Series Connection of Snubberless IGBTs for 6.6 kV Transformerless Converters

We developed a 6.6-kV 1-MVA transformerless converter making use of a snubberless insulated gate bipolar transistor (IGBT) 8-series connection using an active-gate-control. The active-gate-control can balance the collector voltage of IGBTs connected in series enabling the IGBT series connection. It allows the converter to output a high enough AC voltage to directly connect to 6.6-kV distribution lines. Therefore, the converter does not need a step-up and step-down transformer, and is extremely small and compact.