Optimization of adiabatic inverter transformers

A major weight component in switching type power inverters is the power transformer. The design method presented in provides for a reduction in the transformer weight, for intermittent duty units, which is at least an order of magnitude lighter than conventional transformer designs. In the special applications of significance to the Air Force, (i.e., power (1Os to 1000s of kW), weight sensitive, limited time missions (5 to 120 s)), the weight of the power conditioning inverter transformer all but disappears. The transformer weight is minimized by optimising the geometric configuration and in addition by designing the transformer for adiabatic operation and a maximum temperature rise over the mission time consistent with reliable operation. The burst times considered are up to about 75 seconds. The reliable maximum operating temperature is based on using high temperature materials and assuming that the number of operational life cycles for the application is an order of a few hundred. This suggests a maximum temperature rise of about 200/spl deg/C. Thermal end of life is determined by insulation failure. The failure for class C (or H) materials is based on 2500 hours of continuous operation at 180/spl deg/C. The estimated life at 250/spl deg/C is about 20 hours of continuous operation. Based on these operating parameters and the known transformer core material characteristics it is shown that transformer specific power ratings of the order of l MW/kg (at 5 to 10 second bursts) are feasible at nominal voltage ratings up to 5 kV. Specific powers are shown and have been verified.