Radial Vibration Analysis Of Bearingless Slice Motors

The bearingless slice motor with PM excited two pole rotor naturally shows a non-linear force distribution. It is common to use standard PID-positioncontrollers for industrial applications, hence it is important to know how linear control schemes will be influenced by the non-linear part. Thus, this paper is concerned with rotordynamic phenomena caused by linearly controlled bearingless slice motors. The eigenvalues of the equation of motion illustrate a region of rotational speed, at which instability occurs. It is shown that with an appropriate value of damping established by the controller or by the surrounding medium asymptotical stability can be achieved. Furthermore, the effect of applying arbitrary disturbance forces and the effect of static unbalance are treated and the maximum stationary radial amplitudes of the centre of mass are pictured. Finally, the possible benefits of a complex non-linear controller design will be discussed.