In order to feed IT infrastructure out of the national power grids, the electricity needs to be converted by power supplies. The LLC resonant converter analyzed in this thesis potentially enables a distinct reduction of invest and operational costs based on its superior power density and conversion efficiency. The main obstacles for the adoption of the LLC resonant converter within industrial power supplies are the more disadvantageous control of the power transfer compared to its pulse-width controlled counterparts and the more complex design. This thesis outlines the modeling methods for resonant converters and proposes the extension of the time domain analysis model by a lumped resistive circuit element. The dynamic modeling of the LLC resonant converter is performed utilizing the extended describing functions method, thereby discussing the large variations of the plant characteristic in the dependence on the control variable switching frequency. In addition the problematic short-circuit behavior of the LLC resonant converter is analyzed and a circuit extension proposed. Furthermore this thesis states fundamental design trade-offs within the LLC converter design for industrial power supplies and proposes the usage of numerical optimization with respect to an optimal converter design. Based on the substantial loss contributors, the numerical optimization yields a peak efficiency of 99.2%. As a further aspect the synchronized paralleling of two LLC resonant converters is especially beneficial in case of low output voltages and resulting high output currents. The problematic issue of power imbalance between both converters caused by slightly unequal resonant circuit element values is analyzed in this thesis utilizing the time domain modeling approach.