Comparison between grid side and inverter side current control for parallel interleaved grid connected converters

To meet the ever stringent grid codes, the high power converter systems have multiple converters connected in parallel and require high order filters due to their limited switching capability. Controlling the grid current and, at the same time, ensuring equal current sharing is a challenge that these converters have to face. There are two main methods on how to control the output current of the converter system: either by directly controlling the total grid current and applying the same gate signals for all parallel converters, or by controlling the individual converters' currents. Using simulation and experimental results, this paper presents the advantages and disadvantages of both control methods when applied on a converter system consisting of two parallel interleaved converters connected to the electricity grid through a high order filter. For a better comparison, a controller design for both methods is also included.