A general closed-loop power-decoupling control for reduced-switch converter-fed IM drives

Twice ripple power exists in single-phase to three-phase reduced-switch induction motor drives, which degrades the performance of the drive system, such as larger total harmonic distortion of the grid current, the larger ripple voltage in the dc link and the larger torque ripple. Most existing power decoupling schemes are open-loop decoupling methods. However, the open-loop decoupling method has the disadvantages of heavy computation and strong dependency of parameters. This paper analyzes all steady state solutions of the decoupling capacitor voltage from the point of view of solving differential equations and presents a unified multi-proportional-resonant closed-loop decoupling method to suppress the ripple voltage on the dc bus. The whole drive system adopts a hybrid predictive control strategy with dual loops to coordinate the operation of each part. Comprehensive experimental results are presented to verify the effectiveness of the presented method.