System and Method of Integrated Vibration Monitoring in Motor Drives

• US 20190310130A1
• Filed: 06/24/2019
• Published: 10/10/2019
• Est. Priority Date: 04/10/2017
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Inventors: Miklosovic, Robert J., Chaffee, Mark A.
• Granted Patent: US 10,753,790 B2
• Time in Patent Office: Days
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01H 3/04 Frequency
• CPC Class Codes: G01M 13/00 Testing of machine parts
• CPC Class Codes: G01M 13/028 Acoustic or vibration analysis
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis
• CPC Class Codes: G01M 7/00 Vibration-testing of structures; Shock-testing of structures G01M9/00 takes precedence
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/4436 with a reference signal amplitude comparison G01N29/48
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14
• CPC Class Codes: H02P 23/12 Observer control, e.g. using Luenberger observers or Kalman filters
• CPC Class Codes: H02P 23/14 Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage
• CPC Class Codes: H02P 6/10 Arrangements for controlling torque ripple, e.g. providing reduced torque ripple

Abstract

An improved system and method for analyzing motor performance to detect vibration of an electric machine controlled by a motor drive is disclosed. A load observer determines an estimated torque present as a load on the motor as a function of input signals corresponding to a desired torque to be generated by the motor and to a measured angular position of the motor during operation. The motor drive determines a frequency response of the estimated torque to identify at what magnitude and frequency any vibration components are present within the estimated torque signal. The motor drive compares the frequency response of the estimated torque signal to set points. If the measured magnitude of vibration at a particular frequency, as seen in the frequency response, exceeds a threshold set in one of the set points for that frequency, the motor drive

Claims

1. A method for monitoring vibration in a motor connected to a motor drive, the method comprising the steps of:

generating a torque reference signal with the motor drive, wherein the torque reference signal corresponds to desired operation of the motor connected to the motor drive;

determining an estimated torque signal in a condition monitor module executing on the motor drive, wherein the estimated torque signal corresponds to a load present on the motor;

storing at least one frequency at which the motor drive monitors vibration in a memory device of the motor drive;

generating a frequency response of the estimated torque signal with the controller, wherein the frequency response includes a magnitude of vibration at the at least one frequency;

reading at least one threshold from the memory device, wherein each threshold corresponds to one of the at least one frequencies;

comparing the magnitude of vibration in the frequency response to the threshold for each of the at least one frequencies; and

setting a status flag on the motor drive when the magnitude of vibration in the frequency response is greater than the threshold of the corresponding frequency stored in the memory device.

2. The method of claim 1 further comprising the initial steps of:

storing a plurality of frequencies in the memory device;

storing a plurality of thresholds in the memory device, wherein each of the plurality of thresholds corresponds to one of the plurality of frequencies; and

identifying at least one of the plurality of frequencies as a desired frequency at which to monitor vibration, wherein the at least one frequency at which the motor drive monitors vibration is the desired frequency.

3. The method of claim 2 wherein:

the step of identifying at least one of the plurality of frequencies as the desired frequency includes identifying a plurality of frequencies as a plurality of desired frequencies;

the frequency response includes a magnitude of vibration at each of the plurality of desired frequencies;

a threshold for each of the plurality of desired frequencies is read from the memory device; and

a source of vibration is identified when the magnitude of vibration at each of the plurality of desired frequencies is greater than the corresponding threshold.

4. The method of claim 1 wherein the estimated torque signal isolates a disturbance torque at an output of the motor from the torque reference signal and wherein at least one source of vibration is identified as a function of the disturbance torque.

5. The method of claim 1 further comprising the step of resetting the status flag on the motor drive when the magnitude of vibration in the frequency response is less than the threshold of the corresponding frequency stored in the memory device.

6. The method of claim 1 wherein the step of determining the estimated torque signal further comprises the steps of:

obtaining a position feedback signal from a position feedback device operatively connected to the motor; and

determining the estimated torque as a function of the position feedback signal and of the torque reference signal.

7. The method of claim 6 wherein the step of determining the estimated torque signal further comprises the step of determining one of an angular position, an angular velocity, and an angular acceleration from the position feedback signal, wherein the estimated torque is determined as a function of one of the angular position, the angular velocity, and the angular acceleration determined from the position feedback signal.

19. The motor drive of claim 1.8 wherein the controller is further configured to:

measure the feedback signal from the position feedback device;

determine an angular velocity at which the motor is operating as a function of the position feedback signal; and

determine the at least one predefined frequency as a function of the angular velocity.

8. A method for monitoring vibration in a motor connected to a motor drive, the method comprising the steps of:

determining an estimated torque present at an output of the motor using the motor drive;

generating a frequency response of the estimated torque with the motor drive, wherein the frequency response is determined for at least one predefined frequency;

reading at least one threshold from a memory device in the motor drive, wherein each of the at least one thresholds corresponds to one of the at least one predefined frequencies; and

identifying at least one vibration when a magnitude of the frequency response for the at least one predefined frequency exceeds the at least one threshold for the corresponding frequency.

9. The method of claim 8 further comprising the initial steps of:

storing the at least one predefined frequency in the memory device; and

storing the at least one threshold in the memory device.

10. The method of claim 9 wherein:

the step of generating the frequency response includes determining the frequency response for a plurality of predefined frequencies;

the frequency response includes a magnitude of vibration at each of the plurality of predefined frequencies;

the threshold for each of the plurality of predefined frequencies is read from the memory device; and

at least one vibration is identified when the magnitude of vibration at each of the plurality of desired frequencies is greater than the corresponding threshold.

11. The method of claim 8 further comprising the steps of:

setting a status flag on the motor drive when the magnitude of the at least one predefined frequency in the frequency response is greater than the threshold corresponding to the frequency; and

resetting the status flag on the motor drive when the magnitude of the at least one predefined frequency in the frequency response is less than the threshold corresponding to the frequency.

12. The method of claim 8, further comprising the steps of:

obtaining a position feedback signal from a position feedback device operatively connected to the motor;

determining an angular velocity at which the motor is operating as a function of the position feedback signal; and

determining the at least one predefined frequency as a function of the angular velocity.

13. The method of claim 8 wherein the step of determining the estimated torque present at the output of the motor further comprises the steps of:

obtaining a position feedback signal from a position feedback device operatively connected to the motor; and

determining the estimated torque as a function of the position feedback signal.

14. The method of claim 13 wherein the step of determining the estimated torque present at the output of the motor further comprises the step of determining one of an angular position, an angular velocity, and an angular acceleration from the position feedback signal, wherein the estimated torque is determined as a function of one of the angular position, the angular velocity, and the angular acceleration determined from the position feedback signal.

15. A motor drive operative to determine a vibration in a motor connected to the motor drive, the motor drive comprising:

a first input configured to receive a reference signal corresponding to a desired operation of the motor connected to the motor drive;

a non-transitive memory device configured to store;

a plurality of instructions,

at least one predefined frequency, and

at least one threshold, wherein each threshold corresponds to one of the at least one predefined frequencies; and

a controller configured to execute the plurality of instructions to;

determine an estimated torque present at the motor;

generate a frequency response of the estimated torque, wherein the frequency response is determined for the at least one predefined frequency;

read the at least one threshold from the non-transitory memory device; and

identify at least one vibration when a magnitude of the frequency response for the at least one predefined frequency exceeds the at least one threshold for the corresponding frequency.

16. The motor drive of claim 15 wherein the controller is further configured to:

generate the frequency response of the estimated torque for a plurality of predefined frequencies, wherein the frequency response includes a magnitude of vibration at each of the plurality of predefined frequencies;

read the threshold for each of the plurality of predefined frequencies from the memory device; and

identify at least one vibration when the magnitude of vibration at each of the plurality of desired frequencies is greater than the corresponding threshold.

17. The motor drive of claim 15 wherein the controller is further configured to:

set a status flag on the motor drive when the magnitude of the frequency in the frequency response is greater than the threshold for the corresponding frequency; and

reset the status flag on the motor drive when the magnitude of the frequency in the frequency response is less than the threshold for the corresponding frequency.

18. The motor drive of claim 15 further comprising a second input configured to receive a feedback signal from a position feedback device operatively connected to the motor.

20. The motor drive of claim 18 wherein the controller is further configured to:

measure the feedback signal from the position feedback device; and

determine the estimated torque as a function of the position feedback signal.