A non-intrusive method for measuring switching losses of GaN power transistors

In modern power electronics, the design of power converters relies on accurate modeling of losses of all components. Losses in the switches are usually the most important point to be considered in a converter design; however, switching losses are not always provided in datasheets. Typical methods for measuring switching losses, such as the double-pulse method, need the insertion of current and voltage probes across the device. These probes add parasitic elements into the power loop, which modifies the switching behavior, especially when modern semiconductor devices, such as Gallium Nitride (GaN) transistors, are considered. Thus, with the purpose of precisely measuring switching losses, an opposition method test bench has been built to characterize, under real working conditions, one GaN power transistor. The measurement method employed can accurately estimate turn-on and turn-off losses, separately. It does not add parasitic elements to the circuit, which ensures operation at the same conditions of the real converter. Results obtained from this method show the switching characteristics of a specific GaN device and measurements include the power dissipation in a reverse conduction mode. These results help to show the best operation points of the device to maximize the efficiency of a given application.