The series resonant DC/DC converter with an isolation transformer and bridge mode inverter input junction, at its operation in the Buck case, is investigated, at that input DC supply circuit comprises the qZ (quasi-Z) link as impedance source. Operation at such Buck case can be provided under different inverter bridge control methods. Recommended by the literature sources, is the method of control with rising of switching frequency above the resonant one. Two compromise methods here are proposed too – with phase shift of the bridge legs switching, and the asymmetric control method, when switching pattern of the bridge’s switches is asymmetrical in time. Simplified descriptions of processes in the system for before mentioned control principles are presented, as well expressions for approximate calculation of the main parameters of the system at the methods are derived too. Influence of q-Z link properties on restrictions of resonant processes is described. Computer simulations of the operation cases, approving sufficient correctness of the simplifications accepted at analyses, are provided. Comparison of results regarding to the applied control methods, as well some recommendations about application of the systems, is done.