Virtual Reference-Based Fuzzy Noncascade Speed Control for PMSM Systems With Unmatched Disturbances and Current Constraints
Hu Li, Shuting Wang, Yuanlong Xie, Shiqi Zheng, Peng Shi
Abstract
This article aims to develop a noncascade speed control approach for permanent magnet synchronous motor (PMSM) systems based on the Takagi–Sugeno (T-S) fuzzy model. In noncascade control structures, the lack of firsthand current references imposes a tricky challenge in dealing with current constraints from the circuit and unmatched disturbances caused by load torques. To this end, a virtual reference-based fuzzy noncascade speed control scheme is proposed for PMSM systems. First, unmatched load torques are estimated by a fuzzy disturbance observer. And then, a novel virtual reference planner is constructed to inject the estimated unmatched disturbance into the control channel as feedback compensation. This improves antidisturbance performance, while keeping the current response within the feasible domain and reducing speed overshoot. Furthermore, the noncascade speed regulation problem is converted into a system stabilization problem and addressed by the composite control strategy based on the nonparallel distributed compensation. Finally, closed-loop stability with reduced conservatism is ensured through the fuzzy Lyapunov functions and improved slack variables. Simulations and experiments show that the proposed scheme achieves excellent speed response without overcurrent even under mismatched load torque variations.