Control strategy of achieving input voltage sharing and output voltage sharing for input-series-output-series inverters system

Abstract

This paper explores a new configuration for modular inverters system, namely, input-series output-series (ISOS) connected inverters system, which is very suitable for high input voltage and high output voltage applications. The control objective of such system is to achieve input voltage sharing (IVS) and output voltage sharing (OVS) among the constituent modules. This paper first reveals the relationship between IVS and OVS and points out that IVS and OVS can be simultaneously achieved only by the application of a compound strategy, which involves controlling IVS as well as controlling the magnitudes or phases of the modules' output voltages. Then, a practical implementation of the compound strategy, which combines a method of IVS with synchronization of the output phase angles, is proposed. The decoupling and design of the two control loops are discussed. Finally, experimental results are presented to verify the theoretical analysis.