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Reduction of EMI from a GaN bridge
We have shown that merely limiting dV/dt or dI/dt does not provide the lowest electromagnetic noise (2nd reference below), besides, it increases the energy that is lost in the devices during switching. Instead, high-frequency spectral components should be identified and softened. The figure shows the successful reduction in EMI-generating spectrum of the switch-node voltage spectrum of GaN bridge leg circuit. This is compared against the spectrum achieved when using normal constant-strength drivers. EMI in the band from 300 MHz upwards is reduced without increasing switching loss. We can target the reduction of ringing and cross-talk in problematic bands, which are typically different for each type of converter.
References
J. Wang, J. Dalton, H. C. P. Dymond, D. Liu, B. H. Stark, “Crosstalk Suppression in a 650‑V GaN FET Bridge-leg Converter using 6.7-GHz Active Gate Driver,“ 2017 IEEE Energy Conversion Congress and Exposition (ECCE), Cincinnati, OH, 2017, pp. 1955-1960.
N. F. Oswald, B. H. Stark, D. Holliday, C. Hargis, W. Drury,“Analysis of Shaped Pulse Transitions in Power Electronic Switching Waveforms for Reduced EMI Generation,” IEEE Transactions on Industrial Applications, Volume 47, Issue 5, pp2154-2165, 2011. Won 1st place IEEE IAS Society Prize Journal Paper Award 2012.
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