Open AccessModeling and Feedback Control of LLC Resonant Converters at High Switching Frequency
Author(s) -
Hwa-Pyeong Park,
JeeHoon Jung
Publication year - 2016
Publication title -
journal of power electronics/journal of power electronics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.23
H-Index - 33
eISSN - 2093-4718
pISSN - 1598-2092
DOI - 10.6113/jpe.2016.16.3.849
Subject(s) - converters , switching frequency , control (management) , automatic frequency control , feedback control , resonant inverter , resonant converter , control theory (sociology) , engineering , electrical engineering , electronic engineering , computer science , control engineering , voltage , inverter , artificial intelligence
The high-switching-frequency operation of power converters can achieve high power density through size reduction of passive components, such as capacitors, inductors, and transformers. However, a small-output capacitor that has small capacitance and low effective series resistance changes the small-signal model of the converter power stage. Such a capacitor can make the converter unstable by increasing the crossover frequency in the transfer function of the small-signal model. In this paper, the design and implementation of a high-frequency LLC resonant converter are presented to verify the power density enhancement achieved by decreasing the size of passive components. The effect of small output capacitance is analyzed for stability by using a proper small-signal model of the LLC resonant converter. Finally, proper design methods of a feedback compensator are proposed to obtain a sufficient phase margin in the Bode plot of the loop gain of the converter for stable operation at 500 kHz switching frequency. A theoretical approach using MATLAB, a simulation approach using PSIM, and experimental results are presented to show the validity of the proposed analysis and design methods with 100 and 500 kHz prototype convertersclos