Evaluation of Large-capacity Self-turn-off Power Devices Application from the Aspects of their Turn-off Characteristics, Applied Circuitry and Structure

Abstract

The reason why this paper deals with GTO behavior mainly is that the reverse bias safety operating area (SOA) of GTO is narrower than the ones of GCT and IEGT. On the development of large-capacity GTO converter, it is important to evaluate the performance of snubber circuit. This paper is concerned with the spike voltage V_DSP during turning-off a GTO, and deals with the design and evaluation of stray inductance for snubber circuit, and shows investigation for transient forward voltage of snubber diode. Especially, the method is described that estimates stray inductance from aspect of snubber circuit structure by electromagnetic field analysis before making prototype. The experimental results of spike voltage V_DSP are in approximate agreement with the estimated results. Therefore, investigations on this paper are proper and applicable. The same manner of evaluation is also appropriate to IEGT application, and the development of IEGT converter is easier than in GTO converter because of the gate resistor adjustment for di/dt of main current and a wider SOA.