Study On Improved Turn-on Characteristics Of RSD

Reversely Switched Dynistor is a novel kind of pulse power devices, based on thecontrollable plasma for switching power. As a semiconductor switch, it has characteristics ofsmall size, long lifetime and stable work etc, and could switch a high power as MW~GW,made it a great prospect in the pulsed power technology. Compared with traditionalsemiconductor power switches, RSD has advantages of high power, high di/dt, highefficiency etc, But it still need a deeper research to get a better performance in pulse powersystem, and the thesis focus on the improved device structure and a new switching circuittopology to achieve the goal.The special structure of RSD was analyzed at first, a buffer layer was added to thetraditional structure, and its influence on the device’s switching characteristic is theoreticintroduced. Based on the switching principle of RSD, the demands for normal turn-on wereas follows: the enough plasma stored in the base region of the device during the reversecurrent pre-charge period, and the block time of the magnetic switch should match thepre-charge current width.Compared with traditional structure, the simulation of buffer layer structure modelshowed, under the similar blocking voltage, a obvious improvement happened on the turn-oncharacteristic with a thinner base region, and power dissipation was only the half of thetraditional structure. Aimed at the phenomenon of switching locally under the insufficientpre-charge, investigated the switching mechanism of RSD by the plasma distribution inside,and introduced a device optimized scheme, cathode shunt point ratio is10%and ratio ofanode p+, n+emitter region is1:4, such cell structure had a excellent pre-charge and turn-oncharacteristics, the further refined design of cell structure increased the efficiency of electricconductance modulation. A thinner p-base region is introduced to increase the injectedcompensation with no harm to the blocking ability, a better performance of the uniformturn-on showed under the shorter width of p-base region.Based on the direct pre-charge circuit, a new two-step switching method was introduced,worked with a short width and small amplitude reverse pre-charge current. The simulation indicated a more efficient plasma reservoir got with the shorter width reverse current.Simulation and experiment results both showed that two-step switching increased RSDuniform turn-on characteristic than the direct pre-charge circuit. A proper preliminaryturn-on current passed RSD with the refined circuit parameters, the width and magnitude ofpreliminary current is the design point of two-step switching. By contrast traditionalswitching circuit, the two-step switching lower the demand of the pre-charge circuit, made ita brilliant future in the high voltage and great peak current power field.