MFC/IMC Control Algorithm for Reduction of Load Torque Disturbance in PMSM Servo Drive Systems

The following article presents the MFC/IMC cascade for velocity control of permanent magnet synchronous motor (PMSM) with the aim of reducing the influence of torque load disturbance. A brief description of the MFC/IMC control scheme is given, its structure is an expansion of a classical cascade control loop; the PMSM model was linearized in order for it to be applicable to the proposed solution. Numerical analysis of sensitivity for both systems (i.e. the MFC/IMC cascade and the classical one) is given with regards to their robustness to torque load disturbance. The behavior of these two control schemes are then analyzed on a laboratory test stand with various load disturbances introduced to the system; the methodology and the test stand itself are also briefly presented in the article. The results presented in the form of performance indices and graphs prove that the developed MFC/IMC method is an improvement over the classical cascade for velocities near the operating point.