Constant Delay-Line Repetitive Control Analysis for VSI under Grid-Tied and Intentional Islanding Operation

Proposed paper deals with the complete analysis which is at the basis of the tuning procedure of variable sampling Repetitive Controllers for adjustable output frequency applications such as grid-tied inverters (limited frequency variation) and AC waveform generators (wide frequency variation). The operation of the proposed control strategy is briefly summarized. The effects of the desynchronization between the PWM modulator and the control loop are accurately described, and the inherent delays are expressed in closed form. This investigation helps to introduce a suitable control tuning procedure which can be used in variable sampling applications. Experimental verifications are carried out to prove the effectiveness of the presented analysis and control strategy.