An Improved Inertia Disturbance Suppression Method for PMSM Based on Disturbance Observer and Two-Degree-of-Freedom PI Controller

In this article, an improved inertia disturbance suppression method is proposed for permanent magnet synchronous motor (PMSM) based on disturbance observer and two-degree-of-freedom PI controller (DOB-2DoFC). The DOB-2DoFC is proposed to enhance the speed control performance with variation of inertia caused by load changing. The traditional two-degree-of-freedom controller (2DoFC) is first introduced and the influence of inertia disturbance on 2DoFC is analyzed. Then, the disturbance observer (DOB) is designed to combine with 2DoFC for inertia disturbance suppression. Furthermore, the discretization of DOB-2DoFC is implemented and the impact of discretization is also analyzed, in the meanwhile, the parameters of DOB- 2DoFC is designed based on the premise of stability and good speed control performance. With the designed parameters, better speed control performance can be maintained without tuning any controller coefficients even when the actual inertia is 20 times the controller inertia. Finally, the effectiveness and the correctness of the proposed DOB-2DoFC are verified with experiments on a 400 W PMSM drive platform in two modes.