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New techniques for measuring and analyzing losses in GaN power converters are presented. A 2.4kW synchronous boost converter, switching 300V at IMHz with normally-off, AIN-base gate, AIGaN/GaN HFETs [I], serves as a vehicle to substantiate the results. An infrared camera is utilized to accurately measure temperatures of the upper and lower switches, as a fu nction of switched current. These temperature measurements are correlated to loss in the respective switches, utilizing temperature data obtained via DC loss measurements. The higher temperature observed in the lower switch results fr om the switching loss in that switch, and is clearly evident in the thermal images. Analysis of the temperature dependence exposes the loss due to dynamic on-resistance and the switching loss. The extracted parameters accurately model both the efficiency and junction temperatures versus switching current.

The NIF Power Conditioning System (PCS) resides in four Capacitor Bays, supplying energy to the Master and Power Amplifiers which reside in the two adjacent laser bays. Each capacitor bay will initially house 48 individual power conditioning modules, shown in Figure 2, with space reserved for expansion to 54 modules. The National Ignition Facility (NIF) Power Conditioning System (PCS) is a modular capacitive energy storage system that will be capable of storing nearly 400 MJ of electrical energy and delivering that energy to the nearly 8000 flashlamps in the NIF laser. The first sixteen modules of the power conditioning system have been built, tested and installed. Activation of the first nine power conditioning modules has been completed and commissioning of the first "bundle" of laser beamlines has begun. This paper will provide an overview of the power conditioning system design and describe the status and results of initial testing and activation of the first "bundle" of power conditioning modules.