Magnetic bearing control method and apparatus

Claim 2

A magnetic bearing control method comprising the steps of: sampling a vibration waveform at pulses which are synchronized with the rotation of a rotor; averaging vibration waveform values at each revolution; extracting only the frequency components synchronized with the rotation frequency of said rotor from said vibration waveform; subjecting the extracted components to Fourier transform; processing said Fourier-transformed components in a frequency region; subjecting said processed components to Fourier reverse transform; and controlling a magnetic bearing by a signal obtained by a sequence of said signal processes given above so that vibration components can be suppressed.

Claim 3

A magnetic bearing control method comprising the steps of: generating N sampling pulses of first to N-th pulse (N is an integer) at each revolution of a rotor on a magnetic bearing; detecting deviations of a rotating shaft of said rotor from predetermined positions in two directions within a plane perpendicular to said shaft; sampling said detected deviations in two directions by said first to N th sampling pulses to produce first to N th sampled values; averaging i-th sampled values obtained after start of operation so as to produce an i-th average value each time said i-th sampled values (i=1-N) in two directions are produced; obtaining i-th average values up to that time point from said i-th average value; obtaining complex amplitude values by discrete Fourier transform of said first to N th average values in two directions, and calculating a control signal by discrete Fourier reverse transform of said complex amplitude values after signal processing of a control law suitable for vibration control; and controlling said shaft of said rotor on said magnetic bearing by said control signal.

Claim 4

A magnetic bearing control method comprising the steps of: generating N sampling pulses of first to N-th pulse (N is an integer) at each revolution of a rotor on a magnetic bearing; detecting deviations of a rotating shaft of said rotor from predetermined positions in two directions within a plane perpendicular to said shaft; sampling said detected deviations in two directions by said first to N th sampling pulses to produce first to N th sampled values; averaging i-th sampled values obtained after start of operation so as to produce an i-th average value each time said i-th sampled values (i=1-N) in two directions are produced; obtaining i-th average values up to that time point from said i-th average value; obtaining complex amplitude values by discrete Fourier transform of said first to N th average values in two directions, and calculating a control signal by discrete Fourier reverse transform of said complex amplitude values after signal processing of a control law suitable for vibration control; and controlling said shaft of said rotor on said magnetic bearing by said control signal.

Claim 5

A magnetic bearing control apparatus comprising: pulse generating means for generating N sampling pulses of first to N-th sampling pulses (N is an integer) at each revolution of a rotor on a magnetic bearing; detection means for detecting deviations of a rotating shaft of said rotor from predetermined positions in two directions within a plane perpendicular to said shaft; sampling means for producing first to N-th sampled values by sampling said detected deviations from two directions at said first to N-th sampling pulses; averaging means for obtaining i-th average values from i-th average value of i-th sampled values produced after start of operation up to that time point each time said i-th sampled values (i=1˜N) in two directions are produced from said sampling means; signal processing means for obtaining complex amplitude values by discrete Fourier transform of said first to N-th average values in two directions obtained by said averaging means and for calculating a control signal by discrete Fourier reverse transform of said complex amplitude values after signal processing of a control law suitable for vibration control; and control means for controlling said rotating shaft of said rotor on said magnetic bearing by said control signal.

Claim 6

A magnetic bearing control apparatus comprising: pulse generating means for generating N sampling pulses of first to N-th sampling pulses (N is an integer) at each revolution of a rotor on a magnetic bearing; detection means for detecting deviations of a rotating shaft of said rotor from predetermined positions in two directions within a plane perpendicular to said shaft; sampling means for producing first to N-th sampled values by sampling said detected deviations from two directions at said first to N-th sampling pulses; averaging means for obtaining i-th average values from i-th average value of i-th sampled values produced after start of operation up to that time point each time said i-th sampled values (i=1˜N) in two directions are produced from said sampling means; signal processing means for obtaining complex amplitude values by discrete Fourier transform of said first to N-th average values in two directions obtained by said averaging means and for calculating a control signal by discrete Fourier reverse transform of said complex amplitude values after signal processing of a control law suitable for vibration control; and control means for controlling said rotating shaft of said rotor on said magnetic bearing by said control signal.

Claim 7

A magnetic bearing control apparatus according to claim 3, wherein said i-th average value calculated at that time is subtracted from said i-th sampled values (i=1˜N) in two directions, and the remainders of said subtraction are processed by predetermined control elements to produce a signal, which is supplied to the output of said signal processing means, thereby controlling said magnetic bearing.

Claim 8

A magnetic bearing control apparatus according to claim 3, wherein the Fourier transform processing in said signal processing means is made by use of said i th sampled value when said i th sampled value (i=1˜N) is inputted, said i th average value obtained N sampling pulses before that time point, and said complex amplitude value obtained one sampling pulse before that time point.

Claim 9

A magnetic bearing control apparatus according to claim 4, wherein the Fourier transform processing in said signal processing means is made by use of said i th sampled value when said i th sampled value (i=1˜N) is inputted, said i th average value obtained N sampling pulses before that time point, and said complex amplitude value obtained one sampling pulse before that time point.

Claim 10

A magnetic bearing control apparatus according to claim 3, wherein said pulse generating means is formed of rotation detecting means for producing a pulse at each revolution of said rotating shaft, and a pulse generator for generating N pulses at equal intervals in response to said pulse from said rotation detecting means.

Claim 11

A magnetic bearing control apparatus according to claim 4, wherein said pulse generating means is formed of rotation detecting means for producing a pulse at each revolution of said rotating shaft, and a pulse generator for generating N pulses at equal intervals in response to said pulse from said rotation detecting means.

Claim 12

A magnetic bearing control apparatus according to claim 3, wherein said pulse generating means is an encoder for generating N pulses at each revolution of said rotating shaft.

Claim 13

A magnetic bearing control apparatus according to claim 4, wherein said pulse generating means is an encoder for generating N pulses at each revolution of said rotating shaft.