Servo Robust Control of Uncertain Mechanical Systems: Application in a Compressor/PMSM System

Abstract

High-speed Permanent Magnet Synchronous Motor (PMSM) systems have been widely used in industry and other fields for their advantages of having a simple structure, low processing cost and high efficiency. At present, the control precision of PMSM is required to be higher and higher, but it faces two major challenges. The first is that the PMSM system possesses (possibly fast) time-varying uncertainty. The second is that there exist nonlinear portions in the PMSM system, such as nonlinear elasticity, etc. To resolve these challenges, a novel performance measure β^ is introduced as a dynamic depiction of the constraint-following error, and a new robust control design is proposed based on β^. While this control renders guaranteed performance regardless of uncertainty, an optimal design of a control parameter is further pursued. This inquiry is summed up as a semi-infinite constrained optimization problem. After the induction of the necessary condition, the candidate solutions can be identified. These are further screened by a sufficient condition, which results in the actual solution. To verify the effectiveness of the control design, the compressor powered by a super high-speed PMSM system is simulated, and its performance is discussed.