Repetitive waveform correction technique for CVCF-SPWM inverters

Abstract

A way to synthesize a repetitive controller directly with SPWM inverters is presented. It combines the advantages of repetitive control (low THD with nonlinear loads) and SPWM technique (easy implementation, low cost, reliable operation, etc). To cancel out the high resonant peak of the SPWM inverter, the repetitive controller incorporates a notch filter. Design of the controller is discussed in detail, and a case design is presented. Low THD (1.4%) is achieved with nonlinear load, this proves the method to be a cost-effective upgrading technique for SPWM inverter products.