Improved Robust Model Predictive Current Control via High-Order Terminal Sliding Mode Control for Permanent Magnet Synchronous Motor

The traditional model predictive current control (MPCC) is sensitive to parameter changes, and it is difficult to balance the dynamic and steady-state performance of the current. The PI controller used in the speed loop has poor robustness and tracking accuracy. Therefore, an improved robust MPCC with cascaded high-order fast terminal sliding mode speed controller (HOFTSMSC-IRMPCC) based on high-order sliding mode observer (HOSMO) is proposed. Firstly, a HOSMO is designed to estimate and compensate the parameter changes of the current loop. A dynamic strategy of switching different MPCC schemes according to the running state of motor is proposed, which takes into account the characteristics of fast response of single-vector MPCC and excellent steady-state performance of three-vector MPCC. Then, high-order fast terminal sliding mode speed controller (HOFTSMSC) is proposed to replace the speed loop PI controller. Different from the traditional high-order sliding mode control (HOSMC) scheme, the first-order integral fast sliding mode surface is nested in the second-order non-singular terminal sliding mode surface, which weakens system chattering and improves the convergence speed and tracking accuracy. To further improve the robustness of the speed loop, a HOSMO with the same structure as the current loop is designed. Experimental results demonstrate that HOFTSMSC-IRMPCC has excellent control performance.