Integrated Single-Stage EMI Filters for Grid-Tied Voltage Source Converters: A Design Oriented Approach

This work introduces and elucidates a general framework for designing and evaluating the performance of a standard single-stage, multi-order integrated electromagnetic interference (EMI) filter for grid-tied, 3 phi voltage source converters (VSCs). The proposed methodology is based on designing the EMI filter to meet power quality (PQ) requirements while providing adequate attenuation to both differential mode (DM) and common mode (CM) noise generated by the 3 phi VSC to comply with conducted emissions (CE) recommendations. The impact of switching frequency of the power converter on the filter size is investigated to understand the performance limits of single-stage EMI filters and to offer guidelines as to when such a single-stage filter is feasible. A size comparison for the magnetic components used in the EMI filter has been performed using an area product approach. Additionally, various single-stage CM and DM filter performances have been analyzed and compared. A hardware prototype with a single-stage EMI filter has been implemented based on the proposed design guidelines. Time-domain and CE experimental results for a 3 phi VSC prototype interfaced to the utility grid are provided to showcase the validity of the single-stage integrated EMI filter design to meet multiple performance constraints.