Methods, systems and devices for determining a resonance frequency of a mechanical system

Patent metadata

Field	Value
Publication number	US-2021190582-A1
Application number	US-202017123285-A
Country	US
Kind code	A1
Filing date	Dec 16, 2020
Priority date	Dec 20, 2019
Publication date	Jun 24, 2021
Grant date	—

Abstract

A method for determining a resonance frequency of a mechanical system including an electric motor coupled to a mechanical load, the method including:starting the motor by providing a supply voltage using a motor controller;once the electric motor is running at a predefined target rotational speed, applying a first excitation signal comprising a voltage pulse superimposed to the supply voltage;measuring a mechanical response of the mechanical system, using a measurement system coupled to the motor; andanalyzing the measured response, to determine at least one resonance frequency of the mechanical system.

First claim

1 . A method for determining a resonance frequency of a mechanical system comprising an electric motor coupled to a mechanical load, said method comprising:
starting the motor by providing a supply voltage using a motor controller; once the electric motor is running at a predefined target rotational speed, applying a first excitation signal comprising a voltage pulse superimposed to the supply voltage; measuring a mechanical response of the mechanical system, using a measurement system coupled to the motor; and analyzing the measured response, to determine at least one resonance frequency of the mechanical system.

2 . The method according to claim 1 , wherein measuring a mechanical response of the mechanical system comprises measuring stator currents of the motor and wherein the resonance frequency of the mechanical system is determined based on the measured stator currents.

3 . The method according to claim 2 , wherein determining the resonance frequency of the mechanical system comprises:
calculating, from the measured stator currents, corresponding stator current values expressed in the synchronous frame of the motor; identifying oscillations in the corresponding stator current values; determining the resonance frequency based on the identified oscillations.

4 . The method according to claim 3 , wherein the method further comprises calculating phase difference values between the calculated corresponding stator current values and determining the resonance frequency based on the oscillations identified in the phase difference values.

5 . The method according to claim 1 , wherein measuring a mechanical response of the mechanical system comprises measuring a rotation speed of the motor and wherein the resonance frequency of the mechanical system is determined based on the measured rotation speed.

6 . The method according to claim 1 , wherein the method further comprises applying at least one additional excitation voltage pulse and measuring the corresponding response of the mechanical system, the resonance frequency being determined from the analysis of the measured responses.

7 . The method according to claim 6 , wherein said at least one additional excitation pulse differs from the first excitation pulse by at least one parameter, such as pulse length, or pulse amplitude, or the time interval between two consecutive pulses.

8 . The method according to claim 1 , wherein the method further comprises:
changing the supply voltage using the motor controller to set the motor into a different rotational speed; once the electric motor is running at the new target rotational speed, applying another excitation signal comprising a voltage pulse superimposed to the supply voltage, using the pulse generator; measuring the new mechanical response of the mechanical system, using the measurement system; analyzing the measured response, to determine at least one resonance frequency of the mechanical system.

9 . The method according to claim 1 , wherein starting the motor comprises ramping up the supply voltage towards a threshold voltage value, and wherein the motor controller is placed in an open loop control mode once the electric motor is running at the predefined target rotational speed.

10 . The method according to claim 1 , wherein the method includes determining the type of mechanical coupling between the load and the motor based on the measured mechanical response.

11 . A method for driving a mechanical system comprising an electric motor coupled to a mechanical load, said method comprising:
determining the resonance frequency of the mechanical system using a method in accordance with claim 1 ; modifying at least one operating parameter of the motor to avoid generating excitations near or at the determined resonance frequency.

12 . A device for determining a resonance frequency of a mechanical system comprising an electric motor coupled to a mechanical load, said device being configured to:
start the motor by providing a supply voltage using a motor controller; once the electric motor is running at a predefined target rotational speed, applying a first excitation signal comprising a voltage pulse superimposed to the supply voltage; measure a mechanical response of the mechanical system, using a measurement system coupled to the motor; and analyze the measured response, to determine at least one resonance frequency of the mechanical system.

Assignees

• Schneider Toshiba Inverter Europe Sas

Inventors

• Jebai Al Kassem
• Koteich Mohamad

Classifications

• G01H13/00 Primary

  Measuring resonant frequency · CPC title

• G01M13/00

  Testing of machine parts · CPC title

• H02P29/50

  Reduction of harmonics · CPC title

• H02P29/024

  Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load · CPC title

• H02P29/026

  the fault being a power fluctuation · CPC title