Advantages of GaN in a high-voltage resonant LLC converter

LLC Resonant converters have been popular in recent years by providing highly-efficient, compact isolated power conversion for numerous applications. 48V to 12V and 400V to 12V step-down isolated converters are often required in server, telecom and automotive applications. While the switching losses in LLC converters are eliminated due to zero-voltage switching, the primary-side switch output capacitance limits switching frequency and thus places a lower-bound on the converter size. This switch-node capacitance can be significantly reduced by the use of high-voltage Gallium Nitride (GaN) power transistors. This paper demonstrates a 500W, 380V to 12V LLC converter using GaN transistors which achieves 97.85% efficiency with a 308 W/in3 power density.

[1]  Fred C. Lee,et al.  Evaluation and application of 600V GaN HEMT in cascode structure , 2013, 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[2]  F. C. Lee,et al.  Matrix transformer for LLC resonant converters , 2013, 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[3]  R. Dean,et al.  Evaluation and comparison of silicon and gallium nitride power transistors in LLC resonant converter , 2012, 2012 IEEE Energy Conversion Congress and Exposition (ECCE).

[4]  H. J. Chae,et al.  3.3kW on board charger for electric vehicle , 2011, 8th International Conference on Power Electronics - ECCE Asia.

[5]  F.C. Lee,et al.  A family of high power density unregulated bus converters , 2005, IEEE Transactions on Power Electronics.

[6]  F.C. Lee,et al.  A family of high power density bus converters , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[7]  Charles R. Sullivan,et al.  AC resistance of planar power inductors and the quasidistributed gap technique , 2001 .