Hybrid Modulator Upgrade

72073S03-I Solid state modulators are achieving increased acceptance in many high voltage applications and systems, but size and cost reductions are required. A significant element of the size and cost of these systems is the external fault protection circuitry required to protect the solid state components from external fault conditions. This project will develop and demonstrate two complementary approaches to removing the external fault-current-limiting elements in a solid state modulator: (1) speeding the turn-off time of the switch, and increasing its fault current rating; and (2) adding active, fault-current-limiting circuits. Phase I will design and test active fault-current-limiting gate drive circuits, which will eliminate the need for external current limiting circuits. High-voltage, over-drive pulses will be designed and incorporated in the gate drive circuits to speed switch turn-off. Finally, modifications of the solid state switch modules themselves will be designed to extend the peak specification for turn-off current by 50%. Phase II will complete the development of the active fault-current-limiting circuitry, and build modified components for a hybrid modulator that had been previously developed. Then, the selected circuitry will be implemented on the hybrid modulator, the fault-current-limiting inductors will be removed, and the efficiency improvements will be demonstrated. Commercial Applications and Other Benefits as described by awardee: This significant advance in the design of solid state modulators should have applicability to each of the modulator topologies for the Next Linear Collider, and across a number of commercial modulator designs.