The invention belongs to the technical field of LLC resonant
converters, and provides an efficiency optimization method of a wide-range LLC
resonant converter. The method comprises the following steps: firstly, obtaining a full-bridge LLC
resonant converter topology and a working area; secondly, establishing a full-time-domain equation of the full-bridge LLC
resonant converter topology in an inductive low-
gain output working area, and setting boundary conditions of the full-time-domain equation; then, on the basis of boundary conditions, switching tube turn-off current is calculated, and the switching tube turn-off current is combined with switching tube
switching frequency to be represented as switching tube turn-off loss characteristic quantity related to the
inductance coefficient, the quality factor and the normalized frequency; then, carrying out characteristic analysis on the turn-off current of the switching tube, and setting constraint conditions; and finally, on the basis of the
set constraint conditions, the optimal values of the
inductance coefficient, the quality factor and the normalized frequency are calculated by combining a
differential evolution algorithm, so that the turn-off loss of the switching tube is minimum. According to the invention, the transmission efficiency in a low-
gain mode and a high-
gain mode can be improved, and the turn-off loss of the switching tube is reduced.