Tailoring High-Voltage, High-Current Thyristors for Very High Frequency Switching

Many applications exist requiring high voltage switching in the tens of kilohertz rates with peak currents at the thousands of amps and blocking voltage capabilities greater than several kilovolts. High-voltage, high-current thyristors provide low forward voltage and high peak current rating versus active area but suffer from long recovery times. Optimizing the thyristor for high di/dt capability also allows for tailoring the device to achieve faster recovery. Using these devices we have developed a compact thyristor based switch module capable of achieving greater than 20 kHz pulse rates using only a single low voltage, low power trigger. In present form the module is designed for a maximum blocking voltage of 7.5 kV and a peak current of 3 kA. However, this concept could be easily used to generate higher voltage switches using more devices in series. Also, higher current devices are in development which would increase the peak current rating to 14 kA without a significant increase in the size of the module. This paper will discuss the tailoring of the thyristor, the design of the switch module, and test results showing fast turn-on of greater than 100 kV/mu s and 25 kA/mu s as well as recovery times of less than 10 mu s.