| Abstract |
Large scale solar PV plants are typically connected into medium voltage AC grids using line frequency transformers, which are bulky. In application where size and/or weight are important an attractive alternative is the use of multilevel inverter configurations such as cascaded H-bridge multilevel inverters, where power converters play a vital role in the system architecture. This paper presents the operation, design, optimization and some simulation results for a fixed frequency full-bridge three-level LCL-type high frequency (HF) transformer isolated DC-DC resonant converter for large scale solar PV plants applications. Operation of the converter is illustrated for different operating intervals, including key waveforms and equivalent circuits. A design procedure using approximate analysis for 10 kW, 750 V input voltage, 750 V output voltage and 100 kHz switching frequency is presented. A novel optimization problem to determine the optimal converter design is introduced. The converter is controlled using phase shift technique. Results show that all MOSFETs achieved ZVS for a range of operating points from full-load to light-load. |
