Adaptive PPC-Based SMC of Axial Active Suspension Control With Passive Pitching Suppression for Maglev Wind Yaw System

To reduce the number of suspended converters and failure rates for the two degree-of-freedom (DOF) nacelle suspension, a passive pitching stabilizer (PPS) is designed for the Maglev wind yaw system (MWYS) to passively balance the pitching moment. Two DOF suspension modelling is given based on the damping force and restoring torque deriving from the PPS, which is optimized to minimize pitching vibration energy and power loss, as validated by simulation results. However, higher-frequency vibrations of the pitching angle during the convergence process can still influence the axial stability. Coupled with external time-varying disturbances, an adaptive prescribed performance control (PPC)-based sliding mode control (SMC) with current constraints is proposed to further improve transient performance and disturbance rejection capability. Adaptive techniques are also employed to estimate system parameter perturbations and external disturbances. The Lyapunov stability theorem is applied to prove the stability and convergence of the proposed strategy, and all closed-loop signals and adaptive parameters can converge to the desired neighborhood domain. Experimental results validate the optimized PPS and the proposed axial suspension strategy achieves the suspension objective with minimal tracking error and the effective pitching suppression.