Analysis and Operation of Primary Side Modulated Single Stage Isolated HF Link DC-AC Converter

This paper presents an isolated, high-frequency (HF)-link, single-stage, primary-side phase modulated DC-AC converter, which can be used as an interface to integrate the renewable energy sources such as, photovoltaic, fuel-cell based generation to the grid. This converter consists of a phase modulated full bridge converter, followed by a transformer and a cycloconverter. A primary side modulation strategy is used to operate the DC-AC converter. Although this topology has certain advantages which are useful for integrating the renewable sources to the grid such as, single stage conversion from DC to AC making the efficiency high and high frequency isolation making the power conversion stage compact, it has certain issues as well which are to be taken into account for proper design. A detailed analysis of the operation of the converter is required to address those issues which are due to the effect of the parasitics on the converter performance. In this paper, a detailed analysis of the operation of the converter is presented taking the effect of the system nonidealities into consideration. An expression for the effect of duty ratio loss on the fundamental component of the voltage appearing at the load terminal and the power delivered to the load is derived which would aid in the design of the DC-AC converter. Simulation results are presented to verify the analysis.