Overvoltage Absorption of Sparse Modular Multilevel Converter

A topology is presented that is designed to address overvoltage occurrences when the Sparse Modular Multilevel Converter (SMMC) changes voltage polarity. The proposed topology mitigates overvoltage induced by abrupt changes in bridge arm inductance current during voltage commutation. This is achieved by incorporating dual RCD buffer circuits connected in parallel at both ends of the SMMC bridge arm inductance. Additionally, design formulas for the capacitance and resistance in the dual RCD buffer circuits are derived based on the voltage commutation process and operating conditions of the SMMC. The effectiveness of the proposed topology and the design formulas for RCD parameters were validated through simulation.