Generalized Interleaved Geometric Modulation for Parallel Grid-Connected AC/DC Converters

A generalized interleaved geometric space vector modulation (SVM) method is designed by utilizing the equilateral geometry of the space vector structure. The reference voltage vector in any sector is synthesized using two switched voltage vectors of equal magnitude but displaced by 60 degrees. The proposed method can be iterated to multiparallel converters and multilevel converters, as opposed to existing SVM methods which are tailor made for fixed number of converters in parallel. Two variants of geometric modulation-a four-vector modulation (4VM) and a three-vector modulation (3VM) are proposed for two two-level converters in parallel to minimize the zero sequence circulating current (ZSCC), differential mode circulating current (DMCC), differential mode voltage (DMV), and common-mode voltage (CMV). The 4VM uses the zero DMV vectors to eliminate the ZSCC flow and maintains the CMV within +/-(V-dc/6). The 3VM is designed to restrict the DMCC flow to only one phase leg and the DMV and CMV levels are within +/-(V-dc/3). The efficacy of the proposed methods is validated using hardware experiments. The proposed method can be applied for multiparallel converter applications such as interlinking converters in ac/dc microgrids, electric vehicle charging stations, and so on.