Linear parameter-varying control for active magnetic bearing supported rotor systems

Abstract Model-based control laws play an important role in stabilizing and guaranteeing high performance of active magnetic bearing (AMB) suspended high-speed machines. In the case of rotating machines with significant gyroscopic effects, the modes are separated into forward and backward whirling modes. This often leads to a situation where a single controller with fixed parameters cannot stabilize the full operational region. Addressing the challenges arising from rotating machines with significant gyroscopic effects, the application of $$H_\infty$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>H</mml:mi> <mml:mi>∞</mml:mi> </mml:msub> </mml:math> –based linear parameter varying (LPV) control, scheduled as a function of rotational velocity, is considered in this paper. This approach is combined with an unbalance rejection strategy, where the notch parameter matrix is also updated as a function of velocity. The performance and stability of the MIMO closed-loop control are evaluated using generalized Nyquist diagrams, along with damping ratio and disk margins analysis. Such an analysis will serve as a unified framework to support the analysis as well as design and compare of LPV-based closed loop controllers. Validation of the proposed control approach is verified with experimental electrical machine equipped with AMBs.