Input-output harmonics of line current modulated high-frequency link DC to utility interface power converters

Two types of commutation schemes (called Type I and Type II ) are proposed and analyzed for the line connected inverter (LCI) used in line current modulated high frequency (hf) link DC to utility interface power conditioning (DC/UIPC) systems. In Type I scheme [2,4], the hf inverter is switched off well in advance of the zero crossings of line voltage, allowing the line current to go to zero and enabling the LCI to turn off. A simple lossless forced commutation circuit is used in Type II [2] scheme. The effects of these schemes on line side and input dc side current harmonics are studied in the case of l-ϕ systems, neglecting the effect of controller action. The performance indices are evaluated. The results obtained from prototype experimental systems are used to verify the theory presented. The analysis presented for 1-0 systems is extended to 3-0 systems.