Control of a flexible magnetic levitated rotor using the computed torque method in combination with stabilizing filters

Control of Active Magnetic Bearings in Turbomolecular Pumps for Rotors with Low Resonance Frequencies of the Blade Wheel

“…However, for many industrial applications, also the consideration of the flexible body modes is of great significance. In [6], it was stated that the soft stiffness of magnetic bearings in many applications has a negligible impact on the eigen-frequencies of the flexible modes. Therefore, the flexible eigen-frequencies can be approximately found independent of the control structure.…”

“…A computed torque (CT)-based control structure was already designed in [6]. However, this control structure had no problems with low blade frequencies.…”

“…However, this high bandwidth will lead to very high gains and will affect the bending and blade resonance frequencies. To solve this problem, a speed-variant compensation can be developed according to [6,7]. Using the control law:…”

“…For commissioning of magnetically-levitated rotors, the peak of the sensitivity function is limited to a factor three according to ISO 14839-3. Using the control approach of Equation (12) directly, this robustness measure is hard to fulfill [6]. To decrease the sensitivity peak, a factor z is introduced, which limits the compensation of the gyroscopic effect.…”

“…As a consequence, the tilting and translation modes cannot be treated independently from each other, and the gyroscopic effect couples the motions of the tilting movements. In [6][7][8], decoupling approaches are used based on the inverse dynamics to decouple the system and compensate the impact of the gyroscopic effect on the rigid body movement. In [9][10][11][12][13][14], modern control approaches, such as H∞ and µ-synthesis control theory, were used.…”