Publication Date


Document Type


First Advisor

Zinger, Donald S.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Electrical Engineering


There is an increasing demand for power converters with small size, light weight, high conversion efficiency and higher power density. Also, in many applications, there is a need for DC-to-DC converters to accept DC input voltage and provide regulated and/or isolated DC output voltage at a desired voltage level including telecommunications equipment, process control systems, electric vehicles (EVs), renewable energy applications and in industry applications. At higher power levels (e.g., greater than 1kW), three-phase resonant converters have significant advantages over single-phase ones due to reduced component stresses, smaller filter size requirements, and higher power density. The LLC converter is deemed the most widely used topology as DC/DC converter in server and telecom applications. To increase the output power and reduce the input and output current ripples, three-phase interleaved LLC converter is becoming more and more popular. It has been demonstrated that three interleaved LLC converter can achieve further efficiency improvement at the 3kW power level. However, the magnetic components for multiphase LLC converter are complex, bulky, and difficult to manufacture in a cost-effective manner. This thesis presents the analysis, simulation, and comparison of three-phase high frequency transformer isolated resonant converters. The two topologies compared are LLC and LLC-LC three phase transformer isolated resonant converter. These two converter topologies are connected with star-star and star-delta transformer winding connections and their efficiency is compared from the simulation results. The soft switching of the different transformer connection and topologies are also verified from the simulation results. The designed converters are simulated and compared using PSpice software to predict the performance of the converter for variations in input voltage and load conditions.


76 pages




Northern Illinois University

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