A Current-Sharing Method for Interleaved High-Frequency LLC Converter With Partial Energy Phase Shift Regulation

In this article, a current-sharing method for interleaved high-frequency LLC converter with partial energy phase shift regulation is presented. An auxiliary low-power converter is added in each phase, which is able to achieve natural current sharing and the zero-voltage switching (ZVS) operation for the auxiliary circuit. Meanwhile, the perfect current sharing between phases is achieved by controlling the phase shift angle between the LLC bridge and the auxiliary bridge. Only partial energy is processed by the auxiliary converter; hence, the power losses of the added auxiliary converters are minimized, and the overall high efficiency is maintained. By transforming the current sharing of the resonant converter into phase shift control between the LLC bridge and the auxiliary bridge, the proposed method is simple to implement and easy to extend to multiple phases. The frequency of the auxiliary converter is the same as that of of the main LLC converter, so it is suitable to operate the auxiliary circuit at a high switching frequency to improve the power density. The operating principle, design considerations, and the control schemes are presented, and a 400-kHz two-phase interleaved LLC prototype was built to verify the theoretical analysis.