A reduced-switch-count two-phase interleaved switch-control-capacitor LLC converter with accurate current balancing

In this paper, a reduced-switch-count two-phase interleaved LLC converter with precise current balancing is proposed by using switching-control-capacitor (SCC) technology. Compared with the conventional SCC-LLC converter, the proposed two-phase SCC-LLC converter reduces the switch count with the SCC circuits, and achieves excellent current sharing under all the tolerance conditions between the two-phase resonant elements. In the proposed converter, the SCC circuit is only used in the first phase. The design of the SCC circuit parameters is analyzed to reduce the voltage stress of the SCC circuit and to ensure that two-phase currents are balancing with large tolerance of resonant elements. A 2.16-kW GaN-based two-phase interleaved SCC-LLC converter prototype is established for data center application, and the experimental results show that the 98.1% peak efficiency, the 97.6% full load efficiency, and higher than 96% efficiency at the wide range from 3-A to 40-A load current are achieved. The precise current sharing lower than 1% is achieved by using a cheap ceramic capacitor with high tolerance, which validates the performance of the converter.