Compared to the traditional back-to-back twelve-switch converter, a kind of nine-switch converter applied to the distributed energy systems saves 25% of the switch count. It reduces the volume and cost of the converter, but will cause serious problem of high value of common-mode current. This paper analyzes the common-mode voltage circuit of the compact integrated energy systems in detail and also equivalently simplifies the common-mode circuit. Finally, measures to reduce the common-mode current are proposed based on the simplified model. The simulation model and experimental prototype of the nine-switch topology are built to validate the theoretical findings.
