An electronic circuit device is developed such that the displacement between an electromagnet and a target can be estimated from the coil current measurement. The device is then applied to an active magnetic bearing(AMB) system in the laboratory.
Experimental results show that the resolution of estimated displacement between the magnetic bearing and shaft is about ±15㎛ and the steady state displacement fluctuation of shaft, when the estimated displacement is directly used as the feedback signal, is limited within ±6㎛.
The drawback of the use of estimated displacement as the feedback signal is that the dynamic range and the effective stiffness of the AMB system tend to become far less than those with the direct displacement feedback.
