A Calorimetric and Electrical Method for Measuring Loss Energies of Half-Bridges

For the optimal design of power electronic systems the exact knowledge about the different loss mechanisms of the used semiconductor devices is essential. However, conventional measurement methods based on electrical parameters are facing their limits, as switching speed of modern power devices is steadily increasing enabled by the use of wide bandgap semiconductor materials. For this reason, calorimetric measurement techniques are becoming more and more popular. However, due to the nature of their principle, calorimetric measurement methodologies can usually only determine the total power losses of the device under test. To overcome this disadvantage a methology which combines different calorimetric and electrical measurements to separately determine the switching and conduction energies in a half-bridge with an ohmic-inductive load while maintaining the accuracy of calorimetric measurement methods is developed. In addition, the presented methodology identifies the switching energies of the two different switching transitions within one switching period, depending on the load current as well as the dead time, considering thermal influences. A hardware setup for the presented methology, is realized. Using this test setup, the loss energies of a half-bridge based on silicon carbide MOSFETs are investigated. The resulting measurements are presented and verified by measurements with a power analyzer.