Research on an internal model control algorithm and parameter tuning for metro traction PMSMs

High power density and high efficiency are two important trends in the research of permanent magnet synchronous motors (PMSM) used in metro traction systems. The key to achieving these objectives lies in improving performance in current loop control. However, under control conditions with a low carrier wave ratio, the coupling effect between the <italic>d</italic>-axis and <italic>q</italic>-axis currents intensifies as this ratio decreases. Additionally, digital control delays further amplify this coupling phenomenon. As a result, both the dynamic response speed and the robustness of the current regulator decline. To address these issues, this paper presents the design of an internal model decoupling controller capable of compensating for digital control delays, based on the principle of internal model control (IMC). This controller achieves the precise decoupling of <italic>d</italic>-<italic>q</italic> axis currents, optimizes the dynamic performance of the current regulator, and enhances system robustness. Simulation analyses and experimental verifications conducted on the experimental platform of permanent magnet traction on Xi'an Metro Line 1 demonstrate that, compared to PI current regulators, the designed IMC controller exhibits stronger robustness, faster dynamic response, and reduced torque error, while meeting the design index of 3%.