To compare the result from the datasheet with the loss
values computed experimentally, a linear scaling of datasheet
losses with respect to voltage (the traditional approach) is
assumed. Without loss of generality, the Si(TO-247) (1200V,
36A) is considered. The datasheet gives losses at 125°C, and
800 V over a range of 0 to 30 A. The loss values computed
experimentally at 800 V are found to match the datasheet
values, however at other voltages a large deviation in losses
is observed. TABLE VI. gives a summary of the error
between the extrapolated losses of the datasheet with the
experimental values. The large errors, reaching as high as
206.2%, clearly show that the datasheet values cannot be
linearly extrapolated to compute the losses at different
operating conditions. Further, the errors in turn-off losses are
larger than turn-on losses due to the tail current effects.
Therefore, a conventional datasheet would not be useful in
designing high efficiency direct AC/AC converters and a
more rigorous characterization of devices, involving testing
under many different operation conditions, is essential. This
justifies the research effort performed in this paper of
characterizing multiple devices under varying operating
conditions.