ELEVATOR SPEED CONTROL

• US 20150329317A1
• Filed: 12/13/2012
• Published: 11/19/2015
• Est. Priority Date: 12/13/2012
• Status: Active Grant

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Agirman, Ismail, Piedra, Edward
• Granted Patent: US 9,957,131 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B66B 1/30 effective on driving gear , e.g. acting on power electronics, on inverter or rectifier controlled motor
• CPC Class Codes: B66B 1/308 with AC powered elevator drive
• CPC Class Codes: B66B 5/145 electrical

Abstract

Embodiments are directed to calculating a current associated with a motor of an elevator based on an output of a speed regulator, and controlling the elevator based on the current. Embodiments are directed to examining a feeder current obtained via a converter current sensor of a regenerative drive during a peak power condition, and regulating a speed of an elevator based on the feeder current.

Claims

1. A method comprising:

calculating a current associated with a motor of an elevator based on an output of a speed regulator; and

controlling the elevator based on the current.

2. The method of claim 1, further comprising:

comparing the current to a limit associated with at least one of a drive and the motor,

wherein controlling the elevator comprises finishing an elevator run when the comparison indicates that the current is less than the limit, and

wherein controlling the elevator comprises at least one of (i) halting the elevator, (ii) slowly bringing the elevator to a stop and running the elevator back to an initial position, and (iii) reducing a speed reference and having the elevator proceed to an initial landing, when the comparison indicates that the current is greater than the limit.

3. The method of claim 1, further comprising:

calculating a motor power associated with the motor; and

measuring a bus voltage,

wherein the current is calculated based on the motor power and the bus voltage.

4. The method of claim 3, wherein the motor power is based on a motor torque constant associated with the motor and an encoder speed calculation, and wherein the current is calculated based on a power factor parameter and an efficiency parameter associated with the motor.

5. The method of claim 1, further comprising:

calculating the current based on current references associated with the motor.

6. A method comprising:

examining a feeder current obtained via a converter current sensor of a regenerative drive during a peak power condition; and

regulating a speed of an elevator based on the feeder current.

7. The method of claim 6, further comprising:

comparing the feeder current to a nominal peak current threshold for a given AC line voltage; and

reducing the speed of the elevator when the feeder current exceeds the threshold without increasing a motor current associated with a motor of the elevator.

8. A method comprising:

measuring, during a constant acceleration of an elevator, two voltages associated with a motor at two different speeds of the elevator;

forming a linear equation between motor voltage and elevator speed, the linear equation comprising a slope and an offset;

calculating the slope and the offset based on the two voltages and two different speeds; and

calculating a base speed for the elevator based on the slope, the offset, and a maximum output of a drive associated with the elevator.

9. The method of claim 8, further comprising:

calculating a maximum speed for the elevator based on the base speed and a parameter associated with a percentage of the motor'"'"'s full speed.

10. A system comprising:

a speed regulator configured to receive a speed feedback and a speed reference and generate a torque current reference;

a controller configured to control an elevator'"'"'s operation based on the torque current reference.

11. The system of claim 10, wherein the controller is configured to control the elevator'"'"'s operation based on a comparison of the torque current reference to two different thresholds, wherein a first of the thresholds is associated with holding a car of the elevator, and wherein a second of the thresholds is associated with an acceleration of the car.

12. The system of claim 10, wherein the controller is configured to control the elevator'"'"'s operation based on a calculated motor power associated with a motor of the elevator and a measured bus voltage.

13. The system of claim 12, wherein the measured bus voltage is associated with a battery voltage in a battery-based drive.

14. The system of claim 12, wherein the calculated motor power is based on a motor torque constant associated with the motor and an encoder speed calculation, and wherein the controller is configured to calculate a current associated with the motor based on the calculated motor power and a power factor parameter and an efficiency parameter associated with the motor.

15. The system of claim 10, wherein the controller is configured to control the elevator'"'"'s operation based on a summation of a maximum torque per ampere current and a motor voltage regulator output current.