Method, an arrangement and a frequency converter for identification of torsional natural frequencies of a drivetrain system

An arrangement for identification of torsional natural frequencies of a drivetrain system, said drivetrain system comprising a frequency converter, an electric machine controlled by said frequency converter, and a driven/driving machine system connected to said electric machine,

• wherein said frequency converter is arranged for controlling said electric machine for producing mechanical excitation by said electric machine in said drivetrain system, said excitation comprising torsional excitation as an impulse, random noise, pseudo random noise, or a harmonic excitation sweep, and said excitation effecting an excitation response in said drivetrain system;
• wherein said frequency converter or a data analysis system of said arrangement is arranged for identifying torsional natural frequencies of said drivetrain system utilizing said excitation response;
• and
• wherein said frequency converter is arranged for measuring said excitation response from the current flowing between said frequency converter and said electric machine as measured current data.

A frequency converter for a drivetrain system, said drivetrain system comprising said frequency converter, an electric machine controlled by said frequency converter, and a driven/driving machine system connected to said electric machine, wherein said frequency converter is arranged:

• for controlling said electric machine for producing mechanical excitation by said electric machine in said drivetrain system, said excitation comprising torsional excitation as an impulse, random noise, pseudo random noise, or a harmonic excitation sweep, and said excitation effecting an excitation response in said drivetrain system;
• for identifying torsional natural frequencies of said drivetrain system utilizing said excitation response;
• and
• for measuring said excitation response from the current flowing between said frequency converter and said electric machine as measured current data.