Soft switching of GaN Devices: Modeling based approach

Soft-switching topologies are very popular for a wide range of applications including EV, PV, and power supplies. Measuring switching losses in soft-switching is difficult as the losses are typically very low. We use SPICE models to gain insight into the soft-switching behavior of GaN devices. First, we demonstrate an advanced SPICE model for D-mode normally-off GaN device by modeling the Si MOSFET and GaN HEMT separately. This model matches the measured waveforms and losses in a half-bridge circuit very well. We then use this model to study soft-switching losses by monitoring the internal channel currents. We show how our SuperGaN technology is designed to have low soft-switching losses. Gate resistor optimization is also investigated to further reduce soft-switching losses. The fundamental advantage of GaN is the $3 x$ smaller ZVS deadtime relative to Si super-junction devices which is critical to high-frequency switching and compact converter systems.