The practical application limits of very high power GTOs and very high power bipolar transistors

An overview is given of the practical application limitations of very high power GTOs up to 2500 A I_TCM and 4500 V V_DRM and very high power bipolar transistors up to 2000 A I_C(CON) and 1200 V V_CEX. Some general comments are made about the limitations of medium power GTOs, transistors, Darlingtons and the combined MOS gated charge modulated devices (e.g. insulated gate transistors-IGTs). The latest ideas on extending the performance envelope of very high power GTOs and very high power bipolar transistors are also indicated. Because of the power loss dissipated in these devices which is often of the order of 1 to 2 kW when controlling high power at high switching frequencies it is necessary to use compression bonded double side cooled capsules or press packs for these devices. Not only forced air cooling, but also phase change (freon) and oil cooling may have to be employed to cope with this level of dissipation