Improved Non-Singular Fast Terminal Sliding Mode Control With Disturbance Observer for PMSM Drives

For the purpose of shortening response time and improved anti-disturbance performance of the permanent magnet synchronous motor (PMSM) drives, a compound control method using improved non-singular fast terminal sliding mode controller (NFTSMC) and disturbance observer compensation techniques are developed. First, in order to overcome the contradiction between fast response and heavy chattering of the conventional NFTSMC, a new sliding mode reaching law (NSMRL) is proposed for the improved NFTSMC. The NSMRL, which allows chattering reduction on control output while maintaining high tracking performance of the controller, can dynamically adapt to the variations of the controlled system. Second, to further improve the anti-disturbance performance of the PMSM control system, the sliding mode disturbance observer (SMDO) is introduced to estimate the load disturbance and add to the output of the improved NFTSMC for a feed-forward compensation item. Finally, both the simulation and experimental results applied to PMSM drives show that the proposed control method has better suppression of chattering effect, fast dynamic response, and disturbance rejection ability.