Improving Speed Regulation of a Permanent Magnet Synchronous Motor Using Modified Model Predictive Control With an Adaptive Second-Order Disturbance Observer

In this study, we propose a modified model predictive control (MMPC) approach combined with an adaptive second-order disturbance observer (ASDO) for efficient speed control of permanent magnet synchronous motors in the presence of unknown disturbances, such as system parameter variations and external load torque. The MMPC incorporates feedforward reference compensation (FFRC) and a posterior constraint compensation (PCC) technique. When the motor operates on a nonconstant velocity profile, the FFRC technique reduces the tracking delay associated with conventional MPC methods. In addition, the PCC technique addresses control signal constraints under a step velocity profile without requiring the solution of complex optimization problems at each time step, thereby reducing the computational effort for the controller. Furthermore, the ASDO utilizes a second-order disturbance observer to enhance the robustness of the MMPC. An adaptive observer bandwidth algorithm is proposed to minimize random noise and current ripple. The performance of the proposed methods was evaluated by applying them to an industrial motor drive, confirming their validity and practicality in real-world operations.