Disturbance Observer-Based Sliding Mode Control Using Barrier Function for Output Speed Fluctuation Constraints of PMSM

The speed fluctuation constraints (SFC) of permanent magnet synchronous motors (PMSM) are widely considered in practical applications. However, the multiple disturbances in the PMSM systems lead to extremely complicated SFC control problem. In this paper, a composite barrier function-based sliding mode control (BFSMC) approach is developed to deal with this problem. First, a disturbance observer is constructed to estimate the lumped disturbances, including cogging torque, parameter uncertainties and unknown load torque, which widely exist in the PMSM systems. Then, a novel BFSMC is designed, in which the switching gain is determined by the barrier function to achieve the goal of SFC when facing the above disturbances. Finally, a composite controller is formed by introducing disturbance estimation. The proposed method obtains a smaller flexible switching gain, which not only achieves the target of SFC, but also substantially alleviates the chattering phenomenon. The stability analysis of the closed-loop control system is presented. Both simulations and experimental tests are applied to demonstrate the efficiency of the proposed method.