Method for monitoring the operating condition of an elevator system on the basis of frequency component

1. A method for monitoring the operating condition of an elevator system, comprising the steps of:

taking samples of a control signal of a drive device of an elevator;

determining from the series of samples taken a frequency component that is characteristic to a part of the elevator assembly driven with the drive device; and

monitoring the operating condition of the part of the elevator assembly on the basis of the determined frequency component,

wherein the control signal is speed input and output signals of a frequency converter that includes a cascade speed regulator controlling a speed of said part of the elevator assembly driven with the drive device.

2. The method according to claim 1 , further comprising the steps of:

forming one or more limit values for the frequency components;

comparing the one or more limit values to the determined frequency component; and

monitoring the operating condition of the part of the elevator assembly on the basis of the comparison.

3. The method according to claim 2 , further comprising the step of:

if the determined frequency component deviates from a permitted range specified with the limit values, deducing that the operating condition of the part in question of the elevator assembly has deteriorated.

4. The method according to claim 3 , further comprising the steps of:

determining the remaining service life of a part of the elevator assembly based on the magnitude of the deviation from the permitted range of the determined frequency component; and

forming a monitoring signal for indicating the remaining service life of the part of the elevator assembly.

5. The method according to claim 1 further comprising the step of:

if it is detected that the operating condition of the part of the elevator assembly has deteriorated, forming a monitoring signal for specifying the part of the elevator assembly having a deteriorated operating condition.

6. The method according to claim 1 wherein the drive device is an electric motor and said method further comprises the steps of:

synchronizing the moment of sampling the control signal of the electric motor with the angle between the rotor and the stator of the electric motor; and

determining a frequency component from the series of samples using a DFT algorithm.

7. The method according to claim 1 further comprising the steps of:

adjusting the movement of a rotating part of the elevator assembly with the drive device according to a movement profile to be determined for the movement of the rotating part;

monitoring the operating condition of the rotating part of the elevator assembly; and

changing the movement profile of the rotating part of the elevator assembly on the basis of a change detected in the operating condition of the rotating part of the elevator assembly.

8. The method according to claim 7 , further comprising the step of:

adjusting a frequency component characteristic to a rotating part of an elevator assembly towards a permitted range of the frequency component by changing the movement profile of the rotating part of the elevator assembly in response to the magnitude of the deviation from the permitted range of the frequency component determined from the series of samples.

9. The method according to claim 1 further comprising the steps of:

taking samples of the control signal of the drive device of the elevator when driving one or more parts of the elevator assembly with the drive device;

selecting a plurality of frequency components characteristic to one or more parts of the elevator assembly;

determining the frequency components from the series of samples taken; and

monitoring the operating condition of the one or more parts in question of the elevator assembly on the basis of the determined frequency components.

10. An elevator system, comprising:

a controllable drive device, which is configured to drive one or more parts of an elevator assembly; and

a control device for controlling the drive device,

wherein the control device is configured to perform the method according to claim 1 for monitoring the operating condition of the elevator system.

11. The elevator system according to claim 10 , wherein the drive device is an electric motor of a hoisting machine of an elevator.

12. The elevator system according to claim 11 , wherein a part of the elevator assembly is the traction sheave of the hoisting machine.

13. The elevator system according to claim 11 , wherein a part of the elevator assembly is a diverting pulley of an elevator.

14. The elevator system according to claim 10 , wherein the drive device is an electric motor of a door operator of an elevator.

15. The elevator system according to claim 14 , wherein a part of the elevator assembly is a traction sheave of a door operator of an elevator.

16. The method according to claim 2 , further comprising the step of:

if it is detected that the operating condition of the part of the elevator assembly has deteriorated, forming a monitoring signal for specifying the part of the elevator assembly having a deteriorated operating condition.

17. The method according to claim 3 , further comprising the step of:

if it is detected that the operating condition of the part of the elevator assembly has deteriorated, forming a monitoring signal for specifying the part of the elevator assembly having a deteriorated operating condition.

18. The method according to claim 4 , further comprising the step of:

if it is detected that the operating condition of the part of the elevator assembly has deteriorated, forming a monitoring signal for specifying the part of the elevator assembly having a deteriorated operating condition.

19. The method according to claim 2 wherein the drive device is an electric motor and said method further comprises the steps of:

synchronizing the moment of sampling the control signal of the electric motor with the angle between the rotor and the stator of the electric motor; and

determining a frequency component from the series of samples using a DFT algorithm.

20. A method for monitoring the operating condition of an elevator system including an elevator cart, comprising the steps of:

taking samples of a control signal of a motor of an elevator which drives the elevator cart to move;

determining, from the series of samples taken, a frequency component that is characteristic to at least a rotating part of the elevator assembly driven by the motor, the rotating part being at least one of a traction sheave of a hoisting machine, via which ropes pass to suspend the elevator cart, and a diverting pulley, via which ropes pass into connection with the elevator cart; and

monitoring the operating condition of the part of the elevator assembly on the basis of the determined frequency component.