A fixed frequency ZVS integrated boost dual three-phase bridge dc-dc LCL-type series resonant converter

A new fixed-frequency controlled 3-phase dc-dc LCL-type series resonant converter with integrated boost function is proposed for medium to large power applications with wide input voltage variation that is typical of alternate energy sources. The converter includes dual three-phase LCL-type resonant bridge inverter modules connected in parallel, thus significantly reducing the component stresses when subjected to medium to large power applications. The fixed-frequency control of the output power is achieved by phase shifting the gating signals of one module with respect to the other while the rectified voltage at the secondary windings of a 3-phase high-frequency transformer connected between the two modules is added to the input voltage to boost the supply voltage to the modules. The zero-voltage-switching of all the switches is accomplished by designing the converter to operate in the lagging pf mode for wide variations in the input voltage and the load. Detailed modeling of the 3-phase boost section is done and the steady-state analysis of the proposed converter for 3-phase LCL-type dc-dc converter modules using complex ac circuit analysis method is presented. For illustration purpose, an example dc-dc converter of 600 W is designed, and its performance is verified using PSIM simulations. An experimental model of the converter is built in the laboratory to verify its performance for wide variations input voltage and load changes.