两步式放电改善反向开关晶体管开通特性研究

针对大功率半导体开关反向开关晶体管(RSD)由于预充不足造成的非均匀开通缺陷, 在直接预充放电工作电路的基础上, 设计了一种两步式放电工作电路. 根据RSD结构特点理论分析了正常开通所需条件, 并对器件元胞结构进行建模分析, 模型仿真结果表明RSD在窄脉宽预充电流作用下具有更佳的开通性能, 降低了预充阶段基区载流子复合. 两步式放电实验发现第一步放电电流幅值、脉宽对于两步式放电电路的正常工作起决定作用, 而反向预充电流主要作用于RSD第一步放电的正常开通, 降低了预充电路设计难度. 仿真及实验结果均表明两步式放电电路较直接式预充放电电路提高了RSD的均匀开通性能, 这是由于两步式放电显著提高了基区等离子体积累.

Two-step switching method improved turn-on characteristic in reversely switching dynistor

Due to short of pre-charge, a high power semiconductor switch reversely switching dynistor (RSD) suffers from switching-on locally. Based on the direct pre-charge circuit, a new two-step switching method is introduced. The conditions for the normal turn-on of RSD are analyzed and the model of RSD in a cell structure is built. The model simulation shows that the RSD has better performances: shorter width pre-charge current, and reduced recombination of plasma during the pre-charge. Two-step switching experiment indicates that a proper preliminary turn-on current is important for uniformly switching-on the RSD, and the reverse pre-charge current works mainly for switching preliminary forward current. Simulation and experimental results both show that two-step switching increases RSD uniform turn-on characteristic compared with the direct pre-charge circuit, because the stored charges inside are increased obviously by two-step switching.