| Abstract |
The use of Gate Turn-off Thyristors in ever higher frequency applications increases the importance of the turn-off energy and minimum off-time. The accurate measurement of both parameters is dependent upon the ability to resolve the turn-off tail current to near extinction. A non-linear current transformer has been developed which allows for the accurate measurement of tail current. When used in conjunction with an 8 bit digital storage oscilloscope the unit allows for the tail current to be measured at a lower range of amperes per volt than the rest of the current wave-form. The greater resolution of current per data point, down to some hundreds of milli-amperes for >1000A devices, permit accurate measurement of turn-off time and energy to extinction of the tail current. The results obtained with a prototype non-linear current transformer were compared against other measurement methods and found to offer a good, low cost, solution to this difficult measurement. |
