MAGNETIC BEARING DEVICE

PURPOSE:To support a magnetic bearing device with an auxiliary bearing in a stable state even when abnormal vibration is generated on a rotating shaft by outputting a signal of a specific level when the output signal of a displacement sensor exceeds a set value and by adding between a phase compensating circuit and one power amplifier and exciting an electromagnet to attract the rotating shaft to one side. CONSTITUTION:A signal detected by displacement detection sensors 4a, 4b of a rotating shaft 1 is computed at a position deflection arithmetic circuit 7a to get difference between it and a position setter 6a. This output is compensated at a phase compensating circuit 8a, a comparing circuit 13a compares the output of the position deflection arithmetic circuit 7a and a standard setting circuit 14a and a specific direct current signal is output. Additionally, an electric power amplifier 9 flows a current which is larger than 10a by the output of the comparing circuit 13a to a coil 11a of an electromagnet 2a, and electromagnets 2b, 3b are excited in the Y axis direction in the same way. Accordingly, it is possible to support the rotating shaft 1 with an auxiliary bearing in a stable state without swinging by way of attracting the rotating shaft 1 to the side of the magnet 2a when abnormal vibration is generated on the rotating shaft 1.