Effects of displacement sensor noise on power amplifiers of active magnetic bearings

This paper analyzes the influences of displacement sensor noise on the power amplifiers of active magnetic bearing systems in both current and voltage control schemes. An effective evaluation index has been proposed to guarantee that the comparison is meaningful and fair enough to both control schemes. In addition, an appropriate controller is designed for each control scheme, while each controller is capable of dealing with both linear and nonlinear plants. Three significant findings are obtained through a thorough computer simulation. Firstly, using the proposed evaluation index, the maximum displacement response values are almost identical for the two control schemes, when the same unit pulse of external disturbance force signal is inputted; secondly, the current control scheme is more sensible to the noise; and lastly, the power amplifier in voltage control scheme has better noise suppression capability than current control scheme.