Electrothermal bidirectional coupling for pulsed thyristors with inductive load under repetitive pulses

Thermal runaway and electrical instability in pulsed thyristors under repetitive pulses critically limit the reliability of solid-state and compact high-power pulse generators. However, the bidirectional electrothermal effects of pulsed thyristors under repetitive pulses have not been studied. In this paper, they were explored based on mixed semiconductor device and circuit simulations and scaling experiments. The results show that within a ten-microsecond pulse, the maximum temperature rise occurs in the P2 region between the amplifying gate and the cathode under diode protection, whereas that occurs in the J1 junction near the anode without diode protection. The global maximum temperature decreases, and the heating region gradually expands with increasing pulse width. As the repetition rate increases, the temperature of the thyristor case is higher within the same testing time. Affected by higher temperature, the voltage drop and peak power dissipation increase and the anode current decreases. The residual temperature in the previous pulse further increases the heat generation in the next pulse. The electrothermal bidirectional coupling relationship under repetitive pulses was established theoretically, which can guide the application of high-power pulse generators in repetition rate mode.