JPS6483916A - Control type magnetic bearing device - Google Patents

Abstract

PURPOSE:To enable strict control of a bearing device having no connection with positions for fitting displacement sensors and electromagnets by providing a position correcting circuit for correcting the detected values of the displacement sensors to the displacement values at the positions where the suction forces of the electromagnets are applied. CONSTITUTION:The signals of displacement sensors S1, S1' and S2, S2' for detecting the displacement of a rotary body 1 are multiplied, through displacement detecting circuits 2, 2', by constant (l1-l2)/l1 at coefficient circuits 3, 3', and by constant l2/l1 at coefficient circuits 7, 7' respectively, due to relative positions l1, l2 between the displacement sensors S1, S1', S2, S2' and the electromagnets A1, A1', A2, A2' and they are corrected to displacement value at the position where the suction forces of the magnets are applied. The signals from the coefficient circuit 3, 7' and 3', 7 are respectively added to addition circuits 4, 4', control circuits 5, 5' and driving currents to the electromagnets A1, A1', A2, A2' are controlled through electric power amplification circuits 6, 6'. Thus, strict control can be carried out by the displacement values at the position where the suction force of the electromagnets are applied and also the degree of freedom of a structural design and lay-out can be improved.