Hitachi, Ltd.

Mitsuho Yoneyama

Osami Matsushita

Yasuo Fukushima

Naohiko Takahashi

Minoru Hiroshima

Michiyuki Takagi

Toyomi Sugaya

Yoshiaki Abe

Tadashi Kaneki

Naofumi Sakanashi

Teturo Ohashi

Ikuhiro Saito

Naohumi Sakanashi

A controller of magnetic bearing controls the rotor speed with a reduced drive current while suppressing the rotor vibration. The controller implements the ABS control, N-cross control, N-straight control and FF control in proper combination in addition to the basic PID control. A computer in the controller determines the activation of each control in accordance with a predetermined table of control plan in response to the detected rotor speed.

Method and apparatus for controlling a magnetic bearing

A balancing method for balancing a flexible rotor is disclosed. First, the rotor is rotated and vibration of the rotor is measured to determine resonance speeds. Vibration exciting forces of frequencies synchronized with the rotor rotation in two orthogonal directions are imparted to the rotor or rotor support bearings while rotating the rotor at a speed near the respective resonance speeds. The amplitude and the phase of the vibration exciting force which reduces the resonance vibration of the rotor are then determined. A correction weight on the basis of the amplitude and the phase of the vibration exciting force is then determined. Balancing work on the rotor such as grinding of the rotor or addition of a mass to the rotor in accordance with the correction weight is then carried out, followed by a rotor rotation conducted for the purpose of confirming the effect of the balancing work.

Balancing method for flexible rotor and a balancer applicable to the

A control method and apparatus for suppressing the vibration components of a magnetic bearing. According to this invention, a vibration wave is sampled at pulses synchronized with the rotation of a rotor, the vibration waveform sampled values at each revolution are averaged, and only the frequency components synchronized with the rotation frequency of the rotor are extracted from the vibration waveform. In addition, the extracted components are subjected to Fourier transform, processed in a frequency region and subjected to Fourier reverse transform. The sequence of these signal processes produces a signal, and the vibration components are suppressed by this signal.

Magnetic bearing control method and apparatus

Electromagnetic bearing control apparatus

The present invention reduces the resonance amplitude of the rotational frequency-synchronous unbalance vibration of a rotor supported by an electromagnetic bearing. To this end, the invention disposes an X-direction control servo circuit and a Y-direction control servo circuit each of which detects the deviation of the rotor from a desired position in the radial direction thereof and controls the rotor so as to be held at the desired position on the basis of the detection signal, and a tracking filter which is synchronous with the rotational frequency. Outputs from the filter are crossed to supply the Y-direction control servo circuit with the X-directional output and to supply the X-direction control servo circuit with the Y-directional output signal.

Control apparatus for a rotor supported by an electromagnetic bearing

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Ibaraki, Japan

Mitsuho Yoneyama