Optimal Busbar Design for the Press-Packed IGBT-Based Modular Multilevel Converter Submodule Considering Both Normal and Fault Ride-Through Conditions

Abstract

The performance of the power converter bus bar is not only determined by its normal operational design, but also related to its fault ride-through ability consideration. Conventional busbar design only takes the normal operational performance into account. This article proposes an optimal busbar design method for the modular multilevel converter (MMC) submodule, which takes both the normal and fault ride-through performance into account. The normal operational design is to realize low stray inductance and balanced inductance distribution between parallel capacitor branches. The basic structural design guideline for the MMC submodule is presented. Taking both the stray inductance and manufacturing cost into account, the optimal layout of the busbar is proposed. To balance the capacitor branch currents, the mathematical model of the busbar stray inductance is built. The influence of different busbar structures on the stray inductance is analyzed. The analysis is verified by simulation results. To improve the fault ride-through capability, special consideration is taken into account to reduce the thermal and mechanical stress at the weakest point. Simulation and experimental results verify the efficacy of the proposed approaches.