Method for operating rotating machinery by means of a variable speed drive and variable speed drive for performing the method

Abstract

The present invention is directed at a method for operating rotating machinery, such as an electric motor, by means of a variable speed drive (VSD). The variable speed drive is provided for identifying mechanical resonance points by means of a sensor and corresponding speeds of the machinery; storing the speeds at which the identified mechanical resonance points occur; and bypassing the speeds at which the identified mechanical resonance points occur during operation of the rotating machinery. The invention is also directed at a variable speed drive for performing said method.

Claims

1. A method for operating rotating machinery, such as an electric motor, by means of a variable speed drive, wherein the variable speed drive is provided for identifying mechanical resonance points by means of a sensor and corresponding speeds of the machinery; storing the speeds at which the identified mechanical resonance points occur; and bypassing the speeds at which the identified mechanical resonance points occur during operation of the rotating machinery.

2. The method according to claim 1, wherein the mechanical resonance points and/or the vibration response of the rotating machinery are identified during a speed and frequency sweep performed by the variable speed drive.

3. The method according to claim 1, wherein the mechanical resonance points are calculated from baseline values.

4. The method according to claim 1, wherein the bypass range is adjustable.

5. The method according to claim 1, wherein the method is performed automatically, in particular at given time intervals.

6. The method according to claim 1, wherein the sensor is a sensor of a smart phone which is physically connected to the rotating machinery.

7. The method according to claim 6, wherein the smart phone is connected to the variable speed drive for transmitting sensor data to the variable speed drive and/or for controlling the variable speed drive.

8. The method according to claim 1, wherein the sensor, in particular an accelerometer, is permanently connected to the rotating machinery.

9. A variable speed drive for performing the method according to claim 1.

10. The method according to claim 2, wherein the mechanical resonance points are calculated from baseline values.

11. The method according to claim 2, wherein the bypass range is adjustable.

12. The method according to claim 3, wherein the bypass range is adjustable.

13. The method according to claim 2, wherein the method is performed automatically, in particular at given time intervals.

14. The method according to claim 3, wherein the method is performed automatically, in particular at given time intervals.

15. The method according to claim 4, wherein the method is performed automatically, in particular at given time intervals.

16. The method according to claim 2, wherein the sensor is a sensor of a smart phone which is physically connected to the rotating machinery.

17. The method according to claim 3, wherein the sensor is a sensor of a smart phone which is physically connected to the rotating machinery.

18. The method according to claim 4, wherein the sensor is a sensor of a smart phone which is physically connected to the rotating machinery.

19. The method according to claim 5, wherein the sensor is a sensor of a smart phone which is physically connected to the rotating machinery.

20. The method according to claim 1, wherein the sensor, in particular an accelerometer, is permanently connected to the rotating machinery.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Further details and advantages of the invention are described with reference to the figures. The figures show:

[0034] FIG. 1: a flow chart depicting the presently described method; and

[0035] FIG. 2: a schematic representation of the present invention.

DETAILED DESCRIPTION

[0036] FIG. 1 shows a flow chart depicting the presently described method. A frequency converter 1, which may be part of a variable speed drive, is connected to some rotating machinery, such as an electric motor 2. The terms variable speed drive and frequency converter 1 are used in a broad sense and may be used interchangeably. They may refer to any device or subcomponent used for controlling rotating machinery. One or more vibrations sensors 3 may be mechanically coupled to the motor 2 and/or the frequency converter 1.

[0037] The frequency converter 1 may receive signals from the vibrations sensor 3. Based on the signals received, the frequency converter's 1 computing unit 5 performs a resonance detection computation and controls the motor 2 to bypass speeds at which resonances occur. In particular, a speed controller 4 may be provided such that its reference values are adjusted to omit speeds of the motor 2 at which resonances occur. The signals of the speed controller 4 may be fed back to the computing unit 5 for improving the resonance detection and motor control.

[0038] The variable speed drive is provided for performing the following steps: [0039] identifying mechanical resonance points by means of the sensor 3 and corresponding speeds of the machinery; [0040] storing the speeds at which the identified mechanical resonance points occur; and [0041] bypassing the speeds at which the identified mechanical resonance points occur during operation of the rotating machinery.

[0042] The sensor 3 may be an integral part of the machinery or the drive. Alternatively or additionally, it may be an external sensor 3 of a separate device such as a smart phone.

[0043] The mechanical resonance points and/or the vibration response of the rotating machinery may be identified during a speed and frequency sweep performed by the variable speed drive. In particular, the normal level of vibrations may be established by performing a speed and frequency sweep. The sweep may be performed from a minimum to a maximum speed of the motor 2.

[0044] The mechanical resonance points may be calculated from baseline values. The resonance points and the associated speeds may be calculated automatically. A user of the invention may visualise the resonance points and/or adjust a bypass range and vibrations tolerances. The visualisation may be performed using the dive alone or by means of a device connected to the drive, such as a smart phone. Up to four or more resonance points may be supported in the nominal speed range of the machinery.

[0045] The invention makes it possible to operate the motor 2 exclusively or nearly exclusively outside its resonance points. In addition, if the resonance frequency changes due to e.g. mechanical changes, the correction of the resonance points and the corresponding bypass speeds may also be performed automatically.

[0046] FIG. 2 is a schematic representation of one embodiment of the present invention. Here, the sensor 3 is a sensor 3 of a smart phone 6, which is in physical contact to the rotating machinery 7. The term rotating machinery 7 may be understood in a broad sense and may refer to the electric motor 2 and/or additional components such as the drive or frequency converter 1 and/or additional hardware such as gears or fastening structures not shown in the figures.

[0047] The entire smart phone 6 may be rigidly connected to the rotating machinery 7, the drive and/or other relevant components. An adapter or dedicated machinery or drive portions may be provided for establishing a riding connection between the smart phone 6 and said other components. The connection may be sufficiently rigid so as to ensure that the vibration of the machinery 7 is transferred adequately to the smart phone 6 or, more precisely, to the sensor 3.

[0048] Additionally or alternatively, a dedicated place of deposit may be provided at the drive and/or at the machinery 7. The place of deposit may be shaped such that the smart phone 6 may rest therein safely during the operation of the machinery 7, especially when the machinery 7 is operated at resonance points. The connection between the smart phone 6 and the machinery 7 may be such that vibrations of the machinery 7 may be transmitted adequately to the sensor 3.

[0049] The smart phone 6 may be connected to the variable speed drive for transmitting sensor data to the variable speed drive and/or for controlling the variable speed drive. A wireless connection such as a Bluetooth connection may be provided between the smart phone 6 and the drive. The smart phone 6 may comprise some connection hardware 11, which may interact with corresponding connections hardware 21 of the drive.

[0050] The sensor 3, in particular an accelerometer, may be permanently connected to the rotating machinery 7. In case a sensor 3 is permanently attached to the rotating machinery 7, said sensor 3 may be connected directly to the drive and/or to a smart phone 6. The permanently connected sensor 3 makes it possible to continuously update the baseline and add a frequency-band around the resonance. In one embodiment of the invention, more than one sensors 3 is used, wherein one sensor 3 may be a sensor 3 of the smart phone 6 and another sensor may be fixedly connected to the machinery 7 or the drive.

[0051] The invention is also directed at a variable speed drive for performing the presently described method. The drive may comprise any hardware components, which are necessary for performing the presently described method. In particular, the drive may comprise a dedicated place of deposit and/or some wireless connection means 21 for connecting the drive to a smart phone 6.

[0052] While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.