Reverse recovery characteristics of pulse power thyristor

Due to high withstand voltage, high flow capacity, stable trigger and small size, the pulse power thyristor has been widely used in pulse power system. However, the thyristor reverse recovery characteristics may cause overvoltage damage in the turn-off process of the thyristor, therefore establishing an effective thyristor model to simulate thyristor overvoltage is needed to decrease thyristor overvoltage damage probability. In this paper, pulse thyristors as the research object, with a maximum flow capacity of 150 kA and a withstand voltage of 5.2 kV, were tested in a pulse forming circuit as the prepositive switch. Then the experimental data were analyzed to find out the relationship between on-state current and related parameters in turn-off process such as reverse recovery charge Qrr, reverse recovery current peak value, and cut-off time. The experimental results show that the reverse recovery time decreases with the increase of the on-state current peak value IF; Qrr increases along with the augment of IF, and when the current drop rate di/dt changes among 50~1000 A/s, di/dt and IF has a good linear relationship, so does reverse current peak value IRM and IF. Therefore, under the condition of large pulse current, di/dt and IF can be used as the same parameter when analyzing and deducing relationship between on-state current parameters and reverse recovery parameters. Applying relations fitted from experimental data to the thyristor modeling, a thyristor model with reverse recovery process was established based on Matlab.