Experimental Assessment of Derating Guidelines Applied to Power Electronics Converters

Power transistors are the most vulnerable components in switching converters, and derating is usually applied toincrease their reliability. In this paper, the effectiveness of derating guidelines is experimentally assessed using apush-pull DC-DC converter as a case study, operating in three different environments. After measuring the electricalvariables and temperature, reliability was predicted following the guidelines in MIL HDBK 217F. The sensitivityanalysis performed indicates that temperature has the largest impact on reliability, followed by environment anddevice quality. The results obtained demonstrate that a derating procedure based solely on DC ratings does notensure an adequate performance. Therefore, additional guidelines are suggested to help increase the overallreliability obtained from a power circuit.