Performance Study of High-Power Half-Bridge Interleaved LLC Converter

Equalizing and minimizing output current ripple in an interleaved half-bridge LLC converter is explored to raise output power with high efficiency. A strategy to let the half-bridge LLC work in regions 1, ω > ω
_r1
, is implemented to ensure the two interleaved duty cycle close to 50%, which makes the output current width continuous link without lag and also reduce the component size. In addition, the magnetizing currents can also be equal to mitigate the circulation current in the MOSFETs. In transformer design, the secondary winding is wound with equal-length wire to lead the amplitudes of the full-wave output current ripple almost the same, which equalizes the wire thermal to improve the power efficiency. Further, with sharing the output current, an interleaved half-bridge LLC converter can perform a power conversion up to 2.7 kW with the highest efficiency close to 98%. Besides, in-phase and 90°-phase-shift output currents merging to reduce the output ripple currents are respectively explored in experiment. In this paper, a simple modeling of the interleaved LLC is also explored and a design consideration for implementing a 2.7 kW high-power interleaved half-bridge LLC converter is described. All experimentations including the switching statuses and temperature distribution are displayed and discussed in details.