Study on synchronization methods in switchable fiber ring net for distributed control

Distributed digital control structure is the developing trend of system integration with special power electronics application that features high system complexity and high power stage. Fiber ring net has been used to realize the system standardization and modularization in power electronics systems and a new switchable fiber ring net structure has been proposed to decrease the communication time in one switching cycle. However, the time delay in the fiber ring network influences the performance of the distributed digital control. This paper introduces three synchronization methods in switchable fiber ring net to improve the synchronization accuracy between the slave nodes and proposes a new dual fiber ring net architecture for distributed control of large capacity power electronics systems. The three synchronization methods are command synchronization, series observer synchronization and auxiliary fiber ring net synchronization. Complexity and synchronization accuracy are compared between the three methods. Devices are made to test the performance of the switchable fiber ring net and the three synchronization methods. Experiment results verify the correctness of the analysis in this paper.