A new type of semiconductor switching device appears to have great potential for power system applications. It is called the photoconductive circuit element or PCE. It can be switched rapidly, will conduct large currents and hold off very high voltages. It is also a bilateral device, and the power rating of a single unit can be easily scaled to meet the application. The main objective of the proposed research is to investigate the feasibility of this device for circuit interruption in ac power systems. The project will conduct research along three basic fronts: (1) semiconductor design concepts, (2) device fabrication and testing, and (3) system simulation studies. In the first area, basic research will be conducted to develop more accurate transient and steady-state photoconductive device models. A finite difference approach will be used to develop a precise reference model for the device, from which simpler reduced models will be formulated as equivalent circuits. These will be useful in future system simulation studies for improved evaluation of the proposed power applications. In the fabrication area, low-voltage, scaled-down prototype devices will be fabricated and tested for verification of theoretical design concepts, as well as for validation of transient and steady-state device models. In addition, these devices will be used in scaled-down (but accurate) replicas of power circuit applications, for direct experimental verification of full-scale simulation results. The equipment requested in this proposal represents a key ingredient for the necessary experimental testing of this new power switching concept.
