脉冲功率晶闸管反向恢复特性

为建立有效的晶闸管模型来仿真晶闸管关断时过电压，减小晶闸管过压损坏的概率，以最大通流150 kA、耐压5.2 kV的脉冲晶闸管为研究对象，将其前置于脉冲形成单元回路中作为大功率开关使用，记录放电过程中晶闸管两端电压及电流。实验数据表明：恢复过程中的电流下降率、反向恢复电荷、反向恢复电流峰值随通态电流峰值的增大而增大，晶闸管关断时间随通态电流峰值的增大而减小。此外，在关断过程中，当电流下降率在-50~1000 A/s时，电流下降率与电流峰值为线性关系。因此，在大脉冲电流条件下，推导反向恢复过程参数与通态电流参数的关系时电流下降率可用与电流峰值的线性关系代替。基于Matlab仿真平台，建立了具有反向恢复过程的脉冲晶闸管模型。该模型仿真得到的晶闸管反向恢复电流峰值与实测结果较为吻合，反向恢复电压尚待进一步修正。

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.