Magnetic bearing apparatus and method for reducing vibration caused by magnetic bearing apparatus

A method for reducing vibration caused by a magnetic bearing apparatus which supports a rotational shaft, the method comprising:

• (i) supporting the rotational shaft in a contactless fashion through magnetic levitation by flowing a first electric current with which the rotational shaft is levitated and supported to an electromagnet of the magnetic bearing apparatus and using an electromagnetic force which is generated by the first electric current flown to the electromagnet;
• (ii) detecting vibration by at least one vibration sensor which is provided within an influential range of vibration which is generated by the rotation of the rotational shaft in the (i) supporting the rotational shaft;
• and
• (iii) supporting the rotational shaft in a contactless fashion through magnetic levitation by flowing a second electric current to the electromagnet in place of the first electric current and using an electromagnetic force generated by the second electric current flown to the electromagnet at a predetermined periodic timing so that vibration is reduced to a lower level than a vibration value detected during the (i) supporting the rotational shaft in at least one of setting location of the at least one vibration sensor, the second electric current having an electric current value resulting from adding or deducting by a specific value to or from an electric current value of the first electric current.

A magnetic bearing apparatus for supporting a rotational shaft, the magnetic bearing apparatus comprising:

• a magnetic bearing for supporting the rotational shaft in a contactless fashion through magnetic levitation by using an electromagnetic force which is generated by an electric current flown to an electromagnet;
• a rotation sensor for detecting the rotation of the rotational shaft;
• a controller for controlling the electric current flown to the electromagnet;
• and
• at least one vibration sensor which is provided within an influential range of vibration which is generated by the rotation of the rotational shaft, wherein
• the controller controls the electric current flown to the electromagnet as follows:
• the controller flows a first electric current for levitating and supporting the rotational shaft to the electromagnet to obtain a first vibration value;
• the controller flows a third electric current to the electromagnet at a second periodic timing to obtain a second vibration value;
• wherein the controller determines a second electric current and a first periodic timing based on the first vibration value, the second vibration value, the third electric current, and the second periodic timing so that the vibration is reduced to a lower level than the first vibration value;
• and
• the controller flows the second electric current to the electromagnet at the first periodic timing.