IGCT Switching Behaviour Under Low Current Conditions

As MVDC technology is slowly finding its way into the area of energy distribution, there is a need for reliable, efficient, compact and low maintenance medium voltage DC-DC converters, as a counterpart to AC transformers. Given the typical operating conditions and the design practices, IGCT manufacturers have paid, so far, little attention to the switch's behaviour under low loads (below 10% of the device rated current) and this information is mostly unavailable in the datasheets. Low current turn-off performance of the IGCT, typical to some resonant converters, is explored throughout this paper, supported by TCAD simulations and test results obtained from a dedicated test setup. These tests show the prolonged duration of the turn-off process as the turn-off current decreases, which must be correctly taken into account during converter design.