Loading web-font TeX/Main/Regular
COSS Losses in 600 V GaN Power Semiconductors in Soft-Switched, High- and Very-High-Frequency Power Converters | IEEE Journals & Magazine | IEEE Xplore

COSS Losses in 600 V GaN Power Semiconductors in Soft-Switched, High- and Very-High-Frequency Power Converters


Abstract:

We report losses from charging and discharging the parasitic output capacitor, {\rm C}_{\rm OSS}, in Gallium Nitride (GaN) power devices with voltage ratings over 600 ...Show More

Abstract:

We report losses from charging and discharging the parasitic output capacitor, {\rm C}_{\rm OSS}, in Gallium Nitride (GaN) power devices with voltage ratings over 600 {\rm V}_{\rm DS} . These losses are of particular importance in soft-switched circuits used at MHz switching frequencies, where the output capacitance of the device is charged and discharged once per switching cycle during the device's off-time. This process is assumed lossless. We measure {\rm C}_{\rm OSS} losses from 5–35 MHz sine, square, and Class- \Phi _{2} waveshapes in enhancement-mode and cascode devices, and find that losses are present in all tested devices, equal or greater than conduction losses at MHz frequencies, and exponentially increasing with \mathbf{dV/dt}. The cascode device outperforms the e-mode devices under 300 V, but the e-mode devices are preferred above this operating voltage. Furthermore, we show that, within a device family, losses scale linearly with output energy storage. Packaging appears to have only a minor effect on these losses. Finally, we demonstrate 10 MHz, 200 W dc–dc converters with varying device configurations, showing that, even with constant circulating currents, moving to larger devices with lower {\rm R}_{\rm DS,ON} actually degrades efficiency in certain applications due to {\rm C}_{\rm OSS} losses. In the high-voltage, high-frequency range, these reported losses must be optimized simultaneously with conduction losses on a per-application basis.
Published in: IEEE Transactions on Power Electronics ( Volume: 33, Issue: 12, December 2018)
Page(s): 10748 - 10763
Date of Publication: 31 January 2018

ISSN Information:

Funding Agency:


References

References is not available for this document.