Open-Loop Synchronization Systems for Grid-Tied Power Converters: Literature Overview, Design Considerations, Advantages, and Disadvantages

Primitive grid synchronization systems of power converters were based on a zero-crossing detection (ZCD) algorithm, which is an open-loop synchronization (OLS) system. ZCD algorithms, however, could cause some stability problems for power converters. Therefore, they were gradually replaced by closed-loop synchronization systems. Recently, in parallel with developing closed-loop synchronization systems, designing efficient OLS systems has received much attention. This article aims to provide an overview of recent developments in designing OLS systems, analyze the systems’ advantages/disadvantages, and formulate their design procedure into some general yet simple steps.