Abstract: In the process of optimization, the $Q$ factor of the
converter, the $h$ ratio of magnetizing inductance to resonant
inductance and the maximum flux $B_{\rm max}$ were chosen as the
optimal parameters, the details on the power loss of the converter
was presented, the boundary conditions was deduced and the process
of getting optimum solution was proposed. Finally, a
three-hundred-watt prototype was build; the theoretical and
experimental comparison result verified the feasibility and accuracy
of the design method.

Key words: LLC resonant converter, complex method, optimum design