Generalization of Multiple Series-Connected Three-Level Boost Modules

For modern high-power applications such as fast-charging EV stations, data centers, etc., direct connection to the medium voltage (MV) grid is crucial. Many topologies employ AC/DC front-end converters where these are connected in series to enhance their voltage blocking capability, enabling direct MV grid connection. One such converter is the three-level boost (TLB) based power factor correction (PFC) AC/DC converter, which is well-suited for MV applications due to its reduced inductor size, lower voltage stress and higher efficiency. Multiple TLBs are connected in series to meet the required voltage blocking capacity. While existing literature typically covers configurations with three series TLB units, the actual number needed depends on the MV grid level and the blocking voltage of each switch. Additionally, increasing the number of units introduces multiple regions with varying voltage & duty range, possible states and different equations crucial for proper functioning and control operation of the converter which are not discussed in the literature. This paper analyzes a four and five TLB series-connected converter across different region and possible states, and generalizes regions and equations for multiple series connected three-level boost (MSTLB). The study verifies its findings through simulations, demonstrating the scalability and validity of the proposed generalization.