An algorithm to analyze circulating current for multi-phase resonant converter

An algorithm based on new circulated current model is proposed to analyze the circulating current in the multiphase LLC converter. First of all, a virtual-open concept is introduced and LLC phases are decoupled from each other, Thus, A circulating current model can be achieved from fundamental harmonic approximation (FHA). Secondly, the ac voltages on the equivalent resistor of different phases are assumed same magnitude but different angle viewing from the primary-side. From mentioned above, current sharing error can be calculated, two types calculated results are shown under two-phase independent LLC converter and two-phase common inductor LLC converter. Simulation results from different input voltage levels, different resonant component tolerances, and different total load are compared. A two-phase 600W prototype is built to verify the effectiveness of the proposed analysis method.

[1]  Hans-Peter Nee,et al.  Parallel-Operation of Discrete SiC BJTs in a 6-kW/250-kHz DC/DC Boost Converter , 2014, IEEE Transactions on Power Electronics.

[2]  Eun-Soo Kim,et al.  A novel topology of LLC resonant inverter with two resonant tanks for Power Conditioning System , 2010, 2010 Twenty-Fifth Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[3]  Gun-Woo Moon,et al.  Load sharing characteristic of two-phase interleaved LLC resonant converter with parallel and series input structure , 2009, 2009 IEEE Energy Conversion Congress and Exposition.

[4]  Dehong Xu,et al.  LLC resonant converter for 48 V to 0.9 V VRM , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[5]  P. Mattavelli,et al.  Analysis of multi-phase LLC resonant converters , 2009, 2009 Brazilian Power Electronics Conference.

[6]  Milan M. Jovanovic,et al.  Analysis and evaluation of interleaving techniques in forward converters , 1998 .

[7]  Yongsug Suh,et al.  Parallel Connection of Integrated Gate Commutated Thyristors (IGCTs) and Diodes , 2009, IEEE Transactions on Power Electronics.

[8]  Paolo Mattavelli,et al.  Current sharing in three-phase LLC interleaved resonant converter , 2009, 2009 IEEE Energy Conversion Congress and Exposition.

[9]  Gun-Woo Moon,et al.  Analysis and design of two-phase interleaved LLC resonant converter considering load sharing , 2009, 2009 IEEE Energy Conversion Congress and Exposition.

[10]  Yan-Fei Liu,et al.  An interleaving and load sharing method for multiphase LLC converters , 2013, 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[11]  N. Froehleke,et al.  Paralleling of LLC resonant converters using frequency controlled current balancing , 2008, 2008 IEEE Power Electronics Specialists Conference.

[12]  Yang Chen,et al.  A common inductor multi-phase LLC resonant converter , 2015, 2015 IEEE Energy Conversion Congress and Exposition (ECCE).