METHOD AND SYSTEM FOR AN AUTOMATIC RESCUE OPERATION OF AN ELEVATOR CAR

Abstract

In a system and method for an automatic rescue operation of an elevator car in an elevator system, the elevator system includes a hoisting machine and a battery-operated rescue drive device configured to provide power signals to the hoisting machine and/or hoisting machinery brakes. A load sensor is configured to gather elevator car load information, and the rescue drive device is configured to select, based on the elevator car load information, a first rescue run or a second rescue run.

Claims

1. A method for an automatic rescue operation of an elevator car in an elevator system, said elevator system comprising a hoisting machine and a battery-operated rescue drive device providing power signals to the hoisting machine and/or hoisting machinery brakes, the method comprising the steps of: gathering, by a load sensor, elevator car load information; and selecting based on the elevator car load information, by the rescue drive device, a first rescue run or a second rescue run, wherein said first rescue run comprises supplying electrical power from a battery of the rescue drive device to an electric motor of the hoisting machine and/or hoisting machinery brakes to initiate movement of the elevator car, wherein said second rescue run comprises shorting windings of the electric motor of the hoisting machine to apply dynamic braking of the electric motor, wherein the first rescue run is selected if the elevator car load is within a first range of a rated load of the elevator car, and wherein the second rescue run is selected if the elevator car load is within a second range of the rated load of the elevator car.

2. The method according to claim 1, wherein the first rescue run is selected if the elevator car load is within 25% to 75% of the rated load of the elevator car, and wherein the second rescue run is selected if the elevator car load is within 0% to 25% or 75% to 100% of the rated load of the elevator car.

3. The method according to claim 1, wherein at the beginning of the first rescue run, electrical power is supplied from the battery to resolve a rotor pole position of the electric motor of the hoisting machine, and wherein power signals are provided to the electric motor of the hoisting machine in order to generate pre-torque before the hoisting machinery brakes are opened.

4. The method according to claim 1, wherein the hoisting machinery brakes are opened by supplying power from the battery to the brakes one-by-one, and wherein after opening a brake, a power supply to the brake is reduced to a predefined level required to hold the brake open.

5. The method according to claim 3, wherein during the first rescue run, after opening the hoisting machinery brakes, electrical power is supplied from the battery to the electric motor of the hoisting machine and to the brakes to drive the elevator car towards a landing.

6. The method according to claim 1, wherein in the second rescue run, movement of the elevator car is initiated by activating motor dynamic braking, and wherein all motor phases are connected together using motor inverter power transistors, and subsequently the hoisting machinery brakes are opened one-by-one.

7. The method according to claim 6, wherein in a first mode of the second rescue run, dynamic braking is enabled, a measured speed of the electric motor of the hoisting machine is less than a threshold speed and a velocity control of the elevator car is disabled, and wherein a velocity of the elevator car increases until a dynamic braking torque of the electric motor of the hoisting machine meets a load torque such that a constant velocity is reached.

8. The method according to claim 6, wherein in a second mode of the second rescue run, dynamic braking is disabled, a measured speed of the electric motor of the hoisting machine is less than a threshold speed, velocity control of the elevator car is enabled, and a velocity reference is set equal to a measured velocity of the elevator car.

9. The method according to claim 6, wherein in a third mode of the second rescue run, a measured speed of the electric motor of the hoisting machine is equal to or higher than a threshold speed, velocity control of the elevator car is enabled and a velocity reference is set so that acceleration of the elevator car is continuous and rate-limited, and wherein a final velocity of the elevator car is a desired rescue velocity.

10. The method according to claim 1, wherein if an elevator positioning system indicates that a position of the elevator car is at an edge of a door zone area, power is drawn from the battery to generate braking torque in the electric motor of the hoisting machine.

11. The method according to claim 1, wherein in the second rescue run, to reduce an acceleration of the elevator car after the hoisting machinery brakes are open, windings of the electric motor of the hoisting machine are shorted to apply dynamic braking to the electric motor of the hoisting machine.

12. The method according to claim 1, wherein the rescue drive device determines a velocity of the elevator car by means of a motor encoder, and starts regenerative braking by initiating modulation of power transistors of an inverter of the electric motor of the hoisting machine when the velocity of the elevator car exceeds a predetermined threshold value.

13. The method according to claim 12, wherein for a period of the regenerative braking of the electric motor of the hoisting machine, the rescue drive device operates a speed control loop of the elevator car such that movement of the elevator car proceeds according to a predetermined speed profile towards a landing.

14. The method according to claim 1, wherein at the end of the second rescue run, a distance of the elevator car to a landing is measured, and wherein a brake dropping command is generated when the measured distance is less than a predetermined brake dropping limit.

15. The method according to claim 1, wherein in the second rescue run, a rotor pole position of the electric motor of the hoisting machine is resolved from operating parameters of the rotating electric motor during the dynamic braking of the electric motor.

16. A system for an automatic rescue operation of an elevator car, said elevator system comprising a hoisting machine and a battery-operated rescue drive device configured to provide power signals to the hoisting machine and/or hoisting machinery brakes, wherein a load sensor is configured to gather elevator car load information, and the rescue drive device is configured to select, based on the elevator car load information, a first rescue run or a second rescue run, wherein said first rescue run comprises supplying electrical power from a battery of the rescue drive device to an electric motor of the hoisting machine and/or hoisting machinery brakes to initiate movement of the elevator car, wherein said second rescue run comprises shorting windings of the electric motor of the hoisting machine to apply dynamic braking of the electric motor, wherein the battery-operated rescue drive device is configured to select the first rescue run if the elevator car load is within a first range of a rated load of the elevator car, and wherein the battery-operated rescue drive device is configured to select the second rescue run if the elevator car load is within a second range of the rated load of the elevator car.

17. The method according to claim 1, wherein the hoisting machinery brakes are opened by supplying pick power from the battery to the brakes one-by-one, and wherein after opening a brake, a power supply to the brake is reduced to a predefined level required to hold the brake open.

18. The method according to claim 2, wherein at the beginning of the first rescue run, electrical power is supplied from the battery to resolve a rotor pole position of the electric motor of the hoisting machine, and wherein power signals are provided to the electric motor of the hoisting machine in order to generate pre-torque before the hoisting machinery brakes are opened.

19. The method according to claim 2, wherein the hoisting machinery brakes are opened by supplying power from the battery to the brakes one-by-one, and wherein after opening a brake, a power supply to the brake is reduced to a predefined level required to hold the brake open.

20. The method according to claim 3, wherein the hoisting machinery brakes are opened by supplying power from the battery to the brakes one-by-one, and wherein after opening a brake, a power supply to the brake is reduced to a predefined level required to hold the brake open.

Description

[0045] For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. The invention is explained in more detail below using exemplary embodiments, which are specified in the schematic figures of the drawings, in which:

[0046] FIG. 1 shows a graph of an elevator speed profile during an automatic rescue operation according to an embodiment of the invention;

[0047] FIG. 2 shows a graph of an elevator speed profile during the automatic rescue operation according to the embodiment of the invention;

[0048] FIG. 3 shows a graph of a car position, a car velocity, a brake torque and a motor torque at an elevator load torque of 25% according to the embodiment of the invention; and

[0049] FIG. 4 shows a graph of the car position, the car velocity, the brake torque and the motor torque at an elevator load torque of 0% according to the embodiment of the invention.

[0050] Unless indicated otherwise, like reference numbers or signs to the figures indicate like elements.

[0051] FIG. 1 shows an example embodiment of an elevator speed profile during an automatic rescue operation when the elevator car load is lower than 25% or higher than 75% of a rated load of the elevator car. The figure shows a situation where the speed of the electric motor 12a of the hoisting machine 12 reaches a threshold speed SP2 during dynamic braking.

[0052] In the first mode M1 of a second rescue run, dynamic braking DB is enabled, a measured speed SP1 of the electric motor 12a of the hoisting machine 12 is less than a threshold speed SP2 and a velocity control VC of the elevator car 10 is disabled.

[0053] A velocity CV of the elevator car 10 increases until a dynamic braking torque of the electric motor 12a of the hoisting machine 12 meets a load torque such that a constant velocity CV is reached.

[0054] In a third phase M3 of the second rescue run R2, a measured speed SP1 of the electric motor 12a of the hoisting machine 12 is equal to or higher than the threshold speed SP2, velocity control VC of the elevator car 10 is enabled and a velocity reference is set so that acceleration of the elevator car 10 is continuous and rate-limited, wherein a final velocity of the elevator car 10 is a desired rescue velocity CV.

[0055] FIG. 2 shows a situation where the motor speed is saturated due to the dynamic braking. Dynamic braking is enabled and the measured motor speed is under the threshold speed SP2. In this mode, speed control is disabled. The elevator velocity accelerates due to gravity.

[0056] The velocity of the elevator car 10 increases until motor dynamic braking torque meets the load torque such that constant speed is reached. Motor torque is zero or opposite to the traveling direction such that the elevator car 10 is braked by the electric motor of the hoisting machine by its own regenerating electrical energy.

[0057] The depicted mode 2 is then subsequently used. Dynamic braking is disabled and the measured motor speed SP1 is under the threshold value SP2. The elevator accelerates due to gravity. In this mode, speed control is enabled and speed reference is set equal to the measured speed SP1.

[0058] Subsequently, the third mode M3 is used if the motor speed SP1 is equal to or higher than the threshold speed SP2. Speed control is enabled and the speed reference is formed so that acceleration is continuous and rate-limited and a final speed is the desired rescue speed SP3. Motor torque is opposite to the traveling direction, i.e. the elevator car is braked by the electric motor of the hoisting machine by regenerating electrical energy.

[0059] FIG. 3 shows a graph of a car position, a car velocity, a brake torque and a motor torque at an elevator load torque of 25% according to the embodiment of the invention

[0060] The system and method for an automatic rescue operation of an elevator car 10 in an elevator system 1 is depicted. Said elevator system 1 further comprises a hoisting machine 12 and a battery-operated rescue drive device 14 providing power signals to the hoisting machine 12 and/or hoisting machinery brakes 16. The method comprises gathering, by a load sensor 18, elevator car load information. Furthermore, the method comprises selecting based on the elevator car load information, by the rescue drive device 14, a first rescue run R1 or a second rescue run R2.

[0061] Said first rescue run R1 comprises supplying electrical power from a battery 20 of the rescue drive device 14 to an electric motor 12a of the hoisting machine 12 and/or hoisting machinery brakes 16 to initiate movement of the elevator car 10.

[0062] Said second rescue run R2 comprises shorting windings of the electric motor 12 of the hoisting machine to apply dynamic braking DB of the electric motor 12, wherein the first rescue run R1 is selected if the elevator car load is within a first range B1 of a rated load of the elevator car. The second rescue run R2 is selected if the elevator car load is within a second range B2 of the rated load of the elevator car.

[0063] In addition, the first rescue run R1 is selected if the elevator car load is within 25% to 75% of the rated load of the elevator car 10. The second rescue run R2 is selected if the elevator car load is within 0% to 25% or 75% to 100% of the rated load of the elevator car. The rated load is understood to be the full load of the elevator car. However, those ranges are only exemplary and may vary based on a balancing ratio of the elevator car, i.e. whether a counterweight is dimensioned to 50% of the weight of a full load plus the elevator car or alternatively, for example, to 40%.

[0064] At the beginning of the first rescue run R1, electrical power is supplied from the battery 20 to resolve a rotor pole position of the electric motor 12a of the hoisting machine 12. Subsequently, power signals are provided to the electric motor 12a of the hoisting machine 12 in order to generate a pre-torque before the hoisting machinery brakes 16 are opened. The hoisting machinery brakes 16 are opened by supplying power, in particular pick power, from the battery 20 to the brakes one-by-one. After opening a brake, a power supply to the brake is reduced to a predefined level required to hold the brake open. At first pick power is supplied to the first brake and consequently to the second brake after power supply to the first brake has been reduced to the limit for holding the first brake open. This way momentary net power required by the brakes can be reduced.

[0065] During the first rescue R1, after opening the hoisting machinery brakes 16, electrical power is supplied from the battery 20 to the electric motor 12a of the hoisting machine 12 and to the brakes to drive the elevator car 10 towards a landing L. The car position CP of the elevator car moves from a starting position to a door zone DZ, said door zone being indicated by the letters A, B, C and D.

[0066] When an elevator positioning system 22 indicates that the elevator car position is at the edge of the door zone DZ area and the elevator car 10 has to be stopped to reach the destination floor level, power is drawn from the battery 20 since the electric motor 12a no longer acts as a generator when motor torque begins to decelerate the elevator car.

[0067] To avoid drawing excessive current from the battery during the deceleration phase, motor torque reference or motor current reference is limited to the same value the motor torque reference or motor current reference is at the time if the measured battery current or the measured battery power exceeds the defined battery current limit or battery power limit. The car velocity CV of the elevator car 10 follows a smooth run profile SRP. Alternatively, the elevator car can be controlled according to a ramp stop CSR or alternatively, by means of machinery brakes.

[0068] In addition, the blending of brake torque BT and motor torque MT is shown with respect to the car position CP and the car velocity CV of the elevator car 10, wherein a motor torque limit MTL is due to a battery current limitation. Motor torque and current may be limited during the deceleration phase to avoid exceeding battery current limits.

[0069] FIG. 4 shows a graph of the car position, the car velocity, the brake torque and the motor torque at an elevator load torque of 0% according to the embodiment of the invention.

[0070] Motor torque is limited during the deceleration phase of the automatic rescue run due to battery current limitation or a battery power limitation. The brake torque is equal and opposite to the elevator load torque at the start and stop when the elevator car 10 is not moving. Stopping procedures are started when the elevator car positioning system 22 indicates that the elevator car 10 is at the edge of the door zone DZ.

[0071] Stopping is started either with a smooth run profile SRP at t1 but actual speed follows the curve CSR since motor torque becomes limited. In this example, machinery brakes are dropped at t2 when the elevator car position overshoots the exact floor level at the boundary between regions B and C.

[0072] In the second rescue run R2, movement of the elevator car 10 is initiated by activating motor dynamic braking DB. All motor phases are connected together using motor inverter power transistors, and subsequently the hoisting machinery brakes 16 are opened one-by-one.

[0073] If the elevator positioning system 22 indicates that the position of the elevator car 10 is at the edge of the door zone DZ area, power is drawn from the battery 20 to generate torque in the electric motor 12a of the hoisting machine 12.

[0074] To reduce an acceleration of the elevator car 10 after the hoisting machinery brakes 16 are open, windings of the electric motor 12a of the hoisting machine 12 are shorted to apply dynamic braking DB to the electric motor 12a of the hoisting machine 12.

[0075] The rescue drive device 14 determines a velocity of the elevator car 10 by means of a motor encoder, and starts regenerative braking by initiating modulation of power transistors of an inverter of the electric motor 12a when the velocity of the elevator car 10 exceeds a predetermined threshold value.

[0076] For a period of the regenerative braking of the electric motor 12a, the rescue drive device 14 operates a speed control loop of the elevator car 10 such that movement of the elevator car 10 proceeds according to the predetermined speed profile, i.e. SRP or CSR, towards the landing L.

[0077] According to an embodiment, at the end of the second rescue run R2, a distance of the elevator car 10 to the landing L is measured, wherein a brake dropping command is generated when the measured distance is less than a predetermined brake dropping limit.