An enhanced level‐increased nearest level modulation for modular multilevel converter

Summary An enhanced level‐increased nearest level modulation (eNLM) method is proposed to improve the performance of modular multilevel converter (MMC) with relatively small number of submodules. The eNLM method can almost double the level number of ac output voltage, compared with conventional NLM. Consequently, the ac output voltage quality of the MMC using eNLM is significantly enhanced. The proposed method inherits the advantages of the conventional NLM such as simple implication and low switching loss and avoids the disadvantages of the existing improved NLM method such as increasing in submodule capacitor voltage ripple amplitude and voltage offset, arm inductor voltage peak, complexity in topology, etc. PSCAD/EMTDC simulation results confirmed the effectiveness of the proposed method.