Load adaptive zero-phase-shift direct repetitive control for stand-alone four-leg VSI

This paper deals with a dedicated load adaptive phase compensation algorithm to be used in repetitive control based stand-alone 4-leg VSI. Plant model is achieved and its inherent modification according to the operating point are highlighted. Modification of the repetitive control structure is described to obtain the desired phase compensation capabilities. This allows to increase the gain exhibit to the RC at high order harmonics yielding a better VSI output voltages with strongly reduced THD.