چكيده به لاتين
One of the important equipment in the 15-KV/16.7-Hz Or 25-KV/50-Hz electric locomotives that occupies large volume of space locomotives is traction transformers. In recent decades, one of the researchers topic has been power electronic transformers (PET) which reduce the volume of traction transformers by increasing their frequencies. PET is new equipment that cause the volume to reduce in the transformer and locomotive which has been replaced with conventional traction transformer by controllable semiconductor switching at high frequencies. In this dissertation, design and simulation of a 2.5kw PET prototype that presented in chapter 6. Introduction and history is expressed in chapter 1. In chapter 2, Structure of PET and Performance in different modes have addressed. Modeling of PET using approximated equations and state space averaging technique by first harmonic or DC component described in chapter 3. In chapter 4, component design of PET such as LLC network, high frequency transformer and inductor, input inductor, DC link capacitor, control circuit and printed circuit board (PCB) and calculation of PET losses presented. In chapter 5, simulation and experimental results with control frequency and without it have described. PLL tests, PET startup, implemented protection, bipolar and unipolar modulation, control circuit response, load variation, reactive power control, regenerative mode, PET performance in no load condition, THD of grid current, nominal voltage results, ZVS mode of DC-DC-LLC converter, LLC grid current in variable loads, current balance between two cells, output capacitor effect on resonance current and PET efficiency without control frequency conditions presented.
