Assignment of turn-on and turn-off power and energy losses in a GTO

The latest IEC proposed standards for turn-on and turn-off power and energy losses in a GTO (gate-turn-off) thyristors are discussed and compared with some manufacturer´s approaches. It is shown that the definition of turn-on and turn-off power and energy losses in these standards does not adequately include all losses associated with the turn-on and turn-off events. Thus, it will be difficult to account for all the losses related to heating effects unless improvements are made. An example shows that the error can be substantial, 8 to 15%. Improved definitions are proposed, potentially leading to an underestimation of only 1 to 2% of the switching losses. It is also shown that gate losses during turn-off must be accounted for and that improved measuring techniques and instrumentation are both needed and possible.<>