DC-link voltage control of small capacitor PMSM drive system based on MPC algorithm

The permanent magnet synchronous motor (PMSM) drive system with small dc-link capacitor will have the problem of unstable drive system due to the small damping of the LC filter and the negative impedance characteristics of the constant power load. The input LC filter can suppress interference and is essential for the normal operation of the drive, but it may not match the impedance of the post-stage inverter, causing the drive system to become unstable. In this paper, by constructing the dc-link voltage prediction model, combined with the PMSM current predictive control, the weighted cost function of the model predictive control (MPC) strategy is designed to realize the motor optimal control and the dc-link voltage fluctuation suppression control. To avoid introducing additional sensors when constructing the dc-link voltage model, a source state observer that can estimate the dc-link voltage and input current is constructed. Simulation and experimental results are provided to verify the effectiveness of the proposed method.