LCLC resonant converter for hold up mode operation

In computer and telecommunication power supplies, the front end DC-DC stage is required to operate with a wide input voltage range to provide hold up time when AC voltage fails. Conventional LLC converter serving as the DC-DC stage is not suitable for this task, as the normal operation efficiency at 400Vin will be penalized once the converter is designed to achieve high peak gain, i.e. the wide input voltage range. This paper examines the operation of the LCLC converter and proposes a design methodology of LCLC converter to increase the peak gain without sacrificing the efficiency at normal input voltage condition. In normal operation, LCLC converter behaves like an LLC converter with large magnetizing inductor Lm, hence the magnetizing inductor current is reduced. During the hold-up condition, by reducing the switching frequency, the equivalent magnetizing inductive reactance of the LCLC converter will reduce more than that of the LLC converter, thus the converter enjoys higher peak gain. To verify the effectiveness of the LCLC converter for hold up operation, analysis will be presented, a design method based on capacitor voltage stress will be introduced, and experimental results from a 250V-400V input and 12V/500W prototype will be demonstrated.

[1]  F. Lee,et al.  LLC resonant converter for front end DC/DC conversion , 2002, APEC. Seventeenth Annual IEEE Applied Power Electronics Conference and Exposition (Cat. No.02CH37335).

[2]  Gun-Woo Moon,et al.  A Half-Bridge LLC Resonant Converter Adopting Boost PWM Control Scheme for Hold-Up State Operation , 2014, IEEE Transactions on Power Electronics.

[3]  Lipei Huang,et al.  A combined front end DC/DC converter , 2003, Eighteenth Annual IEEE Applied Power Electronics Conference and Exposition, 2003. APEC '03..

[4]  Robert L. Steigerwald.  A comparison of half-bridge resonant converter topologies , 1987 .

[5]  C. Adragna,et al.  Design-oriented steady-state analysis of LLC resonant converters based on FHA , 2006, International Symposium on Power Electronics, Electrical Drives, Automation and Motion, 2006. SPEEDAM 2006..

[6]  Moon-Young Kim,et al.  LLC series resonant converter with auxiliary hold-up time compensation circuit , 2011, 8th International Conference on Power Electronics - ECCE Asia.

[7]  Yan-Fei Liu,et al.  Cycle-by-cycle average input current sensing method for LLC resonant topologies , 2013, 2013 IEEE Energy Conversion Congress and Exposition.

[8]  Gun-Woo Moon,et al.  LLC series resonant converter with auxiliary circuit for hold-up time , 2009, INTELEC 2009 - 31st International Telecommunications Energy Conference.

[9]  G. Moon,et al.  A New LLC Series Resonant Converter with a Narrow Switching Frequency Variation and Reduced Conduction Losses , 2014, IEEE Transactions on Power Electronics.

[10]  Peng Xu,et al.  Range winding for wide input range front end DC/DC converter , 2001, APEC 2001. Sixteenth Annual IEEE Applied Power Electronics Conference and Exposition (Cat. No.01CH37181).

[11]  Yan Xing,et al.  A Secondary-Side Phase-Shift-Controlled LLC Resonant Converter With Reduced Conduction Loss at Normal Operation for Hold-Up Time Compensation Application , 2015, IEEE Transactions on Power Electronics.