A fuzzy variable structure control (FVSC) scheme based on a Takagi-Sugeno (T-S) model is proposed in this paper for a permanent-magnet synchronous motor (PMSM) drive system in order to solve the speed tracking problem. A T-S fuzzy model is first formed to represent the non-linear system of the PMSM. To convert the tracking control into a stabilization problem, a new control design is proposed to define the internal desired states. Then, an FVSC controller for the PMSM system with parameter variation and load disturbances is designed on the basis of this fuzzy model. The FVSC scheme can drive the dynamics of the PMSM into a designated sliding surface in finite time, and guarantee the property of asymptotical stability. It is also shown that information on the upper bound of modelling errors, as well as on perturbations, is not required when using the FVSC controller. The performance of the proposed controller is verified by simulation and experimental results on a PMSM system.
Application of Fuzzy Variable Structure Control in DC Source of Plasma Arc Welding
