Dual Converter Fed Open-End Transformer Topology with Parallel Converters and Integrated Magnetics

Research on the Filters for Dual-Inverter Fed Open-End Winding Transformer Topology in Photovoltaic Grid-Tied Applications

“…The above analysis suggests that the special working characteristic (the harmonic cancellation characteristic) of the DI-OEWT topology should be considered when designing the filter. The "common capacitor type filter" (here we call it "Type-2 filter") for DI-OEWT topology, which is presented in [21,22], seems to be a reasonable one, as illustrated in Figure 7. Two inverters are connected to a common shunt capacitor branch of the filter through the two inverter-side inductors, respectively.…”

“…It is uneconomic to reduce this voltage because that will increase the system installation costs and narrow the maximum power point tracking (MPPT) voltage operation range [2]. In addition, it will be better for the dual-inverter to be supplied by two separate arrays (two DC sources), which can not only achieve multiple MPPTs, but also suppress the circulating current among the two inverters [21,22]. The fault tolerance capability cannot be a special advantage of the dual-inverter because the multi-parallel inverter topology has the same capability as well.…”

“…One is the "individual capacitor type filter", that the two inverters of the DI-OEWT topology are connected to the open-end windings of the transformer through two individual inductor-capacitor filters. The other one is the "common capacitor type filter", which is also presented in [21,22], that the two inverters are connected to the open-end windings of the transformer through two individual inductors but one common capacitor. However, the authors in [30] were mainly focused on active damping methods of the two different filters, and the authors in [21,22] were mainly focused on the magnetic integration design of the filter inductors, none of these papers analyzed the harmonic suppression capability or the parameter design method of these filters.…”

“…In light of the above, this paper aims to research the filters for the DI-OEWT topology used in photovoltaic grid-tied applications. First, the equivalent circuits of the existing two kinds of high order filters presented in [21,22,30] are derived, and based on this, the harmonic suppression capabilities of these filters are analyzed and compared. According to the analysis results, a new high order filter for DI-OEWT topology is also proposed.…”

Open‐end transformer‐based power tap for interconnection of AC/DC micro‐grids

“…The open-end operation of transformers was previously studied in [23], in which an inductor was integrated into the open-end transformer to limit the circulating current between parallel connected converters. Gohil et al [24] designed an LCL filter for the harmonic cancelation of the open-end transformer proposed in [23].…”