Comparison of GaN HEMT Power Loss Calculation Methods for Dual Active Bridge Converter

Converters based on dual active bridge (DAB) topology are becoming more popular with its high-power density and possibility of bi-directional power flow. Popular applications include renewable energy storage and conversion and electric vehicle charging, but it could also be used for electric transport of lower power rating, like electric scooters and bicycles. The advances in wide band-gap (WBG) semiconductor technology, such as gallium nitride (GaN) high-electron mobility transistors (HEMTs), have prompted the use of these transistors which have lower conduction losses and work with higher switching frequencies. Calculations for Silicon MOSFET switching losses are well established, but as GaN HEMT have smaller parasitic capacitances, the latest transistor switching transients do not fully match with the existing model’s Miller effect. Switching loss calculation has been proposed that takes into consideration this difference. In this paper the regular MOSFET switching loss calculation is compared with the updated GaN HEMT switching loss results. A 300W GaN based DAB prototype was built to compare both of the calculation results with experimental measurements.