Characterization of commercial IGBT modules for pulsed power applications

One of the key components of pulsed power technology is the switch, which is increasingly realized using semiconductor switches. Use of solid state switches, if properly designed, provides longer lifetime, reliability, and reduces maintenance as compared to the conventional spark gaps which are used in Marx generators or other devices for pulsed power applications today. An analysis of commercial semiconductor switches favors the IGBT for pulsed power applications, in particular for high average power, high pulse repetition rate applications, due to its widespread use in drive applications and its availability. High power IGBT modules rated at 4.5 kV / 800 A of two different technologies have been investigated in this work: the planar technology and the trench³ technology. Both types of semiconductor switches were tested in a special low inductance setup to characterize the IGBT for pulsed power applications. For this characterization, the development of a dedicated gate drive unit enables the IGBT to generate fast rise times for the collector current and fast fall times for the collector-emitter voltage. The results show that the planar technology is preferable for pulsed power applications. The IGBT with the planar technology was characterized at a DC link voltage of 4kV and a peak current of 2kA. The switching time of the IGBT stays in the region of 200ns (t_{fall time(20-80%)}) of the collector-emitter voltage, while the rise time of the collector current is 160ns (t_{rise time(10-90%)}) with peak power losses of 1.41MW. The associated junction temperature of the chip will be increased by approximately 1K only. This allows to use the IGBT at higher pulse repetition rates (PRF) up to 2kHz, at a pulse duration of 1μs, without additional cooling. The switching speed of the IGBT can be influenced by the matching network and depends on the application which will be realized with the IGBT. The IGBT with the trench³ techno- ogy shows gate voltage oscillations at peak currents above 1 kA, which infers that the gate source capacitance will be slowly destroyed by overvoltage. These oscillations can be explained with the higher gate source capacitance of the trench³ technology as compared to the planar technology, in combination with the unavoidable gate inductance. The planar technology, on the other hand, is realized with a low inductance gate runner topology and can thus be used at shorter pulse rise times. The results present a commercial semiconductor which is suitable for a pulsed power application. The IGBT with the planar technology can be used with the right choice of the driver matching network for a pulsed power application. Furthermore there is no need to design a switch using small, discrete semiconductor devices. That saves cost and keeps the circuit development simple. Only the gate drive unit is developed in-house particularly for pulsed power applications. The technical functions and the economic efficiency are accordingly balanced as well.