A Foil-Magnetic Thrust Bearing Using LCR Circuit

An ac magnet based on the LCR resonance circuit shares load with a foil thrust bearing with eight pads, which supports the weight and impeller thrust load of a vertically oriented gas compressor. For the stability o f the combined beari ng, the amplitude of excit ation voltage to the LCR circuit is controlled as a function of rotor speed. To augment the low damping inherent in the ac suspension, a velocity feedback control is applied to modulate the excitation vo ltage and achieve electricdamping.