Si-based Structure Optimization And Si C-based Model Study For Reversely Switched Dynistor RSD

The development of modern pulsed power technology increasingly requires higher operating frequency to meet their application in the defense security, industrial fields,biomedical engineering and environmental protection. As the key technology of the pulsed power system, switching device is more focused on the device characteristics of low-loss, high power, high repetition rate and long service life. Compared to other power devices, Reversely Switched Dynistor( RSD) which is based on the principle of controlled plasma layers conduction can meet the requirement of the pulsed power technology on power switches well, for its good voltage-sharing performance, high current conduction capability and high di/dt capability.Based on the expression of RSD turn-on voltage which is deduced from bipolar plasma drift model, RSD has a high peak of turn-on voltage, and it is bad for pulse power system. This paper studies how to reduce the opening loss of RSD devices from two aspects: Si RSD device's structural optimization and using the new materials(4H-Si C)devices.This paper has studied the relationship between the turn-on voltage and the blocking voltage of the Si RSD device, and compares the turn-on waveform between the two Si RSD devices of 0.8k V and 2.5k V blocking voltage, the experimental waveform display that the former has a higher turn-on voltage peak than the latter at the same voltage discharge. Meanwhile, the buffer layer introduced to RSD can optimizes the structure parameters and then improves the switching characteristics. This paper uses orthogonal design method to assess the turn-on characteristic of the buffer layer structure RSD with different structure parameters. Comparing the RSD with 2.5k V blocking voltage,experiment's results show that the energy consumption of the RSD with buffer layer structure decreases 18.96% than traditional structures RSD at the same conditions.On the basis of the optimization of new RSD structure, this thesis tries to optimizethe RSD characteristics from the new materials. This paper first proposed to manufacture RSD by the third generation wide bandgap semiconductor materials(Si C) instead of Si materials, and built the numerical model of RSD to do some specific simulation. Using typical 4H-Si C material parameters, considering typical physical effects at the heavy injection conditions and combined with the circuit model, the turn-on process of Si C RSD is simulated. Simulation results show that the Si C RSD has a excellent on-state characteristics than Si RSD at the same high blocking voltage.