiter with a speed control unit.

6. The method according to claim 5, further comprising the step of computing the power consumption of the motor depending on the detected speed of the motor and a torque current of the motor with the power consumption detector.

7. The method according to claim 5, further comprising the step of detecting that the motor is consuming power if the computed power consumption of the alternating current motor is of a positive (+) value, and detecting that the motor is generating power if the computed power consumption of the motor is of a negative (−

) value with the power consumption detector.

8. The method according to claim 5, further comprising the step of subtracting a speed command from the motor speed signal so that the power consumption of the alternating current motor does not exceed a maximum capacity of the power supply unit with the speed limiter.