Method, an arrangement and a frequency converter for controlling vibration of an electric machine

An arrangement for controlling lateral vibration of a variable-frequency-driven electric machine that is an electric motor connected to a driven machine system via a coupling arrangement, said arrangement comprising:

• a frequency converter, and
• one or more vibration sensors,
• wherein said one or more vibration sensors is/are arranged for measuring the lateral vibration from said variable-frequency-driven electric machine and for producing measured vibration data, wherein said one or more vibration sensors are attached on the variable-frequency-driven electric machine;
• and
• wherein said frequency converter is arranged for generating a control torque and for exerting said control torque on a stator of said variable-frequency-driven electric machine, said control torque being determined utilizing said measured vibration data as a time-dependent function of measured vibrations, said control torque being a reactive control torque that acts in an opposite direction to an action torque that rotates a rotor of said variable-frequency-driven electric machine, wherein said exerted control torque produces a variation of horizontal displacement for suppression of horizontal vibration of said variable-frequency-driven electric machine to compensate the horizontal vibrational displacement of said variable-frequency-driven electric machine, wherein said exerted control torque is used for suppression of horizontal vibration of said variable-frequency-driven electric machine at least to control two low frequency horizontal vibration modes, where a stator-frame and the rotor of said variable-frequency-driven electric machine move horizontally with both ends in a same phase.