Three‐dimensional vibration characteristics of the permanent magnet–HTSC magnetic bearing

AbstractThe three‐dimensional vibration of the rotor in a permanent magnet– HTSC magnetic bearing system is studied. We have developed a magnetic bearing system which can revolve at up to 12,000 rpm, and three‐dimensional vibration of the rotor is measured with laser displacement sensors. To consider the rotor vibration in a mechanical resonance state, the static lateral and vertical pinning forces of the magnetic bearing are measured. The results are used to obtain the resonant frequency. There are two factors in the mechanical resonance caused by the magnetic bearing. One is the lateral equivalent spring coefficient and the other is the vertical equivalent spring coefficient. The influence of mechanical resonance caused by the lateral spring coefficient is large, and that of the vertical one is small. The three‐dimensional vibration of the rotor position around the mechanical resonant frequency is measured. Because the revolution of the rotor increases the lateral force to the center, the resonant frequency obtained in a free revolution experiment is larger than that obtained from pinning force measurement. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(3): 58–64, 2008; Publi