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Abstract

A high-performance, three-phase power factor corrected (PFC) front-end converter with universal input (i.e. 208 V-480 V AC) and 400 V DC output voltage is desirable for applications including Electric Vehicle (EV) battery chargers and data centers. Products that operate with a universal input reduce development and manufacturing costs, in lieu of multiple products for different values of AC input voltages. Three-phase AC inputs reduce the cost of electric circuit cabling and a 400 V DC output is favorable as it reduces the stress on the back-end isolated DC/DC converter stage between the PFC converter and DC output. This dissertation focuses on the best practices and solutions for a universal three-phase AC input PFC converter with 400 V DC output. A detailed review of existing solutions is presented with their advantages and drawbacks noted. The conventional solution of three phase boost follows buck was prototyped and used as a benchmark against the proposed solutions. An adaptive intermediate bus voltage control method is proposed to maximize the efficiency in a three-phase six-switch boost-follows-buck converter. A prototype was developed and experimentally tested to confirm the expected efficiency improvement. In addition, a novel truly universal input (i.e. single-phase or three-phase) PFC with 400 V DC output is also proposed and implemented which can serve the dual purpose of single-phase and three-phase operation. It is shown by analysis and experiments that this solution is not only highly efficient for both single-phase and three-phase operation, but also the components sized for single-phase mode of operation are not oversized for three-phase. Finally, a novel universal input single-stage SEPIC based third harmonic injection three-phase AC/DC PFC is proposed. Control simplicity and single-stage operation are among the main features for this topology.