Two simulation approaches for prediction of energy loss in high-voltage power transistors (~600V) operating under ZVS (Zero-Voltage-Switching) and near-ZVS conditions are presented and proved by experiment in this work. The first approach is based on finite-element simulation whereas the second one proposes a new SPICE model. Different from prior works, both models feature COSS hysteresis and related energy loss, thus showing high precision in replicating waveforms and energy loss for real tests in the primary-side of LLC resonant converters. I.

The feasibility of a 1.2kV GaN switch based on two series-connected 650V GaN transistors is demonstrated in this paper. Aside to achieve ultra-fast transitions and reduced switching energy loss, stacking GaN transistors enables compatibility with high-voltage GaN-on-Silicon technologies. A proof-of-concept is provided by electrical characterization and hard-switching operation of a GaN Super-Cascode built with discrete components. Further investigations to enhance stability with auxiliary components are carried out by simulations and co-integrated prototypes are proven at wafer level.

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Switching losses of power transistors usually are the most relevant energy losses in high-frequency power converters. Soft-switching techniques allow a reduction of these losses, but even under soft-switching conditions, these losses can be significant, especially at light load and very high switching frequency. In this paper, hysteresis and energy losses are shown during the charge and discharge of the output capacitance (COSS) of commercial high voltage Superjunction MOSFETs. Moreover, a simple methodology to include information about these two phenomena in datasheets using a commercial system is suggested to manufacturers. Simulation models including COSS hysteresis and a figure of merit considering these intrinsic energy losses are also proposed. Simulation and experimental measurements using an LLC resonant converter have been performed to validate the proposed mechanism and the usefulness of the proposed simulation models.