Large chip area SiC PiN diodes demonstrated for thyristor protection in a pulsed system
Asymmetric thyristors require protection from voltage and current reversals in high-inductance capacitor discharge systems. Silicon carbide (SiC) PiN diodes capable of blocking up to 16 kV were demonstrated to have the high-current capability to transmit forward pulse current in a series configuration with a thyristor, and to clamp reverse current in an anti-parallel configuration. In series with a thyristor, diodes were switched 1000 pulses at a single-shot rate at 2000 A peak current (3.8 kA/cm2 over anode area and 2100 A2s per pulse) without any notable increases in forward voltage or reverse leakage current. In the reverse clamp configuration, a parallel pair of PiN diodes was demonstrated to block 12 kV charge on the capacitor bank, then clamp a total of 4200 A current reversal with good parallel current sharing. These evaluations demonstrate that for high current density pulsing above 10 kV, individual 16 kV PiN diodes yield lower on-state voltage loss (16 V at 2000 A) than series-stacked assemblies of 9 kV SiC PiN diodes or 6 kV Si diodes.