μ control of a high speed spindle thrust magnetic bearing

Experimental results demonstrate that μ synthesis provides an excellent tool for increasing the dynamic stiffness of thrust magnetic bearings. Accurate system modeling and appropriate uncertainty descriptions are critical to obtaining such results and are described in detail. Both complex μ and mixed μ synthesis were used to design controllers. The performance of the μ controllers is compared to that of an optimized PID controller. The dynamic stiffness of the spindle´s thrust axis was increased by a factor of two over that obtained with optimized PID control